A review of the application of propensity score methods yielded increasing use, advantages in specific settings, but not substantially different estimates compared with conventional multivariable methods

Target Trial Emulation Using Cohort Studies: Estimating the Effect of Antihypertensive Medication Initiation on Incident Dementia

BACKGROUND

Observational studies link high midlife systolic blood pressure to increased dementia risk. However, the synthesis of evidence from randomized controlled trials has not definitively demonstrated that antihypertensive medication use reduces dementia risk. Here, we emulate target trials of antihypertensive medication initiation on incident dementia using three cohort studies, with attention to potential violations of necessary assumptions.

METHODS

We emulated trials of antihypertensive medication initiation on incident dementia using data from the Atherosclerosis Risk in Communities study, Cardiovascular Health Study, and Health and Retirement Study. We used data-driven methods to restrict participants to initiators and noninitiators with overlap in propensity scores and positive control outcomes to look for violations of positivity and exchangeability assumptions.

RESULTS

Analyses were limited by the small number of cohort participants who met eligibility criteria. Associations between antihypertensive medication initiation and incident dementia were inconsistent and imprecise (Atherosclerosis Risk in Communities: HR = 0.30 [0.05, 1.93]; Cardiovascular Health Study: HR = 0.66 [0.27, 1.64]; Health and Retirement Study: HR = 1.09 [0.75, 1.59]). More stringent propensity score restrictions had little effect on findings. Sensitivity analyses using a positive control outcome unexpectedly suggested antihypertensive medication initiation increased the risk of coronary heart disease in all three samples.

CONCLUSIONS

Positive control outcome analyses suggested substantial residual confounding in effect estimates from our target trials, precluding conclusions about the impact of antihypertensive medication initiation on dementia risk through target trial emulation. Formalized processes for identifying violations of necessary assumptions will strengthen confidence in target trial emulation and avoid inappropriate confidence in emulated trial results.

Disparities in telehealth utilization between US rural and urban areas during the COVID-19 pandemic

PURPOSE

During the COVID-19 pandemic, telehealth services were expanded across the United States to meet the increased demand and safety requirements of care. This observational study aims to understand rural-urban differences in telehealth utilization during the early part of the COVID-19 pandemic.

METHODS

Individual-level data from the National Health Interview Survey 2020-2021 (age ≥18) were analyzed for this study. The Propensity Score Matching method with multivariable Ordinary Least Square was used to analyze 2 outcome variables-(1) having a medical appointment by video or phone in the past 12 months and (2) having a virtual one for reasons related to the pandemic. Event study models were analyzed to understand the trend of telehealth utilization throughout 6 quarters of the pandemic. Subgroup analysis by health insurance, age, sex, race, citizenship, and disability status was performed to identify underlying disparities between rural and urban residents.

FINDINGS

Analysis reveals that rural respondents (N = 6,984) were 8.7 percentage points (P<.001) less likely than urban respondents (N = 40,207) to have a medical appointment by video or phone. Rural residents were 8.1 percentage points (P<.001) less likely to have had a virtual medical appointment because of reasons related to the COVID-19 pandemic than urban users. The event study showed that rural-urban telehealth utilization disparities persisted throughout the pandemic. Subgroup analysis revealed significant rural-urban disparities in telehealth utilization by demographic characteristics.

CONCLUSIONS

Results demonstrate that rural residents were less likely than urban residents to utilize telehealth services during the COVID-19 pandemic, highlighting concerns about access to care for rural residents.

Long-term Outcomes Following Individualized Elective Primary Tumor CTV Delineation Based on Stepwise Spread Patterns of Nasopharyngeal Carcinoma Treated with Intensity-modulated Radiotherapy

PURPOSE

Our institution has developed an individualized elective primary tumor clinical target volume (CTVp) delineation protocol for nasopharyngeal carcinoma (NPC) based on stepwise tumor spread patterns in intensity-modulated radiotherapy (IMRT) for over ten years. Herein, we report the long-term efficacy and toxicities in NPC patients treated under this protocol.

METHODS AND MATERIALS

A total of 7,262 histologically proven, nonmetastatic NPC patients treated with IMRT following this individualized delineation protocol were retrospectively evaluated. The 5-year rates for local relapse-free survival (LRFS), regional relapse-free survival (RRFS), distant metastasis-free survival (DMFS), progression-free survival (PFS), and overall survival (OS) were estimated. Dose-volume histogram (DVH) parameters for patients with local relapse were compared to those of propensity score-matched (PSM) without local relapse. Dosimetric comparisons of our delineation protocol with the 2018 International Guideline (2018-IG) were conducted on representative early- and advanced-stage NPC cases.

RESULTS

The 5-year LRFS, RRFS, DMFS, PFS and OS were 93.6%, 94.4%, 86.8%, 77.8%, and 86.0%, respectively. 92.3% of local relapses and 86.0% of regional relapses occurred within the 95% isodose lines and were considered GTV in-field failures. No significant differences in DVH parameters were observed between the local relapse group and the propensity score-matched non-relapse group. Compared with the 2018-IG, our contouring protocol resulted in a 58.4% and 48.3% reduction in PTV70, and an 80.8% and 62.8% reduction in PTV60 for early and advanced-stage disease, respectively. Late grade 3 toxicities included ototoxicity (1.8%), xerostomia (0.2%), dysphagia (0.2%), temporal lobe injury (0.2%), and trismus (0.1%).

CONCLUSION

Individualized elective CTVp delineation based on the stepwise spread patterns of nasopharyngeal carcinoma achieved excellent long-term outcomes and reduced the irradiated volumes at equivalent dose levels compared to the 2018-IG.

Survival Analysis of Conversion Surgery in Borderline Resectable and Locally Advanced Unresectable Pancreatic Ductal Adenocarcinoma Addressing Selection and Immortal Time Bias: A Retrospective Single-Center Study

BACKGROUND

The purpose of this study was to provide a detailed evaluation of the oncological advantages of surgery following neoadjuvant chemotherapy (NAC) for patients with borderline resectable (BR) or unresectable (UR) pancreatic ductal adenocarcinoma (PDAC), with a focus on minimizing biases. Recently, NAC has become the standard care for BR or UR locally advanced (UR-LA) PDAC, however, many studies have assessed survival benefits and favorable variables without consideration for biases, particularly immortal time bias.

PATIENTS AND METHODS

This study included patients diagnosed with BR or UR-LA PDAC at Juntendo University Hospital from 2019 to 2022. To mitigate bias, we applied methods such as propensity score matching (PSM), time-dependent covariate Cox proportional hazard regression analysis (TDC), landmark analysis, and multivariable Cox proportional hazards regression model.

RESULTS

The study analyzed 124 patients, dividing them into a surgery group (n = 57) and a chemotherapy-only group (n = 67). After PSM, there were 21 matched pairs. Survival analysis using TDC analysis showed that the surgery group had significantly better overall survival compared with the chemotherapy-only group in both the entire cohort and the matched pairs. Cox regression analysis of the entire cohort also revealed a similar superiority of surgery, while the landmark analysis showed varying results depending on the landmark setting.

CONCLUSIONS

After careful adjustment for selection and immortal time biases, surgery following NAC appears to significantly extend survival in patients with BR or UR PDAC.

Maternal and Neonatal Perinatal Outcomes of Singleton Pregnancies in Advanced-Age Women Undergoing IVF/ICSI-ET Compared with Spontaneous Conception: A Retrospective Propensity Score Matched Cohort Study

Objective

To assess the safety and efficiency of in vitro fertilization/ intracytoplasmic sperm injection and embryo transfer (IVF/ICSI-ET) on maternal and neonatal perinatal outcomes in women (≥40y) with singleton pregnancies.

Methods

This multi-center retrospective cohort study, carried out from January 2018 to June 2023, enrolled 1762 women (≥40y) with singleton pregnancies of at least 28 weeks. Participants were divided into two groups: the IVF/ICSI-ET group (204 cases) and the spontaneous conception (SC) group (1558 cases). After 1:2 propensity score matching (PSM), the two groups were compared for maternal and neonatal outcomes. The SC group (1558 cases) was further divided by age into the <43 years group (1195 cases) and the ≥43 years group (363 cases) for subgroup analysis.

Results

Adverse maternal and neonatal outcomes were comparable between the IVF/ICSI-ET group and the SC group, with a higher cesarean section rate (78% vs 67.5%, P =0.013), an increased maternal ICU admissions rate (5.5% vs 1.3%, P =0.008), and a lower birth defects rate (1.1% vs 4.6%, P =0.037) in the IVF/ICSI-ET group. Subgroup analysis showed that women aged ≥43 years had higher incidences of gestational diabetes, gestational hypertension, cesarean section, and neonatal asphyxia compared to women aged <43 years.

Conclusion

This study indicated IVF/ICSI-ET is relatively safe for women ≥40 years with singleton pregnancies. However, advanced maternal age deteriorated maternal and neonatal outcomes, and IVF/ICSI-ET further heightened the risk of cesarean section and maternal ICU admissions. Therefore, enhanced care and vigilance are crucial for women over 40 undergoing IVF/ICSI-ET.

Impact of discontinuing disease-modifying therapies on health care utilization among midlife patients with multiple sclerosis in the United States

BACKGROUND

Multiple sclerosis (MS) is a lifelong progressive neurological disease treated primarily with disease-modifying therapies (DMTs). Disease activity tends to decline as patients age. Midlife represents a crossroads where the risks of DMT may outweigh the benefits, prompting providers to consider DMT discontinuation to reduce treatment burden. However, real-world evidence on the impact of DMT discontinuation among midlife patients is lacking.

OBJECTIVE

To evaluate the association between DMT discontinuation and health care utilization among midlife patients with MS.

METHODS

Midlife patients with MS who received an injectable or oral DMT between 2001 and 2018 were identified from the MarketScan commercial claims database. DMT discontinuation, defined as a treatment gap exceeding 90 days in days supply, was the independent variable. Patients who discontinued DMTs had their index date set as the last gap day, whereas index dates for those who continued DMTs were matched based on the time distribution of index dates of discontinuers. Inpatient hospitalizations (all-cause, MS-related, and non-MS-related), emergency department (ED) visits (all-cause, MS-related, and non-MS-related), and relapse-related hospitalizations and outpatient visits were independently evaluated during the 365-day follow-up. Patients were observed until the occurrence of an event (depending on the model), deviation from the treatment group, disenrollment, death, end of follow-up, or data unavailability. Stabilized inverse probability of treatment weighting (sIPTW) was employed to balance the 2 groups. The associations between DMT discontinuation and each utilization outcome were estimated using Cox proportional hazard regression models with sIPTW.

RESULTS

Of 149,721 midlife patients with MS, 22.8% discontinued DMTs and 77.2% continued DMTs. Patients who discontinued DMTs had a higher cumulative incidence for all utilization outcomes during the 365-day follow-up than those who continued DMTs. Cox regression showed that DMT discontinuation was associated with a 10.3% and 24.9% higher rate of all-cause and non-MS-related inpatient hospitalizations, respectively, with no significant association found for MS-related hospitalizations. Patients discontinuing DMTs exhibited higher utilization rates for ED visits, with an increase of 21.3% for all-cause, 23.0% for MS-related, and 20.9% for non-MS-related visits compared with those who continued DMTs. We also observed a 15.9% and 52.1% higher rate of relapse-related hospitalizations and outpatient visits associated with DMT discontinuation, respectively.

CONCLUSIONS

This study revealed that DMT discontinuation was associated with higher health care services utilization among midlife patients with MS, especially relapse-related outpatient visits. DMT discontinuation during midlife may be premature, and DMTs may still be necessary to reduce health care utilization.

Nulliparous Individuals with Class III Obesity: Adverse Outcomes with Labor versus Planned Cesarean Delivery

OBJECTIVE

 Individuals with class III obesity (body mass index [BMI] ≥ 40 kg/m2) are at increased risk of cesarean delivery (CD) and peripartum complications. We ascertained compositive neonatal and maternal adverse outcomes among individuals with class III obesity who labored versus had planned CD.

STUDY DESIGN

 This was a retrospective cohort study from 2016 to 2021 using the National Vital Statistics System database. Nulliparous individuals with class III obesity prepregnancy were included if they had singleton, nonanomalous pregnancies and delivered at 37 to 41 weeks of gestation. Individuals were excluded if they had hypertensive disorders or diabetes. The primary outcome was a composite neonatal adverse outcome (CNAO), consisting of Apgar score less than 5 at 5 minutes, assisted ventilation > 6 hours, neonatal seizure, or neonatal death. The secondary outcome was a composite maternal adverse outcome (CMAO) that included admission to the intensive care unit, maternal transfusion, uterine rupture, or unplanned hysterectomy. A sensitivity analysis using a CMAO without transfusion was performed. A multivariable Poisson regression model was performed to calculate adjusted relative risks (aRRs) with 95% confidence intervals (CIs).

RESULTS

 Of 192,298 individuals who met inclusion criteria, 169,676 (88.2%) labored and 22,622 (11.8%) had a planned CD. Compared with neonates delivered by planned CD, the risk of CNAO was significantly lower in those who delivered after labor (aRR: 0.79, 95% CI: 0.71-0.87). There was no significant difference in the risk of CMAO between groups (aRR: 1.11, 95% CI: 0.87-1.41). However, the risk of CMAO without transfusion was lower in individuals who labored (aRR: 0.57, 95% CI: 0.40-0.83).

CONCLUSION

 In nulliparous individuals with class III obesity, the risk of CNAO and of CMAO without transfusion were significantly lower in individuals who labored, versus those who had a planned CD.

KEY POINTS

· Labor in class III obesity: 21% fewer adverse neonatal outcomes.. · Class III obesity: 43% less maternal morbidity with labor.. · Labor in nulliparous individuals with class III obesity is safe..

Association between serum potassium, risk and prognosis of peritonitis in peritoneal dialysis patients - results from the Peritoneal Dialysis Telemedicine-assisted Platform Cohort (PDTAP) Study

BACKGROUND

Hypokalemia has been associated with an increased risk of peritoneal dialysis (PD)-associated peritonitis. However, hypokalemia is commonly associated with malnutrition, inflammation, and severe coexisting comorbidities, which thus are suspected of being potential confounders. This study was aimed at testing whether hypokalemia was independently associated with the occurrence and prognosis of PD-associated peritonitis.

METHODS

A national-level dataset from the Peritoneal Dialysis Telemedicine-assisted Platform Cohort (PDTAP) Study was used to explore the independent association of serum potassium with PD-associated peritonitis. Unmatched and propensity score-adjusted multivariate competing risk models, as well as univariate competing risk models following 1:1 propensity score matching, were conducted to balance potential biases between patients with and without hypokalemia. The association between potassium levels prior to peritonitis and treatment failure due to peritonitis was also investigated.

RESULTS

During a median follow-up of 25.7 months in 7220 PD patients, there was a higher incidence of peritonitis in patients with serum potassium below 4.0 mmol/L compared to those with higher serum levels (677 [0.114/patient-year] vs. 914 [0.096/patient-year], P = 0.001). After adjusting for demographics, laboratory tests, residual renal function, and medication use, baseline potassium levels below 4.0 mmol/L were not linked to an increased risk of peritonitis, with a hazard ratio of 0.983 (95% CI 0.855-1.130, P = 0.810). This result remained consistent in both the propensity score adjusted multivariate competing risk regression (HR = 0.974, 95% CI 0.829-1.145, P = 0.750) and the univariate competing risk regression after 1:1 propensity score matching (Fine-Gray test, P = 0.218). The results were similar when analyzing patients with serum potassium level above or below 3.5 mmol/L. Lastly, hypokalemia before the occurrence of peritonitis was not independently associated with treatment failure.

CONCLUSION

Hypokalemia was not found to be an independent risk factor for PD-associated peritonitis or treatment failure of peritonitis in China.

Effectiveness of early rehabilitation interventions in patients with traumatic brain injury using a large database

BACKGROUND

Rehabilitation is important for patients with moderate-to-severe traumatic brain injury (TBI). However, the timing of early rehabilitation initiation is ambiguous, and its safety and effectiveness are unknown.

OBJECTIVE

To examine the effectiveness and safety of early rehabilitation in patients with moderate-to-severe TBI using propensity score analysis and a large database.

DESIGN

Retrospective cohort study.

SETTING

A large medical database (JMDC database) of tertiary care facilities was used to compare outcomes of early and delayed rehabilitation.

PATIENTS

Patients aged between 20 and 90 years who were diagnosed with TBI were admitted to acute care hospitals. Inclusion criteria were patients undergoing rehabilitation within 7 days of admission with a Glasgow Coma Scale score of 3 to 12 on admission. This study included 3074 patients with moderate-to-severe TBI.

INTERVENTIONS

Patients were classified into an early rehabilitation group (within 2 days of admission) or a delayed rehabilitation group (3 to 7 days postadmission), depending on when rehabilitation started after TBI. Rehabilitation was defined as any type or intensity of intervention provided by a physical, occupational, and/or speech/language therapist. Interventions were not controlled.

MAIN OUTCOME MEASURE(S)

The primary outcome was Barthel Index (BI) efficiency (BI gain/length of stay). Secondary outcomes included BI gain (discharge BI - admission BI), incidence of aspiration pneumonia complications during hospitalization, discharge to home, mortality, and length of stay.

RESULTS

After applying inverse probability weighting with propensity scores, the total was 6152 patients. 3074 (50.0%) patients received early rehabilitation. The early rehabilitation group showed no difference in inpatient mortality (p = .438), improved BI efficiency (β = 0.86, p < .001), and shorter length of stay (β = -5.00, p = .018).

CONCLUSIONS

Early rehabilitation in patients with moderate-to-severe TBI is associated with more efficient functional improvement and reduced hospital stays without an increase in inpatient mortality.

Effect of vaccine hesitancy on female college students' willingness to receive the HPV vaccine in China: a multicenter cross-sectional study

OBJECTIVE

To analyse the influencing factors of vaccine hesitancy on HPV vaccination willingness of female college students in order to promote the promotion of HPV vaccine in female college student population.

METHODS

From September-October 2022, a convenience sampling method was used to conduct a questionnaire survey among freshman female students from four higher vocational colleges in Henan Province, China. The survey comprised a general information questionnaire, as well as inquiries regarding vaccine hesitancy and willingness to receive the human papillomavirus (HPV) vaccine. In PSM analyses, vaccine-hesitant students were matched with non-vaccine-hesitant students at a 1:1 ratio; subsequently, both univariate and multivariatble logistic regression analyses were applied to assess the impact of vaccine hesitancy on female university students' willingness to receive the HPV vaccine.

RESULTS

The results revealed a vaccine hesitancy rate of 44.75% among female university students, with 82.9% expressing willingness to receive the HPV vaccine. The results of the multivariable ordinal logistic regression analysis indicated vaccine hesitancy is a risk factor for HPV vaccination intentions among female university students [OR = 4.38, 95% CI (2.74, 6.99), P < 0.001]. Furthermore, the field of study (P = 0.01) and independently seeking information about the HPV vaccine (P = 0.04) were identified as factors influencing female university students' willingness to receive the HPV vaccine.

CONCLUSIONS

Non-vaccine-hesitant students were more likely to be willing to receive the HPV vaccine than vaccine-hesitant students. Healthcare providers and educators should focus on vaccine attitudes among female college students to reduce vaccine hesitancy and enhance community education on cervical cancer, HPV infection and prevention through multichannel campaigns.

Plasma B-type natriuretic peptide is independently associated with cardiovascular events and mortality in patients with chronic kidney disease

The association between B-type natriuretic peptide (BNP) and cardiovascular (CV) events and mortality has not been well characterized in patients with chronic kidney disease (CKD). We prospectively investigated whether BNP was associated with CV events or mortality beyond cardiac alterations in 1078 patients with CKD. Participants were divided into the following 3 groups according to circulating BNP concentration: < 40 pg/mL, low; 40-100 pg/mL, middle; and > 100 pg/mL, high. Primary outcome was fatal or nonfatal CV events, and alternative outcome was a composite of fatal or nonfatal CV events, or non-CV deaths. During a median follow-up of 2.6 years, CV and composite events occurred in 158 and 248 participants, respectively. Cox analyses after adjustment for covariates, including cardiac parameters, showed that the hazard ratios (HRs) (95% confidence intervals [CIs]) for CV events of middle and high groups were 1.00 (0.63, 1.58) and 1.72 (1.06, 2.79), respectively, compared with low group. Additionally, similar results were obtained for composite events; the HRs (95% CIs) of middle and high groups were 1.10 (0.77, 1.57) and 1.54 (1.04, 2.27), respectively, compared with low group. Thus, in CKD, high BNP concentrations were independently associated with CV events and mortality, independent of cardiac alterations.

Ondansetron and the Risk of Sudden Cardiac Death among Individuals Receiving Maintenance Hemodialysis

Key Points

In hemodialysis, ondansetron initiation versus initiation of lesser QT-prolonging antiemetics associated with higher 10-day sudden cardiac death risk. Analyses considering additional cardiac outcomes had consistent findings.

Background

Individuals receiving hemodialysis have a high incidence of sudden cardiac death and are susceptible to QT interval–prolonging medication–related cardiac complications. Ondansetron, an antiemetic with known QT-prolonging potential, is associated with fatal arrhythmias in the general population when administered intravenously. The cardiac safety of ondansetron in the hemodialysis population is unknown.

Methods

We conducted a new-user, active-comparator, cohort study using United States Renal Data System data (2012–2019) to examine the association between the initiation of oral ondansetron versus antiemetics with lesser QT-prolonging potential (promethazine, metoclopramide, or prochlorperazine) and the 10-day risk of sudden cardiac death among individuals receiving hemodialysis. We used inverse probability of treatment-weighted survival models to estimate adjusted hazard ratios, risk differences, and 95% confidence intervals (CIs). We used an intention-to-treat approach in which non-sudden cardiac death was considered a competing event. We examined additional cardiac outcomes in secondary analyses.

Results

Of 119,254 study patients, 64,978 (55%) initiated ondansetron and 54,276 (45%) initiated a comparator antiemetic. Initiation of ondansetron versus a comparator antiemetic was associated with higher relative and absolute 10-day risks of sudden cardiac death (adjusted hazard ratio, 1.44 [95% CI, 1.08 to 1.93]; adjusted risk difference, 0.06% [95% CI, 0.01% to 0.11%]). The number needed to harm was 1688. Analyses of additional cardiac outcomes yielded similar findings.

Conclusions

Compared with initiation of antiemetics with lesser QT-prolonging potential, initiation of ondansetron was associated with higher short-term cardiac risks among people receiving hemodialysis.

Carbonylation of Runx2 at K176 by 4-Hydroxynonenal Accelerates Vascular Calcification

BACKGROUND

Vascular calcification, which is characterized by calcium deposition in arterial walls and the osteochondrogenic differentiation of vascular smooth muscle cells, is an actively regulated process that involves complex mechanisms. Vascular calcification is associated with increased cardiovascular adverse events. The role of 4-hydroxynonenal (4-HNE), which is the most abundant stable product of lipid peroxidation, in vascular calcification has been poorly investigated.

METHODS

Serum was collected from patients with chronic kidney disease and controls, and the levels of 4-HNE and 8-iso-prostaglandin F2α were measured. Sections of coronary atherosclerotic plaques from donors were immunostained to analyze calcium deposition and 4-HNE. A total of 658 patients with coronary artery disease who received coronary computed tomography angiography were recruited to analyze the relationship between coronary calcification and the rs671 mutation in aldehyde dehydrogenase 2 (ALDH2). ALDH2 knockout (ALDH2-/-) mice, smooth muscle cell-specific ALDH2 knockout mice, ALDH2 transgenic mice, and their controls were used to establish vascular calcification models. Primary mouse aortic smooth muscle cells and human aortic smooth muscle cells were exposed to medium containing β-glycerophosphate and CaCl2 to investigate cell calcification and the underlying molecular mechanisms.

RESULTS

Elevated 4-HNE levels were observed in the serum of patients with chronic kidney disease and model mice and were detected in calcified artery sections by immunostaining. ALDH2 knockout or smooth muscle cell-specific ALDH2 knockout accelerated the development of vascular calcification in model mice, whereas overexpression or activation prevented mouse vascular calcification and the osteochondrogenic differentiation of vascular smooth muscle cells. In patients with coronary artery disease, patients with ALDH2 rs671 gene mutation developed more severe coronary calcification. 4-HNE promoted calcification of both mouse aortic smooth muscle cells and human aortic smooth muscle cells and their osteochondrogenic differentiation in vitro. 4-HNE increased the level of Runx2 (runt-related transcription factor-2), and the effect of 4-HNE on promoting vascular smooth muscle cell calcification was ablated when Runx2 was knocked down. Mutation of Runx2 at lysine 176 reduced its carbonylation and eliminated the 4-HNE-induced upregulation of Runx2.

CONCLUSIONS

Our results suggest that 4-HNE increases Runx2 stabilization by directly carbonylating its K176 site and promotes vascular calcification. ALDH2 might be a potential target for the treatment of vascular calcification.

Can propensity score matching replace randomized controlled trials?

Randomized controlled trials (RCTs) have long been recognized as the gold standard for establishing causal relationships in clinical research. Despite that, various limitations of RCTs prevent its widespread implementation, ranging from the ethicality of withholding potentially-lifesaving treatment from a group to relatively poor external validity due to stringent inclusion criteria, amongst others. However, with the introduction of propensity score matching (PSM) as a retrospective statistical tool, new frontiers in establishing causation in clinical research were opened up. PSM predicts treatment effects using observational data from existing sources such as registries or electronic health records, to create a matched sample of participants who received or did not receive the intervention based on their propensity scores, which takes into account characteristics such as age, gender and comorbidities. Given its retrospective nature and its use of observational data from existing sources, PSM circumvents the aforementioned ethical issues faced by RCTs. Majority of RCTs exclude elderly, pregnant women and young children; thus, evidence of therapy efficacy is rarely proven by robust clinical research for this population. On the other hand, by matching study patient characteristics to that of the population of interest, including the elderly, pregnant women and young children, PSM allows for generalization of results to the wider population and hence greatly increases the external validity. Instead of replacing RCTs with PSM, the synergistic integration of PSM into RCTs stands to provide better research outcomes with both methods complementing each other. For example, in an RCT investigating the impact of mannitol on outcomes among participants of the Intensive Blood Pressure Reduction in Acute Cerebral Hemorrhage Trial, the baseline characteristics of comorbidities and current medications between treatment and control arms were significantly different despite the randomization protocol. Therefore, PSM was incorporated in its analysis to create samples from the treatment and control arms that were matched in terms of these baseline characteristics, thus providing a fairer comparison for the impact of mannitol. This literature review reports the applications, advantages, and considerations of using PSM with RCTs, illustrating its utility in refining randomization, improving external validity, and accounting for non-compliance to protocol. Future research should consider integrating the use of PSM in RCTs to better generalize outcomes to target populations for clinical practice and thereby benefit a wider range of patients, while maintaining the robustness of randomization offered by RCTs.

Gender Identity and Mental Health Symptom Severity Among Adolescents Admitted to an Inpatient Psychiatric Hospital

Transgender youth are at an increased risk of suicide, substance use, experiencing violent assaults, and reporting major depressive episodes and greater psychological distress compared to their cisgender counterparts. This study examined mental health symptom severity in adolescents admitted to an inpatient psychiatric hospital who wished they were of a different gender compared to those who did not. A group of 180 adolescents admitted to an inpatient psychiatric hospital completed assessments to measure mental health symptom severity at admission. Gender diverse (n = 90) and cisgender (n = 90) groups were established. Analyses of variance (ANOVA) were used to examine between group (gender diverse vs. cisgender) difference on depression, anxiety, suicide risk, nighttime sleep quality, and emotion regulation problems. Results revealed significant differences in emotion regulation difficulties at admission, specifically in nonacceptance and awareness. There were no significant differences on measures of depression, anxiety, suicide risk, and nighttime sleep quality at admission. This study is one of the first to measure mental health symptom severity in gender diverse adolescents while admitted to an inpatient psychiatric setting. Adolescents in the gender diverse group had significantly higher level of difficulty with emotion regulation, which may indicate an increased risk of developing psychiatric symptoms such as depression and anxiety. This paper demonstrates the importance of using targeted interventions to address difficulties with emotion regulation in at-risk adolescents.

Characterizing Imbalance in the Tails of the Propensity Score Distribution

Understanding characteristics of patients with propensity scores in the tails of the propensity score (PS) distribution has relevance for inverse-probability-of-treatment-weighted and PS-based estimation in observational studies. Here we outline a method for identifying variables most responsible for extreme propensity scores. The approach is illustrated in 3 scenarios: 1) a plasmode simulation of adult patients in the National Ambulatory Medical Care Survey (2011-2015) and 2) timing of dexamethasone initiation and 3) timing of remdesivir initiation in patients hospitalized for coronavirus disease 2019 from February 2020 through January 2021. PS models were fitted using relevant baseline covariates, and tails of the PS distribution were defined using asymmetric first and 99th percentiles. After fitting of the PS model in each original data set, values of each key covariate were permuted and model-agnostic variable importance measures were examined. Visualization and variable importance techniques were helpful in identifying variables most responsible for extreme propensity scores and may help identify individual characteristics that might make patients inappropriate for inclusion in a study (e.g., off-label use). Subsetting or restricting the study sample based on variables identified using this approach may help investigators avoid the need for trimming or overlap weights in studies.

Risk of cardiovascular disease in patients with multiple sclerosis treated with fingolimod compared to natalizumab: A nationwide cohort study of 2095 patients in Denmark

BACKGROUND

Fingolimod may be associated with risk of developing cardiovascular disease (CVD). Studies including reference groups and long follow-up are scarce.

OBJECTIVES

We hypothesized that patients treated with fingolimod would be at higher risk of developing CVD compared to patients treated with natalizumab.

METHODS

A nationwide 12-year cohort study linking individual-level data from the Danish Multiple Sclerosis Registry with health registries on 2095 adult patients with multiple sclerosis (MS) without any health records of CVD at follow-up start. Exposure to fingolimod and natalizumab was defined by the first treatment of at least 3 months. Cohort entry was from 2011 to 2018. We defined CVD as a composite measure, including hypertension, ischemic heart disease, atrial fibrillation, heart failure, and stroke. We used multivariable adjusted Cox regression.

RESULTS

There were 28.8 and 17.4 CVD events per 1000 person-years in fingolimod and natalizumab groups, respectively. Compared to natalizumab-treated patients, fingolimod-treated patients had a higher risk of CVD (hazard ratio (HR) = 1.57; 95% confidence interval (CI) = 1.18-2.08). Hypertension comprised 200 of 244 CVD events.

CONCLUSION

We found an increased risk of CVD in patients with MS treated with fingolimod. This increased risk was mainly due to hypertension.

Oral chemotherapy versus observation alone in nasopharyngeal carcinoma patients with persistently detected circulating cell-free Epstein-Barr virus DNA during follow-up

AIM

Despite the high risk of tumor recurrence, patients with nasopharyngeal carcinoma (NPC) with persistently (at least twice) detected circulating cell-free Epstein-Barr virus (EBV) DNA levels during follow-up are routinely recommended to keep observation. For these patients, whether administering more aggressive treatment could improve survival outcomes remains unknown.

MATERIALS AND METHODS

We retrospectively included 431 patients with nonmetastatic NPC with persistently detected EBV DNA during follow-up, who do not have clinical or imaging evidence of recurrence. Among these patients, 79 were administered oral chemotherapy, and the remaining 352 underwent observation alone. Baseline characteristics were balanced with propensity score matching (PSM) analysis. The primary endpoint was modified disease-free survival (mDFS), defined as time from detectable EBV DNA result to tumor recurrence or death. The secondary endpoints were disease-free survival (DFS) and overall survival (OS).

RESULTS

One-to-three PSM resulted in 251 eligible patients (oral chemotherapy group, 73; observation group, 178). In the matched cohort, the oral chemotherapy group had higher median mDFS (12.9 months [95 % confidence interval [CI] 9.6-16.3] vs. 6.8 months [95 % CI 5.8-7.8], p = 0.009) and DFS (24.1 months [95 % CI 18.5-29.7] vs. 16.7 months [95 % CI 14.4-19.1], p = 0.035) than the observation group. The median OS was numerically higher in the oral chemotherapy group than in the observation group (57.9 months [95 % CI 42.5-73.3] vs. 50.8 months [95 % CI 39.7-61.9], p = 0.71). A consistent benefit favoring oral chemotherapy was observed for mDFS in all subgroups analyses for male, <45 years, stage III-IVa disease, pretreatment EBV DNA load ≥ 4,000 copies/mL, no induction chemotherapy, or a detectable EBV DNA load ≥ 1,200 copies/mL. After adjusting for other confounders in the multivariate analysis, oral chemotherapy remained a significantly favorable factor for both mDFS (hazard ratio [HR] 0.67, 95 % CI 0.50-0.89; p = 0.006) and DFS (HR 0.68, 95 % CI 0.51-0.91; p = 0.01), but not a significant factor for OS (HR 0.89, 95 % CI 0.62-1.27; p = 0.52).

CONCLUSIONS

In patients with NPC having persistently detected EBV DNA levels but without clinical or imaging evidence of recurrence during follow-up, oral chemotherapy significantly prolongs mDFS and DFS. Employing oral chemotherapy as a more aggressive treatment option, as opposed to mere observation, could potentially benefit these patients, although further prospective validation is necessitated.

A prospective cohort study of preconception COVID-19 vaccination and miscarriage

STUDY QUESTION

To what extent is preconception maternal or paternal coronavirus disease 2019 (COVID-19) vaccination associated with miscarriage incidence?

SUMMARY ANSWER

COVID-19 vaccination in either partner at any time before conception is not associated with an increased rate of miscarriage.

WHAT IS KNOWN ALREADY

Several observational studies have evaluated the safety of COVID-19 vaccination during pregnancy and found no association with miscarriage, though no study prospectively evaluated the risk of early miscarriage (gestational weeks [GW] <8) in relation to COVID-19 vaccination. Moreover, no study has evaluated the role of preconception vaccination in both male and female partners.

STUDY DESIGN, SIZE, DURATION

An Internet-based, prospective preconception cohort study of couples residing in the USA and Canada. We analyzed data from 1815 female participants who conceived during December 2020-November 2022, including 1570 couples with data on male partner vaccination.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Eligible female participants were aged 21-45 years and were trying to conceive without use of fertility treatment at enrollment. Female participants completed questionnaires at baseline, every 8 weeks until pregnancy, and during early and late pregnancy; they could also invite their male partners to complete a baseline questionnaire. We collected data on COVID-19 vaccination (brand and date of doses), history of SARS-CoV-2 infection (yes/no and date of positive test), potential confounders (demographic, reproductive, and lifestyle characteristics), and pregnancy status on all questionnaires. Vaccination status was categorized as never (0 doses before conception), ever (≥1 dose before conception), having a full primary sequence before conception, and completing the full primary sequence ≤3 months before conception. These categories were not mutually exclusive. Participants were followed up from their first positive pregnancy test until miscarriage or a censoring event (induced abortion, ectopic pregnancy, loss to follow-up, 20 weeks' gestation), whichever occurred first. We estimated incidence rate ratios (IRRs) for miscarriage and corresponding 95% CIs using Cox proportional hazards models with GW as the time scale. We used propensity score fine stratification weights to adjust for confounding.

MAIN RESULTS AND THE ROLE OF CHANCE

Among 1815 eligible female participants, 75% had received at least one dose of a COVID-19 vaccine by the time of conception. Almost one-quarter of pregnancies resulted in miscarriage, and 75% of miscarriages occurred <8 weeks' gestation. The propensity score-weighted IRR comparing female participants who received at least one dose any time before conception versus those who had not been vaccinated was 0.85 (95% CI: 0.63, 1.14). COVID-19 vaccination was not associated with increased risk of either early miscarriage (GW: <8) or late miscarriage (GW: 8-19). There was no indication of an increased risk of miscarriage associated with male partner vaccination (IRR = 0.90; 95% CI: 0.56, 1.44).

LIMITATIONS, REASONS FOR CAUTION

The present study relied on self-reported vaccination status and infection history. Thus, there may be some non-differential misclassification of exposure status. While misclassification of miscarriage is also possible, the preconception cohort design and high prevalence of home pregnancy testing in this cohort reduced the potential for under-ascertainment of miscarriage. As in all observational studies, residual or unmeasured confounding is possible.

WIDER IMPLICATIONS OF THE FINDINGS

This is the first study to evaluate prospectively the relation between preconception COVID-19 vaccination in both partners and miscarriage, with more complete ascertainment of early miscarriages than earlier studies of vaccination. The findings are informative for individuals planning a pregnancy and their healthcare providers.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by the Eunice Kennedy Shriver National Institute of Child Health and Human Development, the National Institute of Health [R01-HD086742 (PI: L.A.W.); R01-HD105863S1 (PI: L.A.W. and M.L.E.)], the National Institute of Allergy and Infectious Diseases (R03-AI154544; PI: A.K.R.), and the National Science Foundation (NSF-1914792; PI: L.A.W.). The funders had no role in the study design, data collection, analysis and interpretation of data, writing of the report, or the decision to submit the paper for publication. L.A.W. is a fibroid consultant for AbbVie, Inc. She also receives in-kind donations from Swiss Precision Diagnostics (Clearblue home pregnancy tests) and Kindara.com (fertility apps). M.L.E. received consulting fees from Ro, Hannah, Dadi, VSeat, and Underdog, holds stock in Ro, Hannah, Dadi, and Underdog, is a past president of SSMR, and is a board member of SMRU. K.F.H. reports being an investigator on grants to her institution from UCB and Takeda, unrelated to this study. S.H.-D. reports being an investigator on grants to her institution from Takeda, unrelated to this study, and a methods consultant for UCB and Roche for unrelated drugs. The authors report no other relationships or activities that could appear to have influenced the submitted work.

TRIAL REGISTRATION NUMBER

N/A.

Atypical Antipsychotics and the Risk of Sudden Cardiac Death among Individuals Receiving Maintenance Hemodialysis

Objective

Individuals receiving hemodialysis have high rates of sudden cardiac death (SCD). This study characterized oral atypical antipsychotic use and compared the cardiac safety of atypical antipsychotics with QT prolongation FDA warnings to that of atypical antipsychotics without such warnings among outpatients receiving hemodialysis.

Methods

Data for this active-comparator, new-user cohort study were obtained from the U.S. Renal Data System (2007-2019). The primary outcome was 1-year SCD risk. Fine and Gray proportional subdistribution hazard models with inverse probability of treatment weighting were used to estimate adjusted hazard ratios (aHR) and 95% confidence intervals (CI).

Results

The quetiapine vs. atypical antipsychotic without QT prolongation warning cohort included 18,943 quetiapine new-users and 19,571 non-warning atypical antipsychotic new-users. When compared to new-use of atypical antipsychotics without QT prolongation warnings, quetiapine new-use was not associated with the risks of SCD (aHR (95% CI) = 1.00 (0.93, 1.07)) or broader cardiac outcomes. Comparisons of all atypical antipsychotics with QT prolongation warnings vs. atypical antipsychotics without warnings generated similar results.

Conclusions

Quetiapine, which carries an FDA warning for QT prolongation, did not associate with cardiac risk compared to atypical antipsychotics without warnings among hemodialysis outpatients. Findings may inform prescriber selection of atypical antipsychotics in this population.

Sex differences in the association between urate metabolism and kidney outcomes in patients with chronic kidney disease

BACKGROUND

The association between serum uric acid (SUA) concentration and kidney outcomes in patients with chronic kidney disease (CKD) is controversial. Furthermore, there are no reports regarding the association of clearance of uric acid (CUA) with kidney outcomes. We aimed to determine whether SUA or CUA was associated with kidney outcomes in patients with CKD stratified by sex.

METHODS

The present prospective study was conducted in 815 patients (523 men and 292 women) with CKD. The participants were divided into quartiles (Q1-Q4) of SUA or CUA for each sex. Endpoints were defined as a composite of doubling of serum creatinine (SCr), end-stage kidney disease (ESKD), or death (outcome 1) and a composite of doubling of SCr or ESKD (outcome 2).

RESULTS

During a median follow-up of 2.5 years, outcomes 1 and 2 occurred in 363 and 321 patients, respectively. Multivariable-adjusted Cox analyses showed that in men, the hazard ratios (95% confidence intervals) for outcome 1 of Q1, Q2, and Q3 of CUA were 2.08 (1.18-3.70), 2.03 (1.22-3.39), and 1.85 (1.17-2.95), respectively, compared with Q4. Additionally, there were similar associations between lower CUA quartiles and outcome 2 in men. However, no associations between SUA and either outcome were observed in men. Conversely, in women, neither SUA nor CUA was associated with an outcome.

CONCLUSION

In CKD, lower CUA was independently associated with poor kidney outcomes only in men, and in both sexes, there was no association of SUA with kidney outcomes.

Determining the effect of one decade on fitness of elite Austrian youth soccer players using propensity score matching

Current trends in attacking strategies and increases in external workload have led to a need for fast and well-conditioned athletes in modern soccer. More recently, progressions in speed, coordination, power and endurance were found over a decade in elite Austrian youth players. However, possible confounders such as relative age, maturation, learning effects, and academy philosophy may have influenced these changes. The present study aimed to determine the decade effect on fitness under statistical control of players' exact age, height, body mass, test location as well as total number of pretests and time interval between test and pretest. Players annually completed a battery of anthropometric, general and soccer-specific fitness tests. MANCOVA was calculated to identify the overall impacts of the covariates on fitness. To balance the covariates of initially 2,530 "former" (2002 to 2005) and 2,611 "recent" (2012 to 2015) players, 1:1 nearest neighbor propensity score (PS) matching was used, resulting in 587 U13, 573 U14, 475 U15, 325 U16, 262 U17, and 129 U18 matched pairs. The decade effect on fitness was assessed by independent t-tests and Cohen's d separately at each age group. Superior performances of recent players were found for linear sprint across all age categories (d = 0.154-0.476) as well as for agility (d = 0.125-0.340) and change-of-direction speed (d = 0.172-0.466) in U15 to U18. Reaction speed increased in U13 (d = 0.288) and U15 (d = 0.310). Flexibility reduced over the decade in all age categories (d = -0.151 to -0.589) and upper-limb power decreased (d = -0.278 to -0.347) in U13 and U14. Balancing the covariate distribution via PS matching generally confirmed previous findings, with fitness decade effects reflecting the athletic needs for modern soccer. Since fitness performance changed over time, reference values should be periodically updated. Coaches favor both physical and cognitive fast players nowadays. Thus, training should target all aspects of speed, without disregarding flexibility, upper-limb power and other preventive strategies that keep the players on the pitch.

Propensity Scores in Health Disparities Research: The Example of Cognitive Aging and the Hispanic Paradox

BACKGROUND

Individuals of Mexican ancestry in the United States experience substantial socioeconomic disadvantages compared with non-Hispanic white individuals; however, some studies show these groups have similar dementia risk. Evaluating whether migration selection factors (e.g., education) associated with risk of Alzheimer disease and related dementia (ADRD) explain this paradoxical finding presents statistical challenges. Intercorrelation of risk factors, common with social determinants, could make certain covariate patterns very likely or unlikely to occur for particular groups, which complicates their comparison. Propensity score (PS) methods could be leveraged here to diagnose nonoverlap and help balance exposure groups.

METHODS

We compare conventional and PS-based methods to examine differences in cognitive trajectories between foreign-born Mexican American, US-born Mexican American, and US-born non-Hispanic white individuals in the Health and Retirement Study (1994-2018). We examined cognition using a global measure. We estimated trajectories of cognitive decline from linear mixed models adjusted for migration selection factors also associated with ADRD risk conventionally or with inverse probability weighting. We also employed PS trimming and match weighting.

RESULTS

In the full sample, where PS overlap was poor, unadjusted analyses showed both Mexican ancestry groups had worse baseline cognitive scores but similar or slower rates of decline compared with non-Hispanic white adults; adjusted findings were similar, regardless of method. Focusing analyses on populations where PS overlap was improved (PS trimming and match weighting) did not alter conclusions.

CONCLUSIONS

Attempting to equalize groups on migration selection and ADRD risk factors did not explain paradoxical findings for Mexican ancestry groups in our study.

Causal inference between aggressive extrathyroidal extension and survival in papillary thyroid cancer: a propensity score matching and weighting analysis

Background

Extrathyroidal extension is a major risk factor for poor prognosis in papillary thyroid cancer. However, the effect of different degrees of extrathyroidal extension on prognosis remains controversial. We performed a retrospective study to elucidate how the extent of extrathyroidal extension in papillary thyroid cancer affected the clinical prognosis of patients and its covariates.

Methods

The study included 108,426 patients with papillary thyroid cancer. We categorized the extent of extension into none, capsule, strap muscles, and other organs. Three causal inference methods for retrospective studies, namely, inverse probability of treatment weighting, standardized mortality ratio weighting, and propensity score matching analysis, were used to minimize potential selection bias. Kaplan-Meier analysis and univariate Cox regression analyses were applied to analyze the precise effect of ETE on survival in papillary thyroid cancer patients.

Results

In the Kaplan-Meier survival analysis, only extrathyroidal extension into or beyond the strap muscles was statistically significant for both overall survival (OS) and thyroid cancer-specific survival (TCSS). In univariate Cox regression analyses before and after matching or weighting based on causal inference, extrathyroidal extension into soft tissues or other organs is a high-risk factor for both overall survival and thyroid cancer-specific survival. Sensitivity analysis revealed that lower overall survival was observed in patients with older age (≥55) and larger tumor size (>2 cm) of papillary thyroid cancer with extrathyroidal extension into or beyond the strap muscles.

Conclusions

Our study indicates that extrathyroidal extension into soft tissues or other organs is a high-risk factor in all papillary thyroid cancer. Even though invasion into the strap muscles did not seem to be a marker for poor prognosis, it still impaired the overall survival of patients with older age (≥55 years old) or larger tumor size (>2 cm). Further investigation is needed to confirm our results and to clarify further risk factors independent of extrathyroidal extension.

Heart Failure Among Patients with Multiple Myeloma Treated with Carfilzomib-Based Versus Non-Carfilzomib-Based Regimens in the United States by Race

BACKGROUND

Carfilzomib treatment for multiple myeloma (MM) can increase heart failure risk. Whether this risk differs by race is unknown.

PATIENTS AND METHODS

We sought to estimate the incidence rates (IRs) of heart failure hospitalization among mostly 65-years-and-older US patients with MM by race treated with carfilzomib- and non-carfilzomib-based regimens in the real-world using Centers for Medicare & Medicaid Services Medicare Fee-for-Service data, Optum Clinformatics Data Mart, and Humana Research Database. The risk of heart failure hospitalization associated with a carfilzomib-based regimen was evaluated using propensity score matching among Black and White patients receiving second or later lines of therapy.

RESULTS

Most patient-episodes (88%) were in persons 65 years or older for the 3 cohorts combined. The IR (95% CI) of heart failure hospitalization was higher for patient-episodes treated with a carfilzomib-based regimen than those with a non-carfilzomib-based regimen for both White (14.5 [12.2-17.0] vs. 10.7 [10.3-11.2] events per person-years) and Black patients (15.8 [10.1-23.5] vs. 12.1 [10.9-13.4] events per person-years) in the Medicare cohort. After propensity score matching, the hazard ratio (95% CI) of increased heart failure hospitalization comparing carfilzomib-based to non-carfilzomib-based regimens for White patients (1.6 [1.3-2.0]) was similar to that of Black patients (1.7 [1.0-2.9]) in the Medicare Database, and in the Humana Database (1.4 [0.8-2.6] and 1.2 [0.4-3.5], respectively).

CONCLUSION

Although the IR of heart failure among patients with MM treated with a carfilzomib-based regimen was slightly higher, no evidence suggested the relative risk was different between White and Black patients with MM.

Comparative effectiveness of TNF inhibitor vs IL-6 receptor inhibitor as monotherapy or combination therapy with methotrexate in biologic-experienced patients with rheumatoid arthritis: An analysis from the CorEvitas RA Registry

OBJECTIVE

Randomized controlled trials (RCTs) in biologic-naïve rheumatoid arthritis (RA) patients with high disease activity and inadequate response/intolerance to methotrexate have shown interleukin-6 (IL-6) receptor inhibitors (IL-6Ri) to be superior to tumor necrosis factor inhibitors (TNFi) as monotherapy. This observational study aimed to compare the effectiveness of TNFi vs IL-6Ri as mono- or combination therapy in biologic/targeted synthetic (b/ts) -experienced RA patients with moderate/high disease activity.

METHODS

Eligible b/ts-experienced patients from the CorEvitas RA registry were categorized as TNFi and IL-6Ri initiators, with subgroups initiating as mono- or combination therapy. Mixed-effects regression models evaluated the impact of treatment on Clinical Disease Activity Index (CDAI), patient-reported outcomes, and disproportionate pain (DP). Unadjusted and covariate-adjusted effects were reported.

RESULTS

Patients initiating IL-6Ri (n = 286) vs TNFi monotherapy (n = 737) were older, had a longer RA history and higher baseline CDAI, and were more likely to initiate as third-line therapy; IL-6Ri (n = 401) vs TNFi (n = 1315) combination therapy initiators had higher baseline CDAI and were more likely to initiate as third-line therapy. No significant differences were noted in the outcomes between TNFi and IL-6Ri initiators (as mono- or combination therapy).

CONCLUSION

This observational study showed no significant differences in outcomes among b/ts-experienced TNFi vs IL-6Ri initiators, as either mono- or combination therapy. These findings were in contrast with the previous RCTs in biologic-naïve patients and could be explained by the differences in the patient characteristics included in this study. Further studies are needed to help understand the reasons for this discrepancy in the real-world b/ts-experienced population.

Is it feasible and ethical to randomize patients between surgery and non-surgical treatments for gastrointestinal cancers?

Background

In several settings in the treatment of gastrointestinal cancers, it is unclear if the addition of surgery to a multimodal treatment strategy, or in some circumstances its omission, lead to a better outcome for patients. In such situations of clinical equipoise, high-quality evidence from randomised-controlled trials is needed to decide which treatment approach is preferable.

Objective

In this article, we outline the importance of randomised trials comparing surgery with non-surgical therapies for specific scenarios in the treatment of gastrointestinal cancers. We explain the difficulties and solutions of designing these trials and recruiting patients in this context.

Methods

We performed a selective review based on a not systematic literature search in core databases, supplemented by browsing health information journals and citation searching. Only articles in English were selected. Based on this search, we discuss the results and methodological characteristics of several trials which randomised patients with gastrointestinal cancers between surgery and non-surgical treatments, highlighting their differences, advantages, and limitations.

Results and conclusions

Innovative and effective cancer treatment requires randomised trials, also comparing surgery and non-surgical treatments for defined scenarios in the treatment of gastrointestinal malignancies. Nevertheless, potential obstacles to designing and carrying out these trials must be recognised ahead of time to avoid problems before or during the trial.

Association between NMR metabolomic signatures of healthy lifestyle and incident coronary artery disease

AIMS

To identify metabolites associated with a healthy lifestyle and explore the possible mechanisms of lifestyle in coronary artery disease (CAD).

METHODS AND RESULTS

The nuclear magnetic resonance metabolomics platform was applied to perform metabolomic profiling of baseline plasma samples from a randomly selected subset of 121 733 UK Biobank participants. Cox proportional hazards models with covariate adjustments were used to investigate the associations between validated lifestyle-associated metabolites and incident CAD and to estimate the accuracy of the inclusion of metabolites to predict CAD compared with traditional prediction models. The discriminatory ability of each model was evaluated using Harrell's C statistic, integrated discrimination improvement (IDI), and continuous net reclassification improvement (NRI) indexes. During a median of 8.6 years of follow-up, 5513 incident CAD cases were documented. Among the 111 lifestyle-associated metabolites, 65 were significantly associated with incident CAD after multivariate adjustment (Bonferroni P < 3.11 × 10-04). The addition of these metabolites to classic risk prediction models [Framingham Risk Score (FRS) using lipids; FRS using body mass index] improved CAD prediction accuracy as assessed by the C statistic (increasing to 0.739 [95% CI, 0.731-0.747] and 0.752 [95% CI, 0.746-0.758]), respectively; continuous NRI (0.274 [0.227-0.325] and 0.266 [0.223-0.317]) and IDI (0.003 [0.002-0.004] and 0.003 [0.002-0.004]).

CONCLUSION

Healthy lifestyle-associated metabolites are associated with the incidence of CAD and may help improve the prediction of CAD risk. The use of metabolite information combined with the FRS model warrants further investigation before clinical implementation.

Neck level Ib-sparing versus level Ib-irradiation in intensity-modulated radiotherapy for the treatment of nasopharyngeal carcinoma with high-risk factors: A propensity score-matched cohort study

AIM

Level Ib lymph nodes metastasis is rare in nasopharyngeal carcinoma (NPC). We aimed to evaluate the feasibility of sparing level Ib-irradiation in NPC patients with high-risk factors.

MATERIALS AND METHODS

Four hundred forty-three NPC patients with radiologic extranodal extension (rENE) or level II lymph node maximal axial diameter (MAD) ≥ 20 mm treated by intensity-modulated radiotherapy (IMRT) between 2009 and 2012 were included in this study. Propensity score matching (PSM) was applied to balance potential prognostic factors (including age, sex, T and N stage, pretreatment EBV DNA level, and level II rENE and MAD) between patients who received and omitted level Ib irradiation. Kaplan-Meier analysis and the log-rank test were used to compare regional survival outcomes.

RESULTS

PSM resulted in 169 matched pairs of eligible patients. The median follow-up period was 119 months in the matched cohort. The number of level Ib failure in the level Ib-sparing and level-Ib irradiation groups were 3/169 (1.8 %) vs 2/169 (1.2 %), P > 0.999. And the 5-year regional relapse-free survival (RRFS) rates of the two groups were 88.4 % vs 92.6 %, respectively. After PSM, RRFS (hazard ratio [HR]: 1.508, 95 % confidence interval [CI]: 0.762-2.986, P = 0.239), OS (HR: 1.219, 95 % CI: 0.754-1.972, P = 0.418), distant metastasis-free survival (DMFS) (HR: 1.605, 95 % CI: 0.900-2.863, P = 0.109), and local relapse-free (LRFS) (HR: 0.956, 95 % CI: 0.436-2.095, P = 0.910) were similar in the two arms. The incidence of grade ≥ 1 dry mouth after 5 years was higher in the level Ib-irradiation group (27.5 % vs 16.5 %, P = 0.029). However, the incidences of grade 3-4 late toxicities were similar between the two groups.

CONCLUSION

Neck level Ib-sparing appears to be safe and feasible in NPC patients with rENE or level II MAD ≥ 20 mm and negative level Ib lymph nodes. Compared with cervical level Ib-irradiation, omission of irradiation to level Ib provides less dry mouth symptom.

Logistic regression frequently outperformed propensity score methods, especially for large datasets: a simulation study

OBJECTIVES

In observational studies, researchers must select a method to control for confounding. Options include propensity score (PS) methods and regression. It remains unclear how dataset characteristics (size, overlap in PSs, and exposure prevalence) influence the relative performance of the methods.

STUDY DESIGN AND SETTING

A simulation study to evaluate the role of dataset characteristics on the performance of PS methods, compared to logistic regression, for estimating a marginal odds ratio was conducted. Dataset size, overlap in PSs, and exposure prevalence were varied.

RESULTS

Regression showed poor coverage for small sample sizes, but with large sample sizes was relatively robust to imbalance in PSs and low exposure prevalence. PS methods displayed suboptimal coverage as overlap in PSs decreased, which was exacerbated at larger sample sizes. Power of matching methods was particularly affected by a lack of overlap, low exposure prevalence, and small sample size. The advantage of regression for large data size was reduced in sensitivity analysis with a complementary log-log outcome generation mechanism and unmeasured confounding, with superior bias and error but inferior coverage to matching methods.

CONCLUSION

Dataset characteristics influence performance of methods for confounder adjustment. In many scenarios, regression may be the preferable option.

Flexible propensity score estimation strategies for clustered data in observational studies

Existing studies have suggested superior performance of nonparametric machine learning over logistic regression for propensity score estimation. However, it is unclear whether the advantages of nonparametric propensity score modeling are carried to settings where there is clustering of individuals, especially when there is unmeasured cluster-level confounding. In this work we examined the performance of logistic regression (all main effects), Bayesian additive regression trees and generalized boosted modeling for propensity score weighting in clustered settings, with the clustering being accounted for by including either cluster indicators or random intercepts. We simulated data for three hypothetical observational studies of varying sample and cluster sizes. Confounders were generated at both levels, including a cluster-level confounder that is unobserved in the analyses. A binary treatment and a continuous outcome were generated based on seven scenarios with varying relationships between the treatment and confounders (linear and additive, nonlinear/nonadditive, nonadditive with the unobserved cluster-level confounder). Results suggest that when the sample and cluster sizes are large, nonparametric propensity score estimation may provide better covariate balance, bias reduction, and 95% confidence interval coverage, regardless of the degree of nonlinearity or nonadditivity in the true propensity score model. When the sample or cluster sizes are small, however, nonparametric approaches may become more vulnerable to unmeasured cluster-level confounding and thus may not be a better alternative to multilevel logistic regression. We applied the methods to the National Longitudinal Study of Adolescent to Adult Health data, estimating the effect of team sports participation during adolescence on adulthood depressive symptoms.

Testing the Limit: Evaluating Drinking Water Arsenic Regulatory Levels Based on Adverse Pregnancy Outcomes in Bangladesh

(1) Background: Arsenic (As) is a common drinking water contaminant that is regulated as a carcinogen. Yet, As is a systemic toxicant and there is considerable epidemiological data showing As adversely impacts reproductive health. This study used data from a birth cohort in Bangladesh (2008−2011) to examine associations between drinking water As levels and reproductive outcomes. (2) Methods: Pregnant individuals (n = 1597) were enrolled at <16 weeks gestation and drinking water As was measured. Participants with live births (n = 1130) were propensity score matched to participants who experienced miscarriage (n = 132), stillbirth (n = 72), preterm birth (n = 243), and neonatal mortality (n = 20). Logistic regression was used to examine drinking water As recommendations of 50, 10, 5, 2.5, and 1 µg/L on the odds of adverse birth outcomes. (3) Results: The odds of miscarriage were higher for pregnant women exposed to drinking water ≥2.5 versus <2.5 µg As/L [adjusted odds ratio (OR) 1.90, 95% Confidence Interval (CI): 1.07−3.38)]. (4) Conclusions: These preliminary findings suggest a potential threshold where the odds of miscarriage increases when drinking water As is above 2.5 µg/L. This concentration is below the World Health Organizations and Bangladesh’s drinking water recommendations and supports the re-evaluation of drinking water regulations.

Theory and practice of propensity score analysis

Propensity score analysis has been widely used in observational studies to make a causal inference. This study introduces three assumptions for causal inferences-conditional exchangeability, positivity, and consistency-and five steps for propensity score (PS) analysis-1) construct appropriate PS models, 2) check overlap in PS, 3) apply appropriate weighting (inverse probability of treatment weighting, standardized mortality ratio weighting, matching weights, and overlap weights) or matching methods according to the target of inference, 4) check the balance of covariates, and 5) estimate the effect of exposure appropriately. Finally, the advantages of PS analyses over conventional multivariable regression are discussed.

Increased symptom severity in adults and adolescents admitting to an inpatient psychiatric hospital during the COVID-19 pandemic

While the negative effects of Coronavirus Disease-2019 (COVID-19) on general mental health are well-established, less is known about the impact on those with severe mental illness. Thus, this study examined symptom severity among psychiatric inpatients admitted prior to versus during the COVID pandemic. Self-reported anxiety (GAD-7), depression (PHQ-9), emotional dysregulation (DERS-SF), sleep quality (PSQI), nightmares (DDNSI), and suicidal ideation (SBQ-R) were examined in 470 adults (n = 235 admitted pre-pandemic) and 142 children and adolescents (n = 65 admitted pre-pandemic) at admission. Adults also completed measures of disability (WHODAS) and substance use (WHOASSIST). Adults admitted during the COVID pandemic reported significantly higher levels of anxiety [p < .001, partial η²=0.18], depression [p < .001, partial η²=0.06], emotion dysregulation [p < .001, partial η²=0.05], nightmares [p = .013, partial η²=0.01], and disability [p < .001, partial η²=0.04] compared to adults admitted pre-COVID. Levels of anxiety [p = .005, partial η²=0.05], depression [p = .005, partial η²=0.06], and sleep quality [p = .011, partial η²=0.05] were significantly higher among adolescents admitted during COVID compared to pre-COVID. The findings help identify areas of prioritization for future mental health prevention/intervention efforts for future disease outbreaks.

Avoiding Systematic Bias in Orthopedics Research Through Informed Variable Selection: A Discussion of Confounders, Mediators, and Colliders

There are 3 common variable types in orthopedic research-confounders, colliders, and mediators. All 3 types of variables are associated with both the exposure (eg, surgery type, implant type, body mass index) and outcome (eg, complications, revision surgery) but differ in their temporal ordering. To reduce systematic bias, the decision to include or exclude a variable in an analysis should be based on the variable's relationship with the exposure and outcome for each research question. In this article, we define 3 types of variables with case examples from orthopedic research. Please visit the followinghttps://youtu.be/V-grpgB1ShQfor videos that explain the highlights of the article in practical terms.

Comparison of the cumulative live birth rates after 1 in vitro fertilization cycle in women using gonadotropin-releasing hormone antagonist protocol vs. progestin-primed ovarian stimulation: a propensity score-matched study

OBJECTIVE

To determine whether gonadotropin-releasing hormone (GnRH) antagonist protocol can improve cumulative live birth rates (CLBRs) and shorten the time to live birth (TTLB) in unselected patients compared with progestin-primed ovarian stimulation (PPOS).

DESIGN

A propensity score-matched retrospective cohort study design.

SETTING

Tertiary-care academic medical center.

PATIENT(S)

A total of 6,520 women with infertility aged 20-50 years were included.

INTERVENTION(S)

Patients underwent either the GnRH antagonist protocol (n = 5,004) or PPOS (n = 1,516) on the basis of the assessment of the attending physicians. One-to-one propensity score matching was performed with a caliper of 0.02. Women who were not matched were excluded from the analyses.

MAIN OUTCOME MEASURE(S)

The CLBR of which the ongoing status had to be achieved within 22 months from the day of ovarian stimulation and TTLB.

RESULT(S)

Each group comprised 1,424 couples after propensity score matching, and the baseline demographic characteristics of the couples after matching were comparable between the 2 groups. The cycle cancellation rate was significantly lower in the GnRH antagonist group than in the PPOS group (12.9% vs. 19.6%). The implantation rate, clinical pregnancy rate, ongoing pregnancy rate, and live birth rate per transfer were comparable between the 2 groups. However, CLBRs after 1 complete IVF cycle were significantly higher in the GnRH antagonist group than in the PPOS group (36.0% vs. 32.2%; Risk ratio = 1.12; 95% confidence interval [CI], 1.01-1.24). The average TTLB was significantly shorter in the GnRH antagonist group than in the PPOS group (9.3 months vs. 12.4 months). Using the Kaplan-Meier analysis, the cumulative incidence of ongoing pregnancy leading to live birth was significantly higher in the GnRH antagonist group than in the PPOS group (85.1% vs. 66.1%, Log-rank test). A Cox proportional hazard model revealed that women who underwent the antagonist protocol were 2.32 times more likely to achieve a live birth than those who used PPOS (hazard ratio [HR] = 2.32; 95% CI, 1.91-2.83). Subgroup analysis revealed that women who used the antagonist protocol were more likely to achieve a live birth than women who used PPOS across the 3 antral follicle count (AFC) strata (AFC ≤ 5, AFC 6-15, and AFC > 15), 2 age strata (<35 and ≥35 years), and first cycle or repeated cycle. The difference was greatest among women whose AFC was ≤5 and who were aged ≥35 years, effectively becoming smaller in the group with high ovarian reserve and younger age.

CONCLUSION(S)

In unselected women undergoing IVF, the GnRH antagonist protocol was associated with a higher CLBR and a shorter TTLB compared with PPOS.

Pharmacoepidemiological Research on N-Nitrosodimethylamine-Contaminated Ranitidine Use and Long-Term Cancer Risk: A Population-Based Longitudinal Cohort Study

N-Nitrosodimethylamine (NDMA), a carcinogenic chemical, has recently been identified in ranitidine. We conducted a population-based study to explore ranitidine use and cancer emergence over time. Using the Taiwan National Health Insurance Research Database, a population-based cohort study was conducted. A total of 55,110 eligible patients who received ranitidine between January 2000 and December 2018 were enrolled in the treated cohort. We conducted a 1:1 propensity-score-matching procedure to match the ranitidine-treated group with the ranitidine-untreated group and famotidine controls for a longitudinal study. The association of ranitidine exposure with cancer outcomes was assessed. A multivariable Cox regression analysis that compared cancer risk with the untreated groups revealed that ranitidine increased the risk of liver (hazard ratio (HR): 1.22, 95% confidence interval (CI): 1.09-1.36, p < 0.001), lung (HR: 1.17, CI: 1.05-1.31, p = 0.005), gastric (HR: 1.26, CI: 1.05-1.52, p = 0.012), and pancreatic cancers (HR 1.35, CI: 1.03-1.77, p = 0.030). Our real-world observational study strongly supports the pathogenic role of NDMA contamination, given that long-term ranitidine use is associated with a higher likelihood of liver cancer development in ranitidine users compared with the control groups of non-ranitidine users treated with famotidine or proton-pump inhibitors.

Clinical effectiveness of Qilong capsule in patients with ischemic stroke: A prospective, multicenter, non-randomized controlled trial

BACKGROUND

The Qilong capsule (QLC) is a Chinese patented medicine characterized by an equal emphasis on replenishing Qi and activating blood circulation. In 2000, China's FDA approved the use of QLC for ischemic stroke (IS). However, there is not yet much high-quality evidence of the clinical effectiveness of QLC combined with conventional treatment (CT) for IS with Qi deficiency and blood stasis syndrome.

PURPOSE

In this study, we conducted a prospective, multicenter, non-randomized controlled trial at 7 hospitals in China to investigate the clinical effectiveness of QLC combined with CT for IS with Qi deficiency and blood stasis syndrome.

METHODS

Participants aged 35 to 80 years old diagnosed as IS with Qi deficiency and blood stasis syndrome in TCM were recruited. Participants were treated with QLC (intervention group) or non-QLC (control group). The intervention course of QLC was 12 weeks. All participants in two groups received standard treatment. All participants returned for in-person follow-up visits at the 12th week and 24th week. Primary outcome measures included a modified Rankin Scale (mRS), the National Institute of Health Stroke Scale (NIHSS), and the Barthel Index (BI). Secondary outcome measures included TCM syndromes (Qi deficiency syndrome score, blood stasis syndrome score), psychological index (self-rating depression scale, SDS; self-rating anxiety scale, SAS), blood lipid index, blood coagulation index, homocysteine, and favorable functional outcome (mRS 0 - 3). Multiple imputations were used for any missing data. Propensity score matching (PSM) was used to deal with any confounding factors (age, gender, scale score, etc.). Rank alignment transformation variance analysis (ART ANOVA) and generalized linear mixed model (GLMM) were introduced to improve the scientific and accuracy of repeated measurement data. All statistical calculations were carried out with R 3.6.1 statistical analysis software.

RESULTS

A total of 2468 participants were screened from November 2016 to January 2019. Finally, 2302 eligible participants were included in the analysis. There were 1260 participants in the intervention group (QLC group) and 1042 participants in the control group (non-QLC group). After PSM matching, sub-samples of 300 participants in the QLC group and 300 participants in the non-QLC group were finally formed. The final results of clinical effectiveness are the same results shared by the total samples and sub-samples after PSM. In the 24th week after treatment, QLC combined with CT proved to be significantly better than CT alone in reducing the scores of mRS (p < 0.05), NIHSS (p < 0.001), Qi deficiency syndrome (p < 0.01), and blood stasis syndrome (p < 0.001), SAS (p < 0.05), as well as in improving BI score (p < 0.05). The favourable functional outcome (mRS score of 0 to 3 at week 12) was statistically different between QLC and non-QLC group in the sub-samples (p < 0.01, 97% vs 91.7%). The results of the ART ANOVA showed that the improvement of mRS (p < 0.01), BI (p < 0.05) and NIHSS (p < 0.001) in QLC group was better than non-QLC group when the interaction effect was considered. The results of GLMM showed that the reduction of mRS and NIHSS scores of patients in the QLC group were better than those of the non-QLC group (p < 0.001). The BI score of the QLC group in the sub-samples after PSM increased more than the non-QLC group (p < 0.001). There was no evidence showing that QLC can cause serious adverse reactions (ADRs) in treating patients with IS.

CONCLUSION

QLC combined with CT was better than CT alone in reducing mRS score, NIHSS score, Qi deficiency syndrome score, blood stasis syndrome score, and SAS score, as well as improving BI score after treatment. Further high-quality RCTs are needed to confirm the positive results. The study protocol was embedded in a registry study that registered in the Clinical Trials USA Registry (registration No. NCT03174535).

A Prospective Cohort Study of COVID-19 Vaccination, SARS-CoV-2 Infection, and Fertility

Some reproductive-aged individuals remain unvaccinated against coronavirus disease 2019 (COVID-19) because of concerns about potential adverse effects on fertility. Using data from an internet-based preconception cohort study, we examined the associations of COVID-19 vaccination and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection with fertility among couples trying to conceive spontaneously. We enrolled 2,126 self-identified female participants aged 21-45 year residing in the United States or Canada during December 2020-September 2021 and followed them through November 2021. Participants completed questionnaires every 8 weeks on sociodemographics, lifestyle, medical factors, and partner information. We fit proportional probabilities regression models to estimate associations between self-reported COVID-19 vaccination and SARS-CoV-2 infection in both partners with fecundability (i.e., the per-cycle probability of conception), adjusting for potential confounders. COVID-19 vaccination was not appreciably associated with fecundability in either partner (female fecundability ratio (FR) = 1.08, 95% confidence interval (CI): 0.95, 1.23; male FR = 0.95, 95% CI: 0.83, 1.10). Female SARS-CoV-2 infection was not strongly associated with fecundability (FR = 1.07, 95% CI: 0.87, 1.31). Male infection was associated with a transient reduction in fecundability (for infection within 60 days, FR = 0.82, 95% CI: 0.47, 1.45; for infection after 60 days, FR = 1.16, 95% CI: 0.92, 1.47). These findings indicate that male SARS-CoV-2 infection may be associated with a short-term decline in fertility and that COVID-19 vaccination does not impair fertility in either partner.

Methodological perspectives on the study of the health effects of unemployment - reviewing the mode of unemployment, the statistical analysis method and the role of confounding factors

Introduction

Studying the relationship between unemployment and health raises many methodological challenges. In the current study, the aim was to evaluate the sensitivity of estimates based on different ways of measuring unemployment and the choice of statistical model.

Methods

The Northern Swedish cohort was used, and two follow-up surveys thereof from 1995 and 2007, as well as register data about unemployment. Self-reported current unemployment, self-reported accumulated unemployment and register-based accumulated unemployment were used to measure unemployment and its effect on self-reported health was evaluated. Analyses were conducted with G-computation, logistic regression and three estimators for the inverse probability weighting propensity scores, and 11 potentially confounding variables were part of the analyses. Results were presented with absolute differences in the proportion with poor self-reported health between unemployed and employed individuals, except when logistic regression was used alone.

Results

Of the initial 1083 pupils in the cohort, our analyses vary between 488–693 individuals defined as employed and 61–214 individuals defined as unemployed. In the analyses, the deviation was large between the unemployment measures, with a difference of at least 2.5% in effect size when unemployed was compared with employed for the self-reported and register-based unemployment modes. The choice of statistical method only had a small influence on effect estimates and the deviation was in most cases lower than 1%. When models were compared based on the choice of potential confounders in the analytical model, the deviations were rarely above 0.6% when comparing models with 4 and 11 potential confounders. Our variable for health selection was the only one that strongly affected estimates when it was not part of the statistical model.

Conclusions

How unemployment is measured is highly important when the relationship between unemployment and health is estimated. However, misspecifications of the statistical model or choice of analytical method might not matter much for estimates except for the inclusion of a variable measuring health status before becoming unemployed. Our results can guide researchers when analysing similar research questions. Model diagnostics is commonly lacking in publications, but they remain very important for validation of analyses.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12874-022-01670-1.

Bootstrap vs asymptotic variance estimation when using propensity score weighting with continuous and binary outcomes

We used Monte Carlo simulations to compare the performance of asymptotic variance estimators to that of the bootstrap when estimating standard errors of differences in means, risk differences, and relative risks using propensity score weighting. We considered four different sets of weights: conventional inverse probability of treatment weights with the average treatment effect (ATE) as the target estimand, weights for estimating the average treatment effect in the treated (ATT), matching weights, and overlap weights. We considered sample sizes ranging from 250 to 10 000 and allowed the prevalence of treatment to range from 0.1 to 0.9. We found that, when using ATE weights and sample sizes were ≤ 1000, then the use of the bootstrap resulted in estimates of SE that were more accurate than the asymptotic estimates. A similar finding was observed when using ATT weights and sample sizes were ≤ 1000 and the prevalence of treatment was moderate to high. When using matching weights and overlap weights, both the asymptotic estimator and the bootstrap resulted in accurate estimates of SE across all sample sizes and prevalences of treatment. Even when using the bootstrap with ATE weights, empirical coverage rates of confidence intervals were suboptimal when sample sizes were low to moderate and the prevalence of treatment was either very low or very high. A similar finding was observed when using the bootstrap with ATT weights when sample sizes were low to moderate and the prevalence of treatment was very high.

Neoadjuvant tyrosine kinase inhibitor therapy for patients with gastrointestinal stromal tumor: A propensity-matched analysis

BACKGROUND

Tyrosine kinase inhibitor (TKI) neoadjuvant therapy (NAT) is often given in gastrointestinal stromal tumors (GISTs) with the goal to facilitate less morbid resections and improve oncologic outcomes; however, the use of NAT for GIST is poorly studied.

METHODS

We reviewed patients with resected nonmetastatic GIST from 2003 to 2019. Overall (OS) and recurrence-free survival (RFS) were assessed with Kaplan-Meier modeling. We performed 1:1 propensity-matching for relevant clinicopathologic variables for receipt of NAT.

RESULTS

We identified 254 patients. Propensity 1:1 matching resulted in 33 patients per group. The median follow-up was 77 months with no difference in 10-year OS (68% vs. 73%), 5-year RFS (13% vs. 10%), or median RFS (24 vs. 27 months) for patients treated with NAT versus upfront resection (all P > 0.9). Hospital length-of-stay (both median 7 days) and Clavien-Dindo ≥ III complications (12% vs. 3%) were not different between groups (both P ≥ 0.35).

DISCUSSION

TKI NAT can be used to facilitate resection in select patients with surgically higher-risk GIST, however it does not result in an independent oncologic benefit.

Propensity Score and Instrumental Variable Techniques in Observational Transplantation Studies: An Overview and Worked Example Relating to Pre-Transplant Cardiac Screening

Inferring causality from observational studies is difficult due to inherent differences in patient characteristics between treated and untreated groups. The randomised controlled trial is the gold standard study design as the random allocation of individuals to treatment and control arms should result in an equal distribution of known and unknown prognostic factors at baseline. However, it is not always ethically or practically possible to perform such a study in the field of transplantation. Propensity score and instrumental variable techniques have theoretical advantages over conventional multivariable regression methods and are increasingly being used within observational studies to reduce the risk of confounding bias. An understanding of these techniques is required to critically appraise the literature. We provide an overview of propensity score and instrumental variable techniques for transplant clinicians, describing their principles, assumptions, strengths, and weaknesses. We discuss the different patient populations included in analyses and how to interpret results. We illustrate these points using data from the Access to Transplant and Transplant Outcome Measures study examining the association between pre-transplant cardiac screening in kidney transplant recipients and post-transplant cardiac events.

The effect of timing of high-efficacy therapy on processing speed performance in multiple sclerosis

BACKGROUND

The potential influence of the timing of high-efficacy disease-modifying therapies (heDMTs) on processing speed (PS) performance is critically lacking in current literature.

OBJECTIVE

To assess the extent to which early commencement of heDMTs would be associated with a better PS evolution as compared to moderate efficacy disease-modifying therapies (meDMTs) and delayed commencement of heDMTs.

METHODS

In this ongoing prospective longitudinal study, the 695 MS patients that have received a PS evaluation at 12-month of follow-up measured by the iPad®-based Processing Speed Test (PST) were retained for the analysis. All patients who had ever been prescribed a high efficacy disease-modifying therapy (heDMT) were classified in tertiles according to the proportion of their disease duration that had been on heDMTs. Based on these tertiles and the time to the first heDMT from the disease onset, patients were divided into the early heDMT group and the delayed heDMT group. Between-group differences in mean PST standardized (Z-score) change from baseline were analyzed using a linear mixed model.

RESULTS

In the multivariable model, each year of delay in starting a heDMT was associated with increased odds of cognitive worsening at 12-month (OR = 1.0324, 95% CI = 1.014-1.062, p<0.05). MeDMT-treated patients were at a significantly higher risk for cognitive worsening than early heDMT patients (OR= 2.57, 95%CI = 1.02-6.17). Linear mixed model-based adjusted mean change in PST Z-score from baseline was significantly better in those patients with the longest proportion of their disease duration treated with heDMT (highest tertile) compared to the lowest tertile (difference 0.37 [95%CI 0.02-0.92;p=0.036) and medium tertile (difference 0.39 [95%CI 0.06-0.31;p=0.037).

CONCLUSION

Early he-DMT-treated patients are at significantly lower risk for cognitive worsening. Early administration of heDMTs is associated with greater cognitive functioning improvements than delayed commencement or meDMTs.

Propensity score methods for observational studies with clustered data: A review

Propensity score methods are a popular approach to mitigating confounding bias when estimating causal effects in observational studies. When study units are clustered (eg, patients nested within health systems), additional challenges arise such as accounting for unmeasured confounding at multiple levels and dependence between units within the same cluster. While clustered observational data are widely used to draw causal inferences in many fields, including medicine and healthcare, extensions of propensity score methods to clustered settings are still a relatively new area of research. This article presents a framework for estimating causal effects using propensity scores when study units are nested within clusters and are nonrandomly assigned to treatment conditions. We emphasize the need for investigators to examine the nature of the clustering, among other properties, of the observational data at hand in order to guide their choice of causal estimands and the corresponding propensity score approach.

Self-matched learning to construct treatment decision rules from electronic health records

Electronic health records (EHRs) collected from large-scale health systems provide rich subject-specific information on a broad patient population at a lower cost compared to randomized controlled trials. Thus, EHRs may serve as a complementary resource to provide real-world data to construct individualized treatment rules (ITRs) and achieve precision medicine. However, in the absence of randomization, inferring treatment rules from EHR data may suffer from unmeasured confounding. In this article, we propose a self-matched learning method inspired by the self-controlled case series (SCCS) design to mitigate this challenge. We alleviate unmeasured time-invariant confounding between patients by matching different periods of treatments within the same patient (self-controlled matching) to infer the optimal ITRs. The proposed method constructs a within-subject matched value function for optimizing ITRs and bears similarity to the SCCS design. We examine assumptions that ensure Fisher consistency, and show that our method requires weaker assumptions on unmeasured confounding than alternative methods. Through extensive simulation studies, we demonstrate that self-matched learning has comparable performance to other existing methods when there are no unmeasured confounders, but performs markedly better when unobserved time-invariant confounders are present, which is often the case for EHRs. Sensitivity analyses show that the proposed method is robust under different scenarios. Finally, we apply self-matched learning to estimate the optimal ITRs from type 2 diabetes patient EHRs, which shows our estimated decision rules lead to greater advantages in reducing patients' diabetes-related complications.

Propensity Score Matching Underestimates Real Treatment Effect, in a Simulated Theoretical Multivariate Model

Propensity Score Matching (PSM) is a useful method to reduce the impact of Treatment-Selection Bias in the estimation of causal effects in observational studies. After matching, the PSM significantly reduces the sample under investigation, which may lead to other possible biases (due to overfitting, excess of covariation or a reduced number of observations). In this sense, we wanted to analyze the behavior of this PSM compared with other widely used methods to deal with non-comparable groups, such as the Multivariate Regression Model (MRM). Monte Carlo Simulations are made to construct groups with different effects in order to compare the behavior of PSM and MRM estimating these effects. In addition, the Treatment Selection Bias reduction for the PSM is calculated. With the PSM a reduction in the Treatment Selection Bias is achieved (0.983 [0.982, 0.984]), with a reduction in the Relative Real Treatment Effect Estimation Error (0.216 [0.2, 0.232]), but despite this bias reduction and estimation error reduction, the MRM reduces this estimation error significantly more than the PSM (0.539 [0.522, 0.556], p < 0.001). In addition, the PSM leads to a 30% reduction in the sample. This loss of information derived from the matching process may lead to another not known bias and thus to the inaccuracy of the effect estimation compared with the MRM.

Estimation of Relative Vaccine Effectiveness in Influenza: A Systematic Review of Methodology

BACKGROUND

When new vaccine components or platforms are developed, they will typically need to demonstrate noninferiority or superiority over existing products, resulting in the assessment of relative vaccine effectiveness (rVE). This review aims to identify how rVE evaluation is being performed in studies of influenza to inform a more standardized approach.

METHODS

We conducted a systematic search on PubMed, Google Scholar, and Web of Science for studies reporting rVE comparing vaccine components, dose, or vaccination schedules. We screened titles, abstracts, full texts, and references to identify relevant articles. We extracted information on the study design, relative comparison made, and the definition and statistical approach used to estimate rVE in each study.

RESULTS

We identified 63 articles assessing rVE in influenza virus. Studies compared multiple vaccine components (n = 38), two or more doses of the same vaccine (n = 17), or vaccination timing or history (n = 9). One study compared a range of vaccine components and doses. Nearly two-thirds of all studies controlled for age, and nearly half for comorbidities, region, and sex. Assessment of 12 studies presenting both absolute and relative effect estimates suggested proportionality in the effects, resulting in implications for the interpretation of rVE effects.

CONCLUSIONS

Approaches to rVE evaluation in practice is highly varied, with improvements in reporting required in many cases. Extensive consideration of methodologic issues relating to rVE is needed, including the stability of estimates and the impact of confounding structure on the validity of rVE estimates.

Prognostic significance of wait time for radical radiotherapy in locoregionally advanced nasopharyngeal carcinoma

BACKGROUND

The prognostic significance of wait time between definite diagnosis and initial radical radiotherapy is not well established in patients with locoregionally advanced nasopharyngeal carcinoma (LA-NPC) receiving both induction chemotherapy (IC) and concurrent chemoradiotherapy (CCRT).

METHODS

From 2010 to 2018, 648 patients with LA-NPC treated with IC followed by CCRT were included.

RESULTS

A total of 172 pairs of patients with LA-NPC were selected by propensity score matching (PSM). Compared to patients with an acceptable wait time (≤75 days), patients with a prolonged wait time (>75 days) had a significant lower 5-year DMFS rate (86.6% vs. 74.1%, p = 0.006). Subgroup analyses indicated that the unfavorable effects of longer waiting times were mainly seen among stage IVa patients.

CONCLUSIONS

A prolonged wait time (>75 days) between definite diagnosis and initial radical radiotherapy has negative prognostic effects on patients with LA-NPC receiving IC plus CCRT, particularly those with IVa stage.