Improved Outcomes with Heavy Silicone Oil in Complex Primary Retinal Detachment: A Large Multicenter Matched Cohort Study

PURPOSE

To establish whether Densiron 68, a heavier-than-water endotamponade agent, is an effective alternative to conventional light silicone oil in primary rhegmatogenous retinal detachment (RD) surgery for eyes with inferior breaks in the detached retina and severe proliferative vitreoretinopathy (PVR).

DESIGN

Cohort study of routinely collected data from the European Society of Retina Specialists and British and Eire Association of Vitreoretinal Surgeons vitreoretinal database between 2015 and 2022.

PARTICIPANTS

All consecutive eyes that underwent primary rhegmatogenous RD surgery using Densiron 68 or light silicone oil as an internal tamponade agent.

METHODS

To minimize confounding bias, we undertook 2:1 nearest-neighbor matching on inferior breaks, large inferior rhegmatogenous RDs, PVR, and, for visual analyses, baseline visual acuity (VA) between treatment groups. We fit regression models including prognostically relevant covariates, treatment-covariate interactions, and matching weights. We used g-computation with cluster-robust methods to estimate marginal effects. For nonlinear models, we calculated confidence intervals (CIs) using bias-corrected cluster bootstrapping with 9999 replications.

MAIN OUTCOME MEASURES

Presence of a fully attached retina and VA at least 2 months after oil removal.

RESULTS

Of 1061 eyes enrolled, 426 and 239 were included in our matched samples for anatomic and visual outcome analyses, respectively. The primary success rate was higher in the Densiron 68 group (113 of 142; 80%) compared with the light silicone oil group (180 of 284; 63%), with an adjusted odds ratio of 1.90 (95% CI, 1.63-2.23, P < 0.001). We also observed a significant improvement favoring Densiron 68 of -0.26 logarithm of the minimum angle of resolution (logMAR) in postoperative VA between the 2 groups (95% CI, -0.43 to -0.10, P = 0.002). The anatomic benefit of using Densiron 68 in eyes with inferior retinal breaks and large detachments was more pronounced among eyes with PVR grade C. We found no evidence of visual effect moderation by anatomic outcome or foveal attachment.

CONCLUSIONS

Densiron achieved higher anatomic success rates and improved visual outcomes compared with conventional light silicone oil in eyes with inferior retinal pathology and severe PVR.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Augmenting external control arms using Bayesian borrowing: a case study in first-line non-small cell lung cancer

Aim: This study aimed to improve comparative effectiveness estimates and discuss challenges encountered through the application of Bayesian borrowing (BB) methods to augment an external control arm (ECA) constructed from real-world data (RWD) using historical clinical trial data in first-line non-small-cell lung cancer (NSCLC). Materials & methods: An ECA for a randomized controlled trial (RCT) in first-line NSCLC was constructed using ConcertAI Patient360™ to assess chemotherapy with or without cetuximab, in the bevacizumab-inappropriate subpopulation. Cardinality matching was used to match patient characteristics between the treatment arm (cetuximab + chemotherapy) and ECA. Overall survival (OS) was assessed as the primary outcome using Cox proportional hazards (PH). BB was conducted using a static power prior under a Weibull PH parameterization with borrowing weights from 0.0 to 1.0 and augmentation of the ECA from a historical control trial. Results: The constructed ECA yielded a higher overall survival (OS) hazard ratio (HR) (HR = 1.53; 95% CI: 1.21-1.93) than observed in the matched population of the RCT (HR = 0.91; 95% CI: 0.73-1.13). The OS HR decreased through the incorporation of BB (HR = 1.30; 95% CI: 1.08-1.54, borrowing weight = 1.0). BB was applied to augment the RCT control arm via a historical control which improved the precision of the observed HR estimate (1.03; 95% CI: 0.86-1.22, borrowing weight = 1.0), in comparison to the matched population of the RCT alone. Conclusion: In this study, the RWD ECA was unable to successfully replicate the OS estimates from the matched population of the selected RCT. The inability to replicate could be due to unmeasured confounding and variations in time-periods, follow-up and subsequent therapy. Despite these findings, we demonstrate how BB can improve precision of comparative effectiveness estimates, potentially aid as a bias assessment tool and mitigate challenges of traditional methods when appropriate external data sources are available.

Unveiling peripheral neuropathy and cognitive dysfunction in diabetes: an observational and proof-of-concept study with video games and sensor-equipped insoles

Background

Proactive screening for cognitive dysfunction (CD) and peripheral neuropathy (PNP) in elderly patients with diabetes mellitus is essential for early intervention, yet clinical examination is time-consuming and prone to bias.

Objective

We aimed to investigate PNP and CD in a diabetes cohort and explore the possibility of identifying key features linked with the respective conditions by machine learning algorithms applied to data sets obtained in playful games controlled by sensor-equipped insoles.

Methods

In a cohort of patients diagnosed with diabetes (n=261) aged over 50 years PNP and CD were diagnosed based on complete physical examination (neuropathy symptom and disability scores, and Montreal Cognitive Assessment). In an observational and proof-of-concept study patients performed a 15 min lasting gaming session encompassing tutorials and four video games with 5,244 predefined features. The steering of video games was solely achieved by modulating plantar pressure values, which were measured by sensor-equipped insoles in real-time. Data sets were used to identify key features indicating game performance with correlation regarding CD and PNP findings. Thereby, machine learning models (e.g. gradient boosting and lasso and elastic-net regularized generalized linear models) were set up to distinguish patients in the different groups.

Results

PNP was diagnosed in 59% (n=153), CD in 34% (n=89) of participants, and 23% (n=61) suffered from both conditions. Multivariable regression analyses suggested that PNP was positively associated with CD in patients with diabetes (adjusted odds ratio = 1.95; 95% confidence interval: 1.03-3.76; P=0.04). Predictive game features were identified that significantly correlated with CD (n=59), PNP (n=40), or both (n=59). These features allowed to set up classification models that were enriched by individual risk profiles (i.e. gender, age, weight, BMI, diabetes type, and diabetes duration). The obtained models yielded good predictive performance with the area under the receiver-operating-characteristic curves reaching 0.95 for CD without PNP, 0.83 for PNP without CD, and 0.84 for CD and PNP combined.

Conclusions

The video game-based assessment was able to categorize patients with CD and/or PNP with high accuracy. Future studies with larger cohorts are needed to validate these results and potentially enhance the discriminative power of video games.

Community exposure to armed conflict and subsequent onset of alcohol use disorder

AIMS

To measure the independent consequences of community-level armed conflict beatings on alcohol use disorders (AUD) among males in Nepal during and after the 2000-2006 conflict.

DESIGN

A population-representative panel study from Nepal, with precise measures of community-level violent events and subsequent individual-level AUD in males. Females were not included because of low AUD prevalence.

SETTING

Chitwan, Nepal.

PARTICIPANTS

Four thousand eight hundred seventy-six males from 151 neighborhoods, systematically selected and representative of Western Chitwan. All residents aged 15-59 were eligible (response rate 93%).

MEASUREMENTS

Measures of beatings in the community during the conflict (2000-2006), including the date and distance away, were gathered through neighborhood reports, geo-location and official resources, then linked to respondents' life histories of AUD (collected in 2016-2018) using the Nepal-specific Composite International Diagnostic Interview with life history calendar. Beatings nearby predict the subsequent onset of AUD during and after the armed conflict. Data were analyzed in 2021-2022.

FINDINGS

Cohort-specific, discrete-time models revealed that within the youngest cohort (born 1992-2001), those living in neighborhoods where armed conflict beatings occurred were more likely to develop AUD compared with those in other neighborhoods (odds ratio = 1.66; 95% confidence interval = 1.02-2.71). In this cohort, a multilevel matching analysis designed to simulate a randomized trial showed the post-conflict incidence of AUD for those living in neighborhoods with any armed conflict beatings was 9.5% compared with 5.3% in the matched sample with no beatings.

CONCLUSIONS

Among male children living in Chitwan, Nepal during the 2000-2006 armed conflict, living in a neighborhood where armed conflict beatings occurred is associated with increased odds of developing subsequent alcohol use disorder. This association was independent of personal exposure to beatings and other mental disorders.

Stratified analysis in comparative effectiveness studies that emulate randomized trials

PURPOSE

For observational cohort studies that employ matching by propensity scores (PS), preliminary stratification by consequential predictors of outcome better emulates stratified randomization and potentially reduces variance and bias through relaxed dependence on modeling assumptions. We assessed the impact of pre-stratification in two real-life examples. For both, prior evidence from placebo-controlled randomized clinical trials (RCTs) suggested small or no risk reduction, but observational analysis suggested protection, presumably the result of confounding bias.

STUDY DESIGN AND SETTING

The study populations consisted of Medicare beneficiaries (2014-18) with type 2 diabetes initiating either (i) empagliflozin versus dipeptidyl peptidase-4 inhibitors (DPP-4i) or (ii) empagliflozin versus glucagon-like peptide-1 receptor agonists (GLP-1RA). The outcome was myocardial infarction or stroke. We estimated hazard ratios (HR) and rate differences (RD) after controlling for 143 pre-exposure covariates via 1:1 PS matching after (1) PS estimation in the total cohort (total-cohort PS-matching) and (2) PS estimation separately by baseline cardiovascular disease (stratified PS matching).

RESULTS

Stratified PS matching resulted in HRs that exceeded those from total-cohort PS-matching by 13% and 9%, respectively, for the comparisons of empagliflozin to DPP-4i and GLP-1RA. Against both comparators, HRs and RDs after stratified PS matching were closer to the null, with slightly higher variances (2%-3%) than those after total-cohort PS matching.

CONCLUSION

Stratified PS matching produced effect estimates closer to the expected trial findings than total-cohort PS matching. The price paid in increased variance was minimal.

Biologic versus synthetic prosthesis for chest wall reconstruction: a matched analysis

OBJECTIVES

The aim of this study was to compare postoperative outcomes between biologic and synthetic reconstructions after chest wall resection in a matched cohort.

METHODS

All patients who underwent reconstruction after full-thickness chest wall resection from 2000 to 2022 were reviewed and stratified by prosthesis type (biologic or synthetic). Biologic prostheses were of biologic origin or were fully absorbable and incorporable. Integer matching was performed to reduce confounding. The study end point was surgical site complications requiring reoperation. Multivariable analysis was performed to identify associated risk factors.

RESULTS

In total, 438 patients underwent prosthetic chest wall reconstruction (unmatched: biologic, n = 49; synthetic, n = 389; matched: biologic, n = 46; synthetic, n = 46). After matching, the median (interquartile range) defect size was 83 cm2 (50-142) for the biologic group and 90 cm2 (48-146) for the synthetic group (P = 0.97). Myocutaneous flaps were used in 33% of biologic reconstructions (n = 15) and 33% of synthetic reconstructions (n = 15) in the matched cohort (P = 0.99). The incidence of surgical site complications requiring reoperation was not significantly different between biologic and synthetic reconstructions in the unmatched (3 [6%] vs 29 [7%]; P = 0.99) and matched (2 [4%] vs 4 [9%]; P = 0.68) cohorts. On the multivariable analysis, operative time [adjusted odds ratio (aOR) = 1.01, 95% confidence interval (CI), 1.00-1.01; P = 0.006] and operative blood loss (aOR = 1.00, 95% CI, 1.00-1.00]; P = 0.012) were associated with higher rates of surgical site complications requiring reoperation; microvascular free flaps (aOR = 0.03, 95% CI, 0.00-0.42; P = 0.024) were associated with lower rates.

CONCLUSIONS

The incidence of surgical site complications requiring reoperation was not significantly different between biologic and synthetic prostheses in chest wall reconstructions.

Firearm Injuries In Children And Adolescents: Health And Economic Consequences Among Survivors And Family Members

More US children and adolescents today die from firearms than any other cause, and many more sustain firearm injuries and survive. The clinical and economic impact of these firearm injuries on survivors and family members remains poorly understood. Using 2007-21 commercial health insurance claims data, we studied 2,052 child and adolescent survivors compared to 9,983 matched controls who did not incur firearm injuries, along with 6,209 family members of survivors compared to 29,877 matched controls, and 265 family members of decedents compared to 1,263 matched controls. Through one year after firearm injury, child and adolescent survivors experienced a 117 percent increase in pain disorders, a 68 percent increase in psychiatric disorders, and a 144 percent increase in substance use disorders relative to the controls. Survivors' health care spending increased by an average of $34,884-a 17.1-fold increase-with 95 percent paid by insurers or employers. Parents of survivors experienced a 30-31 percent increase in psychiatric disorders, with 75 percent more mental health visits by mothers, and 5-14 percent reductions in mothers' and siblings' routine medical care. Family members of decedents experienced substantially larger 2.3- to 5.3-fold increases in psychiatric disorders, with at least 15.3-fold more mental health visits among parents. Firearm injuries in youth have notable health implications for the whole family, along with large effects on societal spending.

Effects of Remote Patient Monitoring Use on Care Outcomes Among Medicare Patients With Hypertension : An Observational Study

BACKGROUND

Remote patient monitoring (RPM) is a promising tool for improving chronic disease management. Use of RPM for hypertension monitoring is growing rapidly, raising concerns about increased spending. However, the effects of RPM are still unclear.

OBJECTIVE

To estimate RPM's effect on hypertension care and spending.

DESIGN

Matched observational study emulating a longitudinal, cluster randomized trial. After matching, effect estimates were derived from a regression analysis comparing changes in outcomes from 2019 to 2021 for patients with hypertension at high-RPM practices versus those at matched control practices with little RPM use.

SETTING

Traditional Medicare.

PATIENTS

Patients with hypertension.

INTERVENTION

Receipt of care at a high-RPM practice.

MEASUREMENTS

Primary outcomes included hypertension medication use (medication fills, adherence, and unique medications received), outpatient visit use, testing and imaging use, hypertension-related acute care use, and total hypertension-related spending.

RESULTS

192 high-RPM practices (with 19 978 patients with hypertension) were matched to 942 low-RPM control practices (with 95 029 patients with hypertension). Compared with patients with hypertension at matched low-RPM practices, patients with hypertension at high-RPM practices had a 3.3% (95% CI, 1.9% to 4.8%) relative increase in hypertension medication fills, a 1.6% (CI, 0.7% to 2.5%) increase in days' supply, and a 1.3% (CI, 0.2% to 2.4%) increase in unique medications received. Patients at high-RPM practices also had fewer hypertension-related acute care encounters (-9.3% [CI, -20.6% to 2.1%]) and reduced testing use (-5.9% [CI, -11.9% to 0.0%]). However, these patients also saw increases in primary care physician outpatient visits (7.2% [CI, -0.1% to 14.6%]) and a $274 [CI, $165 to $384]) increase in total hypertension-related spending.

LIMITATION

Lacked blood pressure data; residual confounding.

CONCLUSION

Patients in high-RPM practices had improved hypertension care outcomes but increased spending.

PRIMARY FUNDING SOURCE

National Institute of Neurological Disorders and Stroke.

Action needed to make carbon offsets from forest conservation work for climate change mitigation

Carbon offsets from voluntary avoided-deforestation projects are generated on the basis of performance in relation to ex ante deforestation baselines. We examined the effects of 26 such project sites in six countries on three continents using synthetic control methods for causal inference. We found that most projects have not significantly reduced deforestation. For projects that did, reductions were substantially lower than claimed. This reflects differences between the project ex ante baselines and ex post counterfactuals according to observed deforestation in control areas. Methodologies used to construct deforestation baselines for carbon offset interventions need urgent revisions to correctly attribute reduced deforestation to the projects, thus maintaining both incentives for forest conservation and the integrity of global carbon accounting.

An overview of propensity score matching methods for clustered data

Propensity score matching is commonly used in observational studies to control for confounding and estimate the causal effects of a treatment or exposure. Frequently, in observational studies data are clustered, which adds to the complexity of using propensity score techniques. In this article, we give an overview of propensity score matching methods for clustered data, and highlight how propensity score matching can be used to account for not just measured confounders, but also unmeasured cluster level confounders. We also consider using machine learning methods such as generalized boosted models to estimate the propensity score and show that accounting for clustering when using these methods can greatly reduce the performance, particularly when there are a large number of clusters and a small number of subjects per cluster. In order to get around this we highlight scenarios where it may be possible to control for measured covariates using propensity score matching, while using fixed effects regression in the outcome model to control for cluster level covariates. Using simulation studies we compare the performance of different propensity score matching methods for clustered data across a number of different settings. Finally, as an illustrative example we apply propensity score matching methods for clustered data to study the causal effect of aspirin on hearing deterioration using data from the conservation of hearing study.

Robust weights that optimally balance confounders for estimating marginal hazard ratios

Covariate balance is crucial in obtaining unbiased estimates of treatment effects in observational studies. Methods that target covariate balance have been successfully proposed and largely applied to estimate treatment effects on continuous outcomes. However, in many medical and epidemiological applications, the interest lies in estimating treatment effects on time-to-event outcomes. With this type of data, one of the most common estimands of interest is the marginal hazard ratio of the Cox proportional hazards model. In this article, we start by presenting robust orthogonality weights, a set of weights obtained by solving a quadratic constrained optimization problem that maximizes precision while constraining covariate balance defined as the correlation between confounders and treatment. By doing so, robust orthogonality weights optimally deal with both binary and continuous treatments. We then evaluate the performance of the proposed weights in estimating marginal hazard ratios of binary and continuous treatments with time-to-event outcomes in a simulation study. We finally apply robust orthogonality weights in the evaluation of the effect of hormone therapy on time to coronary heart disease and on the effect of red meat consumption on time to colon cancer among 24,069 postmenopausal women enrolled in the Women's Health Initiative observational study.

Examining sources of post-acute care inequities with layered target matching

OBJECTIVE

To examine factors associated with racial inequities in discharge location, skilled nursing facility (SNF) utilization, and readmissions.

DATA SOURCES

A 20% sample of longitudinal Medicare claims from 2016 to 2018.

STUDY DESIGN

We present layered target matching, a method for studying sources of inequities. Layered target matching examines a fixed target population profile representing any race, ethnicity, or vulnerable population, sequentially adjusting for sets of characteristics that may contribute to inequities these groups endure. We use the method to study racial inequities in post-acute care use and readmissions.

DATA COLLECTION/EXTRACTION METHODS

We studied Black and non-Hispanic White fee-for-service Medicare beneficiaries aged 66+ admitted to short-term acute-care hospitals for qualifying diagnoses or procedures between January 1, 2016 and November 30, 2018.

PRINCIPAL FINDINGS

Admitted Black patients tended to be younger, had significantly higher rates of risk factors such as diabetes, stroke, or renal disease, and were much more frequently admitted to large or academic hospitals. Relative to demographically similar White patients, Black patients were significantly more likely to be discharged to SNFs (21.8% vs. 19.3%, difference = 2.5%, p < 0.0001) and to receive any SNF care within 30 days of discharge (25.3% vs. 22.4%, difference = 2.9%, p < 0.0001). Black patients were also significantly more likely to experience 30-day readmission (18.7% vs. 14.5%, difference = 4.2%, p < 0.0001). Differences in reasons for hospitalization and risk factors explained most of the differences in discharge location, post-acute care use, and readmission rates, while additional adjustment for differences in hospital characteristics and complications made little difference for any of the measures studied.

CONCLUSIONS

We found significant Black-White differences in discharge to SNFs, SNF utilization, and readmission rates. Using layered target matching, we found that differences in risk factors and reasons for hospitalization explained most of these differences, while differences in hospitals did not materially impact the differences.

Evaluating the Efficacy of Povidone-Iodine Solution Infection Prophylaxis in Immediate Tissue Expander-Based Breast Reconstruction: A Controlled Retrospective Analysis

Background: There is currently no consensus among plastic surgeons regarding the optimal infection prophylaxis for immediate tissue expander placement following mastectomy. The goal of this study was to determine whether irrigation with 1 L of standard triple antibiotic solution (TAS) can achieve similar infection rates compared to a regimen of 180 mL of TAS with povidone-iodine solution (Betadine) painted on the field immediately prior to the placement of the expander. Methods: The 2 regimens were compared via retrospective propensity matching of all patients of the 2 senior authors who underwent bilateral tissue expander placement immediately following mastectomy with one of 3 mastectomy surgeons from January 2013 to December 2019 (n = 281). Groups were controlled for mastectomy surgeon, mastectomy type, mastectomy weight, age, race, body mass index, diabetes, hypertension, smoking, smoking status, prepectoral/subpectoral placement, use of acellular dermal matrix, operating room time, and duration of postoperative antibiotics. Results: Compared to the Betadine cohort (n = 65), the non-Betadine cohort (n = 65) experienced a similar rate of infections (13.8% vs 12.3%, P = 1.00), including major injections requiring intravenous antibiotic treatment (10.8% vs 9.2%, P = 1.00), after propensity matching. Infections in the non-Betadine cohort did not grow different bacteria on culture, require different antibiotic coverage, or result in prolonged duration of average antibiotic therapy (12.0 days vs 19.3 days, P = .19). Rates of subsequent expander washout and exchange (P = 1.00) and overall complications that required return to the operating room (P = .826) were similar between groups. Conclusion: The addition of Betadine solution to TAS added no benefit to infection prophylaxis or reduction of surgical complications in immediate tissue expander placement procedures.

Effect of Hypoxemia on Outcome in Respiratory Failure Supported With Extracorporeal Membrane Oxygenation: A Cardinality Matched Cohort Study

Venovenous extracorporeal membrane oxygenation (ECMO) is recommended in adult patients with refractory acute respiratory failure (ARF), but there is limited evidence for its use in patients with less severe hypoxemia. Prior research has suggested a lower PaO 2 /FiO 2 at cannulation is associated with higher short-term mortality, but it is unclear whether this is due to less severe illness or a potential benefit of earlier ECMO support. In this exploratory cardinality-matched observational cohort study, we matched 668 patients who received venovenous ECMO as part of a national severe respiratory failure service into cohorts of "less severe" and "very severe" hypoxemia based on the median PaO 2 /FiO 2 at ECMO institution of 68 mmHg. Before matching, ICU mortality was 19% in the 'less severe' hypoxemia group and 28% in the "very severe" hypoxemia group (RR for mortality = 0.69, 95% CI 0.54-0.88). After matching on key prognostic variables including underlying diagnosis, this difference remained statistically present but smaller: (23% vs. 30%, RR = 0.76, 95% CI 0.59-0.99). This may suggest the observed survival benefit of venovenous ECMO is not solely due to reduced disease severity. Further research is warranted to examine the potential role of ECMO in ARF patients with less severe hypoxemia.

A Comparison of Caregiver and Patient Preferences for Treating Duchenne Muscular Dystrophy

Background and Objectives

Caregivers routinely inform medical and regulatory decision making in rare pediatric diseases. While differences in treatment preferences across caregivers and patients have been observed for Duchenne muscular dystrophy, this evidence was limited by small samples of patients and results were confounded by patient age and disease progression. We tested caregiver and patient preference concordance for treating Duchenne.

Methods

Preferences and demographic/clinical information from 115 caregivers and 107 patients were collected in an international study (response = 80%) using a previously developed discrete-choice experiment consisting of 12 experimentally controlled choice tasks. Each task presented two profiles that varied across four attributes: disease progression, drug failure probability, kidney damage risk, and fracture risk. Caregivers and patients were matched 1:1 based on patient age. We tested for concordance across each task and by comparing caregivers’ and patients’ maximum acceptable risk of drug failure, kidney damage, and fracture for a slowing of disease progression.

Results

The final analysis included 77 caregivers and 77 patients. No differences were observed in nationality (p = 0.969), disease stage (p = 0.180), or demographic/clinical factors (p = 0.093–0.857); however, patients were more optimistic (p = 0.030). Caregivers and patients chose similarly across tasks (p = 0.101–0.993). To slow disease progression by 1 year, caregivers and patients would tolerate a 9% and 11% increase in drug failure probability, respectively (p = 0.267). Alternatively, they would accept a 3% and 4% increase in the risk of kidney damage (p = 0.719) or a 15% and 20% increase in the risk of fracture (p = 0.534).

Conclusions

Caregivers and patients had concordant preferences for treating Duchenne. Providers and regulators can trust both caregiver and patient report of preferences to inform medical decision making.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40271-022-00574-y.

Profile Matching for the Generalization and Personalization of Causal Inferences

We introduce profile matching, a multivariate matching method for randomized experiments and observational studies that finds the largest possible unweighted samples across multiple treatment groups that are balanced relative to a covariate profile. This covariate profile can represent a specific population or a target individual, facilitating the generalization and personalization of causal inferences. For generalization, because the profile often amounts to summary statistics for a target population, profile matching does not always require accessing individual-level data, which may be unavailable for confidentiality reasons. For personalization, the profile comprises the characteristics of a single individual. Profile matching achieves covariate balance by construction, but unlike existing approaches to matching, it does not require specifying a matching ratio, as this is implicitly optimized for the data. The method can also be used for the selection of units for study follow-up, and it readily applies to multivalued treatments with many treatment categories. We evaluate the performance of profile matching in a simulation study of the generalization of a randomized trial to a target population. We further illustrate this method in an exploratory observational study of the relationship between opioid use and mental health outcomes. We analyze these relationships for three covariate profiles representing: (i) sexual minorities, (ii) the Appalachian United States, and (iii) the characteristics of a hypothetical vulnerable patient. The method can be implemented via the new function profmatch in the designmatch package for R, for which we provide a step-by-step tutorial.

Changes in Health Care Spending, Use, and Clinical Outcomes After Nonfatal Firearm Injuries Among Survivors and Family Members : A Cohort Study

BACKGROUND

Despite increasing awareness of firearm-related deaths, evidence on the clinical and economic implications of nonfatal firearm injuries is limited.

OBJECTIVE

To measure changes in clinical and economic outcomes after nonfatal firearm injuries among survivors and their family members.

DESIGN

Cohort study.

SETTING

MarketScan Medicare and commercial claims data, 2008 to 2018.

PARTICIPANTS

6498 survivors of firearm injuries matched to 32 490 control participants and 12 489 family members of survivors matched to 62 445 control participants.

INTERVENTION

Exposure to nonfatal firearm injury as a survivor or family member of a survivor.

MEASUREMENTS

Changes in health care spending, use, and morbidity from preinjury through 1 year postinjury relative to control participants, on average and by type and severity of firearm injury.

RESULTS

After nonfatal firearm injury, medical spending increased $2495 per person per month (402%) and cost sharing increased $102 per person per month (176%) among survivors relative to control participants (P < 0.001) in the first year after injury, driven by an increase in the first month of $25 554 (4122%) in spending and $1112 (1917%) in cost sharing per survivor (P < 0.001). All categories of health care use increased relative to the control group. Survivors had a 40% increase in pain diagnoses, a 51% increase in psychiatric disorders, and an 85% increase in substance use disorders after firearm injury relative to control participants (P < 0.001), accompanied by increased pain and psychiatric medications. Family members had a 12% increase in psychiatric disorders relative to their control participants (P = 0.003). These overall clinical and economic changes were driven by intentional firearm injuries and more severe firearm injuries.

LIMITATION

Precision of diagnostic codes and generalizability to other patient populations, including Medicaid and uninsured patients.

CONCLUSION

In survivors, nonfatal firearm injuries led to increases in psychiatric disorders, substance use disorders, and pain diagnoses, alongside substantial increases in health care spending and use. In addition, mental health worsened among family members.

PRIMARY FUNDING SOURCE

National Institutes of Health.

Community-Level Social Support Infrastructure and Adult Onset of Major Depressive Disorder in a South Asian Postconflict Setting

IMPORTANCE

Individual-level social support protects against major depressive disorder (MDD) among adults exposed to trauma. Little is known about the consequences of community-level interventions in the general population.

OBJECTIVE

To determine the potential consequences of neighborhood social infrastructure on incident MDD in a high-risk general population.

DESIGN, SETTING, AND PARTICIPANTS

This longitudinal, multilevel study estimated associations between a neighborhood-level program in a case-control design and subsequent individual outcomes across 10 years (2006-2015) in a cohort of young adults. Exogenously placed social programs simulate natural experiment conditions in a high-poverty population experiencing armed conflict (1998-2006). The western Chitwan valley in Nepal has a general population at high risk of MDD, with neighborhoods exposed to interventions to improve social support. From a random sample (response rate 93%) selected to represent the general population in 2016, participants aged 25 to 34 years in 2006 were studied. These individuals resided within 149 neighborhoods that varied in their availability of active social support programs. The analyses were conducted between October 2020 and November 2021.

EXPOSURES

The Small Farmers Development Program (SFDP) uses shared, joint liability financial credit among neighbors to build social capital and cohesion within neighborhoods.

MAIN OUTCOMES AND MEASURES

Onset of DSM-IV MDD after the conflict, assessed by the Nepal-specific, clinically validated World Mental Health Composite International Diagnostic Interview with a life history calendar. The hypothesis tested was that exposure to SFDP reduced adult onset of MDD.

RESULTS

Of the 1917 survey participants, 886 (46.2%) were women, and 856 (44.7%) were of Brahmin or Chhetri ethnicity. Of the 149 neighborhoods, 21 had an active SFDP group, and 156 of 1917 (8.1%) participants experienced MDD between 2006 and 2015. Discrete-time hazard models showed participants living in neighborhoods with an SFDP experienced incident MDD at nearly half the rate as others (odds ratio = 0.55; 95% CI, 0.30-1.02; P = .06). A multivariate, multilevel matching analysis showed the incidence of MDD among adults living in neighborhoods with an SFDP was 19 of 256 (7.4%), compared with 33 of 256 (12.9%) in the matched sample with no SFDP (z = 2.05; P = .04).

CONCLUSIONS AND RELEVANCE

Living in a neighborhood with community-level social support infrastructure was associated with reduced subsequent rates of adult-onset MDD, even in this high-risk population. Investments in such infrastructure may reduce population-level MDD, supporting clinical focus on potentially unpreventable cases.

Autologous hematopoietic stem cell transplantation vs low-dose immunosuppression in secondary-progressive multiple sclerosis

Background and purpose

Effectiveness of autologous haematopoietic stem cell transplantation (AHSCT) in relapsing–remitting multiple sclerosis (MS) is well known, but in secondary–progressive (SP)‐MS it is still controversial. Therefore, AHSCT activity was evaluated in SP‐MS using low‐dose immunosuppression with cyclophosphamide (Cy) as a comparative treatment.

Methods

In this retrospective monocentric 1:2 matched study, SP‐MS patients were treated with intermediate‐intensity AHSCT (cases) or intravenous pulses of Cy (controls) at a single academic centre in Florence. Controls were selected according to baseline characteristics adopting cardinality matching after trimming on the estimated propensity score. Kaplan–Meier and Cox analyses were used to estimate survival free from relapses (R‐FS), survival free from disability progression (P‐FS), and no evidence of disease activity 2 (NEDA‐2).

Results

A total of 93 SP‐MS patients were included: 31 AHSCT, 62 Cy. Mean follow‐up was 99 months in the AHSCT group and 91 months in the Cy group. R‐FS was higher in AHSCT compared to Cy patients: at Year 5, 100% versus 52%, respectively (p < 0.0001). P‐FS did not differ between the groups (at Year 5: 70% in AHSCT and 81% in Cy, p = 0.572), nor did NEDA‐2 (p = 0.379). A sensitivity analysis including only the 31 “best‐matched” controls confirmed these results. Three neoplasms (2 Cy, 1 AHSCT) and two fatalities (2 Cy) occurred.

Conclusions

This study provides Class III evidence, in SP‐MS, on the superior effectiveness of AHSCT compared to Cy on relapse activity, without differences on disability accrual. Although the suppression of relapses was observed in the AHSCT group only, AHSCT did not show advantages over Cy on disability, suggesting that in SP‐MS disability progression becomes based more on noninflammatory neurodegeneration than on inflammation.

Matching One Sample According to Two Criteria in Observational Studies

Multivariate matching has two goals: (i) to construct treated and control groups that have similar distributions of observed covariates, and (ii) to produce matched pairs or sets that are homogeneous in a few key covariates. When there are only a few binary covariates, both goals may be achieved by matching exactly for these few covariates. Commonly, however, there are many covariates, so goals (i) and (ii) come apart, and must be achieved by different means. As is also true in a randomized experiment, similar distributions can be achieved for a high-dimensional covariate, but close pairs can be achieved for only a few covariates. We introduce a new polynomial-time method for achieving both goals that substantially generalizes several existing methods; in particular, it can minimize the earthmover distance between two marginal distributions. The method involves minimum cost flow optimization in a network built around a tripartite graph, unlike the usual network built around a bipartite graph. In the tripartite graph, treated subjects appear twice, on the far left and the far right, with controls sandwiched between them, and efforts to balance covariates are represented on the right, while efforts to find close individual pairs are represented on the left. In this way, the two efforts may be pursued simultaneously without conflict. The method is applied to our on-going study in the Medicare population of the relationship between superior nursing and sepsis mortality. The match2C package in R implements the method.

Differences Between Patients With Intermittent Claudication and Critical Limb Ischemia Undergoing Endovascular Intervention: Insights From the Excellence in Peripheral Artery Disease Registry

BACKGROUND

There are limited data on differences in angiographic distribution of peripheral artery disease and endovascular revascularization strategies in patients presenting with intermittent claudication (IC) and critical limb ischemia (CLI). We aimed to compare anatomic features, treatment strategies, and clinical outcomes between patients with IC and CLI undergoing endovascular revascularization.

METHODS

We examined 3326 patients enrolled in the Excellence in Peripheral Artery Disease registry from 2006 to 2019 who were referred for endovascular intervention for IC (n=1983) or CLI (n=1343). The primary outcome was 1-year major adverse limb events, which included death, repeat target limb revascularization, or target limb amputation.

RESULTS

Patients with CLI were older and more likely to have diabetes and chronic kidney disease and less likely to receive optimal medical therapy compared with IC. Patients with IC had higher femoropopliteal artery interventions (IC 87% versus CLI 65%; P<0.001), while below the knee interventions were more frequent in CLI (CLI 47% versus IC 12%; P<0.001). Patients with CLI were more likely to have multilevel peripheral artery disease (CLI 32% versus IC 15%, P<0.001). Patients with IC were predominantly revascularized with stents (IC 48% versus CLI 37%; P<0.001) while balloon angioplasty was more frequent in CLI (CLI 37% versus IC 25%; P<0.001). All-cause mortality was higher in patients with CLI (CLI 4% versus IC 2%; P=0.014). Major adverse limb event rates for patients with IC and CLI were 16% and 26%, respectively (P<0.001) and remained higher in CLI after multivariable adjustment of baseline risk factors.

CONCLUSIONS

Patients with IC and CLI have significant anatomic, lesion, and treatment differences with significantly higher mortality and adverse limb outcomes in CLI. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT01904851. Graphic Abstract: A graphic abstract is available for this article.

Association of Hospital Telestroke Adoption With Changes in Initial Hospital Presentation and Transfers Among Patients With Stroke and Transient Ischemic Attacks

IMPORTANCE

It has been proposed that the implementation of telestroke services (a web-based approach to using video telecommunication to treat patients with stroke before hospital admission) changes where patients with stroke symptoms receive care, but this proposal has not been rigorously assessed.

OBJECTIVE

To assess whether the implementation of telestroke services is associated with changes in where and how patients initially present with stroke symptoms, in their decision to be transferred to another hospital, and which hospitals they are transferred to.

DESIGN, SETTING, AND PARTICIPANTS

This cross-sectional study compared changes in stroke systems of care between a sample of 593 US hospitals that adopted telestroke during the period from 2009 to 2016 but were not comprehensive stroke centers, major teaching hospitals, or thrombectomy-capable hospitals vs 593 matched control hospitals without telestroke based on rural location, critical access hospital status, bed size, primary stroke center status, presence of hospital alternatives in the community, hospital stroke volume, census region, and ownership. With the use of data on 100% of Medicare fee-for-service beneficiaries, all stroke and transient ischemic attack admissions from 2008 to 2018 were identified.

EXPOSURES

For each hospital pair (telestroke plus matched control), the telestroke hospital's implementation date and difference-in-differences approach were used to quantify the association between telestroke implementation and changes in care from 2 years before implementation to 2 years after implementation. Models also controlled for differences in observed patient characteristics.

MAIN OUTCOMES AND MEASURES

Hospital stroke volume, patients' ambulance transport distance to initial hospital, hospital case mix, interhospital transfer proportion, and size of the receiving hospital for transferred patients.

RESULTS

Of the 669 telestroke hospitals and 2143 potential control hospitals, 593 hospital pairs were matched; in each category, 261 hospitals (44.0%) were located in a rural area, 179 (30.2%) were primary stroke centers, and 130 (21.9%) were critical access hospitals. The changes in the preimplementation to postimplementation period were similar at telestroke and control hospitals in mean annual stroke volume (telestroke hospitals, decreased from 79.6 to 76.3 patients; control hospitals, decreased from 78.8 to 75.5 patients [-3.3 patients per year for both; difference-in-differences, 0.009; P ≥ .99]). Similarly, no differences were seen in ambulance transport distance, case mix, interhospital transfers, or bed size of receiving hospitals among transferred patients.

CONCLUSIONS AND RELEVANCE

This study suggests that, across a national sample of hospitals implementing telestroke, no association between telestroke adoption and changes in stroke systems of care were found.

Relationship between changing malaria burden and low birth weight in sub-Saharan Africa: A difference-in-differences study via a pair-of-pairs approach

Background

According to the World Health Organization (WHO), in 2018, an estimated 228 million malaria cases occurred worldwide with most cases occurring in sub-Saharan Africa. Scale-up of vector control tools coupled with increased access to diagnosis and effective treatment has resulted in a large decline in malaria prevalence in some areas, but other areas have seen little change. Although interventional studies demonstrate that preventing malaria during pregnancy can reduce the rate of low birth weight (i.e. child's birth weight <2500 g), it remains unknown whether natural changes in parasite transmission and malaria burden can improve birth outcomes.

Methods

We conducted an observational study of the effect of changing malaria burden on low birth weight using data from 18,112 births in 19 countries in sub-Saharan African countries during the years 2000-2015. Specifically, we conducted a difference-in-differences study via a pair-of-pairs matching approach using the fact that some sub-Saharan areas experienced sharp drops in malaria prevalence and some experienced little change.

Results

A malaria prevalence decline from a high rate (Plasmodium falciparum parasite rate in children aged 2-up-to-10 (i.e. PfPR2-10) > 0.4) to a low rate (PfPR2-10 < 0.2) is estimated to reduce the rate of low birth weight by 1.48 percentage points (95% confidence interval: 3.70 percentage points reduction, 0.74 percentage points increase), which is a 17% reduction in the low birth weight rate compared to the average (8.6%) in our study population with observed birth weight records (1.48/8.6 ≈ 17%). When focusing on first pregnancies, a decline in malaria prevalence from high to low is estimated to have a greater impact on the low birth weight rate than for all births: 3.73 percentage points (95% confidence interval: 9.11 percentage points reduction, 1.64 percentage points increase).

Conclusions

Although the confidence intervals cannot rule out the possibility of no effect at the 95% confidence level, the concurrence between our primary analysis, secondary analyses, and sensitivity analyses, and the magnitude of the effect size, contribute to the weight of the evidence suggesting that declining malaria burden can potentially substantially reduce the low birth weight rate at the community level in sub-Saharan Africa, particularly among firstborns. The novel statistical methodology developed in this article-a pair-of-pairs approach to a difference-in-differences study-could be useful for many settings in which different units are observed at different times.

Funding

Ryan A. Simmons is supported by National Center for Advancing Translational Sciences (UL1TR002553). The funder had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Matching Methods for Confounder Adjustment: An Addition to the Epidemiologist's Toolbox

Propensity score weighting and outcome regression are popular ways to adjust for observed confounders in epidemiological research. Here, we provide an introduction to matching methods, which serve the same purpose but can offer advantages in robustness and performance. A key difference between matching and weighting methods is that matching methods do not directly rely on the propensity score and so are less sensitive to its misspecification or to the presence of extreme values. Matching methods offer many options for customization, which allow a researcher to incorporate substantive knowledge and carefully manage bias/variance trade-offs in estimating the effects of nonrandomized exposures. We review these options and their implications, providing guidance for their use, and comparison with weighting methods. Because of their potential advantages over other methods, matching methods should have their place in an epidemiologist's methodological toolbox.

Reperfusion Treatment and Stroke Outcomes in Hospitals With Telestroke Capacity

Importance

Telestroke is increasingly used in hospital emergency departments, but there has been limited research on its impact on treatment and outcomes.

Objective

To describe differences in care patterns and outcomes among patients with acute ischemic stroke who present to hospitals with and without telestroke capacity.

Design, Setting, and Participants

Patients with acute ischemic stroke who first presented to hospitals with telestroke capacity were matched with patients who presented to control hospitals without telestroke capacity. All traditional Medicare beneficiaries with a primary diagnosis of acute ischemic stroke (approximately 2.5 million) who presented to a hospital between January 2008 and June 2017 were considered. Matching was based on sociodemographic and clinical characteristics, hospital characteristics, and month and year of admission. Hospitals included short-term acute care and critical access hospitals in the US without local stroke expertise. In 643 hospitals with telestroke capacity, there were 76 636 patients with stroke who were matched 1:1 to patients at similar hospitals without telestroke capacity. Data were analyzed in July 2020.

Main Outcomes and Measures

Receipt of reperfusion treatment through thrombolysis with alteplase or thrombectomy, mortality at 30 days from admission, spending through 90 days from admission, and functional status as measured by days spent living in the community after discharge.

Results

In the final sample of 153 272 patients, 88 386 (57.7%) were female, and the mean (SD) age was 78.8 (10.4) years. Patients cared for at telestroke hospitals had higher rates of reperfusion treatment compared with those cared for at control hospitals (6.8% vs 6.0%; difference, 0.78 percentage points; 95% CI, 0.54-1.03; P < .001) and lower 30-day mortality (13.1% vs 13.6%; difference, 0.50 percentage points; 95% CI, 0.17-0.83, P = .003). There were no differences in days spent living in the community following discharge or in spending. Increases in reperfusion treatment were largest in the lowest-volume hospitals, among rural residents, and among patients 85 years and older.

Conclusions and Relevance

Patients with ischemic stroke treated at hospitals with telestroke capacity were more likely to receive reperfusion treatment and have lower 30-day mortality.

Rasagiline effects on glucose metabolism, cognition, and tau in Alzheimer's dementia

BACKGROUND

A Phase II proof of concept (POC) randomized clinical trial was conducted to evaluate the effects of rasagiline, a monoamine oxidase B (MAO-B) inhibitor approved for Parkinson disease, in mild to moderate Alzheimer's disease (AD). The primary objective was to determine if 1 mg of rasagiline daily for 24 weeks is associated with improved regional brain metabolism (fluorodeoxyglucose-positron emission tomography [FDG-PET]) compared to placebo. Secondary objectives included measurement of effects on tau PET and evaluation of directional consistency of clinical end points.

METHODS

This was a double-blind, parallel group, placebo-controlled, community-based, three-site trial of 50 participants randomized 1:1 to receive oral rasagiline or placebo (NCT02359552). FDG-PET was analyzed for the presence of an AD-like pattern as an inclusion criterion and as a longitudinal outcome using prespecified regions of interest and voxel-based analyses. Tau PET was evaluated at baseline and longitudinally. Clinical outcomes were analyzed using an intention-to-treat (ITT) model.

RESULTS

Fifty patients were randomized and 43 completed treatment. The study met its primary end point, demonstrating favorable change in FDG-PET differences in rasagiline versus placebo in middle frontal (P < 0.025), anterior cingulate (P < 0.041), and striatal (P < 0.023) regions. Clinical measures showed benefit in quality of life (P < 0.04). Digit Span, verbal fluency, and Neuropsychiatric Inventory (NPI) showed non-significant directional favoring of rasagiline; no effects were observed in Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS-cog) or activities of daily living. Rasagiline was generally well tolerated with low rates of adverse events and notably fewer neuropsychiatric symptoms in the active treatment group.

DISCUSSION

These outcomes illustrate the potential benefits of rasagiline on clinical and neuroimaging measures in patients with mild to moderate AD. Rasagiline appears to affect neuronal activity in frontostriatal pathways, with associated clinical benefit potential warranting a more fully powered trial. This study illustrated the potential benefit of therapeutic repurposing and an experimental medicine proof-of-concept design with biomarkers to characterize patient and detect treatment response.

Impact of COVID-19 Restrictions on Demographics and Outcomes of Patients Undergoing Medically Necessary Non-Emergent Surgeries During the Pandemic

Background

The COVID-19 pandemic has resulted in large-scale healthcare restrictions to control viral spread, reducing operating room censuses to include only medically necessary surgeries. The impact of restrictions on which patients undergo surgical procedures and their perioperative outcomes is less understood.

Methods

Adult patients who underwent medically necessary surgical procedures at our institution during a restricted operative period due to the COVID-19 pandemic (March 23-April 24, 2020) were compared to patients undergoing procedures during a similar time period in the pre-COVID-19 era (March 25-April 26, 2019). Cardinal matching and differences in means were utilized to analyze perioperative outcomes.

Results

857 patients had surgery in 2019 (pre-COVID-19) and 212 patients had surgery in 2020 (COVID-19). The COVID-19 era cohort had a higher proportion of patients who were male (61.3% vs. 44.5%, P < 0.0001), were White (83.5% vs. 68.7%, P < 0.001), had private insurance (62.7% vs. 54.3%, p 0.05), were ASA classification 4 (10.9% vs. 3%, P < 0.0001), and underwent oncologic procedures (69.3% vs. 42.7%, P < 0.0001). Following 1:1 cardinal matching, COVID-19 era patients (N = 157) had a decreased likelihood of discharge to a nursing facility (risk difference-8.3, P < 0.0001) and shorter median length of stay (risk difference-0.6, p 0.04) compared to pre-COVID-19 era patients. There was no difference between the two patient cohorts in overall morbidity and 30-day readmission.

Conclusions

COVID-19 restrictions on surgical operations were associated with a change in the racial and insurance demographics in patients undergoing medically necessary surgical procedures but were not associated with worse postoperative morbidity. Further study is necessary to better identify the causes for patient demographic differences.

Supplementary Information

The online version contains supplementary material available at (10.1007/s00268-021-05958-z).

Comparing the Performance of Statistical Adjustment Methods by Recovering the Experimental Benchmark from the REFLUX Trial

Much evidence in comparative effectiveness research is based on observational studies. Researchers who conduct observational studies typically assume that there are no unobservable differences between the treatment groups under comparison. Treatment effectiveness is estimated after adjusting for observed differences between comparison groups. However, estimates of treatment effectiveness may be biased because of misspecification of the statistical model. That is, if the method of treatment effect estimation imposes unduly strong functional form assumptions, treatment effect estimates may be inaccurate, leading to inappropriate recommendations about treatment decisions. We compare the performance of a wide variety of treatment effect estimation methods for the average treatment effect. We do so within the context of the REFLUX study from the United Kingdom. In REFLUX, participants were enrolled in either an randomized controlled trial (RCT) or an observational study arm. In the RCT, patients were randomly assigned to either surgery or medical management. In the patient preference arm, participants selected to either have surgery or medical management. We attempt to recover the treatment effect estimate from the RCT using the data from the patient preference arms of the study. We vary the method of treatment effect estimation and record which methods are successful and which are not. We apply more than 20 different methods, including standard regression models as well as advanced machine learning methods. We find that simple propensity score matching methods provide the least accurate estimates versus the RCT benchmark. We find variation in performance across the other methods, with some, but not all recovering the experimental benchmark. We conclude that future studies should use multiple methods of estimation to fully represent uncertainty according to the choice of estimation approach.

Exposure to Armed Conflict in Childhood vs Older Ages and Subsequent Onset of Major Depressive Disorder

Importance

This study offers a rare opportunity to evaluate life-course differences in the likelihood of developing major depressive disorder (MDD) after exposure to georeferenced neighborhood-level violence during an armed conflict.

Objective

To examine age cohort (age <11 vs ≥11 years) differences in associations of neighborhood-level violence with subsequent depression onset, independently of individual exposure and other key characteristics.

Design, Setting, and Participants

The Chitwan Valley Family Study is a population-representative panel study (1995 to present) conducted in Western Chitwan in Nepal, a low-income country that experienced a medium-intensity armed conflict from 2000 to 2006. Data for violent events were collected during the armed conflict and were linked to lifetime histories of MDD (collected in 2016-2018). The present cohort study analyzes 10 623 participants within 151 neighborhoods, systematically selected and representative of Western Chitwan. All residents aged 15 to 59 years at MDD assessment were eligible (response rate, 93%). Data analysis was performed from May 2019 to July 2020.

Exposures

Georeferenced number of armed conflict-related physical beatings within 1 km of residential neighborhood.

Main Outcomes and Measures

The main outcome was onset of MDD, as defined by Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition), during or after the conflict, stratified by children (aged <11 years) and older individuals (aged ≥11 years), assessed by the Nepal-specific World Mental Health-Composite International Diagnostic Instrument 3.0 with a life history calendar.

Results

In total, 10 623 participants (5745 female [54.08%]; 4074 [38.35%] aged <11 years at the conflict start) contributed 171 899 person-years of exposure to the risk of MDD. Two or more beatings occurred within 1 km of 15 neighborhoods (9.9%). Discrete-time survival models showed that children (but not older individuals) living in neighborhoods with 2 or more beatings had a higher likelihood of developing MDD than those who lived in a community with no beatings (odds ratio, 1.82; 95% CI, 1.17-2.84; P = .008); there was also a significant interaction between age group and neighborhood beatings (odds ratio, 1.85; 95% CI, 1.27-2.70; P = .001). A confirmatory, multivariable, multilevel matching analysis showed a neighborhood association for children (z = -2.66; P = .008), but not older individuals (z = -0.454; P = .65). The mean (SE) incidence of MDD among children living in neighborhoods with 2 or more beatings nearby was 12.69% (2.37%) vs 5.08% (1.56%) in the matched unexposed sample.

Conclusions and Relevance

The youngest individuals may be the most at risk during times of violence, with mental health consequences lasting long after conflicts have subsided and should be a priority for population-level interventions. Future research should consider other disorders, other types of violence, and elderly individuals.

New multivariate tests for assessing covariate balance in matched observational studies

We propose new tests for assessing whether covariates in a treatment group and matched control group are balanced in observational studies. The tests exhibit high power under a wide range of multivariate alternatives, some of which existing tests have little power for. The asymptotic permutation null distributions of the proposed tests are studied and the P-values calculated through the asymptotic results work well in simulation studies, facilitating the application of the test to large data sets. The tests are illustrated in a study of the effect of smoking on blood lead levels. The proposed tests are implemented in an R package BalanceCheck.

The uniform general signed rank test and its design sensitivity

A sensitivity analysis in an observational study tests whether the qualitative conclusions of an analysis would change if we were to allow for the possibility of limited bias due to confounding. The design sensitivity of a hypothesis test quantifies the asymptotic performance of the test in a sensitivity analysis against a particular alternative. We propose a new, nonasymptotic, distribution-free test, the uniform general signed rank test, for observational studies with paired data, and examine its performance under Rosenbaum’s sensitivity analysis model. Our test can be viewed as adaptively choosing from among a large underlying family of signed rank tests, and we show that the uniform test achieves design sensitivity equal to the maximum design sensitivity over the underlying family of signed rank tests. Our test thus achieves superior design sensitivity, indicating it will perform well in sensitivity analyses on large samples. We support this conclusion with simulations and a data example, showing that the advantages of our test extend to moderate sample sizes as well.

Comparative Effectiveness Assessment of Two Powered Surgical Stapling Platforms in Laparoscopic Sleeve Gastrectomy: A Retrospective Matched Study

Objective

To compare outcomes between the two latest innovations in powered stapling technology, the ECHELON FLEX™ GST system (GST) and the Signia™ Stapling System (SIG), among patients undergoing sleeve gastrectomy for obesity.

Patients and Methods

Using the Premier Healthcare Database of US hospital discharge records, we selected patients undergoing inpatient sleeve gastrectomy with dates of surgical admission between March 1, 2017 (SIG launch), and December 31, 2018. Outcomes measured during the surgical admission included in-hospital hemostasis-related complications (bleeding/transfusion; primary outcome), leak, total hospital costs, length of stay (LOS), and operating room time; 30-, 60-, and 90-day all-cause inpatient readmissions were also examined. We used 1:1 cardinality matching to balance the GST and SIG groups on numerous patient and hospital/provider characteristics, allowing a maximum standardized mean difference (SMD) ≤0.05 for all matching covariates. Generalized estimating equations (GEE) accounting for hospital-level clustering were used to compare the study outcomes between the GST and SIG groups.

Results

Of the 5573 identified cases, there were 491 patients in each group (982 total) after matching. The observed incidence proportion of hemostasis-related complications during the surgical admission was lower in the GST group as compared with the SIG group (3 events/491 [0.61%] vs 11 events/491 [2.24%]; odds ratio [SIG=reference] = 0.28, 95% CI=0.13–0.60, P=0.0012). Differences between the GST and SIG groups were not statistically significant for leak, total hospital costs, LOS, OR time, and all-cause inpatient readmission at 30, 60, and 90 days.

Conclusion

In this retrospective study of 982 matched patients undergoing sleeve gastrectomy, the ECHELON FLEX™ GST system was associated with a lower rate of hemostasis-related complications as compared with the Signia™ Stapling System. Further controlled prospective studies are needed to confirm the validity of this finding.

Difference Between Users and Nonusers of a Patient Portal in Health Behaviors and Outcomes: Retrospective Cohort Study

BACKGROUND

Patient portals are frequently used in modern health care systems as an engagement and communication tool. An increased focus on the potential value of these communication channels to improve health outcomes is warranted.

OBJECTIVE

This paper aimed to quantify the impact of portal use on patients' preventive health behavior and chronic health outcomes.

METHODS

We conducted a retrospective, observational cohort study of 10,000 patients aged 50 years or older who were treated at the University of Pennsylvania Health System (UPHS) from September 1, 2014, to October 31, 2016. The data were sourced from the UPHS electronic health records. We investigated the association between patient portal use and patients' preventive health behaviors or chronic health outcomes, controlling for confounders using a novel cardinality matching approach based on propensity scoring and a subsequent bootstrapping method to estimate the variance of association estimates.

RESULTS

Patient-level characteristics differed substantially between portal users, comprising approximately 59.32% (5932/10000) of the cohort, and nonusers. On average, users were more likely to be younger (63.46 years for users vs 66.08 years for nonusers), white (72.77% [4317/5932] for users vs 52.58% [2139/4068] for nonusers), have commercial insurance (60.99% [3618/5932] for users vs 40.12% [1632/4068] for nonusers), and have higher annual incomes (US $74,172/year for users vs US $62,940/year for nonusers). Even after adjusting for these potential confounders, patient portal use had a positive and clinically meaningful impact on patients' preventive health behaviors but not on chronic health outcomes.

CONCLUSIONS

This paper contributes to the understanding of the impact of patient portal use on health outcomes and is the first study to identify a meaningful subgroup of patients' health behaviors that improved with portal use. These findings may encourage providers to promote portal use to improve patients' preventive health behaviors.

Matched Retrospective Cohort Study of Thiamine to Treat Persistent Hyperlactatemia in Pediatric Septic Shock

OBJECTIVES

Thiamine deficiency may propagate lactate production by limiting pyruvate dehydrogenase activity, and studies suggest benefit for thiamine administration in septic adults. We studied the effect of thiamine on physiologic and clinical outcomes for children with septic shock and hyperlactatemia.

DESIGN

Retrospective matched cohort study.

SETTING

Single academic PICU.

PATIENTS

Six thiamine-treated cases and nine matched controls.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The primary outcome was change in blood lactate from prethiamine (T0, cases) or maximum (T0, controls) lactate through 24 hours later (T24). Secondary outcomes were change in lactate over 48 hours (T48) and 72 hours (T72), time to lactate normalization, changes in vasoactive-inotrope score, organ dysfunction severity (daily Pediatric Logistic Organ Dysfunction 2 score), and creatinine, PICU length of stay, and hospital mortality. Lactate was greater than 5 mmol/L for a median of 39 hours (range, 16.1-64.3 hr) prior to thiamine administration for cases compared with 3.4 hours (range, 0-22.9 hr) prior to maximum lactate for controls (p = 0.002). There was no difference in median (interquartile range) change in lactate from T0 to T24 between thiamine-treated cases and controls (-9.0, -17.0 to -5.0 vs -7.2, -9.0 to -5.3 mmol/L, p = 0.78), with both groups exhibiting a rapid decrease in lactate. There were also no differences in secondary outcomes between groups.

CONCLUSIONS

Treatment of pediatric septic shock with thiamine was followed by rapid improvement in physiologic and clinical outcomes after prolonged hyperlactatemia. Although we are not able to infer that thiamine provided benefit over usual care, the rapid decline in lactate after thiamine despite a prolonged period of hyperlactatemia raises the possibility that thiamine helped to reverse lactate production.

A review and empirical comparison of causal inference methods for clustered observational data with application to the evaluation of the effectiveness of medical devices

Observational studies are commonplace in medicine. A frequent concern is confounding bias due to differences in patient characteristics across treatment groups, but other important issues include dependency among observations nested within clusters (e.g. patients clustered within physicians or surgeons) and confounding due to cluster characteristics (e.g. physician or surgeon experience or training). Given the frequency with which these issues arise in medical research, as well as their relative complexity, methods for the analysis of clustered observational data are reviewed. We argue for estimating causal treatment effects using marginal models that either match or weight observations using a suitable distance metric (e.g. the propensity score). Simulation results demonstrated that methods incorporating clustering into calculation of the variance were generally more accurate than those that did not. Moreover, methods that account for cluster confounding when estimating the treatment effect were least biased and most accurate. Throughout the paper we illustrate the proposed methods in a medical device setting that compares the effectiveness of femoral heads used in total hip replacements. Whenever possible the clustered aspect of the data should be considered in the design of the study when constructing the distance measure or in the matching process, as well as in the analysis when estimating the variance of the treatment effect.