Immortal time bias in observational studies of drug effects

Comparative effectiveness of sodium-glucose cotransporter-2 inhibitors and dipeptidyl peptidase-4 inhibitors in improvement of fatty liver index in patients with type 2 diabetes mellitus and metabolic dysfunction-associated steatotic liver disease: A retrospective nationwide claims database study in Japan

AIM

To date, there are limited clinical studies and real-world evidence investigating whether sodium-glucose cotransporter-2 inhibitors (SGLT2i) are associated with improved hepatic steatosis. This study aimed to evaluate the effectiveness of SGLT2i compared with that of dipeptidyl peptidase-4 inhibitors (DPP4i) in improving the fatty liver index (FLI) in patients with type 2 diabetes mellitus (T2DM) and metabolic dysfunction-associated steatotic liver disease (MASLD).

MATERIALS AND METHODS

This retrospective cohort study included new users of SGLT2i or DPP4i with T2DM and MASLD from a large claims database (JMDC Claims Database). The primary outcome was the incidence of improvement of the FLI. Cox proportional hazard models, weighted using propensity scores for predicting the initiation of treatment, were fitted to estimate hazard ratios with 95% confidence intervals (CIs). Time-course changes in the FLI values were also assessed.

RESULTS

This study included 9127 SGLT2i and 12 286 DPP4i initiators. SGLT2i showed a higher incidence of improvement in the FLI (≥30%, ≥40% and ≥50% reduction from baseline FLI) compared with DPP4i, and the weighted hazard ratios were 1.27 (95% CI 1.18-1.38), 1.24 (95% CI 1.13-1.37) and 1.19 (95% CI 1.05-1.33), respectively. SGLT2i indicated a greater decreased in FLI values compared with DPP4i at up to 3 years of the follow-up period.

CONCLUSION

SGLT2is use appeared to be associated with a greater improvement of the FLI than DPP4i use in patients with T2DM and MASLD. In the absence of direct head-to-head comparisons from clinical studies, our study, using real-world data, may support physicians' decision-making in clinical practice.

Estimating the Effects of Cancer Screening in Clinical Practice Settings: The Role of Selective Uptake and Suboptimal Adherence along the Cancer Screening Continuum

Randomized controlled trials (RCT) are the gold standard in determining efficacy of cancer screening tests. Yet, systematic differences between RCT and the general populations eligible for screening raise concerns about the generalizability and relevance of RCT findings to guide the development and dissemination of cancer screening programs. Observational studies from clinical practice settings have documented selective uptake in screening-i.e., variation across subgroups regarding who is screened and not screened-as well as suboptimal adherence to screening recommendations, including follow-up of positive findings with subsequent imaging studies and diagnostic invasive procedures. When the effectiveness of a screening intervention varies across subgroups, and there is selective uptake and suboptimal adherence to screening in clinical practice relative to that in the RCT, the effects of screening reported in RCTs are not expected to generalize to clinical practice settings. Understanding the impacts of selective uptake and suboptimal adherence on estimates of the effectiveness of cancer screening in clinical practice will generate evidence that can be used to inform future screening recommendations and enhance shared decision-making tools.

Risk of Mortality Associated with Potentially Inappropriate Medication Use Including Opioids in Older Adults

INTRODUCTION AND OBJECTIVE

As the population ages, understanding the potential risks associated with inappropriate medication use becomes increasingly important. Given the lack of studies in this area, our objective was to study the risk of mortality associated with potentially inappropriate medication use involving opioids in community-dwelling older adults.

METHODS

Data came from a longitudinal study on older adults aged ≥ 65 years recruited in primary care clinics between 2011 and 2013 with an average follow-up of 4.25 years. Older adults were excluded if they used an opioid or had a malignant tumor diagnosis in the year before the study survey. A nested case-control within a cohort of older adults with at least one opioid claim during follow-up was used to evaluate the risk of all-cause mortality. Four controls per case were matched on follow-up time using risk-set sampling, i.e., while still at risk of death when their matched case died. The risk of mortality was estimated using conditional logistic regression analyses. Exposure to potentially inappropriate medication use involving opioids, defined using the Beers 2019 criteria, was assessed from provincial drug claims data in the 0-90 days before death.

RESULTS

In a cohort of 472 community-dwelling older adults with an incident episode of opioid use, there were 40 cases matched to 160 controls. Exposure to inappropriate medication use involving opioids in the 90 days before death was associated with an increased risk of mortality (odds ratio 6.81, 95% confidence interval 1.69-27.47), after adjusting for potential confounders.

CONCLUSIONS

Exposure to inappropriate medication use involving opioids in the 90 days before death is associated with an increased risk of mortality in older adults. These findings can be used to encourage safer pain management strategies in older adults.

Incident HIV-Associated Wasting/Low Weight Is Associated with Nearly Doubled Mortality Risk in the Modern ART Era

HIV-associated wasting (HIVAW) is an underappreciated AIDS-defining illness, despite highly effective antiretroviral therapy (ART). We (a) assessed the association between incident HIVAW/low weight and all-cause mortality and (b) described virologic outcomes after people with HIV (PWH) experienced HIVAW/low weight while on ART. In the Observational Pharmaco-Epidemiology Research & Analysis (OPERA®) cohort, PWH without prior HIVAW/low weight who were active in care in 2016-2020 were followed through the first of the following censoring events: death, loss to follow-up, or study end (October 31, 2021). HIVAW/low weight was a diagnosis of wasting or low body mass index (BMI)/underweight or a BMI measurement <20 kg/m2. Hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between time-dependent HIVAW/low weight and mortality were estimated with extended Cox regression models. Over a median follow-up of 45 months (interquartile range: 27, 65), there were 4,755 (8%) cases of HIVAW/low weight and 1,354 (2%) deaths among 62,314 PWH. PWH who experienced HIVAW/low weight had a significantly higher risk of death than those who did not (HR: 1.96; 95% CI: 1.68, 2.27) after adjusting for age, race, ethnicity, and changes in viral load (VL) and Veterans Aging Cohort Study Mortality Index scores over follow-up. Among 4,572 PWH on ART at HIVAW/low weight, 68% were suppressed (VL of <200 copies/mL); subsequent virologic failure was uncommon (7%). Among viremic PWH, 70% and 60% achieved suppression and undetectability (VL of <50 copies/mL), respectively, over follow-up. HIVAW remains a challenge for some PWH. Particular attention needs to be paid to HIVAW/low weight and virologic control to restore health and potentially reduce the risk of death.

Survival among patients receiving eteplirsen for up to 8 years for the treatment of Duchenne muscular dystrophy and contextualization with natural history controls

INTRODUCTION/AIMS

Eteplirsen, approved in the US for patients with Duchenne muscular dystrophy (DMD) with exon 51 skip-amenable variants, is associated with attenuated ambulatory/pulmonary decline versus DMD natural history (NH). We report overall survival in a US cohort receiving eteplirsen and contextualize these outcomes versus DMD NH.

METHODS

US patients with DMD receiving eteplirsen were followed through a patient support program, with data collected on ages at eteplirsen initiation and death/end of follow-up. Individual DMD NH data were extracted by digitizing Kaplan-Meier (KM) curves from published systematic and targeted literature reviews. Overall survival age was analyzed using KM curves and contextualized with DMD NH survival curves; subanalyses considered age groups and duration of eteplirsen exposure. Overall survival time from treatment initiation was also evaluated.

RESULTS

A total of 579 eteplirsen-treated patients were included. During a total follow-up of 2119 person-years, median survival age was 32.8 years. DMD NH survival curves extracted from four publications (follow-up for 1224 DMD NH controls) showed overall pooled median survival age of 27.4 years. Eteplirsen-treated patients had significantly longer survival from treatment initiation versus age-matched controls (age-adjusted hazard ratio [HR], 0.65; 95% confidence interval [CI], 0.44-0.98; p < .05). Longer treatment exposure was associated with improved survival (HR, 0.15; 95% CI, 0.05-0.41; p < .001). Comparisons using different DMD NH cohorts to address common risks of bias yielded consistent findings.

DISCUSSION

Data suggest eteplirsen may prolong survival in patients with DMD across a wide age range. As more data become available, the impact of eteplirsen on survival will be further elucidated.

Effect of surgery versus chemotherapy in pancreatic cancer patients: a target trial emulation

BACKGROUND

To estimate the causal effect of surgery vs chemotherapy on survival in patients with T1-3NxM0 pancreatic cancer in a rigorous framework addressing selection bias and immortal time bias.

METHODS

We used population-based Danish health-care registries to conduct a cohort study emulating a hypothetical randomized trial to estimate the absolute difference in survival, comparing surgery with chemotherapy. We included pancreatic cancer patients diagnosed during 2008-2021. Exposure was surgery or chemotherapy initiated within a 16-week grace period after diagnosis. At the time of diagnosis, data of each patient were duplicated; one copy was assigned to the surgery protocol, and one copy to the chemotherapy protocol of the hypothetical trial. Copies were censored when the assigned treatment deviated from the observed treatment. To account for informative censoring, uncensored patients were weighted according to confounders. For comparison, we also applied a more conventional analysis using propensity score-based inverse probability weighting.

RESULTS

We included 1744 patients with a median age of 68 years: 73.6% underwent surgery, and 18.6% had chemotherapy without surgery; 7.8% received no treatment. The 3-year survival was 39.7% (95% confidence interval [CI] = 36.7% to 42.6%) after surgery and 22.7% (95% CI = 17.7% to 28.4%) after chemotherapy, corresponding to an absolute difference of 17.0% (95% CI = 10.8% to 23.1%). In the conventional survival analysis, this difference was 23.0% (95% CI = 17.0% to 29.0%).

CONCLUSION

Surgery was superior to chemotherapy in achieving long-term survival for pancreatic cancer. The difference comparing surgery and chemotherapy was substantially smaller when using the clone-censor-weight approach than conventional survival analysis.

Long-term use of prescription opioids for non-cancer pain and mortality: a population-based, propensity-weighted cohort study

OBJECTIVE

The objective of this study was to identify factors associated with long-term opioid use and to assess the association between long-term use and death.

STUDY DESIGN

Retrospective cohort study combining several population-wide databases and covering a population of five million inhabitants, including all adults who were initiated on opioid treatment from 2014 to 2018 for non-cancer pain.

METHODS

We used logistic regression models to identify factors associated with chronic opioid use and carried out survival analyses using multivariable Cox regression modelling for all-cause mortality during follow-up using inverse probability of treatment weighting (IPTW) and propensity scores based on the probability of using opioids chronically.

RESULTS

Among 760,006 patients, 82,423 (10.85%) used opioids for 90 days or more after initiation. Initial therapy characteristics associated with higher risk for long-term use were initiating with long- and short-acting opioids (when compared to tramadol, odds ratio [OR]: 2.63, 95% confidence interval [CI]: 2.57, 2.69 and OR: 1.60, 95%CI: 1.46, 1.76, respectively), using higher daily doses (when compared to 50 morphine milligramme equivalent [MME] or less, prescribing 50 to 89 daily MME, OR: 1.76, 95%CI: 1.65, 1.87; 90 to 119 daily MME, OR: 2.44, 95%CI: 1.99, 3.01; and more than 120 daily MME, OR: 1.77, 95%CI: 1.64, 1.91), and overlapping with gabapentinoids (OR: 2.26, 95%CI: 2.20, 2.32), benzodiazepines (OR: 1.32, 95%CI: 1.30, 1.35), and antipsychotics (OR: 1.21, 95%CI: 1.16, 1.26). After IPTW, chronic opioid use was associated with higher risk of all-cause mortality when compared to short-term use (Hazard Ratio (HR): 1.37, 95%CI: 1.32, 1.42). Sensitivity analyses provided similar results.

CONCLUSION

These findings may help healthcare managers to identify and address patients at higher risk of long-term use and riskier prescription patterns.

The effect of inhaler prescription on the development of lung cancer in COPD: a nationwide population-based study

BACKGROUND

COPD is associated with the development of lung cancer. A protective effect of inhaled corticosteroids (ICS) on lung cancer is still controversial. Hence, this study investigated the development of lung cancer according to inhaler prescription and comorbidties in COPD.

METHODS

A retrospective cohort study was conducted based on the Korean Health Insurance Review and Assessment Service database. The development of lung cancer was investigated from the index date to December 31, 2020. This cohort included COPD patients (≥ 40 years) with new prescription of inhalers. Patients with a previous history of any cancer during screening period or a switch of inhaler after the index date were excluded.

RESULTS

Of the 63,442 eligible patients, 39,588 patients (62.4%) were in the long-acting muscarinic antagonist (LAMA) and long-acting β2-agonist (LABA) group, 22,718 (35.8%) in the ICS/LABA group, and 1,136 (1.8%) in the LABA group. Multivariate analysis showed no significant difference in the development of lung cancer according to inhaler prescription. Multivariate analysis, adjusted for age, sex, and significant factors in the univariate analysis, demonstrated that diffuse interstitial lung disease (DILD) (HR = 2.68; 95%CI = 1.86-3.85), a higher Charlson Comorbidity Index score (HR = 1.05; 95%CI = 1.01-1.08), and two or more hospitalizations during screening period (HR = 1.19; 95%CI = 1.01-1.39), along with older age and male sex, were independently associated with the development of lung cancer.

CONCLUSION

Our data suggest that the development of lung cancer is not independently associated with inhaler prescription, but with coexisting DILD, a higher Charlson Comorbidity Index score, and frequent hospitalization.

Escalating to medium- versus high-efficacy disease modifying therapy after low-efficacy treatment in relapsing remitting multiple sclerosis

BACKGROUND

In patients with relapsing remitting multiple sclerosis (RRMS) on low-efficacy disease modifying therapies (DMT), the optimal strategy on how to escalate treatment once needed, remains unknown.

METHODS

We studied RRMS patients on low-efficacy DMTs listed in the Swiss National Treatment Registry, who underwent escalation to either medium- or high-efficacy DMTs. Propensity score-based matching was applied using 12 clinically relevant variables. Both groups were also separately matched with control subjects who did not escalate therapy. Time to relapse and to disability worsening were evaluated using Cox proportional hazard models.

RESULTS

Of 1037 eligible patients, we 1:1 matched 450 MS patients who switched from low-efficacy to medium-efficacy (n = 225; 76.0% females, aged 42.4 ± 9.9 years [mean ± SD], median EDSS 3.0 [IQR 2-4]) or high-efficacy DMTs (n = 225; 72.4% females, aged 42.2 ± 10.6 years, median EDSS 3.0 [IQR 2-4]). Escalation to high-efficacy DMTs was associated with lower hazards of relapses than medium-efficacy DMTs (HR = 0.67, 95% CI 0.47-0.95, p = .027) or control subjects (HR = 0.61, 95% CI 0.44-0.84, p = .003). By contrast, escalation from low to medium-efficacy DMTs did not alter the hazard for relapses when compared to controls (i.e. patients on low-efficacy DMT who did not escalate DMT during follow-up) CONCLUSION: Our nationwide registry analysis suggests that, once escalation from a low-efficacy DMT is indicated, switching directly to a high-efficacy treatment is superior to a stepwise escalation starting with a moderate-efficacy treatment.

How appropriate is treating patients diagnosed with advanced esophageal cancer with anticancer drugs? A multicenter retrospective cohort Spanish study

AIM

To assess the appropriateness of systemic oncological treatments (SOT) provided to patients diagnosed with advanced esophageal cancer (EC) across a group of participating hospitals.

METHODS

Multicenter, retrospective cohort study in five Spanish hospitals including newly confirmed advanced EC cases between July 1, 2014, and June 30, 2016, with a 5-year follow-up.

RESULTS

We identified 157 patients fulfilling the inclusion criteria (median age: 65 years, 85.9% males). Most patients, 125 (79.6%) were treated at least with one active treatment, and 33% received two or more lines of SOT. The 1-, 2- and 5-year overall survival rates were 30.3% [95%CI: 23.8, 38.7], 14.0% [95%CI: 9.3, 21.0], and 7.1% [95% CI: 3.8, 13.1] respectively, and the median survival time 8 months (95% CI: 6, 19) for stages IIIb IIIc and 7 months (95% CI: 5, 9) for stage IV. Clinical stage, receiving more than one line of SOT, and treatment with radiotherapy accelerated the time to death (0.4, 0.9-, and 0.8-times shorter survival respectively, p < 0.05). Better performance status (ECOG < 2) extended survival time by 2.2 times (p = 0.04). Age < 65 years (OR 9.4, 95% CI 3.2, 31.4, p < 0.001), and being treated in one particular hospital (OR 0.2, 95% CI 0.0, 0.8, p < 0.01) were associated with the administration of two or more lines of SOT. Altogether, 18.9% and 9.0% of patients received chemotherapy in the last four and two weeks of life, respectively. Moreover, 2.5% of patients were prescribed a new line of chemotherapy during the last month of life. The proportion of all patients who did not have access to palliative care reached 29.3%, and among those who had access to it, 34.2% initiated it in the last month of life.

CONCLUSION

A high proportion of advanced EC patients receive many treatments not based on sound evidence and they do not benefit enough from palliative care services. The most accepted appropriateness indicators point out that some of the analyzed patients could have been overtreated. This study provides important insights into the quality of care provided to advanced EC, and furthermore, for giving valuable insight and opportunities for improvement.

Letter: Association between chronic kidney disease, hepatitis B and antiviral treatments

This article is linked to Choi et al papers. To view these articles, visit https://doi.org/10.1111/apt.17819 and https://doi.org/10.1111/apt.17875

Interpersonal violent injury and subsequent risk of suicide and deliberate self-harm: a register-based national cohort study from Norway, 2010-2018

Background

Interpersonal violence is a leading cause of morbidity, with potentially severe adverse consequences for the mental health of the injured persons. The extent to which violent injury is associated with subsequent suicidal behavior, however, remains unclear. This study aimed to examine how violent injury was associated with subsequent deliberate self-harm and death by suicide.

Methods

This retrospective cohort study used nationwide longitudinal registry data from Norway to identify all individuals presenting to emergency services in 2010-2018 with a violence-related injury, along with sex- and age-matched control individuals from the general population. The primary outcomes were any emergency visit for deliberate self-harm (DSH) and suicide death, observed through 31 December 2018. Rates of each outcome were compared between violence-injured patients and comparison individuals using stratified multivariable Cox regression models, controlling for sociodemographic characteristics as well as history of psychiatric treatment and DSH. Secondary analyses tested for moderation by sex, age, and prior psychiatric treatment.

Findings

Violence-injured patients (n = 28,276) had substantially higher rates of DSH (946.7 per 100,000 person-years) and suicide death (74.5 per 100,000) when compared to controls (n = 282,760; 90.0 and 15.2 per 100,000, respectively). The hazard ratios (HRs) remained significantly higher even after accounting for covariates (HRadj for DSH: 5.11; 95% CI: 4.62, 5.66; HRadj for suicide: 2.40; 95% CI: 1.78, 3.24). Sex differences in this association were negligible, but the association between violence injury and DSH increased with age. Violence-injured patients with prior psychiatric treatment had the highest risk of suicidal behavior.

Interpretation

Violence-injured patients experience significantly excess rates of suicidal behavior, a finding with potential to inform both clinical intervention and population-level suicide prevention strategies.

Funding

Fulbright Norway Scholarship.

Impact on Survival of Early Versus Late Initiation of Adjuvant Chemotherapy After Pancreatic Adenocarcinoma Surgery: A Target Trial Emulation

BACKGROUND

We examined the impact of early (0-4 weeks after discharge) versus late (> 4-8 weeks after discharge) initiation of adjuvant chemotherapy on pancreatic adenocarcinoma survival.

METHODS

We used Danish population-based healthcare registries to emulate a hypothetical target trial using the clone-censor-weight approach. All eligible patients were cloned with one clone assigned to 'early initiation' and one clone assigned to 'late initiation'. Clones were censored when the assigned treatment was no longer compatible with the actual treatment. Informative censoring was addressed using inverse probability of censoring weighting.

RESULTS

We included 1491 patients in a hypothetical target trial, of whom 32.3% initiated chemotherapy within 0-4 weeks and 38.3% between > 4 and 8 weeks after discharge for pancreatic adenocarcinoma surgery; 206 (13.8%) initiated chemotherapy after > 8 weeks, and 232 (15.6%) did not initiate chemotherapy. Median overall survival was 30.4 and 29.9 months in late and early initiators, respectively. The absolute differences in OS, comparing late with early initiators, were 3.2% (95% confidence interval [CI] - 1.5%, 7.9%), - 0.7% (95% CI - 7.2%, 5.8%), and 3.2% (95% CI - 2.8%, 9.3%) at 1, 3, and 5 years, respectively. Late initiators had a higher increase in albumin levels as well as higher pretreatment albumin values.

CONCLUSIONS

Postponement of adjuvant chemotherapy up to 8 weeks after discharge from pancreatic adenocarcinoma surgery is safe and may allow more patients to receive adjuvant therapy due to better recovery.

Statins and Mortality in COPD: A Methodological Review of Observational Studies

Randomized controlled trials and observational studies have reported conflicting results on the potential beneficial effects of statins on mortality in patients with chronic obstructive pulmonary disease (COPD). We performed a systematic search of the literature to review all observational studies reporting relative risks of death with statin use in COPD, focusing on potential sources of bias. We identified 15 observational studies, out of 2835, of which 12 were affected by time-related and other biases and the remaining 3 by confounding bias. All 15 studies were also subject to confounding bias due to lack of adjustment for important COPD-related factors. The risk of death associated with statin use was reduced across all 15 studies (pooled relative risk (PRR) 0.66; 95% CI: 0.59-0.74). The reduction was observed in 7 studies with immortal time bias (PRR 0.62; 95%: 0.53-0.72), two with collider-stratification bias (PRR 0.60; 95% CI: 0.45-0.80), one with time-window bias (RR 0.61; 95% CI: 0.38-0.98), one with immeasurable time bias (RR 0.50; 95% CI: 0.40-0.62), and one with exposure misclassification (RR 0.86; 95% CI: 0.72-1.03). The three studies that avoided these biases were, however, affected by confounding bias resulting in a PRR of 0.77 (95% CI: 0.61-0.98). In conclusion, the observational studies investigating statin use and mortality in COPD are affected by major biases, many of which can result in spurious protective effects. Well-designed observational studies that carefully emulate randomized trials are needed to resolve this uncertainty regarding the potential beneficial benefits of statins on mortality in patients with COPD.

Health care system costs related to potentially inappropriate medication use involving opioids in older adults in Canada

BACKGROUND

Older adults are at risk of potentially inappropriate medication use given polypharmacy, multimorbidity, and age-related changes, which contribute to the growing burden associated with opioid use. The objective of this study was to estimate the costs of health service utilization attributable to opioid use and potentially inappropriate medication use involving opioids in older adults in a public health care system.

METHODS

The sample included 1201 older adults consulting in primary care, covered by the public drug plan, without a cancer diagnosis and opioid use in the year before interview. Secondary analyses were conducted using two data sources: health survey and provincial administrative data. Health system costs included inpatient and outpatient visits, physician billing, and medication costs. Unit costs were calculated using annual financial and activity reports from 2013-2014, adjusted to 2022 Canadian dollars. Opioid use and potentially inappropriate medication use involving opioids were identified over 3 years. Generalized linear models with gamma distribution were employed to model 3-year costs associated with opioid use and potentially inappropriate medication use involving opioids. A phase-based approach was implemented to provide descriptive results on the costs associated with each phase: i) no use, ii) opioid use, and iii) potentially inappropriate medication use involving opioids.

RESULTS

Opioid use and potentially inappropriate medication use involving opioids were associated with adjusted 3-year costs of $2,222 (95% CI: $1,179-$3,264) and $8,987 (95% CI: $7,370-$10,605), respectively, compared to no use. In phase-based analyses, costs were the highest during inappropriate use.

CONCLUSIONS

Potentially inappropriate medication use involving opioids is associated with higher costs compared to those observed with opioid use and no use. There is a need for more effective use of health care resources to reduce costs for the health care system.

Association of Bypass Surgery and Mortality in Moyamoya Disease

Background Patients with moyamoya disease (MMD) have a high risk of stroke or death. We investigated whether extracranial to intracranial bypass surgery can reduce mortality by preventing strokes in patients with MMD. Methods and Results This nationwide retrospective cohort study encompassed patients with MMD registered under the Rare Intractable Diseases program via the Relieved Co-Payment Policy between 2006 and 2019, using the Korean National Health Insurance Service database. Following a 4-year washout period, landmark analyses were employed to assess mortality and stroke occurrence between the bypass surgery group and the nonsurgical control group at specific time points postindex date (1 month and 3, 6, 12, and 36 months). The study included 18 480 patients with MMD (mean age, 40.7 years; male to female ratio, 1:1.86) with a median follow-up of 5.6 years (interquartile range, 2.5-9.3; mean, 6.1 years [SD, 4.0 years]). During 111 775 person-years of follow-up, 265 patients in the bypass surgery group and 1144 patients in the nonsurgical control group died (incidence mortality rate of 618.1 events versus 1660.3 events, respectively, per 105 person-years). The overall adjusted hazard ratio (HR) revealed significantly lower all-cause mortality in the bypass surgery group from the 36-month landmark time point, for any stroke mortality from 3- and 6-month landmark time points, and for hemorrhagic stroke mortality from the 6-month landmark time point. Furthermore, the overall adjusted HRs for hemorrhagic stroke occurrence were beneficially maintained from all 5 landmark time points in the bypass surgery group. Conclusions Bypass surgery in patients with MMD was associated with a lower risk of all-cause and hemorrhagic stroke mortality and hemorrhagic stroke occurrence compared with nonsurgical control.

Prognostic impact of severe neutropenia in colorectal cancer patients treated with TAS-102 and bevacizumab, addressing immortal-time bias

BACKGROUND

Several studies have reported an association between severe neutropenia and long-term survival in patients treated with trifluridine-tipiracil (TAS-102). Because some of these studies failed to address immortality time bias, however, their findings should be interpreted with caution. Additionally, the association between severe neutropenia and survival in patients receiving TAS-102 in combination with bevacizumab (Bmab) remains unclear.

PATIENTS AND METHODS

We conducted a single-center retrospective cohort study in patients with colorectal cancer who received Bmab + TAS-102. We compared overall survival (OS) between patients who developed grade ≥ 3 neutropenia during the treatment period and those who did not. To account for immortal time bias, we used two approaches, time-varying Cox regression and landmark analysis.

RESULTS

Median OS was 15.3 months [95% CI: 14.1-NA] in patients with grade ≥ 3 neutropenia and 10.0 months [95% CI: 8.1-NA] in those without. In time-varying Cox regression, onset grade ≥ 3 neutropenia was significantly related to longer survival after adjustment for age and modified Glasgow Prognostic Score. Additionally, 30-, 60-, 90-, and 120-day landmark analysis showed that grade ≥ 3 neutropenia was associated with longer survival after adjustment for age and modified Glasgow Prognostic Score, with respective HRs of 0.30 [0.10-0.90], 0.65 [0.30-1.42], 0.39 [0.17-0.90], and 0.41 [0.18-0.95].

CONCLUSION

We identified an association between long-term survival and the development of severe neutropenia during the early cycle of Bmab + TAS-102 using an approach that addressed immortality time bias.

Immortal Time Bias With Time-Varying Exposures in Environmental Epidemiology: A Case Study in Lung Cancer Survival

Immortal time bias is a well-recognized bias in clinical epidemiology but is rarely discussed in environmental epidemiology. Under the target trial framework, this bias is formally conceptualized as a misalignment between the start of study follow-up (time 0) and treatment assignment. This misalignment can occur when attained duration of follow-up is encoded into treatment assignment using minimums, maximums, or averages. The bias can be exacerbated in the presence of time trends commonly found in environmental exposures. Using lung cancer cases from the California Cancer Registry (2000-2010) linked with estimated concentrations of particulate matter less than or equal to 2.5 μm in aerodynamic diameter (PM2.5), we replicated previous studies that averaged PM2.5 exposure over follow-up in a time-to-event model. We compared this approach with one that ensures alignment between time 0 and treatment assignment, a discrete-time approach. In the former approach, the estimated overall hazard ratio for a 5-μg/m3 increase in PM2.5 was 1.38 (95% confidence interval: 1.36, 1.40). Under the discrete-time approach, the estimated pooled odds ratio was 0.99 (95% confidence interval: 0.98, 1.00). We conclude that the strong estimated effect in the former approach was likely driven by immortal time bias, due to misalignment at time 0. Our findings highlight the importance of appropriately conceptualizing a time-varying environmental exposure under the target trial framework to avoid introducing preventable systematic errors.

Prediagnostic Prescription Antibiotics Use and Survival in Patients with Colorectal Cancer: A Swedish National Register-Based Study

BACKGROUND

Antibiotics use is associated with higher colorectal cancer risk, but little is known regarding any potential effects on survival.

METHODS

We conducted a nationwide cohort study, using complete-population data from Swedish national registers between 2005 and 2020, to investigate prediagnostic prescription antibiotics use in relation to survival in colorectal cancer patients.

RESULTS

We identified 36,061 stage I-III and 11,242 stage IV colorectal cancer cases diagnosed between 2010 and 2019. For stage I-III, any antibiotics use (binary yes/no variable) was not associated with overall or cancer-specific survival. Compared with no use, moderate antibiotics use (total 11-60 days) was associated with slightly better cancer-specific survival [adjusted HR (aHR) = 0.93; 95% confidence interval (CI), 0.86-0.99)], whereas very high use (>180 days) was associated with worse survival [overall survival (OS) aHR = 1.42; 95% CI, 1.26-1.60, cancer-specific survival aHR = 1.31; 95% CI, 1.10-1.55]. In analyses by different antibiotic types, although not statistically significant, worse survival outcomes were generally observed across several antibiotics, particularly macrolides and/or lincosamides. In stage IV colorectal cancer, inverse relationships between antibiotics use and survival were noted.

CONCLUSIONS

Overall, our findings do not support any substantial detrimental effects of prediagnostic prescription antibiotics use on cancer-specific survival after colorectal cancer diagnosis, with the possible exception of very high use in stage I-III colorectal cancer. Further investigation is warranted to confirm and understand these results.

IMPACT

Although the study findings require confirmation, physicians probably do not need to factor in prediagnostic prescription antibiotics use in prognosticating patients with colorectal cancer.

Despite warnings, co-medication with proton pump inhibitors and dasatinib is common in chronic myeloid leukemia, but XS004, a novel oral dasatinib formulation, provides reduced pH-dependence, minimizing undesirable drug-drug interactions

BACKGROUND

Dasatinib and other tyrosine kinase inhibitors (TKI) have revolutionized the treatment of chronic myeloid leukemia (CML). However, as a lipophilic weak base, crystalline monohydrate, dasatinib (Sprycel®) is poorly soluble, rendering a pH-dependent absorption and a highly variable bioavailability. Thus, co-medication with proton pump inhibitors (PPI) profoundly impairs dasatinib uptake and is clearly recommended against. XS004 is a novel oral immediate release and amorphous solid dispersion (ASD) formulation of dasatinib and is bioequivalent to the original crystalline dasatinib at 30% lower dosages. XS004 is designed to mitigate gastric pH dependency, thus optimizing absorption and bioavailability.

METHODS

We investigated the prevalence of dasatinib and PPI co-medication among chronic-phase CML patients in a real-world setting and assessed the plasma pharmacokinetics (PK) of XS004 with and without PPI co-medication (omeprazole) in healthy volunteers.

RESULTS

Using the Swedish CML and Prescribed Drug Registers, we identified 676 TKI-treated CML patients; 320 (47%) had been prescribed PPI at some point after CML diagnosis. Among dasatinib-treated patients, the 2-year cumulative PPI co-medication was 24%. Interestingly, the 5-year overall survival was significantly lower for TKI-treated CML patients with versus without PPI co-medication (79% vs. 94%; hazard ratio 3.5; 95% confidence interval, 2.1-5.3; p < .0001). When assessing PK of XS004, neither Cmax nor area under the plasma concentration curve levels in plasma were significantly altered by the PPI co-medication.

CONCLUSION

In conclusion, despite warnings, PPI co-medication is common among dasatinib-treated CML patients in a real-world setting. The new XS004 ASD formulation of dasatinib provided, in contrast to original crystalline dasatinib, superior pH independence with stable bioavailability, thereby minimizing drug-drug interactions. This may improve the long-term efficacy and tolerability of dasatinib in CML.

Dysthyroidism during immune checkpoint inhibitors is associated with improved overall survival in adult cancers: data mining of 1385 electronic patient records

BACKGROUND

Dysthyroidism (DT) is a common toxicity of immune checkpoint inhibitors (ICIs) and prior work suggests that dysthyroidism (DT) might be associated with ICI efficacy.

PATIENTS AND METHODS

ConSoRe, a new generation data mining solution, was used in this retrospective study, to extract data from electronic patient records of adult cancer patients treated with ICI at Institut Paoli-Calmettes (Marseille, France). Every DT was verified and only ICI-induced DT was retained. Survival analyses were performed by Kaplan-Meier method (log-rank test) and Cox model. To account for immortal time bias, a conditional landmark analysis was performed (2 months and 6 months), together with a time-varying Cox model.

RESULTS

Data extraction identified 1385 patients treated with ICI between 2011 and 2021. DT was associated with improved overall survival (OS) (HR 0.46, (95% CI 0.33 to 0.65), p<0.001), with a median OS of 35.3 months in DT group vs 15.4 months in non-DT group (NDT). Survival impact of DT was consistent using a 6-month landmark analysis with a median OS of 36.7 months (95% CI 29.4 to not reported) in the DT group vs 25.5 months (95% CI 22.8 to 27.8) in the NDT group. In multivariate analysis, DT was independently associated with improved OS (HR 0.49, 95% CI 0.35 to 0.69, p=0.001). After adjustment in time-varying Cox model, this association remained significant (adjusted HR 0.64, 95% CI 0.45 to 0.90, p=0.010). Moreover, patients with DT and additional immune-related adverse event had increased OS compared with patients with isolated DT, with median OS of 38.8 months vs 21.4 months, respectively.

CONCLUSION

Data mining identified a large number of patients with ICI-induced DT, which was associated with improved OS accounting for immortal time bias.

Effect of Helicobacter pylori Eradication Therapy on the Incidence of Noncardia Gastric Adenocarcinoma in a Large Diverse Population in the United States

BACKGROUND & AIMS

High-quality data regarding the effect of Helicobacter pylori eradication on the risk of noncardia gastric adenocarcinoma (NCGA) remain limited in the United States. We investigated the incidence of NCGA after H pylori eradication therapy in a large, community-based US population.

METHODS

We performed a retrospective cohort study of Kaiser Permanente Northern California members who underwent testing and/or treatment for H pylori between 1997 and 2015 and were followed through December 31, 2018. The risk of NCGA was evaluated using the Fine-Gray subdistribution hazard model and standardized incidence ratios.

RESULTS

Among 716,567 individuals with a history of H pylori testing and/or treatment, the adjusted subdistribution hazard ratios and 95% confidence intervals of NCGA for H pylori-positive/untreated and H pylori-positive/treated individuals were 6.07 (4.20-8.76) and 2.68 (1.86-3.86), respectively, compared with H pylori-negative individuals. When compared directly with H pylori-positive/untreated individuals, subdistribution hazard ratios for NCGA in H pylori-positive/treated were 0.95 (0.47-1.92) at <8 years and 0.37 (0.14-0.97) ≥8 years of follow-up. Compared with the Kaiser Permanente Northern California general population, standardized incidence ratios (95% confidence interval) of NCGA steadily decreased after H pylori treatment: 2.00 (1.79-2.24) ≥1 year, 1.01 (0.85-1.19) ≥4 years, 0.68 (0.54-0.85) ≥7 years, and 0.51 (0.38-0.68) ≥10 years.

CONCLUSION

In a large, diverse, community-based population, H pylori eradication therapy was associated with a significantly reduced incidence of NCGA after 8 years compared with no treatment. The risk among treated individuals became lower than the general population after 7 to 10 years of follow-up. The findings support the potential for substantial gastric cancer prevention in the United States through H pylori eradication.

A Road Map for Peer Review of Real-World Evidence Studies on Safety and Effectiveness of Treatments

The growing acceptance of real-world evidence (RWE) in clinical and regulatory decision-making, coupled with increasing availability of health care data and advances in automated analytic approaches, has contributed to a marked expansion of RWE studies of diabetes and other diseases. However, a recent spate of high-profile retractions highlights the need for improvements in the conduct of RWE research as well as in the associated peer review and editorial processes. We review best pharmacoepidemiologic practices and common pitfalls regarding design, measurement, analysis, data validity, appropriateness, and generalizability of RWE studies. To enhance RWE study assessments, we propose that journal editors require 1) study authors to complete RECORD-PE, a reporting guideline for pharmacoepidemiological studies on routinely collected data, 2) availability of predetermined study protocols and analysis plans, 3) inclusion of pharmacoepidemiologists on the peer review team, and 4) provision of detail on data provenance, characterization, and custodianship to facilitate assessment of the data source. We recognize that none of these steps guarantees a high-quality research study. Collectively, however, they permit an informed assessment of whether the study was adequately designed and conducted and whether the data source used was fit for purpose.

Relationship Between Azithromycin and Cardiovascular Outcomes in Unvaccinated Patients With COVID-19 and Preexisting Cardiovascular Disease

Background Empiric antimicrobial therapy with azithromycin is highly used in patients admitted to the hospital with COVID-19, despite prior research suggesting that azithromycin may be associated with increased risk of cardiovascular events. Methods and Results This study was conducted using data from the ISACS-COVID-19 (International Survey of Acute Coronavirus Syndromes-COVID-19) registry. Patients with a confirmed diagnosis of SARS-CoV-2 infection were eligible for inclusion. The study included 793 patients exposed to azithromycin within 24 hours from hospital admission and 2141 patients who received only standard care. The primary exposure was cardiovascular disease (CVD). Main outcome measures were 30-day mortality and acute heart failure (AHF). Among 2934 patients, 1066 (36.4%) had preexisting CVD. A total of 617 (21.0%) died, and 253 (8.6%) had AHF. Azithromycin therapy was consistently associated with an increased risk of AHF in patients with preexisting CVD (risk ratio [RR], 1.48 [95% CI, 1.06-2.06]). Receiving azithromycin versus standard care was not significantly associated with death (RR, 0.94 [95% CI, 0.69-1.28]). By contrast, we found significantly reduced odds of death (RR, 0.57 [95% CI, 0.42-0.79]) and no significant increase in AHF (RR, 1.23 [95% CI, 0.75-2.04]) in patients without prior CVD. The relative risks of death from the 2 subgroups were significantly different from each other (Pinteraction=0.01). Statistically significant association was observed between AHF and death (odds ratio, 2.28 [95% CI, 1.34-3.90]). Conclusions These findings suggest that azithromycin use in patients with COVID-19 and prior history of CVD is significantly associated with an increased risk of AHF and all-cause 30-day mortality. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT05188612.

Regarding "Neoadjuvant Versus Adjuvant Chemotherapy for Resectable Metastatic Colon Cancer in Non-academic and Academic Programs"

This letter to the editor expresses concerns related to immortal time bias that may partially account for recently published study results.

Dopamine agonists and risk of lung cancer in patients with restless legs syndrome

PURPOSE

To examine the association between long-term use of dopamine agonists (DAs) and the risk of lung cancer in patients with restless legs syndrome (RLS).

METHODS

We conducted a retrospective cohort study using Optum Clinformatics® database. We included adults ≥40 years diagnosed with RLS during the study period (1/2006-12/2016). Follow-up started with the first RLS diagnosis and ended on the earliest of: incident diagnosis of lung cancer, end of enrollment in the database or end of the study period. The exposure of interest was cumulative duration of DAs use, measured in a time-varying manner. We constructed a multivariable Cox regression model to estimate HRs and 95% CIs for the association between lung cancer and cumulative durations of DA use, adjusting for potential confounding variables.

RESULTS

We identified 295 042 patients with a diagnosis of RLS. The mean age of the cohort was 62.9; 66.6% were women and 82.3% were white. The prevalence of any DA exposure was 40.3%. Compared to the reference group (no use and ≤1 year), the crude HRs for lung cancer were 1.16 (95% CI 0.99-1.36) and 1.14 (95% CI 0.86-1.51) for 1-3 years and >3 years of cumulative DA use, respectively. The adjusted HR for lung cancer was 1.05 (95% CI 0.88-1.25) for 1-3 years and 1.02 (95% CI 0.76-1.37) for >3 years of cumulative DA use, respectively.

CONCLUSIONS

At typical doses for the clinical management of RLS, long-term DA use was not associated with risk of lung cancer.

The Effect of Home Care Support Clinics on Hospital Readmission in Heart Failure Patients in Japan

BACKGROUND

Heart failure is common and is associated with high rates of hospitalization. Home care support clinics/hospitals (HCSCs) and enhanced HCSCs were introduced in Japan in 2006 and 2012, respectively.

OBJECTIVE

This study aimed to examine the effect of post-discharge care by conventional or enhanced HCSCs on readmission, compared with general clinics.

DESIGN

Retrospective cohort study using the Japanese nationwide health insurance claims database.

PARTICIPANTS

Participants were ≥65 years of age, admitted for heart failure and discharged between July 2014 and August 2015 and received a home visit within a month following the discharge (n=12,393).

MAIN MEASURES

The exposure was the type of medical facility that provides post-discharge home healthcare: general clinics, conventional HCSCs, and enhanced HCSCs. The primary outcome was all-cause readmission for 6 months after the first visit; the incidence of emergency house calls was a secondary outcome. We used a competing risk regression using the Fine and Gray method, in which death was regarded as a competing event.

KEY RESULTS

At 6 months, readmissions were lower in conventional (38%) or enhanced HCSCs (38%) than general clinics (43%). The adjusted subdistribution hazard ratio (sHR) of readmission was 0.87 (95% CI: 0.78-0.96) for conventional and 0.86 (0.78-0.96) for enhanced HCSCs. Emergency house calls increased with conventional (sHR: 1.77, 95% CI:1.57-2.00) and enhanced HCSCs (sHR: 1.93, 95% CI: 1.71-2.17).

CONCLUSIONS

Older Japanese patients with heart failure receiving post-discharge home healthcare by conventional or enhanced HCSCs had lower readmission rates, possibly due to compensation with more emergency house calls. Conventional and enhanced HCSCs may be effective in reducing the risk of rehospitalization. Further studies are necessary to confirm the medical functions performed by HCSCs.

Sodium-glucose cotransporter-2 inhibitors use and the risk of gout: a systematic review and meta-analysis

Objective

To assess the relationship between use of sodium-glucose cotransporter-2 inhibitors (SGLT2i) and the risk of gout among patients with type 2 diabetes mellitus (T2DM).

Methods

A systemic review and meta-analysis were designed by reviewing articles published between 2000 January 1 and 2022 December 31 using PubMed system and Web of Science system based on the PRISMA 2020 guidelines. The end point of interest was gout (including gout flares, gout events, starting uric-acid lowering therapy and starting anti-gout drugs use) among patients with T2DM using SGLT2i versus not using SGLT2i. A random-effects model was utilized to measure the pooled hazard ratio (HR) with 95% confidence interval (CI) for the risk of gout associated with SGLT2i use.

Results

Two prospective post-hoc analyses of randomized controlled trials and 5 retrospective electronic medical record-linkage cohort studies met the inclusion criteria. The meta-analysis demonstrated that there was a decreased risk of developing gout for SGLT2i use as comparing with non-use of SGLT2i among patients with T2DM (pooled HR=0.66 and 95%CI=0.57-0.76).

Conclusions

This meta-analysis demonstrates that SGLT2i use is associated with a 34% decreased risk of developing gout among patients with T2DM. SGLT2i may be the treatment options for patients with T2DM who are at high risk of gout. More randomized controlled trials and real-world data are needed to confirm whether there is a class effect of SGLT2i for the risk reduction of gout among patients with T2DM.

Prevalence and bleeding risk associated with the concomitant use of direct oral anticoagulants and antiarrhythmic drugs in patients with atrial fibrillation, based on the French healthcare insurance database

PURPOSE

Pharmacokinetic interactions exist between apixaban or rivaroxaban, and CYP3A4 and P-glycoprotein inhibitors such as amiodarone, verapamil and diltiazem. We aimed to estimate the prevalence of exposure to this drug-drug association (DDA) and to assess the bleeding risk associated in patients with atrial fibrillation (AF).

METHODS

We conducted a cohort study using a representative 1/97^th sample of the French healthcare insurance database between 2014 and 2019. Patients with AF receiving apixaban or rivaroxaban were included and followed-up until hospitalization for bleeding, death, discontinuation of apixaban or rivaroxaban, exposure to strong CYP3A4 inhibitor, or until December 31^st 2019, whichever came first. Primary outcome was hospitalization for bleeding registered as primary diagnosis. The association between the exposure to the DDA and hospitalization for bleeding was evaluated as a time-dependent variable in Cox model.

RESULTS

Between 2014 and 2019, the AF population under apixaban or rivaroxaban represented 10,392 patients. During the study period, the annual average prevalence of DDA exposure in this population was 38.9%. Among the 10,392 patients, 223 (2.1%) were hospitalized for bleeding, of which 75 (33.6%) received the association and 148 (66.4%) received apixaban or rivaroxaban alone. There was no association between DDA exposure and risk of hospitalization for bleeding (aHR = 1.19, [95% CI: 0.90, 1.58]). Age (HR 1.03 [1.02, 1.05]) and male gender (HR 1.72 [1.28, 2.30]) were associated with an increased risk of hospitalization for bleeding.

CONCLUSION

Exposure to antiarrhythmic drugs was not associated with an increased risk of hospitalization for bleeding in patients with AF under rivaroxaban or apixaban.

Metformin and Cancer: Solutions to a Real-World Evidence Failure

The quest to repurpose metformin, an antidiabetes drug, as an agent for cancer prevention and treatment, which began in 2005 with an observational study that reported a reduction in cancer incidence among metformin users, generated extensive experimental, observational, and clinical research. Experimental studies revealed that metformin has anticancer effects via various pathways, potentially inhibiting cancer cell proliferation. Concurrently, multiple nonrandomized observational studies reported remarkable reductions in cancer incidence and outcomes with metformin use. However, these studies were shown, in 2012, to be affected by time-related biases, such as immortal time bias, which tend to greatly exaggerate the benefit of a drug. The observational studies that avoided these biases did not find an association. Subsequently, the randomized trials of metformin for the treatment of type 2 diabetes and as adjuvant therapy for the treatment of various cancers, advanced or metastatic, did not find reductions in cancer incidence or outcomes. Most recently, the largest phase 3 randomized trial of metformin as adjuvant therapy for breast cancer, which enrolled 3,649 women with a 5-year follow-up, found no benefit for disease-free survival or overall survival with metformin. This major failure of observational real-world evidence studies in correctly assessing the effects of metformin on cancer incidence and outcomes was caused by preventable biases which, surprisingly, are still prominent in 2022. Rigorous approaches for observational studies that emulate randomized trials, such as the incident and prevalent new-user designs along with propensity scores, avoid these biases and can provide more accurate real-world evidence for the repurposing of drugs such as metformin.

Metanalyses on metformin's role in pancreatic cancer suffer from severe bias and low data quality - An umbrella review

AIMS

Discrepancies in the preclinical evidence, retrospective studies, and randomized trials evaluating metformin's role in pancreatic cancer are difficult to disentangle. We aimed to critically and systematically examine the quality and sources of heterogeneity between meta-analyses investigating the association between metformin intake and the prognosis of patients with pancreatic cancer.

MATERIALS AND METHODS

We performed a literature search on PubMed, MEDLINE, Embase, and Scopus on October 31, 2021 to identify meta-analyses investigating the impact of metformin treatment on the prognosis of patients with pancreatic cancer. Meta-analyses quality was assessed using according to the AMSTAR 2 criteria. We assessed bias in individual studies included in the meta-analyses, with particular attention to immortal time bias and quality of reporting.

RESULTS

Eleven meta-analyses describing 24 individual studies were included. All meta-analyses were rated low (n = 5) or critically low (n = 6) quality. Only 4 followed PRISMA reporting guidelines and only in 5 presented data were sufficient to replicate the analyses. Most meta-analyses combined results from clinical trials and retrospective studies (n = 6); patients with different cancer stages (resectable vs advanced) and from studies with different control group definitions. Immortal time bias was present and not accounted for in most (65.2%) of the individual retrospective studies; almost all (n = 9) meta-analyses failed to identify and correct for this source of bias.

CONCLUSIONS

Meta-analyses describing the association of metformin use in patients with pancreatic cancer are plagued by various types of bias inherent in retrospective studies. The quality of evidence linking metformin to decreased pancreatic cancer mortality is generally low.

Association Between Increased Linezolid Plasma Concentrations and the Development of Severe Toxicity in Multidrug-Resistant Tuberculosis Treatment

BACKGROUND

Treatment of multidrug-resistant (MDR) tuberculosis with linezolid is characterized by high rates of adverse events. Evidence on therapeutic drug monitoring to predict drug toxicity is scarce. This study aimed to evaluate the association of linezolid trough concentrations with severe toxicity.

METHODS

We retrospectively assessed consecutive patients started on linezolid for MDR tuberculosis between 2011 and 2017. The primary outcome was severe mitochondrial toxicity (SMT) due to linezolid, defined as neurotoxicity or myelotoxicity leading to drug discontinuation. The impact of plasma linezolid trough concentrations >2 mg/L was assessed in multivariate Cox proportional hazards models including time-varying covariates.

RESULTS

SMT occurred in 57 of 146 included patients (39%) at an incidence rate of 0.38 per person-year (95% confidence interval, .30-.49). A maximum linezolid trough concentration >2 mg/L was detected in 52 patients (35.6%), while the mean trough concentration was >2 mg/L in 22 (15%). The adjusted hazard ratio for SMT was 2.35 (95% confidence interval, 1.26-4.38; P = .01) in patients with a mean trough concentration >2 mg/L and 2.63 (1.55-4.47; P < .01) for SMT after the first detection of a trough concentration >2 mg/L. In an exploratory analysis, higher maximum trough concentrations were dose-dependently associated with toxicity, while lowering elevated trough concentrations did not restore baseline risk.

CONCLUSIONS

Linezolid trough concentrations >2 mg/L are strongly associated with the development of severe treatment-emergent toxicity in patients treated for MDR tuberculosis. Pending further prospective evidence, an individual risk-benefit assessment on the continuation of linezolid treatment is warranted in any patient with trough concentrations >2 mg/L.

Sodium channel-inhibiting drugs and cancer-specific survival: a population-based study of electronic primary care data

OBJECTIVES

Antiepileptic and antiarrhythmic drugs inhibit voltage-gated sodium (Na+) channels (VGSCs), and preclinical studies show that these medications reduce tumour growth, invasion and metastasis. We investigated the association between VGSC inhibitor use and survival in patients with breast, bowel and prostate cancer.

DESIGN

Retrospective cohort study.

SETTING

Individual electronic primary healthcare records extracted from the Clinical Practice Research Datalink.

PARTICIPANTS

Records for 132 996 patients with a diagnosis of breast, bowel or prostate cancer.

OUTCOME MEASURES

Adjusted Cox proportional hazards regression was used to analyse cancer-specific survival associated with exposure to VGSC inhibitors. Exposure to non-VGSC-inhibiting antiepileptic medication and other non-VGSC blockers were also considered. Drug exposure was treated as a time-varying covariate to account for immortal time bias.

RESULTS

During 1 002 225 person-years of follow-up, there were 42 037 cancer-specific deaths. 53 724 (40.4%) patients with cancer had at least one prescription for a VGSC inhibitor of interest. Increased risk of cancer-specific mortality was associated with exposure to this group of drugs (HR 1.59, 95% CI 1.56 to 1.63, p<0.001). This applied to VGSC-inhibiting tricyclic antidepressants (HR 1.61, 95% CI 1.50 to 1.65, p<0.001), local anaesthetics (HR 1.49, 95% CI 1.43 to 1.55, p<0.001) and anticonvulsants (HR 1.40, 95% CI 1.34 to 1.48, p<0.001) and persisted in sensitivity analyses. In contrast, exposure to VGSC-inhibiting class 1c and 1d antiarrhythmics was associated with significantly improved cancer-specific survival (HR 0.75, 95% CI 0.64 to 0.88, p<0.001 and HR 0.54, 95% CI 0.33 to 0.88, p=0.01, respectively).

CONCLUSIONS

Association between VGSC inhibitor use and mortality in patients with cancer varies according to indication. Exposure to VGSC-inhibiting antiarrhythmics, but not anticonvulsants, supports findings from preclinical data, with improved survival. However, additional confounding factors may underlie these associations, highlighting the need for further study.

Thiazolidinedione use is associated with reduced risk of dementia in patients with type 2 diabetes mellitus: A retrospective cohort study

BACKGROUND

Type 2 diabetes mellitus (T2DM) and dementia cause heavy health burden in mainland China, where few studies have investigated the association between glucose-lowering agents and dementia risk. We aimed to assess the association between use of thiazolidinediones (TZDs) and dementia incidence in a mainland Chinese population with T2DM.

METHODS

A retrospective cohort of T2DM patients who were new users of TZDs or alpha glucosidase inhibitors (AGIs) was assembled using the Yinzhou Regional Health Care Database. A Cox model with inverse probability of treatment weighting (IPTW) for controlling potential founding was applied to estimate the hazard ratio (HR) of the association between use of TZDs and dementia risk.

RESULTS

A total of 49 823 new users of AGIs and 12 752 new users of TZDs were included in the final cohort. In the primary analysis, the incidence of dementia was 195.7 and 78.2 per 100 000 person-years in users of AGIs and TZDs respectively. TZD use was associated with a reduced risk of incident dementia after adjusting for potential confounding using IPTW, with a HR of 0.51 (95% CI, 0.38-0.67). The results in various subgroup analyses and sensitivity analyses were consistent with the findings of the primary analysis.

CONCLUSIONS

Use of TZDs is associated with a decreased risk of dementia incidence in a mainland Chinese population with T2DM.

An overview of methodological flaws of real-world studies investigating drug safety in the post-marketing setting

INTRODUCTION

The evaluation of the post-marketing safety profile of drugs is a continuous monitoring process for approved and marketed medicines and it is crucial for detecting new adverse drug reactions. As such, real-world studies are essential to complement pre-marketing evidence with information concerning drug risk-benefit profile and use in wider patient populations and they have a great potential to support post-marketing drug safety evaluations.

AREAS COVERED

A detailed description of the main limitations of real-world data sources (i.e. claims databases, electronic healthcare records, drug/disease registers and spontaneous reporting system databases) and of the main methodological challenges of real-world studies in generating real-world evidence is provided.

EXPERT OPINION

Real-world evidence biases can be ascribed to both the methodological approach and the specific limitations of the different real-world data sources used to carry out the study. As such, it is crucial to characterize the quality of real-world data, by establishing guidelines and best practices for the assessment of data fitness for purpose. On the other hand, it is important that real-world studies are conducted using a rigorous methodology, aimed at minimizing the risk of bias.

HARmonized Protocol Template to Enhance Reproducibility of hypothesis evaluating real-world evidence studies on treatment effects: A good practices report of a joint ISPE/ISPOR task force

PROBLEM

Ambiguity in communication of key study parameters limits the utility of real-world evidence (RWE) studies in healthcare decision-making. Clear communication about data provenance, design, analysis, and implementation is needed. This would facilitate reproducibility, replication in independent data, and assessment of potential sources of bias.

WHAT WE DID

The International Society for Pharmacoepidemiology (ISPE) and ISPOR-The Professional Society for Health Economics and Outcomes Research (ISPOR) convened a joint task force, including representation from key international stakeholders, to create a harmonized protocol template for RWE studies that evaluate a treatment effect and are intended to inform decision-making. The template builds on existing efforts to improve transparency and incorporates recent insights regarding the level of detail needed to enable RWE study reproducibility. The overarching principle was to reach for sufficient clarity regarding data, design, analysis, and implementation to achieve 3 main goals. One, to help investigators thoroughly consider, then document their choices and rationale for key study parameters that define the causal question (e.g., target estimand), two, to facilitate decision-making by enabling reviewers to readily assess potential for biases related to these choices, and three, to facilitate reproducibility.

STRATEGIES TO DISSEMINATE AND FACILITATE USE

Recognizing that the impact of this harmonized template relies on uptake, we have outlined a plan to introduce and pilot the template with key international stakeholders over the next 2 years.

CONCLUSION

The HARmonized Protocol Template to Enhance Reproducibility (HARPER) helps to create a shared understanding of intended scientific decisions through a common text, tabular and visual structure. The template provides a set of core recommendations for clear and reproducible RWE study protocols and is intended to be used as a backbone throughout the research process from developing a valid study protocol, to registration, through implementation and reporting on those implementation decisions.

Core concepts in pharmacoepidemiology: Key biases arising in pharmacoepidemiologic studies

Pharmacoepidemiology has an increasingly important role in informing and improving clinical practice, drug regulation, and health policy. Therefore, unrecognized biases in pharmacoepidemiologic studies can have major implications when study findings are translated to the real world. We propose a simple taxonomy for researchers to use as a starting point when thinking through some of the most pervasive biases in pharmacoepidemiology. We organize this discussion according to biases best assessed with respect to the study population (including confounding by indication, channeling bias, healthy user bias, and protopathic bias), the study design (including prevalent user bias and immortal time bias), and the data source (including misclassification bias and missing data/loss to follow up). This tutorial defines, provides a curated list of recommended references, and illustrates through relevant case examples these key biases to consider when planning, conducting, or evaluating pharmacoepidemiologic studies.

The influence of immortal time bias in observational studies examining associations of antifibrotic therapy with survival in idiopathic pulmonary fibrosis: A simulation study

Background

Immortal time bias (ITB) has been overlooked in idiopathic pulmonary fibrosis (IPF). We aimed to identify the presence of ITB in observational studies examining associations between antifibrotic therapy and survival in patients with IPF and illustrate how ITB may affect effect size estimates of those associations.

Methods

Immortal time bias was identified in observational studies using the ITB Study Assessment Checklist. We used a simulation study to illustrate how ITB may affect effect size estimates of antifibrotic therapy on survival in patients with IPF based on four statistical techniques including time-fixed, exclusion, time-dependent and landmark methods.

Results

Of the 16 included IPF studies, ITB was detected in 14 studies, while there were insufficient data for assessment in two others. Our simulation study showed that use of time-fixed [hazard ratio (HR) 0.55, 95% confidence interval (CI) 0.47-0.64] and exclusion methods (HR 0.79, 95% CI 0.67-0.92) overestimated the effectiveness of antifibrotic therapy on survival in simulated subjects with IPF, in comparison of the time-dependent method (HR 0.93, 95% CI 0.79-1.09). The influence of ITB was mitigated using the 1 year landmark method (HR 0.69, 95% CI 0.58-0.81), compared to the time-fixed method.

Conclusion

The effectiveness of antifibrotic therapy on survival in IPF can be overestimated in observational studies, if ITB is mishandled. This study adds to the evidence for addressing the influence of ITB in IPF and provides several recommendations to minimize ITB. Identifying the presence of ITB should be routinely considered in future IPF studies, with the time-dependent method being an optimal approach to minimize ITB.

Left truncation in linked data: A practical guide to understanding left truncation and applying it using SAS and R

Time-to-event data such as time to death are broadly used in medical research and drug development to understand the efficacy of a therapeutic. For time-to-event data, right censoring (data only observed up to a certain point of time) is common and easy to recognize. Methods that use right censored data, such as the Kaplan-Meier estimator and the Cox proportional hazard model, are well established. Time-to-event data can also be left truncated, which arises when patients are excluded from the sample because their events occur before a specific milestone, potentially resulting in an immortal time bias. For example, in a study evaluating the association between biomarker status and overall survival, patients who did not live long enough to receive a genomic test were not observed in the study. Left truncation causes selection bias and often leads to an overestimate of survival time. In this tutorial, we used a nationwide electronic health record-derived de-identified database to demonstrate how to analyze left truncated and right censored data without bias using example code from SAS and R.

Association of menopausal hormone therapy with gastric and colorectal cancer risks in Korean women: A nationwide population-based cohort study

BACKGROUND

Menopausal hormone therapy (MHT) has been associated with a decreased risk of gastric cancer (GC) and colorectal cancer (CRC); however, few studies have been conducted in diverse ethnic groups, particularly in the Asian population. Therefore, the current study evaluated if MHT is inversely associated with GC and CRC in East Asia using a representative population-based study in Korea.

METHODS

This retrospective cohort study was conducted using the National Health Insurance Service-National Sample Cohort 2.0 in South Korea from 2002 to 2015. A total of 196,095 women aged ≥40 years were included in the study. The numbers of participants who did and did not use MHT were 19,063 (9.7 %) and 177,032 (90.3 %), respectively. Hazard ratios (HRs) and the corresponding 95 % confidence intervals (CIs) were estimated using a time-dependent Cox proportional hazards model. Age was considered as a time scale, and other confounding factors, including income levels based on insurance premiums, region of residence, and comorbidities, were included in the multivariable-adjusted model.

RESULTS

The total number of incident cases of GC and CRC were 1339 (0.68 %) and 1428 (0.73 %), respectively. We observed an inverse association of the use of estrogen replacement therapy (ERT; estrogen-containing therapy regardless of other regimen types) with GC [HR (95 % CI):0.68 (0.51-0.90)], CRC [0.57 (0.42-0.78)] and gastrointestinal cancer [GI, 0.63 (0.51-0.77)]. In the analyses by CRC subsite, the risks of both colon and rectal cancers were associated with ERT. In addition, both estrogen and combined estrogen and progestogen regimens were significantly associated with CRC and GI cancer.

CONCLUSION

ERT was associated with a decreased risk of GC and CRC. Our findings support the protective effect of estrogen against GC and CRC in Korean women.