Association between Ranibizumab Injections and Risk of Acute Myocardial Infarction in Age-related Macular Degeneration: A Case-crossover Study

Evaluating the use of methods to mitigate bias from non-transient medications in the case-crossover design: A systematic review

PURPOSE

The case-crossover design is a self-controlled study design used to compare exposure immediately preceding an event occurrence with exposure in earlier control periods. The design is most suitable for transient exposures in order to avoid biases that can be problematic when using the case-crossover design for non-transient (i.e., chronic) exposures. Our goal was to conduct a systematic review of case-crossover studies and its variants (case-time-control and case-case-time-control) in order to compare design and analysis choices by medication type.

METHODS

We conducted a systematic search to identify recent case-crossover, case-time-control, and case-case-time-control studies focused on medication exposures. Articles indexed in MEDLINE and EMBASE using these study designs that were published between January 2015 and December 2021 in the English language were identified. Reviews, methodological studies, commentaries, articles without medications as the exposure of interest, and articles with no available full text were excluded. Study characteristics including study design, outcome, risk window, control window, reporting of discordant pairs, and inclusion of sensitivity analyses were summarized overall and by medication type. We further evaluated the implementation of recommended methods to account for biases introduced by non-transient exposures among articles that used the case-crossover design on a non-transient exposure.

RESULTS

Of the 2036 articles initially identified, 114 articles were included. The case-crossover was the most common study design (88%), followed by the case-time-control (17%), and case-case-time-control (3%). Fifty-three percent of the articles included only transient medications, 35% included only non-transient medications, and 12% included both. Across years, the proportion of case-crossover articles evaluating a non-transient medication ranged from 30% in 2018 to 69% in 2017. We found that 41% of the articles that evaluated a non-transient medication did not apply any of the recommended methods to account for biases and more than half of which were conducted by authors with no previous publication history of case-crossover studies.

CONCLUSION

Using the case-crossover design to evaluate a non-transient medication remains common in pharmacoepidemiology. Researchers should apply appropriate design and analysis choices when opting to use a case-crossover design with non-transient medication exposures.

Effect Modification by Indication to the Risks of Major Thromboembolic Adverse Events in Patients Receiving Intravitreal Anti-Vascular Endothelial Growth Factor Treatment: A Population-Based Retrospective Cohort Study

BACKGROUND

The association between intravitreal anti-vascular endothelial growth factor (anti-VEGF) treatment and the risk of major thromboembolic adverse events (TAEs) remains under debate. This study aimed to examine associated risks of TAEs in patients receiving intravitreal anti-VEGF treatment, and effect modification by different indications.

METHODS

This retrospective cohort study analyzed Taiwan's National Health Insurance Database during 2011-2017 to identify neovascular age-related macular degeneration (nAMD) or diabetic macular edema (DME) patients newly receiving intravitreal aflibercept or ranibizumab. We followed up patients for 2 years, or until the occurrence of TAEs, including ischemic heart disease, ischemic stroke, transient ischemic attack, deep vein thrombosis, and pulmonary embolism, death, or the end of the study period (i.e., 31 December 2018). We compared the risk of TAEs between patients with aflibercept and ranibizumab using Cox-proportional hazard models. We examined statistical interactions between the anti-VEGF treatment (i.e., ranibizumab and aflibercept) and indications (i.e., nAMD and DME) with regard to the outcome of TAEs.

RESULTS

We included 12,215 nAMD and 7532 DME patients. Among nAMD patients, those receiving aflibercept had lower risk of TAEs (adjusted hazard ratio [HR] 0.85; 95% CI 0.77-0.94) compared with those receiving ranibizumab. However, among DME patients, those receiving aflibercept had no differences in the risk of TAEs (1.14; 0.97-1.35) compared with those receiving ranibizumab. Among patients treated with ranibizumab, the DME group had a higher risk of TAEs than the nAMD group (HR 1.15; 95% CI 1.03-1.28); similar results were observed in patients treated with aflibercept (HR 1.53; 95% CI 1.27-1.85). When DME patients were treated with aflibercept, the risk of TAEs was 31% higher than when nAMD patients were treated with ranibizumab (HR 1.31; 95% CI 1.09-1.56; p < 0.05). The p-value for statistical interaction between the anti-VEGF treatment and indications was 0.0033.

CONCLUSIONS

Patients treated with aflibercept or ranibizumab for different indications may be associated with varying risk of TAEs. The findings provide evidence to support treatment selection, taking indications and TAE risk into consideration.

Monoclonal antibodies in diabetic retinopathy

INTRODUCTION

Diabetic retinopathy (DR), as one of the main complications of diabetes, is among the leading causes of blindness and visual impairment worldwide.

AREAS COVERED

Current clinical therapies include photocoagulation, vitrectomy, and anti-vascular endothelial growth factor (VEGF) therapies. Bevacizumab and ranibizumab are two monoclonal antibodies (mAbs) inhibiting angiogenesis. Intravitreal ranibizumab and bevacizumab can decrease the rate of blindness and retinal thickness, and improve visual acuity whether as monotherapy or combined with other treatments. They can increase the efficacy of other treatments and decrease their adverse events. Although administered intravitreally, they also might enter the circulation and cause systemic effects. This study is aimed to review our current knowledge about mAbs, bevacizumab and ranibizumab, in DR including superiorities, challenges, and limitations. Meanwhile, we tried to shed light on new ideas to overcome these limitations. Our latest search was done in April 2021 mainly through PubMed and Google Scholar. Relevant clinical studies were imported.

EXPERT OPINION

Future direction includes detection of more therapeutic targets considering other components of DR pathophysiology and shared pathogenesis of DR and neurodegenerative diseases such as Parkinson's disease and Alzheimer's disease, the treat-and-extend regimen, and new ways of drug delivery and other routes of ocular drug administration.

A novel weighting method to remove bias from within-subject exposure dependency in case-crossover studies

BACKGROUND

Case-crossover studies have been widely used in various fields including pharmacoepidemiology. Vines and Farrington indicated in 2001 that when within-subject exposure dependency exists, conditional logistic regression can be biased. However, this bias has not been well studied.

METHODS

We have extended findings by Vines and Farrington to develop a weighting method for the case-crossover study which removes bias from within-subject exposure dependency. Our method calculates the exposure probability at the case period in the case-crossover study which is used to weight the likelihood formulae presented by Greenland in 1999. We simulated data for the population with a disease where most patients receive a cyclic treatment pattern with within-subject exposure dependency but no time trends while some patients stop and start treatment. Finally, the method was applied to real-world data from Japan to study the association between celecoxib and peripheral edema and to study the association between selective serotonin reuptake inhibitor (SSRI) and hip fracture in Australia.

RESULTS

When the simulated rate ratio of the outcome was 4.0 in a case-crossover study with no time-varying confounder, the proposed weighting method and the Mantel-Haenszel odds ratio reproduced the true rate ratio. When a time-varying confounder existed, the Mantel-Haenszel method was biased but the weighting method was not. When more than one control period was used, standard conditional logistic regression was biased either with or without time-varying confounding and the bias increased (up to 8.7) when the study period was extended. In real-world analysis with a binary exposure variable in Japan and Australia, the point estimate of the odds ratio (around 2.5 for the association between celecoxib and peripheral edema and around 1.6 between SSRI and hip fracture) by our weighting method was equal to the Mantel-Haenszel odds ratio and stable compared with standard conditional logistic regression.

CONCLUSION

Case-crossover studies may be biased from within-subject exposure dependency, even without exposure time trends. This bias can be identified by comparing the odds ratio by the Mantel-Haenszel method and that by standard conditional logistic regression. We recommend using our proposed method which removes bias from within-subject exposure dependency and can account for time-varying confounders.