Symmetry analysis for monitoring safety of newly marketed drugs

Risk of Liver Injury Associated with Intravenous Lipid Emulsions: A Prescription Sequence Symmetry Analysis

Aims: To determine the risk of liver injury associated with the use of different intravenous lipid emulsions (LEs) in large populations in a real-world setting in China. Methods: A prescription sequence symmetry analysis was performed using data from 2015 Chinese Basic Health Insurance for Urban Employees. Patients newly prescribed both intravenous LEs and hepatic protectors within time windows of 7, 14, 28, 42, and 60 days of each other were included. The washout period was set to one month according to the waiting-time distribution. After adjusting prescribing time trends, we quantify the deviation from symmetry of patients initiating LEs first and those initiating hepatic protectors first, by calculating adjusted sequence ratios (ASRs) and relevant 95% confidence intervals. Analyses were further stratified by age, gender, and different generations of LEs developed. Results: In total, 416, 997, 1,697, 2,072, and 2,342 patients filled their first prescriptions with both drugs within 7, 14, 28, 42, and 60 days, respectively. Significantly increased risks of liver injury were found across all time windows, and the strongest effect was observed in the first 2 weeks [ASR 6.97 (5.77-8.42) ∼ 7.87 (6.04-10.61)] in overall patients. In subgroup analyses, female gender, age more than 60 years, and soybean oil-based and alternative-LEs showed higher ASRs in almost all time windows. Specially, a lower risk for liver injury was observed in the first 14 days following FO-LEs administration (ASR, 3.42; 95% CI, 0.81-14.47), but the risk started to rise in longer time windows. Conclusion: A strong association was found between LEs use and liver injury through prescription sequence symmetry analysis in a real-world setting, which aligns with trial evidence and clinical experience. Differences revealed in the risks of liver injury among various LEs need further evaluation.

Association of atorvastatin with the risk of hepatotoxicity: a pilot prescription sequence symmetry analysis

Purpose

This study aimed to evaluate Atorvastatin (ATO)-associated hepatotoxicity using prescription sequence symmetry analysis (PSSA), based on a health insurance database of a Chinese population living in Jiangsu Province, China.

Methods

Patients prescribed ATO and hepatoprotective drugs in 2017 were identified, and the run-in period was determined based on the "waiting-time" distribution. Adjusted sequence ratio (ASR) and 95% confidence interval (95% CI) were calculated to estimate the risk of ATO-associated hepatotoxicity under different time intervals or based on gender and age stratification.

Results

A total of 2,549 patients, with 1,518 filling the ATO prescription first and 1,031 filling the ATO prescription second, were analyzed. After setting the run-in period as 30 days and the time interval as 15, 30, 60, 90, 120, and 180 days, the ASRs were 1.492 (95% CI: 1.367-1.652), 1.399 (95% CI: 1.308-1.508), 1.280 (95% CI: 1.213-1.357), 1.292 (95% CI: 1.234-1.356), 1.278 (95% CI: 1.226-1.336), and 1.274 (95% CI: 1.229-1.323), respectively. No significant difference was observed between different genders and ages (χ²=0.161, P=0.688; χ²=1.565, P=0.211, respectively).

Conclusion

This is the first study conducted in a real-world setting to evaluate the relationship between ATO and hepatotoxicity using the PSSA in a Chinese population. We found a 1.3- to 1.5-fold increase in risk of hepatotoxicity following ATO, with the greater risk occurring within the first 30 days of treatment.

Effect estimate comparison between the prescription sequence symmetry analysis (PSSA) and parallel group study designs: A systematic review

Prescription sequence symmetry analysis (PSSA), a case-only design introduced in 1996, has been increasingly used to identify unintentional drug effects, and has potential applications as a hypothesis-testing and a hypothesis-generating method, due to its easy application and effective control of time-invariant confounders. The aim of this study is to systematically compare effect estimates from the PSSA to effect estimates from conventional observational parallel group study designs, to assess the validity and constraints of the PSSA study design. We reviewed the MEDLINE, EMBASE, and Web of Science databases until February 2016 to identify studies that compared PSSA to a parallel group design. Data from the eligible articles was extracted and analyzed, including making a Bland-Altman plot and calculating the number of discrepancies between the designs. 63 comparisons (from two studies) were included in the review. There was a significant correlation (p < 0.001) between the effect estimates of the PSSA and the parallel group designs, but the bias indicated by the Bland-Altman plot (0.20) and the percentage of discrepancies (70–80%) showed that this correlation was not accompanied by a considerable similarity of the effect estimates. Overall, the effect estimates of the parallel group designs were higher than those of the PSSA, not necessarily further away from 1, and the parallel group designs also generated more significant signals. However, these results should be approached with caution, as the effect estimates were only retrieved from two separate studies. This review indicates that, even though PSSA has a lot of potential, the effect estimates generated by the PSSA are usually lower than the effect estimates generated by parallel group designs, and PSSA mostly has a lower power than the conventional study designs, but this is based on limited comparisons, and more comparisons are needed to make a proper conclusion.