Work

Comment on: Suissa and Azoulay. Metformin and the Risk of Cancer: Time-Related Biases in Observational Studies. Diabetes Care 2012;35:2665–2673

Year: 2013

Type: letter

Abstract: In a recent article in Diabetes Care , Suissa and Azoulay (1) concluded that the impressive results of the metformin-associated reduced cancer risk were due to many researchers failing to adjust for immortal time bias and not using time-dependent analysis of drug exposure. However, this conclusion is not justified since it remains controversial whether immortal time would introduce substantial bias. We used statins and their effect on cardiovascular disease (CVD) to illustrate how different analyses could yield different results in pharmacoepidemiological studies. In a time-fixed Cox model, statin use was associated with a hazard ratio (HR) of 0.66 (95% CI 0.50–0.88) for CVD, an effect size similar to that in randomized trials despite 48% of the total follow-up time in the statin users being immortal time (i.e., without drug exposure). Herein, immortal time …

Source: Diabetes Care

DOI: 10.2337/dc12-2561

Authors: Xilin Yang, Juliana C.N. Chan

Institutions: Tianjin Medical University, Chinese University of Hong Kong

Language: English

Topic: Metabolism, Diabetes, and Cancer

Subfield: Molecular Biology

Field: Biochemistry, Genetics and Molecular Biology

Domain: Life Sciences

SDG: Good health and well-being

Open Access status: hybrid