Automated pharmacovigilance system finds higher rates of side effects than those reported on drug package inserts
Patient Safety and Quality
Safety concerns have been raised about some commonly used prescription drugs such as varenicline (for smoking cessation) and zolpidem (for insomnia). One way to address these concerns is to develop alternative ways of reporting adverse side effects, especially since it is not known how closely the reporting of side effects on the package inserts for these drugs matches patients’ actual experience.
A team of Boston-based researchers using an automated phone pharmacovigilance system relying on an interactive voice response system (IVRS) found that patients taking varenicline reported significantly greater rates of confusion, depression, hallucination, muscle aches, sexual dysfunction, and fatigue than what is described in the package insert. By contrast, patients taking zolpidem for insomnia reported only one symptom, fatigue, at a significantly greater rate than the package insert. The rates of side effects reported on package inserts are based on findings from premarketing trials.
There may be several reasons for differences in the rates reported in this study compared to those reported in the inserts. Patients in trials are healthier and less diverse than the general population. They are also more carefully monitored than patients in general practice, who may be taking a given drug for an off-label indication that would not have been tested during the premarketing trials. Finally, patients may be more willing to report ‘sensitive’ symptoms, such as depression and sexual dysfunction, to an automated machine than they would to their physician or during participation in a clinical trial.
The participants in the survey were patients taking varenicline (107) and those taking zolpidem (370) in 11 Boston area primary care practices that are part of a large health system. After the office visit in which the drug was prescribed, patients next received an informational letter offering an option for 'opting out.' Four weeks after the office visit, patients who did not opt out were contacted by an automated monitoring system using the IVRS. Patients were asked about adherence to their prescriptions and a prespecified list of symptoms.
The researchers believe that their data underscore the importance of collecting systematic information about symptoms as a proxy for adverse drug events directly from patients to fully assess the safety of prescription drugs.
This study was supported by AHRQ (HS16970). See "Do package inserts reflect symptoms experienced in practice? Assessment using an automated phone pharmacovigilance system with varenicline and zolpidem in a primary care setting," by Jennifer S. Haas, M.D., Mary Amato, Pharm.D., Lucas Marinacci, B.A., and others in Drug Safety 35(8), pp. 624-628, 2012.