As part of a post-approval safety commitment to the U.S. Food and Drug Administration, researchers from RTI Health Solutions have conducted a study to estimate the incidence of 10 common cancers among patients treated with antimuscarinic medications for overactive bladder (AMOABs). Using a retrospective cohort study design, researchers analyzed data from new users of AMOABs with no previous diagnosis of cancer.
Results showed that incidence rates of prostate and bladder cancer were elevated in the first year of AMOAB treatment and that those incidence rates decreased over time. Incidence rates of cancers other than prostate and bladder were not elevated in the first year of treatment.
These findings suggest that while patients’ urinary symptoms prompted treatment with an AMOAB, the symptoms were likely due to cancer that was already present but not yet diagnosed or documented (protopathic bias).
To avoid unnecessary delays in the diagnosis of prostate and bladder cancer, researchers recommended that physicians should consider these cancers as a cause of overactive bladder symptoms when evaluating patients.
Kaye JA, Margulis AV, Fortuny J, McQuay LJ, Plana E, Bartsch JL, Bui CL, Perez-Gutthann S, Arana A. Cancer incidence after initiation of antimuscarinic medications for overactive bladder in the United Kingdom: evidence for protopathic bias. Pharmacotherapy. 2017 Mar 31. doi: 10.1002/phar.1932.