Cancer in Patients With Gabapentin (GPRD)

The exposure of interest is gabapentin use as defined by prescriptions recorded by the GPRD general practitioner (British National Formulry codes). Data on prescriptions for gabapentin will be extracted for each case and control from entry into the study cohort up to two years prior to the index date (the exposure window). A two year lagged exposure is incorporated to account for latency between cancer onset and GPRD diagnosis, and for protopathic bias (gabapentin prescription for initial pain symptoms of undiagnosed cancer). Gabapentin exposure will be parameterized as follows: (1) Ever versus never exposed; (2) Number of prescriptions; (3) Duration of exposure; and (4) Cumulative dose.