How well do patient reports reflect adverse drug reactions reported by rheumatologists? Agreement of physician- and patient-reported adverse events in patients with rheumatoid arthritis observed in the German biologics register

OBJECTIVE: To analyse the validity of patient reports on adverse drug reactions (ADRs) compared with the reports given by the treating physician. METHODS: Patients with RA enrolled in the German biologics register rheumatoid arthritis observation of biologic therapy (RABBIT) between May 2001 and September 2006 were included in the study. We investigated concordance of reporting and level of agreement between physician- and patient-reported ADRs, taking the physician as gold standard. RESULTS: Data from 4246 patients were analysed. Patients reported on average 1.2 ADRs per patient-year (PY) compared with 0.8 ADRs reported by the physicians (P<0.001). Gastrointestinal disorders were the most frequently reported ADRs by patients (277.8/1000 PYs) and physicians (137.8/1000 PYs), infections were reported with considerably higher frequency by physicians (124/1000 PYs) than by patients (72/1000 PYs). Agreement between patients and physicians (same or similar event reported at the same time) differed according to the nature of the reported ADR. High agreement was found for easily observable, known ADRs (such as alopecia, agreement 76.7%) In contrast, even for some serious ADRs, many patients did not see a connection between the event and the drug taken (e.g. pneumonia, agreement 37.7%). CONCLUSIONS: Patient reports on ADRs are a useful source of information on the safety of new therapies. However, drug surveillance cannot rely on patient reports only, since even life-threatening events were not reported as ADRs by the patients who failed to associate them with the therapy. When coding patient reports on ADRs to a standard coding system, the differences in language and terminology between patients and physicians should be taken into account.