Patient reporting of potential adverse drug reactions: a methodological study

Aims To develop a systematic generic method of enabling patients to report symptoms which they believe to be due to a particular prescribed drug. Methods A piloted body system‐based questionnaire was distributed to patients registered with 79 medical practices in Grampian prescribed one of nine recently marketed ‘black triangle’ drugs. These comprised four antidepressants, three antiepileptics and two analgesics. This requested respondents to identify any symptoms experienced over the previous year which they thought could be due to the ‘black triangle’ drug they had used. A sample of medical records was examined to compare symptoms recorded with those reported by patients. A classification system was developed for the study to enable the assessment of symptoms reported for their potential relationship to patients' drug therapy. All symptoms reported were classified, taking into account information provided by patients on their concomitant drugs and diseases. A specialist pharmacist independently re‐classified a sample of the symptoms to validate the process. Results A 36.3% response rate was obtained (837/2307) with 742 respondents (88.6%) reporting at least one symptom. The median per patient was 6.0 (range 0–71), with almost half (406, 48.5%) reporting fewer than five symptoms. Most symptoms (71.0%) were classified as being probably or possibly related to the drugs studied. Agreement between researcher and specialist on the classification of 75.3% of 716 symptoms was obtained (Kappa=0.563). Responses from patients prescribed antidepressant drugs were more likely to include symptoms potentially caused by these drugs (74.5% of all symptoms reported) than those from patients prescribed analgesics (67.4%) or antiepileptics (65.1%, χ2 = 23.858, d.f. = 2, P