Development of a questionnaire to investigate patient compliance with antirheumatic drug therapy.

OBJECTIVE: To develop a rheumatology oriented questionnaire that measures compliance to drug regimen and identifies factors that contribute to suboptimal compliance in patients with rheumatoid arthritis (RA), polymyalgia rheumatica (PMR), and gout.
METHODS: Thirty-two patients (16 RA, 8 PMR, 8 gout) participated in semistandardized home interviews about their attitude toward their antirheumatic medication, actual drug intake, and reasons for not taking medication. A focus group interview with 7 patients (3 RA, 2 PMR, 2 gout) was held. Following an advertisement in the rheumatology patient organization magazine (>8000 patients) 14 patients (9 RA, 5 PMR) telephoned and explained their reasons for noncompliance. All interviews were recorded on tape, transcribed, and independently reviewed by 2 investigators. Thirty-one statements were selected. After a field test, the phrasing of some items was revised. The questionnaire was then sent by mail to 117 consecutive outpatients (58 RA, 30 PMR, 29 gout).
RESULTS: Twelve items were excluded because of low or high corrected item-total correlation or skew distribution of the answers. Internal consistency of the remaining 19 items was intermediate (0.71). Discriminant analyses with an overall patient self-report compliance measure showed a sensitivity of 98%, a specificity of 67%, and a Cohen's kappa of 0.71. Stepwise discriminant analyses revealed that 3 items classified 84% of all cases correctly with a sensitivity of 99%, specificity 80%, and kappa 0.78.
CONCLUSION: The 19 item measure was well accepted. It is useful to detect possible barriers for optimal compliance and to predict patient compliance to drug regimen.