Drug compliance scale. I. Development of the drug compliance scale

The failure of patients to comply with treatment regimens recommended by their physicians is a significant clinical problem. Researches on the assessment of compliance have, however, been precluded by methodological difficulties such as lack of adequate measures. The purpose of this study was to develop a self-administered questionnaire to evaluate drug compliance. First, questionnaire containing a 52-items complied by two doctors, a pharmacist and a nurse, was tested on 81 outpatients, all volunteers, attending the departments of psychosomatic medicine and internal medicine. Four items were temporarily removed for later analysis because they directly inquired about drug compliance (drug compliance items). The other 48 items were analyzed and three factors consisting of 26 items were further studied: expectation on taking medicine, rejection to taking medicine and seeking knowledge of drugs. Chronback's alpha coefficients representing internal consistency of the three factors were sufficiently high (ranging from .75 to .84). Furthermore, we preformed a simplified pill count to validate the 4 drug compliance items. There was a weak to moderate correlation between the result of pill count and each of 4 drug compliance items. A new self-administered questionnaire of 30 items was thus developed and named the Drug Compliance Scale.