Patient report validated against prescription records for measuring use of and compliance with antihypertensive drugs.

Drug use and patient compliance in antihypertensive treatment were studied by interview and validated with prescription records in a Finnish population. The original study population consisted of 675 hypertensives identified in a 6.6% random survey of the 25-59-year-old population in 1972. At re-examination in 1977, 310 of the 570 participants had then used antihypertensive drugs during the preceding year. Two thirds renewed prescriptions appropriately within 70% of the correct time (considered as good compliance). Prescription filling patterns of the re-examination non-participants did not differ from those of the participants. Eight per cent of the participants reported not having followed prescription instructions. There was 94% agreement between the re-examination and prescription records; 5% reported taking fewer drugs than the records showed and 1% reported taking more. Drug history given by the patient gave accurate information about the number and type of drugs in use. However, patient interview gave an overestimation of compliance.