Variability in antihypertensive drug therapy in general practice: results from a random national survey.

A random national survey of 50 general practitioners was undertaken to ascertain current trends in the pharmacological management of hypertension. Forty general practitioners entered the study, and scripts written by them over a two month period in 1988 were collected and recorded by the pharmaceutical pricing offices of the health department. The general practitioners provided details on whether the script had been written for hypertension, as well as the age and sex of the patients. Information from 37 general practitioners was available for study, involving 2675 scripts written for hypertension for 1858 patients. Sixty point two percent of the treated hypertensives were female, and 58.9% were aged over 60 years. The most commonly prescribed antihypertensives were the diuretics (47.1% of patients) and beta blockers (47.9%). They were followed by angiotensin converting enzyme inhibitors (18.2%) and calcium antagonists (9.7%). There was substantial variability in the prescription of antihypertensives with respect to the age and sex of the patients treated; the mean costs and duration of supply of different generic drug types; and the prescribing habits of general practitioners. By generic type, the mean monthly costs of therapy ranged from $3.77 (diuretics) to $48.19 (calcium antagonists). The age and sex adjusted geometric mean script costs ranged from $17.78 to $49.11 per month (median: $29.30). It seems unlikely that the observed degree of variability is explained by differences in the severity of hypertension between general practice populations.