Trends in the use of blood pressure lowering medications in Auckland, and associated costs, 1982-94.

AIM: To describe the trends to the use of blood pressure lowering medication and associated costs in Auckland, New Zealand between 1982 and 1994. METHODS: Three cross sectional surveys of cardiovascular risk factors in people aged 35-64 years have been conducted in the Auckland region in 1982, 1986-8 and 1993-4, with random selection of 3804 European men and women from Auckland electoral rolls. RESULTS: Mean systolic and diastolic blood pressure fell significantly in both sexes between 1982 and 1993-4. There was a possible trend towards a decrease in the proportion of the survey population taking blood pressure lowering drugs with 9.3% on medication in 1982 and 8.0% in 1993-4, while the number of drugs prescribed per person for blood pressure control declined from 1.41 to 1.15. As a percentage of the total antihypertensive drug use in the population, diuretic use dropped from 40.3% to 11.7%, and beta blockers decreased from 36% to 27%. Angiotensin converting enzyme (ACE) inhibitors that were unavailable in 1982, were the most commonly prescribed antihypertensive at 35.8% in 1993-4 and calcium antagonists increased from 2% in 1982 to 22.1% in 1993-4. In 1995 dollars the average daily cost of blood pressure lowering medication per person has increased from 35 cents in 1982 to 76 cents in 1994. CONCLUSION: Over the 12 year survey period ACE inhibitors, beta blockers and calcium antagonists have replaced diuretics as the major antihypertensive drugs used in the Auckland population. This has resulted in an increase in the average daily cost of antihypertensive drug therapy per person of approximately 100% in the period 1982-94.