Trends in antihypertensive prescribing

To identify trends in the prescribing of antihypertensive medications and measure the changes in government and patient expenditure resulting from any identified change.

The computerised records of 16 069 patients from six Otago practices from 1991-3 were examined. Those patients prescribed any antihypertensive medication in all 3 years were selected for investigation. The antihypertensives prescribed were assigned to one of seven classes. The cohort was then divided into two groups; those remaining on the same class of medication for the three years and those changing medication class at any stage. Reasons for any change were identified. The direct costs of the prescribing decisions taken were evaluated.

914 patients were prescribed antihypertensive in all 3 years. Of these 579 (63.3%) remained on the same class of medication, while 335 (36.7%) changed class. A clinical reason was identified for medication change class. A clinical reason was identified for medication change in 98% of cases available for examination. There was no significant shift in expenditure for those remaining on the same medication, while costs for those remaining on the same medication, while costs increased by 20.6% for those changing.

For this cohort increased expenditure on antihypertensive was driven by those changing medication. Although these changes were prompted by clinical reasons, better health outcomes for patients cannot be assumed due to lack of objective indicators.