Cost analysis of ambulatory blood pressure monitoring in initiating antihypertensive drug treatment in Australian general practice

Objective: To compare the cost of ambulatory blood pressure monitoring (ABPM) with the putative savings made through treatment avoided by identification and non-treatment of those with "white coat" hypertension. Design: A cost analysis based on a model of four alternative strategies (no ABPM, yearly, two-yearly, or three-yearly monitoring) over a seven-year period applied to a case series from Australian general practice. Participants: 62 patients newly diagnosed by their GPs as having hypertension and requiring drug treatment. Main outcome measures: The proportion of patients shown to not need treatment. The discounted costs to the Pharmaceutical Benefits Scheme, Medical Benefits Scheme and patients. Results: 16 of 62 patients (26%; 95% CI, 15%-37%) were normotensive on ABPM and did not require treatment. All monitoring strategies are more expensive in the first year, but the initial costs are offset by year 3 and the monitoring strategies are cost saving thereafter. Sensitivity analysis shows that this result holds across a range of costs of pharmacotherapy and proportion of patients with white coat hypertension. Conclusion: The additional costs of 24-hour ABPM in the first year are offset by savings associated with patients with white coat hypertension who would otherwise have been treated.