Health economics in the Hypertension Optimal Treatment (HOT) study: costs and cost-effectiveness of intensive blood pressure lowering and low-dose aspirin in patients with hypertension.

OBJECTIVES

To investigate the marginal cost-effectiveness of different targets for the reduction of blood pressure and the cost-effectiveness of adding acetylsalicylic acid (ASA) to the treatment of hypertension.

DESIGN

Patients with hypertension were randomized to three target groups for blood pressure; < or =90, < or =85 and < or =80 mmHg. Patients were also randomly assigned ASA and placebo. The average follow-up time was 3.8 years. The direct costs for drugs, visits, hospitalizations, and side-effects were calculated and related to clinical outcome.

SETTING

Resource utilization data from all the 26 countries in the study were pooled, and Swedish unit costs were applied to the aggregated resource utilization.

SUBJECTS

A total of 18 790 patients, 50-80 years of age (mean 61.5 years), with a diastolic blood pressure between 100 and 115 mmHg (mean 105 mmHg).

INTERVENTIONS

Antihypertensive treatment with the long-acting calcium antagonist felodipine was given to all patients. Additional therapy and dose increments in four further steps were prescribed to reach the randomized target blood pressure. Fifty per cent of the patients were randomized to a low dose, 75 mg daily, of acetylsalicylic acid.

MAIN OUTCOME MEASURES

Direct health care costs, major cardiovascular (CV) events (myocardial infarction and stroke) and CV death.

RESULTS

The average cost of drugs and visits increased with more intensive treatment. The increase in treatment costs was partly but not fully offset by a nonsignificant reduction in the cost of CV hospitalizations. For patients with diabetes there were no significant differences in total cost between the target groups. The cost of avoiding a major CV event was negative in the base case analysis, SEK -10 360 (CI: -78 195, 75 630), and SEK 18 450 (CI: -88 789, 192 980) in a sensitivity analysis. For patients on ASA, costs were slightly but significantly higher than for patients on placebo. The estimates of the cost of avoiding a major CV event varied between SEK 41 600 and SEK 477 400, with very wide confidence intervals.

CONCLUSIONS

The treatment cost increases as the target for hypertension treatment is lowered. In patients with diabetes, intensive treatment to a lower target is cost-effective. Because of the nonsignificant difference in events, no conclusion can be made for all patients in the study. Furthermore, no conclusive evidence was found regarding the cost-effectiveness of adding ASA to the treatment of hypertension.