A cluster randomised controlled trial of the effect of a treatment algorithm for hypertension in patients with type 2 diabetes.

Background: Good blood pressure (BP) control reduces the risk of complications in people with type 2 diabetes, yet many do not achieve this. Guidelines for managing hypertension recommend increasing antihypertensive medications until control is achieved, but the effect of such recommendations in routine primary care is unknown.

Aim: To evaluate the effectiveness of a BP treatment algorithm in primary care patients with type 2 diabetes.

Design Of Study: A cluster randomised controlled trial of 1534 patients with type 2 diabetes.

Setting: Forty-two practices in Nottingham, UK.

Method: Practices were randomised to continue usual care or to use a treatment algorithm designed so that practice nurses and GPs would increase antihypertensive treatment in steps until the target of 140/80 mmHg was reached. Participants were assessed by a clinical interview and case note review at recruitment and at 1 year. The primary outcome measure was the proportion of participants achieving target BP at 1 year.

Results: At 1 year there was no difference between the proportions of participants with well controlled BP in the intervention and control arms (36.6% versus 34.3%; P = 0.27). Mean systolic and diastolic blood pressures were identical in the two arms (143/78 mmHg). There was some evidence that participants in the intervention arm were more likely to be receiving higher doses of their antihypertensive drugs, although there was no significant difference in the number of different antihypertensive drugs prescribed. Participants in the intervention arm had a higher rate of primary care BP-related consultations over 12 months than those receiving usual care (rate ratio = 1.55, 95% confidence interval [CI] = 1.26 to 1.88, P<0.001).

Conclusion: Despite increased monitoring and possibly higher doses of medication there was no improvement in blood pressure control. Improvements achieved by specialist nurse-led clinics in secondary care may not translate to people with type 2 diabetes in primary care settings.