How Accurate are Hypertension Treatment Decisions? Absolute Risk Assessment and Prescribing for Moderate Hypertension - A Study of Cambridge General Practitioners

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Abstract
Objective: To determine the factors influencing general practitioners' prescribing for patients with moderate hypertension, and to investigate their ability to assess patients' absolute risk of cardiovascular disease. Design: Decision-making was assessed by a postal questionnaire involving five standardised example patients, send to all general practitioners in the CB-postcode area (Cambridge, UK). Patients varied in age, gender, diabetic and smoking status, blood pressure and total cholesterol, giving 5-year absolute risks ranging from less than 5% to greater than 20%. GP treatment decisions and risk factor influence, age bias, absolute risk calculations and cost-awareness were analysed with SPSS. Absolute risk was calculated using the New Zealand Core Services Committee (NZCSC) Guidelines, 1995. Results: GP response rate was 66%. Sample demographics (mean age 42 years, 39% female) did not differ statistically from local health authority data. High blood pressure alone was the most common reason for instituting therapy (67%), independent of other risk factors. Drug choices did not differ statistically from Prescription Pricing Authority data. This supports the validity of the questionnaire. GP estimations of absolute risk were inconsistent, and there was a significant association between underestimation of elderly patient risk and overestimation of younger patient risk (p = 0.05). Conclusions: The Cambridge GPs more frequently based treatment decisions on patients' blood pressure level alone, rather than considering absolute risk as recommended by NZCSC and WHO guidelines. The relationship between patient age and risk estimations may indicate a ''young age premium'' influencing treatment. The data support the need for risk-based guidelines and education in treatment of hypertension.