The influence of guideline revisions on the process and outcome of hypertension management in general practice: a descriptive study.

BACKGROUND: Blood pressure does not reach guideline targets in the majority of hypertensive patients. Longitudinal data from general practice records on trends in hypertension management and the influence of guideline changes are lacking.
OBJECTIVE: To describe the longitudinal impact of guideline revisions on the process and outcome of hypertension management in a primary care based database.
METHODS: We extracted data from the Nijmegen Monitoring Project (NMP), an academic practice-based research network with 50,000 patients listed. Based on the years of publication of the first Dutch guideline on hypertension (1991) and two revisions (1997 and 2003), we formed three cohorts of patients newly diagnosed with hypertension. We compared data such as patient characteristics, 2-year blood pressure course, type of first-choice antihypertensive drugs, and number of medications after 2 years of treatment.
RESULTS: Both the mean age at time of diagnosis of hypertension and pulse pressure rose between cohorts. In agreement with revisions in the guidelines, the use of diuretics as first-choice drugs increased significantly from the first to the last cohort. The percentage of patients with three or more antihypertensive drugs remained equal. The relative 2-year systolic blood pressure decline did not differ with clinical relevance between the cohorts.
CONCLUSION: Our study has demonstrated that general practitioners achieve substantial and prolonged blood pressure reduction. However, guideline revisions do not seem to influence the amount of reduction, despite clear formulation of stricter treatment goals. In addition to qualitative research to identify the causes of this phenomenon, research to evaluate the effect of expert support systems on risk awareness and risk gain by additional treatment is necessary.