1999 WHO/ISH Guidelines applied to a 1999 MONICA sample from northern Sweden

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Abstract
Treating hypertension with drugs is so far the most cost-effective way to reduce this important risk factor for cardiovascular disease (CVD). It is, however, important to determine absolute risk, and thereby estimate indication for drug treatment, in order to maintain a cost-effective drug treatment. WHO/ISH Hypertension Guidelines from 1999 propose a risk stratification for estimating absolute risk for CVD based on blood pressure and additional risk factors, target organ damage (TOD) and CVD. We studied the consequences of applying the recent WHO/ISH risk stratification scheme to a MONICA sample of 6000 subjects from a geographically defined population in northern Sweden, regarding indications for treatment, target blood pressure and risk distribution. We have risk-classified each of these patients using a computer program, according to the WHO/ISH scheme. Data on TOD were not available. In all, 917 (15%) had drug-treated hypertension. Three-quarters (n = 737) were inadequately treated, with blood pressure levels at or above 140 or 90 mmHg. 1773 (30% of 5997) untreated subjects had a blood pressure of 140/90 or above; 16% in the low-, 62% in the medium-, 8% in the high-, and 14% in the very-high-risk group. The corresponding risk-group pattern for the inadequately treated hypertensives (n = 737) was 5.5, 48.3, 11.1 and 35.2%, respectively. If we shifted the target blood pressure from below 140/90 to below 130/85 for drug-treated subjects under 60 (n = 278) the number of inadequately treated subjects increased by 34 (12.2% of 278); 14 in the low-risk group, 15 in the medium-risk group, and only five in the high- or very-high-risk groups. Only one-fifth of the drug-treated hypertensives were well controlled. Moreover, the incidence of newly detected blood pressure elevation was high. The majority of younger subjects with high blood pressure had low risk, but in those aged 45–54 this had already risen to a medium risk. Changing the target blood pressure to below 130/85, for subjects aged below 60, as recommended by WHO/ISH, affects predominantly low- and medium-risk groups.