Comparison of agreement between clinic and home-measured blood pressure in the Finnish population: the Finn-HOME Study

Background The purpose of this study was to assess the agreement, mean difference, and the detection and control rates of hypertension, between home and clinic blood pressure (BP) measurement in the Finnish population. Variation in home BP during the measurements was also examined. Methods We studied a representative sample of the adult population (2051 45-74-year-old individuals) in Finland. Subjects included in the study underwent a clinical interview and measurement of clinic and home BP. Thresholds for elevated clinic and home BP were 140/90 and 135/85 mmHg. Results The mean difference between home and clinic BP, which increased with BP, was 7.7/3.4 mmHg. Overall agreement in diagnosis was only 75.2% (kappa coefficient 0.50). As compared with home BP, clinic BP overestimated the prevalence of hypertension (48.8 versus 42.5%, P < 0.001) and non-significantly underestimated the control of hypertension (28.7 versus 32.8%, P = 0.11). Evening home BP was 4.1/0.4 mmHg higher than morning BP among untreated subjects, but this difference was non-existent or reversed (0.5/-1.4 mmHg) among treated hypertensive individuals. Home BP decreased with an increasing number of measurements. Conclusions The agreement between home and clinic BP in diagnosing hypertension according to the current guidelines is moderate at best, and the difference between home and clinic BP becomes larger at higher levels of BP. Because of the noticeable differences between these two methods, and the better prognostic accuracy of home BP, we endorse the use of home measurements in clinical practice.