ARE SPOUSES OF PATIENTS WITH HYPERTENSION AT INCREASED RISK OF HAVINGHYPERTENSION - A POPULATION-BASED CASE-CONTROL STUDY

Background Studies of couples, who tend to share an environment but ar e genetically dissimilar, can shed light on the contribution of enviro nmental factors to hypertension. There has been renewed interest in th ese environmental factors following the re-analysis of the INTERSALT s tudy. Aim. To determine whether patients whose spouses have hypertensi on are at increased risk of hypertension, using a population-based cas e-control study. Method. The total study population consisted of all 3 923 patients over 30 years old registered with one general practice. M ale cases with hypertension were matched to male controls without hype rtension. Female cases with hypertension were matched to female contro ls without hypertension. The variables were: diagnosed hypertension; h aving a spouse with diagnosed hypertension; age; sex; weight; height; body-mass index; couple status; diabetes; and systolic and diastolic b lood pressure readings. Results. On multivariate analysis, when age, b ody-mass index, diabetes, couple status, and having a blood pressure r eading were included, men whose spouses had hypertension had a two-fol d increased risk of hypertension (adjusted odds ratio (OR) 2.24; 95% C I 1.77-2.72; P = 0.001). Similarly, on multivariate analysis, women wh ose spouses had hypertension had a two-fold increased risk of hyperten sion (adjusted OR = 2.23; 95% CI 1.75-2.72; P = 0.001). The risk for b oth male and female subjects persisted after adjustment for other vari ables. There was a significant correlation between systolic (r = 0.47; P<0.0001) and diastolic (r = 0.25; P<0.0001) blood pressures between spouse pairs. Conclusion. The independent association between having a spouse with hypertension and increased risk of hypertension supports the view that there are significant environmental factors in the aetio logy of hypertension. The finding has implications for the screening a nd treatment of hypertension in primary care.