Marital status, dipping and nocturnal blood pressure: results from the Dietary Approaches to Stop Hypertension trial

Objective: Blood pressure normally declines during the night ('dipping'); a blunted nocturnal decline is an important cardiovascular risk factor. Marriage may be associated with lower ambulatory blood pressure, although this may be confounded by socio-economic and dietary factors. We examined the association of marital status with nocturnal dipping and night-time SBP amongst individuals on a controlled diet. Methods: We analysed 325 individuals enrolled in the Dietary Approaches to Stop Hypertension trial who had available 24-h SBP data and who ingested a control diet. Logistic and linear regression models were fit to estimate the association of marital status with nocturnal dipping and mean night-time SBP. Results: Of the 325 individuals, 52.9% were men, the average age was 45.1 years and 48.9% reported being married. Compared with nonmarried individuals, those who were married had greater adjusted odds of dipping [odds ratio (OR) 2.26; 95% confidence interval (CI) 1.26-4.03; P = 0.01]. In adjusted models, being married was associated with lower night-time SBP (-2.4 mmHg; 95% CI -3.8 to -0.9 mmHg; P = 0.002), with the suggestion of a greater association in married men compared with married women (-3.1 vs. -1.7 mmHg); there was less difference for married nonblacks compared with married blacks (-2.7 and -2.4 mmHg, respectively). Conclusion: Being married is independently associated with a greater likelihood of nocturnal dipping and with lower night-time SBP among individuals participating in a controlled dietary intervention; the association was particularly strong in married men. Marital status is a variable that may be considered in future analyses of ambulatory blood pressure.