This study suggests that having a spouse with hypertension marginally increases the odds that the other spouse has hypertension independent of both spouses’ risk factors. Our results suggest that there are a modest spousal association of hypertension treatment and a modest spousal association of hypertension control. These results did not differ by race. Additionally, among spousal pairs, our findings support the hypothesis that a shared environment contributes to hypertension, although the impact may be modest in middle-aged adults. The results were symmetric, suggesting that the environmental contribution exerts an equal effect on both the husband and the wife.
This study improves and expands existing literature on the concordance of hypertension among spouses by its improved characterization of hypertension, treatment, and control, as well as by its prospective, longitudinal design with an average of 9 years of follow-up. Our findings confirm results published in previous studies (2
). In a meta-analysis, the correlation of blood pressure within spousal pairs was estimated to be 0.10 for systolic blood pressure and 0.09 for diastolic blood pressure, and the meta-analysis odds ratio for the concordance of hypertension was 1.21 (95% CI: 1.16, 1.26) (2
Five published cross-sectional studies have evaluated the spousal concordance of hypertension (6
). Three of those study samples were not based in the United States, and the odds ratio for spousal concordance of hypertension ranged from 1.20 to 1.42 after adjustment for age, smoking status, body mass index, education, occupation, and family income (7
). Two studies used medical records to show that patients with diagnosed hypertension have an increased odds of having a spouse with hypertension (OR = 1.32, 95% CI: 1.04, 1.67) (7
), a husband (OR = 2.24, 95% CI: 1.77, 2.72), and a wife (OR = 2.23, 95% CI: 1.75, 2.72) (6
). These studies may have estimated a stronger association than ours because they focused on diagnosed hypertension, which may differ from undiagnosed hypertension, and they adjusted only for age and sex, rather than including other risk factors for hypertension such as body mass index and sodium intake. Furthermore, inference from the aforementioned studies is limited by their use of participant's self-report to define hypertension (9
), the use of one spouse to report the other's hypertension status (9
), the use of medical records to define hypertension (7
), and the lack of data on undiagnosed hypertension (6
). Finally, these studies utilized a cross-sectional design, which is weaker than this longitudinal study design.
These study results are similar in magnitude to the only cross-sectional study conducted using a US cohort. That study included Mexican Americans and found that the risk of a self-reported diagnosis of hypertension was predicted by the other spouse's hypertension status and the spouse's risk factors (10
). Those authors reported that associations were similar when the husband's and wife's hypertension status was used as the outcome: for the husband (OR = 1.75, 95% CI: 1.21, 2.54) and for the wife (OR = 1.63, 95% CI: 1.13, 2.36). Additionally, similar to this study's results, the cross-sectional associations appear to be symmetric. Of note, a study of the African-American participants in ARIC found that participants who were not married were at the same risk of hypertension as those who were married, and this association was the same in men and women (3
One explanation for this study's findings is that physiologic conditions shared by married couples influence the development of disease (15
). Cross-sectional data have shown that spouses may be concordant in conditions such as asthma, depression, hyperlipidemia, and peptic ulcers (7
This study has several strengths and extends knowledge of the influence spouses have on each other's health. First, this cohort is a large (4,500 spousal pairs), biracial (white and African American) population-based sample with over 9 years of follow-up. The use of longitudinal measures of hypertension contributes to the elucidation of whether shared environments explain the spousal concordance of hypertension. Additionally, blood pressure was measured, and antihypertensive medication use was collected allowing for the inclusion of diagnosed and undiagnosed hypertension, as well as treated and controlled hypertension. Finally, the models were adjusted for more risk factors associated with hypertension than previous studies.
There are limitations of this work worth noting. First, marital status was ascertained at only one visit. It is unclear whether the spouses remained married throughout the 9-year follow-up period. However, ARIC is a cohort of middle-aged adults who would be less likely to separate over a 9-year period than younger spouses. The study did not collect data on length of marriage or cohabitation and the quality of the marriage. Additionally, because participants were not asked to report whether they were diagnosed with hypertension, we were unable to ascertain whether spouses were concordant on knowledge of hypertension status. Although the focus of our study was spousal pairs, our results may not be generalizable or informative to couples who are not married or single. Finally, we recognize that hypertension treatment guidelines have changed since the start of the ARIC study in the 1980s. However, a major strength of this study is its longitudinal nature, which detects changing trends in hypertension management.
In conclusion, hypertension contributes significantly to the disease burden in the United States and worldwide (16
). As the prevalence of hypertension continues to grow, it is important to identify methods to deliver hypertension education and treatment to decrease the likelihood that a person develops preventable outcomes such as stroke. Although the current public health strategy is based on wide, if not universal, screening for hypertension, there are still gaps in detection. For spouses, this gap may be closed when a physician recognizes that there is a spousal association of hypertension status (18
). It has yet to be examined whether the spousal association of hypertension has practical implications for targeting treatment to spouses. In sum, these results suggest that physicians and public health practitioners may want to target hypertension prevention and screening to spouses as a pair rather than as 2 separate individuals.