This study was based on data collected for the Family Cohort Study in Primary Care. The protocol of this study and written informed consent form were approved by the institutional review board of Asan Medical Center (IRB approval no., 2010-0370). Participants read and signed the informed consent form prior to the start of the study. Cohort data were collected for heterosexual couples, including individuals who were married, cohabitating, separated, and divorced. The recruited participants (couples) were individuals aged between 30 and 80 years who had visited the department of family medicine at hospitals nationwide for the treatment of chronic diseases such as hypertension, type 2 diabetes, and dyslipidemia, or for a periodic health checkup, between April 2009 and June 2011 in any of the 22 university-affiliated hospitals of Korea. A total of 1,040 participants (520 couples) were enrolled.

Demographic characteristics and health behaviors were prospectively collected using a standardized questionnaire, which included questions regarding educational status, monthly income, smoking status, alcohol intake, physical activity, and dietary pattern. An interviewer or primary care physician collected individual medical histories in person and recorded any prior history of hypertension, diabetes, and hyperlipidemia.

Educational level was categorized into three groups: <12 years, 12 years, and >12 years. Monthly income was assessed using total household income, queried with a single question. Monthly income was divided into four categories: <2.00 million won (1,715 US dollar [USD]), 2.00–3.99 million won (1,715–3,430 USD), 4.00–5.99 million won (3,430–5,145 USD), and ≥6.00 million won (5,145 USD). Smoking status was classified as current smoker, ex-smoker, or never-smoker based on the definition of smokers established by the US Centers for Disease Control and Prevention [14]. Never-smokers were participants who smoked fewer than 100 cigarettes in their entire lifetime; participants who had smoked more than 100 cigarettes during their lifetime but were not smoking at the time of this study were classified as exsmokers; and current smokers were participants who smoked more than 100 cigarettes during their lifetime and currently continued to smoke cigarettes. The Alcohol Use Disorders Identification Test-Korean version (AUDIT-K) was used to assess risky alcohol consumption, defined as a total AUDIT-K score of ≥8 [15]. Physical activity was estimated using the International Physical Activity Questionnaire Short-Form, which evaluates the intensity and duration of physical activity performed during the previous 7 days [16]. Physical activity was classified as low, moderate, and high. Low activity level was defined as attainment of <1,500 metabolic equivalent min/wk. Dietary patterns were assessed with a question about the regularity of meal intake, which was divided into always regular, usually regular, or irregular, as well as a question about the frequency of breakfast intake.

The presence of hypertension, diabetes, or dyslipidemia was defined either using participants’ self-report of a disease or from the medical records indicating the use of antihypertensive medications, oral hypoglycemic agents, insulin, or lipid-lowering agents. Depressive mood was evaluated using a Korean-type Center for Epidemiologic Studies Depression Scale, with depressive mood assessed as a score of ≥21 points [17].

Height and body weight were measured to the nearest 0.1 cm and 0.1 kg, respectively, by trained interviewers. BMI was calculated as (weight in kg)/(height in m)² and was categorized into four groups: <18.5 kg/m², 18.5–22.9 kg/m², 23.0–24.9 kg/m², and ≥25.0 kg/m². BMI ≥25.0 kg/m² was defined as overweight, according to 2000 World Health Organization criteria [18].

The chi-square test was used to compare the characteristics of husbands and wives. To evaluate spousal concordance, McNemar tests were used in paired couples. Binary logistic regression analysis was used to estimate the odds ratios (ORs) and 95% confidence intervals (CIs) for lifestyle factors and chronic diseases among spouses after grouping husbands and wives. In addition, potential confounders such as age, education, and income were adjusted in the logistic regression analysis. All statistical analyses were performed using IBM SPSS ver. 21.0 (IBM Corp., Armonk, NY, USA). A P-value of <0.05 was considered to indicate statistical significance.

Table 1 shows the basic characteristics of study participants, grouped into husbands and wives. Most participants (69%) were aged between 50 and 70 years. Approximately 56.7% of husbands and 36.5% of wives had completed >12 years of education. More husbands (21.3%) than wives (1.2%) were current smokers. A total 60.1% of husbands and 40.9% of wives engaged in risky alcohol consumption. About half of both husbands and wives (58.5% and 49.6%) had low physical activity. The frequency of irregular meal intake and skipping breakfast was higher among wives than among husbands, with 15.7% of wives reporting irregular meal intake and 18.4% reporting skipping breakfast; only 10.4% of husbands reported irregular meal intake and 12.8% reported skipping breakfast. In terms of comorbidities, hypertension was the most common disease among couples (46.9% versus 34.6%), and the prevalence of diabetes was 2 times higher among husbands than among wives (27.1% versus 12.3%). Conversely, depressive mood was higher in wives (17.2%) than in husbands (9.8%).

Table 2 shows spousal concordance regarding lifestyle factors and chronic diseases. Among husband and wife pairs, we analyzed the prevalence of both couples having current smoker status (0.6%), risky alcohol consumption (28.8%), low physical activity (26.5%), irregular diet (4.6%), and skipping breakfast (7.4%). In terms of chronic diseases, the prevalence of excessive weight, hypertension, diabetes, and dyslipidemia among both partners in a couple was 18.3%, 23.7%, 5.6%, and 19.5%, respectively. Moreover, spousal concordance regarding depressive mood was 2%.

Table 3 shows the results of logistic regression analysis for individual ORs according to lifestyle factors and chronic disease status of spouses. We calculated age-adjusted ORs and multivariate ORs, adjusted for age, years of education, and income level. In terms of lifestyle factors, low physical activity, irregular diet, and skipping breakfast showed significant spousal concordance. When husbands had low physical activity, the OR of wives for low physical activity was 2.47 (OR, 2.47; 95% CI, 1.54–3.96). When husbands had irregular meal intake, the odds of their wives having irregular meal intake were 4 times higher than those of wives whose husbands ate regularly (OR, 4.30; 95% CI, 3.75–12.48). Moreover, when husbands skipped breakfast, the spousal concordance was high (OR, 6.84; 95% CI, 3.42–11.45). Spousal concordance was also present in couples who were overweight or who had hypertension, diabetes, dyslipidemia, or depressive mood. Participants living with overweight spouses had higher odds of being overweight (OR, 1.73; 95% CI, 1.14–2.63 for husbands; OR, 1.72; 95% CI, 1.13–2.62 for wives). Furthermore, husbands with wives who had hypertension, dyslipidemia, or depressive mood had significantly higher odds of having hypertension (OR, 1.88; 95% CI, 1.23–2.86), dyslipidemia (OR, 2.41; 95% CI, 1.60–3.64), or depression (OR, 5.54; 95% CI, 2.19–13.96). Similar results were found among wives with husbands who had hypertension (OR, 1.93; 95% CI, 1.26–2.97), dyslipidemia (OR, 2.53; 95% CI, 1.66–3.86), and depressive mood (OR, 4.52; 95% CI, 1.77–11.53).