The KNHANES, a cross-sectional and nationwide representative survey, has been conducted by the Korean Ministry of Health and Welfare since 1998.10) This study was based on the available results of the KNHANES 2014–2016. The survey consists of three parts: health interview, health examination, and a nutrition survey. We included 10,092 survey respondents who additionally completed the food frequency questionnaire (FFQ). FFQ were administered to adults aged 19–64. We have excluded participants with missing values for exposure variables, outcome variables and covariates. The final study population was 8,280 (male, 3,194; female, 5,086) (Figure 1).

The KNHANES includes a series of FH related questions, which ask participants if their mother, father or siblings have ever been diagnosed with high blood pressure. We classified individuals into two groups according to whether their first-degree relatives had hypertension. Participants with one or more first-degree FH classified as having a FH.

With regard to hypertension prevalence, awareness, treatment and control, we used the following criteria. Prevalence of hypertension was defined as the proportion of individuals with “systolic blood pressure (SBP) ≥140 mmHg or diastolic blood pressure (DBP) ≥90 mmHg” or “currently taking antihypertensive medication”. Hypertension awareness was defined as self-report of previous hypertension diagnosis by a doctor among the participants with hypertension. Treatment of hypertension was defined as the use of anti-hypertensive medicine more than 20 days a month among the hypertensives. Control of hypertension was defined as SBP <140 mmHg and DBP <90 mmHg among the participants with hypertension.

The survey includes questions evaluating health behaviors. In terms of diets, we defined the criteria for “low sodium intake” based on the ACC/AHA hypertension guideline.3) From results of FFQ (based on the answers of questions on the intake frequency of 112 dietary items), the amount of sodium intake per day was calculated.11) We divided individuals into two groups based on whether they had an intake of sodium less than 1,500 mg per day or not. The low sodium intake was defined as taking less than 1,500 mg of sodium per day. Among the overweight and obese people, they were defined as the “weight management” group when trying to lose weight. In participants with normal weight, they were defined as the “weight management” group when trying to maintain normal weight. Regarding smoking, individuals were divided into two groups, “current smoker” and “non-smoker” (non-smoker includes ex-smoker and never-smoker). Risky drinking was defined as a case of drinking more than twice a week and having an average of ≥7 drinks per occasion for male or ≥5 drinks per occasion for female. Non-risky drinking was defined as a non-alcoholic or drinking less alcohol than risky drinking. Physical activity was assessed using a global physical activity quesquestionnaire (GPAQ).12) According to the World Health Organization recommendations on physical activity for health, adults aged 18–64 should do at least 150 minutes of moderate-intensity aerobic physical activity throughout the week or do at least 75 minutes of vigorous-intensity aerobic physical activity throughout the week or an equivalent combination of moderate- and vigorous-intensity activity. Subjects who met the criteria above were categorized into “sufficient physical activity”. To assess whether participants had undergone hypertension screening, they defined whether they had received a health check-up within the last 2 years.

All of the sociodemographic factors (i.e., age, sex, marital status, education level, employment status, household income, residential area, and medical insurance status), self-rated health status, and FH of chronic diseases (hyperlipidemia, ischemic heart disease, stroke, diabetes mellitus) were based on the self-administered questionnaire of the health interview survey. Body mass index (BMI) was calculated as weight in kilograms divided by height squared in meters (kg/m²).

We conducted descriptive analyses (i.e., means, standard errors, numbers, and percentages) for the basic characteristics and the outcome variables. We used the Student's t-test for means or chi-square test for proportions to determine statistical differences on the variables between participants with and without FH. A P-value less than 0.05 was considered significant. In addition, we conducted logistic regression analyses and evaluated the relationship between having a FH and outcome variables, while adjusting for all the covariates. Subgroup analyses according to the morbidity of hypertension was also conducted, regarding outcomes of health behaviors and health check-up. For the estimation of proportions, adjusted odds ratios (aORs), and 95% confidence intervals (95% CIs), sampling weights were applied to represent the entire Korean adult population. We conducted all analyses using STATA/SE 14 (StataCorp, College Station, TX, USA).

Table 1 showed the baseline characteristics of the subjects by the FH. Of the 8,280 individuals in the study population, 3,626 had a FH. The mean age of the study population was 43.3 years; 61.4% were female. The prevalence of hypertension was estimated to 25.4% in the subjects with FH and 13.3% in the subjects without FH. Regarding healthy behaviors, 8.4% of the participants reported low sodium intake. Among the individuals with a normal weight or overweight/obesity, 35.9% attempted to manage their weight to fit within the normal range. 77.2% of the participants did not smoke, 88.6% pertained to the non-risky drinking group, and 56.1% carried out sufficient physical activity. 61.5% reported to have had a health check-up within the last 2 years. In the variables of weight management, no smoking, and health check-up, there were significant differences between the subjects with FH and those without FH. In terms of the sociodemographic factors and health status, there were significant differences in age, sex, marital status, education level, household income, BMI, and self-rated health status between individuals with FH and those without. Regarding FH of chronic diseases, subjects with FH were more likely to have other family histories, such as hyperlipidemia, ischemic heart disease, stroke and diabetes mellitus.

Hypertension awareness, treatment, and control rates among the participants with hypertension according to the family history of hypertension were presented in Table 2. Among the participants with hypertension, the rates of awareness, treatment and control of hypertension were 60.1%, 56.0%, and 41.0%, respectively, in the individuals with FH, and 44.3%, 38.2%, and 28.3%, respectively, in the individuals without FH.

Tables 3, 4 showed the multivariate logistic regression analysis results and aORs and 95% CIs were reported. Table 3 showed that presence of a FH significantly was associated with the risk of hypertension prevalence (aOR, 2.47; 95% CI, 2.01–3.04), awareness (aOR, 1.97; 95% CI, 1.30–2.99), treatment (aOR, 2.61; 95% CI, 1.71–3.98), and control (aOR, 1.77; 95% CI, 1.19–2.64). According to the adjusted analyses of the all study participants, however, none of the healthy behaviors were significantly associated with having a FH (Table 4). In the subgroup analyses, having a FH was even negatively associated with getting health check-up within the last 2 years among the normotensives, after adjustment (aOR, 0.84; 95% CI, 0.72–0.99).