Prognosis of Resistant Hypertension in Korean Hypertensive Patients: A Nationwide Observational Cohort Study

Objective: The prognosis of resistant hypertension is known to be worse than that of non-resistant hypertension, but studies on the prevalence and outcomes of resistant hypertension in Korean hypertensive patients are scarce. Design and method: A total of 2,086,208 patients, a 25% sample of hypertensive patients, were extracted from the Korean National Health Insurance Service Database from 2013 to 2018. Among them, excluding patients with missing values and those with a history of cardiovascular disease, a total of 935,169 patients were divided into resistant hypertension and non-resistant hypertension with a target blood pressure of 140/90 mm Hg. The primary outcome was a composite of all-cause death, myocardial infarction, stroke, and heart failure events during follow-up. Secondary outcomes were individual events of the primary outcome, end-stage renal disease (ESRD), and atrial fibrillation. Results: The average age of all subjects was 62.3 ± 11.4 years, and 50.1% were men. The prevalence of resistant hypertension was 7.4%. Compared with non-resistant hypertensive patients, resistant hypertensive patients were older, more likely to be male, smokers, non-exercisers, and obese, and had a higher prevalence of diabetes, dyslipidemia, and chronic kidney disease. The median follow-up duration was 6.0 years. The incidence of the primary outcome was 32.7 and 21.5/1000 person-years in the resistant and non-resistant hypertension, respectively. In a multivariable Cox proportional hazards analysis adjusting for age, sex, BMI, alcohol consumption, exercise, income, and comorbidities, the hazard ratio for the primary outcome was 1.32 (95% CI, 1.29-1.35, p<0.001) for resistant hypertension compared with non-resistant hypertension. The risk of all-cause death, myocardial infarction, stroke, heart failure, and atrial fibrillation were each significantly higher in patients with resistant hypertension, and the risk of ESRD was three times higher. Conclusions: This large-scale nationwide observational study showed that Korean patients with resistant hypertension have a significantly higher risk of clinical events compared with non-resistant hypertensive patients, with results like those of the previous studies from other countries. This study emphasizes the need to pay more attention to managing resistant hypertension.