Decision Tree-Based Classification for Maintaining Normal Blood Pressure throughout Early Adulthood and Middle Age: Findings from the Coronary Artery Risk Development in Young Adults (CARDIA) Study

Background: For most individuals, blood pressure (BP) is related to multiple risk factors. By utilizing the decision tree analysis technique, this study aimed to identify the best discriminative risk factors and interactions that are associated with maintaining normal BP over 30 years and to reveal segments of a population with a high probability of maintaining normal BP. Methods: Participants from the Coronary Artery Risk Development in Young Adults study aged 18-30 years with normal BP level at baseline visit (Y0, 1985-1986) were included in this study. Results: Of 3,156 participants, 1,132 (35.9%) maintained normal BP during the follow-up period and 2,024 (64.1%) developed higher BP. Systolic BP (SBP) within the normal range, race, and body mass index (BMI) were the most discriminative factors between participants who maintained normal BP throughout midlife and those who developed higher BP. Participants with a baseline SBP level ≤92 mm Hg and White women with baseline BMI < 23 kg/m2 were the two segments of the population with the highest probability for maintaining normal BP throughout midlife (69.2% and 59.9%, respectively). Among Black participants aged >26.5 years with BMI > 27 kg/m2, only 5.4% of participants maintained normal BP throughout midlife. Conclusions: This study emphasizes the importance of early life factors to later life SBP and support efforts to maintain ideal levels of risk factors for hypertension at young ages. Whether policies to maintain lower BMI and SBP well below the clinical thresholds throughout young adulthood and middle age can reduce later age hypertension should be examined in future studies.