INTERACTION BETWEEN LEPTIN, LEISURE TIME PHYSICAL ACTIVITY, AND HYPERTENSION IN THE COPENHAGEN CITY HEART STUDY: 7B.01

Abstract

Objectives: The mechanisms by which overweight and physical inactivity lead to hypertension are complex. Leptin, an adipocyte-derived hormone, has been linked with hypertension. We studied the relationship between leptin, physical activity, and new-onset hypertension. Methods: A prospective study design based on data from the 3. and 4. Copenhagen City Heart Study (CCHS). From the 3. CCHS, which was performed in 1991 to 1994, we identified 1111 subjects (744 women and 367) who were normotensive. Based on questionnaire items, the participants were divided into two groups with low (n = 674) and high (n = 437) level of leisure time physical activity, respectively. Between the 3. and the 4. CCHS examination, which was performed in 2001 to 2003, 304 had developed hypertension, defined as systolic blood pressure (SBP) ≥140 mm Hg or diastolic blood pressure (DBP) ≥90 mm Hg or use of antihypertensive medication. Results: In a logistic regression model, including age, sex, body mass index, SBP, DBP, level of physical activity, and leptin, we found a significant interaction between leptin and level of physical activity with new-onset hypertension as outcome variable (P = 0.012). When we entered the interaction variables: effect of leptin with low level of physical activity and with high level of physical activity, respectively, in the original model, leptin only predicted new-onset hypertension in participants with low level of physical activity (odds ratio (95% confidence interval): 1.16 (1.01–1.33) for one unit increase in log-transformed leptin levels, P = 0.038), but not in participants with high level of physical activity (0.88 (0.74–1.05), P = 0.15). If we included other risk factors of hypertension and possible mediators of overweight-related hypertension, such as the triglyceride to HDL cholesterol concentration ratio, fibrinogen, glucose, diagnosis of diabetes, adiponectin, and heart rate, in the model, leptin still predicted new-onset hypertension in participants with a low level of leisure time physical activity (P = 0.040). Conclusion: This study is the first prospective study to report that the hypertensive effect of leptin is modified by leisure time physical activity.