Physical Fitness and Hypertension in a Population at Risk for Cardiovascular Disease: The Henry Ford Exercise Testing (FIT) Project | Journal Scan
Increased physical fitness is protective against cardiovascular disease. Is increased fitness inversely associated with hypertension?
The association of fitness with prevalent and incident hypertension was assessed in 57,284 participants from The Henry Ford Exercise Testing (FIT) Project (1991–2009). Fitness was measured during a clinician-referred treadmill stress test. Incident hypertension was defined as a new diagnosis of hypertension on three separate consecutive encounters derived from electronic medical records or administrative claims files. Analyses were performed with logistic regression or Cox proportional hazards models and were adjusted for hypertension risk factors.
The mean age overall was 53 years, with 49% women and 29% black. Mean peak metabolic equivalents (METs) achieved was 9.2 (standard deviation, 3.0). Fitness was inversely associated with prevalent hypertension even after adjustment (≥12 METs vs. <6 METs; odds ratio [OR], 0.73; 95% confidence interval [CI], 0.67-0.80). During a median follow-up period of 4.4 years (interquartile range, 2.2-7.7 years), there were 8,053 new cases of hypertension (36.4% of 22,109 participants without baseline hypertension). The unadjusted 5-year cumulative incidences across categories of METs (<6, 6 to 9, 10 to 11, and ≥12) were 49%, 41%, 30%, and 21%. After adjustment, participants achieving ≥12 METs had a 20% lower risk of incident hypertension compared to participants achieving <6 METs (HR, 0.80; 95% CI, 0.72-0.89). This relationship was preserved across strata of age, sex, race, obesity, resting blood pressure, and diabetes.
The authors concluded that higher fitness is associated with a lower probability of prevalent and incident hypertension independent of baseline risk factors.
The study is important and useful to support recommendations for improving fitness to reduce the most important risk factor for cardiovascular events and disability. The authors acknowledge several important limitations including the definition of hypertension being based on patient testimony of prior diagnosis, electronic medical record problem list-based diagnosis, and use of antihypertensive medication, each of which would overestimate the diagnosis with the bias of inconsistent office-based measures that do not follow standard guidelines. Nevertheless, the strength of the graded inverse association between fitness and hypertension appears to be strong enough to absorb the bias.
Keywords: Antihypertensive Agents, Blood Pressure, Diabetes Mellitus, Electronic Health Records, Exercise Test, Hypertension, Metabolic Equivalent, Obesity, Physical Fitness, Risk Factors
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