Abstract 12532: Maximal Exercise Capacity is Inversely Related to Incident Peripheral Artery Disease: Data From the Henry Ford Exercise Testing (FIT) Project

Abstract

Introduction: Maximal exercise capacity (EC) is a strong, independent predictor of incident coronary and cerebrovascular disease. However, less is known about the relationship between EC and incident peripheral artery disease (PAD). Using data from the Henry Ford Exercise Testing (FIT) Project, we evaluated the relationship between EC and incident PAD. Hypothesis: EC, measured in metabolic equivalents of task (METs), is inversely related to incident PAD. Methods: We assessed 41,268 patients (age= 55±12 yrs, 49% female, and 64% white) who completed a clinically indicated exercise stress test between January 1991 and June 2009 at a Henry Ford Health facility. Patients with established PAD at the time of testing were excluded. METs were estimated from peak treadmill speed and grade and standardized to the equivalent of a 50-year-old male to account for differences in absolute risk for a given MET level by age and sex. METs were categorized as <6, 6-9, 10-11, and > 12. ICD9 codes 440.XX and 443.9 were used to identify first incidence of PAD from the test date through June 2010. Multivariable Cox regression was used to relate METs to incident PAD. Patients were censored at the date of death or last clinic visit. Results: During a median follow-up of 7.1 years (IQR 4.2-11.1 yrs) there were 2,596 (6%) incident diagnoses of PAD. In the adjusted analysis, each 1 MET increase in maximal EC was associated with a 7% lower risk of PAD (aHR=0.93 [0.91, 0.94]). There was a graded, inverse risk of incident PAD by MET category (see Table). A significant interaction was noted for race (overall p=.04; white [HR=0.93 (0.92, 0.95)] vs black [HR=0.91 (0.88, 0.93)], p=.02; white vs other [HR=0.97 (0.87, 1.07)], p=0.47), but not for sex (p=.79). Conclusion: In a diverse cohort that completed a clinically indicated exercise stress test, higher EC measured in METs, is independently and inversely associated with a lower risk of incident PAD.