Rationale and Design of the Henry Ford ExercIse Testing Project (The FIT Project)

Abstract

Although physical fitness is a powerful prognostic marker in clinical medicine, most cardiovascular populationbased studies do not have a direct measurement of cardiorespiratory fitness. In line with the call from the National Heart Lung and Blood Institute for innovative, low-cost, epidemiologic studies leveraging electronic medical record (EMR) data, we describe the rationale and design of the Henry Ford ExercIse Testing Project (The FIT Project). The FIT Project is unique in its combined use of directly measured clinical exercise data retrospective collection of medical history and medication treatment data at the time of the stress test, retrospective supplementation of supporting clinical data using the EMR and administrative databases and epidemiologic follow-up for cardiovascular events and total mortality via linkage with claims files and the death registry. The FIT Project population consists of 69 885 consecutive physician-referred patients (mean age, 54 ± 10 years; 54% males) who underwent Bruce protocol treadmill stress testing at Henry Ford Affiliated Hospitals between 1991 and 2009. Patients were followed for the primary outcomes of death, myocardial infarction, and need for coronary revascularization. The median estimated peak metabolic equivalent (MET) level was 10, with 17% of the patients having a severely reduced fitness level (METs < 6). At the end of the follow-up duration, 15.9%, 5.6%, and 6.7% of the patients suffered all-cause mortality, myocardial infarction, or revascularization procedures, respectively. The FIT Project is the largest study of physical fitness to date. With its use of modern electronic clinical epidemiologic techniques, it is poised to answer many clinically relevant questions related to exercise capacity and prognosis. BackgroundCardiorespiratory fitness is an important marker of cardiovascular heath in the general adult population.1 -4 Reduced fitness is a risk factor for all-cause mortality and cardiovascular disease (CVD), independent of body fatness. 5,6 In contrast, an increase of 1 metabolic equivalent (MET) is associated with 13% decrease in cardiovascular mortality in a recent meta-analysis.

Importance of Assessing Cardiorespiratory Fitness in Clinical Practice: A Case for Fitness as a Clinical Vital Sign: A Scientific Statement From the American Heart Association

“…Comparable findings have been reported in ongoing follow-up studies from cohorts including the Veterans Exercise Testing Study, [17][18][19]22 the Aerobics Center Longitudinal Study (ACLS), 2,5,13,20,51 and the Henry Ford Exercise Testing Project. [52][53][54] Importantly, the overall discriminative ability of CRF in these studies is comparable to that normally obtained in widely used risk models, such as the Framingham risk score and European SCORE (Systematic Coronary Risk Evaluation) algorithm. 55,56 For example, Laukkanen et al 57 reported that a 1-MET increment in CRF and a 1% increment in European risk score were associated with 16% and 15% changes, respectively, in risk for all-cause mortality.…”

Cardiorespiratory Fitness and Incident Diabetes: The FIT (Henry Ford ExercIse Testing) Project

“…Details of the study are described elsewhere (17). In brief, the study population was limited to patients who were at least 18 years of age at the time of stress testing.…”

Cardiorespiratory Fitness and Risk of Incident Atrial Fibrillation

“…8 In short, the FIT Project is a retrospective cohort study of 69 885 patients who underwent physician-referred treadmill stress testing at affiliated hospitals and clinics across metropolitan Detroit, MI, within the Henry Ford Health System between 1991 and 2009. Data pertaining to exercise parameters, demographics, medications, and medical history were obtained by exercise physiologists and nurses and logged after the exercise test encounter.…”