BACKGROUND:
The extent to which cardiorespiratory fitness (CRF) provides meaningful risk stratification among those with a family history (FH) of coronary heart disease (CHD) is yet to be defined. We compare all-cause mortality in individuals with a FH of CHD to those without.
METHODS:
We retrospectively studied 68,947 patients without history of CHD (n=7,980) or heart failure (n=1,564) who underwent physician-referred treadmill stress testing between 1991 and 2009. FH of CHD was defined as a self-reported compatible history of CHD in a first-degree relative. CRF was based on peak estimated metabolic equivalents (METS) and categorized into 4 groups: <6, 6 to 10, 10 to 12, and ≥12 METS. Multivariable-adjusted Cox proportional hazards models were used to study the association between increasing METS categories and risk of mortality using the lowest METS category as the reference. Adjusted mortality rates were calculated using direct standardization. Multiplicative interaction testing was performed for FH and METS categories.
RESULTS:
Overall, 50% (n=34,532) of patients (mean age 53.5±12 years, 49% males) reported a FH of CHD. Compared to those without a FH, those with a FH were more likely to abuse tobacco (43% vs 40%) and have hyperlipidemia (47% vs 42%), but less likely to be diabetic (18% vs 22%). FH was significantly associated with mortality after adjusting for traditional risk factors, however an association was not observed with the addition of METS [HR(95%CI)]: 0.92(0.88-0.97) and 0.96(0.91-1.01), respectively. Adjusted mortality rates were lower with increasing METS categories (43%,19%,10% and 7% in those without a FH vs 34%,15%,8% and 5%, respectively, in those with a FH). In fully adjusted models, increasing METS categories were associated with a lower risk of mortality (figure), without effect modification by FH of CHD (P=0.37).
CONCLUSION:
CRF limited an independent mortality association with FH. Higher levels of CRF were associated with similar reductions in mortality risk in those with and without a FH of CHD.
Cardiorespiratory Fitness Status And Risk Of Mortality Among Obese Female Us Veterans
