Physical activity and all-cause mortality across levels of overall and abdominal adiposity in European men and women: the European Prospective Investigation into Cancer and Nutrition Study (EPIC)
Abstract
Background: The higher
risk of death resulting from excess adiposity may be attenuated by
physical activity (PA). However, the theoretical
number of deaths reduced by eliminating physical
inactivity compared with overall and abdominal obesity remains unclear.
Objective: We examined whether overall and abdominal adiposity modified the association between PA and all-cause mortality and estimated
the population attributable fraction (PAF) and the years of life gained for these exposures.
Design: This was a cohort
study in 334,161 European men and women. The mean follow-up time was
12.4 y, corresponding to 4,154,915
person-years. Height, weight, and waist
circumference (WC) were measured in the clinic. PA was assessed with a
validated self-report
instrument. The combined associations between PA,
BMI, and WC with mortality were examined with Cox proportional hazards
models,
stratified by center and age group, and adjusted
for sex, education, smoking, and alcohol intake. Center-specific PAF
associated
with inactivity, body mass index (BMI; in kg/m2) (>30), and WC (≥102 cm for men, ≥88 cm for women) were calculated and combined in random-effects meta-analysis. Life-tables
analyses were used to estimate gains in life expectancy for the exposures.
Results: Significant
interactions (PA × BMI and PA × WC) were observed, so HRs were estimated
within BMI and WC strata. The hazards
of all-cause mortality were reduced by 16–30% in
moderately inactive individuals compared with those categorized as
inactive
in different strata of BMI and WC. Avoiding all
inactivity would theoretically reduce all-cause mortality by 7.35% (95%
CI:
5.88%, 8.83%). Corresponding estimates for avoiding
obesity (BMI >30) were 3.66% (95% CI: 2.30%, 5.01%). The estimates
for
avoiding high WC were similar to those for physical
inactivity.
Conclusion: The greatest
reductions in mortality risk were observed between the 2 lowest
activity groups across levels of general and
abdominal adiposity, which suggests that efforts to
encourage even small increases in activity in inactive individuals may
be beneficial to public health.
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