The associations of "fatness," "fitness," and physical activity with all-cause mortality in older adults: A systematic review.
OBJECTIVE
This review explored whether cardiorespiratory fitness or physical activity act as either confounders or effect modifiers of the relationship between adiposity markers and all-cause mortality in older adults.


METHODS
Systematic searches were carried out to identify observational studies that examined the association of adiposity markers (BMI, waist circumference, and waist-hip ratio) with all-cause mortality in adults aged ≥ 60 which took into account cardiorespiratory fitness or physical activity. Data from each included study was analyzed to produce a graphical representation of this relationship.


RESULTS
Fourteen of the fifteen identified studies found that increasing BMI had a non-positive association with all-cause mortality, with persistence of the obesity paradox despite adjustment for physical activity or cardiorespiratory fitness. Physical activity measurement methods were all subjective and often unvalidated. The two studies stratifying for cardiorespiratory fitness did not find that fitness had a significant impact on the relationship between excess adiposity and mortality but found that overweight and fit people had better survival than normal-weight unfit people,


CONCLUSIONS
The predominant use of poor physical activity measurement suggests that studies are currently not adequately accounting for possible physical activity confounding. More studies are needed for addressing the modification of the relationship between adiposity markers and mortality by cardiorespiratory fitness.
Department of Public Health and Primary Care, University of Cambridge, Cambridge, UK.
Dharani
D
Yerrakalva
Department of Public Health and Primary Care, University of Cambridge, Cambridge, UK.
Ricky
R
Mullis
Department of Public Health and Primary Care, University of Cambridge, Cambridge, UK.
Jonathan
J
Mant
D050154:Adiposity; D000368:Aged; D015992:Body Mass Index; D002423:Cause of Death; D005260:Female; D006304:Health Status; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D009765:Obesity / Q000401:mortality* / Q000517:prevention & control; D009767:Obesity, Morbid / Q000401:mortality; D010809:Physical Fitness / Q000502:physiology*; D018570:Risk Assessment; D055105:Waist Circumference; D049629:Waist-Hip Ratio