Physical capability in mid-life and survival over 13 years of follow-up: British birth cohort study

Objectives To examine associations between three commonly used objective measures of physical capability assessed at age 53 and a composite score of these measures and all cause mortality; to investigate whether being unable to perform these tests is associated with mortality. Design Cohort study. Setting MRC National Survey of Health and Development in England, Scotland, and Wales. Participants 1355 men and 1411 women with data on physical capability at age 53 who were linked to the National Health Service (NHS) central register for death notification. Main outcome measure All cause mortality between ages 53 (1999) and 66 (2012). Results For each of the three measures of physical capability (grip strength, chair rise speed, and standing balance time) those participants unable to perform the test and those in the lowest performing fifth were found to have higher mortality rates than those in the highest fifth. Adjustment for baseline covariates partially attenuated associations but in fully adjusted models the main associations remained. For example, the fully adjusted hazard ratio of all cause mortality for the lowest compared with the highest fifth of a composite score of physical capability was 3.68 (95% confidence interval 2.03 to 6.68). Those people who could not perform any of the tests had considerably higher rates of death compared with those people able to perform all three tests (8.40, 4.35 to 16.23). When a series of models including different combinations of the measures were compared by using likelihood ratio tests, all three measures of physical capability were found to improve model fit, and a model including all three measures produced the highest estimate of predictive ability (Harrell's C index 0.71, 95% confidence interval 0.65 to 0.77). There was some evidence that standing balance time was more strongly associated with mortality than the other two measures. Conclusions Lower levels of physical capability at age 53 and inability to perform capability tests are associated with higher rates of mortality. Even at this relatively young age these measures identify groups of people who are less likely than others to achieve a long and healthy life.