To examine the individual and combined associations of unhealthy behaviours (low/intermediate
physical activity, consuming fruit and vegetables less than once a day, current smoking/short
term ex-smoking, never/former/heavy alcohol drinking), assessed at start of follow-up,
with hazard of disability among older French adults and to assess the role of potential
mediators, assessed repeatedly, of these associations.
Population based cohort study.
Dijon centre of Three-City study.
3982 (2410 (60.5%) women) French community dwellers aged 65 or over included during
1999-2001; participants were disability-free at baseline when health behaviours were
assessed.
Hierarchical indicator of disability (no, light, moderate, severe) combining data
from three disability scales (mobility, instrumental activities of daily living, basic
activities of daily living) assessed five times between 2001 and 2012.
During the 12 year follow-up, 1236 participants (861 (69.7%) women) developed moderate
or severe disability. Interval censored survival analyses (adjusted for age, sex,
marital status, and education) showed low/intermediate physical activity (hazard ratio
1.72, 95% confidence interval 1.48 to 2.00), consuming fruit and vegetables less than
once a day (1.24, 1.10 to 1.41), and current smoking/short term ex-smoking (1.26,
1.05 to 1.50) to be independently associated with an increased hazard of disability,
whereas no robust association with alcohol consumption was found. The hazard of disability
increased progressively with the number of unhealthy behaviours independently associated
with disability (P<0.001); participants with three unhealthy behaviours had a 2.53
(1.86 to 3.43)-fold increased hazard of disability compared with those with none.
Reverse causation bias was verified by excluding participants who developed disability
in the first four years of follow-up; these analyses on 890 disability events yielded
results similar to those in the main analysis. 30.5% of the association between the
unhealthy behaviours score and disability was explained by body mass index, cognitive
function, depressive symptoms, trauma, chronic conditions, and cardiovascular disease
and its risk factors; the main contributors were chronic conditions and, to a lesser
extent, depressive symptoms, trauma, and body mass index.
An unhealthy lifestyle is associated with greater hazard of incident disability, and
the hazard increases progressively with the number of unhealthy behaviours. Chronic
conditions, depressive symptoms, trauma, and body mass index partially explained this
association.