Objective To quantify the association between long working hours and alcohol
use. Design Systematic review and meta-analysis of published studies and
unpublished individual participant data. Data sources A systematic search of
PubMed and Embase databases in April 2014 for published studies, supplemented
with manual searches. Unpublished individual participant data were obtained
from 27 additional studies. Review methods The search strategy was designed to
retrieve cross sectional and prospective studies of the association between
long working hours and alcohol use. Summary estimates were obtained with
random effects meta-analysis. Sources of heterogeneity were examined with
meta-regression. Results Cross sectional analysis was based on 61 studies
representing 333 693 participants from 14 countries. Prospective analysis was
based on 20 studies representing 100 602 participants from nine countries. The
pooled maximum adjusted odds ratio for the association between long working
hours and alcohol use was 1.11 (95% confidence interval 1.05 to 1.18) in the
cross sectional analysis of published and unpublished data. Odds ratio of new
onset risky alcohol use was 1.12 (1.04 to 1.20) in the analysis of prospective
published and unpublished data. In the 18 studies with individual participant
data it was possible to assess the European Union Working Time Directive,
which recommends an upper limit of 48 hours a week. Odds ratios of new onset
risky alcohol use for those working 49-54 hours and ≥55 hours a week were 1.13
(1.02 to 1.26; adjusted difference in incidence 0.8 percentage points) and
1.12 (1.01 to 1.25; adjusted difference in incidence 0.7 percentage points),
respectively, compared with working standard 35-40 hours (incidence of new
onset risky alcohol use 6.2%). There was no difference in these associations
between men and women or by age or socioeconomic groups, geographical regions,
sample type (population based v occupational cohort), prevalence of risky
alcohol use in the cohort, or sample attrition rate. Conclusions Individuals
whose working hours exceed standard recommendations are more likely to
increase their alcohol use to levels that pose a health risk
