A 15-year prospective study of shift work and disability pension.
OBJECTIVE
To estimate the hazard ratio for disability pension associated with shift work.


METHODS
Cohorts of shift and day workers were identified in three waves of the Danish Work Environment Cohort Study and followed up for incidence of disability pension in a national register of social transfer payment. A total of 3980 female and 4025 male employees were included in the cohorts. Information about shift work status, age, smoking habits, body mass index and ergonomic work environment were updated according to responses in subsequent waves of the survey when possible. Respondents reporting shift work were classified as shift workers in the following waves as well. Respondents were followed in the register from the time of first interview and were censored at the time of their 60th birthday, emigration, death or end of follow-up (18 June 2006). The authors used the Cox proportional hazards model to estimate hazard ratios for incidence of disability pension and 95% confidence intervals.


RESULTS
The authors observed 253 new disability pensions among women and 173 among men during 56 903 and 57 886 person-years at risk respectively, Among women, shift work predicted disability after adjustment for age, general health and socioeconomic status HR 1.39 (95% CI 1.07 to 1.82). After further adjustment for body mass index, smoking habits, socioeconomic status and ergonomic exposures the association remained statistically significant HR 1.34 (95% CI 1.02 to 1.75). Shift work was not associated with disability among men.


CONCLUSIONS
Shift work might be moderately associated with disability pension among women; however, more powerful studies are needed to establish the possible association.
Tüchsen
F
F
National Research Centre for the Working Environment, Lersø Parkallé 105, DK-2100 Copenhagen Ø, Denmark. ftu@nrcwe.dk
Christensen
K B
KB
Lund
T
T
Feveile
H
H
D000293:Adolescent; D000328:Adult; D003718:Denmark / Q000453:epidemiology; D006233:Persons with Disabilities / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009784:Occupational Diseases / Q000453:epidemiology* / Q000209:etiology; D016272:Occupational Health / Q000706:statistics & numerical data; D010415:Pensions / Q000706:statistics & numerical data*; D011446:Prospective Studies; D012179:Retirement; D018570:Risk Assessment / Q000379:methods; D012737:Sex Factors; D014940:Work Schedule Tolerance