The influence of duration of follow-up on the association between alcohol and cause-specific mortality in a prospective cohort study.
OBJECTIVE
To investigate whether duration of follow-up influences the association between alcohol and cause-specific mortality in a prospective cohort study with only baseline assessment of alcohol intake.


METHODS
In a cohort of 14,223 men and women participating in the first investigation of the Copenhagen City Heart Study between 1976 and 1978 and followed until 2001, we assessed whether the association between alcohol and mortality was modified by duration of follow-up. The 24 years of follow-up were divided into four intervals, and Cox survival analyses were conducted separately for these four succeeding 6-year periods of follow-up.


RESULTS
The authors found differences in the predictive values of alcohol and beverage-specific types of alcohol depending on duration of follow-up both in terms of all-cause mortality and death from coronary heart disease and cancer. The apparent protective effect of a moderate alcohol consumption on coronary heart disease attenuated during prolonged follow-up, whereas high alcohol consumption became associated with higher risk of death from cancer with longer follow-up.


CONCLUSIONS
This study accentuates the importance of taking duration of follow-up into consideration when interpreting risk estimates from prospective studies on the association between alcohol and mortality.
Nielsen
Naja Rod
NR
Centre for Alcohol Research, National Institute of Public Health, Copenhagen, Denmark. nrn@niph.dk
Thygesen
Lau Caspar
LC
Johansen
Ditte
D
Jensen
Gorm
G
Grønbaek
Morten
M
D000328:Adult; D000428:Alcohol Drinking / Q000453:epidemiology*; D001515:Beer; D015897:Comorbidity; D003327:Coronary Disease / Q000453:epidemiology* / Q000401:mortality; D005260:Female; D006801:Humans; D008297:Male; D009369:Neoplasms / Q000401:mortality*; D016016:Proportional Hazards Models; D011446:Prospective Studies; D013997:Time Factors; D014920:Wine