How stable is the risk curve between alcohol and all-cause mortality and what factors influence the shape? A precision-weighted hierarchical meta-analysis.

OBJECTIVE

To determine the influence of six determining variables on the shape of the risk curve between alcohol and all-cause mortality.

DATA

Based on a systematic search with clear inclusion criteria, all articles on alcohol and all-cause mortality until 2000 were included.

STATISTICAL METHODS

Precision-weighted pooling of relative risks (RRs); precision-weighted hierarchical analysis.

VARIABLES

For pooling: RRs for different categories of average volume of drinking, lifetime abstainers and ex-drinkers. For hierarchical analysis: on first level: consumption in grams of pure alcohol per day; on second level: length of follow-up time in months; per capita consumption; average age, proportion of abstainers, average volume of drinking, and variability of average volume of drinking at baseline.

OUTCOMES MEASURES

RR of former and current drinkers for all-cause mortality compared to abstainers.

RESULTS

The main hypotheses could be confirmed for males: Ex-drinkers had a higher mortality risk than lifetime abstainers; the higher and the more diverse the average volume of alcohol consumption, the wider the dip of the curve; the older the persons at baseline, the more pronounced the protective effect; and the longer the follow-up time, the less pronounced the protective effect. Except for average volume of drinking effects for females went in the same direction but with one exception did not reach significance.

CONCLUSIONS

There are systematic influences on the shape of the risk curve between alcohol and all-cause mortality. The overall beneficial effect of light to moderate drinking remained under all scenarios, indicating a high validity of the overall shape despite the heterogeneity between studies.