[A prospective study on the association between underweight and mortality from all cause].

OBJECTIVE

To explore the association between underweight and mortality from all cause.

METHOD

We examined the relationship of underweight and mortality among subjects who participated in the survey of cardiovascular risk factors (in 1984-1986 and in 1992). Relative Risks (RRs) were estimated from the COX proportional hazard model by using a BMI between 18.5-24.9 kg/m2 as reference category.

RESULTS

During an average 12.40 years follow-up, we documented 307 deaths of which 158 were from cancer, 93 from cardiovascular diseases, and 56 from other causes. We observed a L-shaped relation between BMI and overall mortality. (P for trend < 0.01); In multivariated analyses, we found that the RR of mortality for a BMI of < 18.5 kg/m2 was 1.58 (95% CI 1.16-2.14) as compared with the risk among subjects with BMI of 18.5-24.9 kg/m2. The RR of overall mortality among subjects with BMI of < 18.5 kg/m2 was still significant after the exclusion of subjects who died from cancers during the first five years follow-up.

CONCLUSION

Total mortality was increased among underweight people, and this association can not been completely explained by smoking and early deaths from cancer.