IgA Level Is Associated with Risk for Mortality in an Eighty-Year-Old Population

Background: Immunoglobulin levels are elevated in the older people. However, it is unknown whether these levels are related to mortality. Object: To evaluate the association between immunoglobulin levels and mortality. Methods: The study population included 697 individuals (277 males and 420 females) of 1,282 eighty-year-old individuals residing in the Fukuoka prefecture, Japan. The participants were followed for 4 years after the baseline examination. Results: The hyper-IgA group, defined as a serum IgA level >400 mg/dl, had high mortality using Kaplan-Meier analysis (log rank, p = 0.037). Multivariate Cox regression analyses revealed a high risk of mortality (hazard rate = 1.233, 95% confidence interval 1.109–1.491, p = 0.031) after adjusting for covariates. The high risk of mortality in the hyper-IgA group was significant in males, but not in females. Moreover, Kaplan-Meier analysis revealed that IgA was related to cancer mortality in males (log rank, p = 0.031), but not to pneumonia or cardiovascular disease. IgM and IgG levels were not related to high risk of mortality. Conclusion: Serum IgA levels appear to be a predictor of mortality, especially cancer mortality in males.