Cell-Mediated Immunity as a Predictor of Morbidity and Mortality in Subjects Over 60

Abstract

Previous studies have suggested an association between depressed cell-mediated immunity and increased mortality in elderly persons. However, the effects of age and existing disease on this association have not been adequately addressed. We studied the association between cell-mediated immunity and subsequent morbidity and mortality in 273 initially healthy persons 60 years of age and older. In 1979, two tests of cell-mediated immunity were conducted--mitogen stimulation with phytohaemagglutinin, and delayed hypersensitivity skin testing. The study group was followed annually for development of pneumonia, cancer, and death. Anergy was associated with all-cause mortality (hazard ratio of 2.16; 95% confidence interval [1.10,4.28]). When the results were adjusted for age, the resulting hazard ratio was 1.89;[0.94,3.79]. A relationship was also suggested between anergy and cancer mortality although this association was not statistically significant. Response to phytohaemagglutinin was a poorer predictor of mortality than was response to delayed hypersensitivity skin testing. The results show that anergy may be a good indicator of subsequent all-cause mortality, and perhaps cancer mortality, in elderly who lack other indicators of poor health.