The importance of comorbidity in HIV-infected patients over 55: A retrospective case-control study

Purpose To study the impact of comorbidity on the course of HIV disease in older patients as compared to a matched cohort of younger patients. Methods In a retrospective case-control study, we compared 43 HIV-infected patients >55 years old to a randomly selected cohort of 86 patients 45 years old, matched by date of HIV diagnosis. We collected data on non-HIV-related morbidity (as assessed by the Charlson comorbidity index), initiator of HIV testing, HIV stage at time of HIV diagnosis (TOHD), AIDS defining diagnoses, AIDS-related illnesses (ARI), observed AIDS-free interval, survival, and frequency of HIV-related and unrelated hospitalizations. Results The older cohort was more likely to have had HIV testing initiated by a health care provider (36 of 36 versus 50 of 66, P = 0.003), and to have acquired HIV from a transfusion (5 of 43 versus 0 of 86, P = 0.001), had lower CD4 cell counts at TOHD (205 versus 429, P = 0.02), a shorter observed AIDS-free interval (24.0 versus 52.8 months, P = 0.0002) and a shorter survival (28.2 versus 58.9 months, P = 0.0002). The older cohort had more HIV-related (13.4 versus 9.2 per 100 patient-months, P = 0.024) and non-HIV-related hospitalizations (12.9 versus 8.1 per 100 patient-months, P = 0.0001). The comorbidity index was significantly higher in the older cohort (0.907 versus 0.198, P = 0.0001) and was a strong predictor of mortality, independent of age group (risk ratio = 1.38 per comorbidity point, P = 0.0003). Conclusions Older HIV-infected patients presented with more advanced disease, which may have been due to lack of HIV awareness in this population. Older patients had a shorter observed AIDS-free interval and shorter survival. In addition, they had more HIV- and non-HIV-related comorbidity. The more rapid course and decreased survival in the elderly may be related to the increase in comorbidity.