Risk factors for hospitalization and medical intensive care unit (MICU) admission among HIV-infected Veterans

Abstract

Objective: With improved survival of HIV-infected persons on antiretroviral therapy and growing prevalence of non-AIDS diseases, we asked whether the VACS Index, a composite measure of HIV-associated and general organ dysfunction predictive of all-cause mortality, predicts hospitalization and medical intensive care unit (MICU) admission. We also asked whether AIDS and non-AIDS conditions increased risk after accounting for VACS Index score.

Methods: We analyzed data from the Veterans Aging Cohort Study (VACS), a prospective study of HIV-infected Veterans receiving care between 2002 and 2008. Data were obtained from the electronic medical record, VA administrative databases, and patient questionnaires and were used to identify comorbidities and calculate baseline VACS Index scores. The primary outcome was first hospitalization within 2 years of VACS enrollment. We used multivariable Cox regression to determine risk factors associated with hospitalization and logistic regression to determine risk factors for MICU admission, given hospitalization.

Results: Of 3410 patients, 1141 were hospitalized within 2 years; 203 (17.8%)/1141 patients included an MICU admission. Median VACS Index scores were 25 (no hospitalization), 34 (hospitalization only), and 51 (MICU). In adjusted analyses, a 5-point increment in VACS Index score was associated with 10% higher risk of hospitalization and MICU admission. In addition to VACS Index score, Hispanic ethnicity, current smoking, hazardous alcohol use, chronic obstructive pulmonary disease, hypertension, diabetes, and prior AIDS-defining event predicted hospitalization. Among those hospitalized, VACS Index score, cardiac disease, and prior cancer predicted MICU admission.

Conclusions: The VACS Index predicted hospitalization and MICU admission as did current smoking, hazardous alcohol use, and AIDS and certain non-AIDS diagnoses.

Figure 1

Kaplan-Meir curves for hospitalization-free survival within two years of baseline VACS Index scores. VACS Index score at study enrollment separated into quartiles with approximately equal number of admissions per group.