Predictors of Short- and Long-term Survival in HIV-Infected Patients Admitted to the ICU: Prognostic Variables
Severity of the acute illness was evaluated using the simplified acute physiology score (SAPS I). Invasive procedures done at any time during the ICU stay (mechanical ventilation and duration of mechanical ventilation, right heart catheterization [Swan-Ganz catheter], and renal failure requiring hemodialysis) were recorded. Continuous positive airway pressure (CPAP) by facial mask and duration of CPAP were recorded only in patients with PCP. Glasgow coma scale scores were recorded during the first day in patients with neurologic impairment. Pa02 on room air (fraction of inspired oxygen [FIo2] = 0.21; and, whenever possible, with an FIo2=1.0 [patients under mechanical ventilation or wearing a facial mask on a CPAP system]) was recorded during the first ICU day in patients with PCP. For the analysis, the following variables were categorized according to their frequency distribution and possible clinical impact: SAPS I (<12, >12) and, in mechanically ventilated patients, the duration of mechanical ventilation (<10 days, >10 days). Airway
Each ICU survivor was followed up until January 1, 1994. Between January 1, 1994, and June 30, 1994, the condition of each survivor was documented by asking his or her general practitioner to answer questions over the telephone or on a printed questionnaire. In addition, death certificate registers at each patient’s place of birth were checked (in France, death certificates are sent to the place of birth). If no information was available, the patient was categorized as unavailable for follow-up. Patients’ relatives were interviewed if necessary. Information on quality of life was obtained whenever possible from each patient’s practitioner.
Differences in the frequency and value of baseline characteristics across groups of patients were tested using x2, and analysis of variance or Student’s t tests, as appropriate. All tests were two sided. The survival analysis included analysis of variance. A univariate survival analysis was carried out using the log-rank test for two samples and Gehan’s and Wilcoxon’s test for multiple samples. Survival rates were estimated from Kaplan-Meier survival tables to assess the survival of patients with a favorable outcome after the ICU stay. Median survival time was estimated using the product-limit method. To assess the independent influence of variables on survival (multivariate analysis), logistic regression analysis was used for in-hospital outcome, and Cox proportional hazard models were constructed for long term-outcome. A software package (Statistica 4.5; StatSoft; Tulsa, Okla) was used for data collection and statistical analysis. Data are presented as mean±SD.