We compared characteristics of patients for whom we obtained a complete clinical chart with those on whom the chart was incomplete or unavailable. We classified discharge diagnoses according to six groups (PJP; bacterial community-acquired pneumonia; tuberculosis (pulmonary and disseminated); other infectious respiratory diseases, non-infectious respiratory diseases, and mixed). Given that the median age of our study population was 34 years (Interquartile range [IQR] 29-42) and therefore not at risk for non-infectious respiratory diseases, we excluded this group from bivariate and multivariate analyses. We conducted bivariate analyses to examine differences between respiratory diagnoses (PJP; bacterial community-acquired pneumonia; tuberculosis; other infectious respiratory diseases; and mixed); patients with HIV diagnosis previous to admission as compared to patients who were diagnosed during hospital stay; and all-cause in-hospital fatalities as compared to surviving patients. Patient characteristics were compared according to each study group using chi-squared tests for categorical variables and Kruskal-Wallis test for continuous variables with non-normal distribution. To investigate the relation between HAART for more than 180 days on respiratory diagnosis, we used polytomous logistic regression with a five-level outcome variable (PJP, tuberculosis, bacterial community-acquired pneumonia, other infectious pneumonia [reference category], and mixed). We calculated adjusted odds ratios (aORs) and 95% confidence intervals (95% CIs). The saturated polytomous regression model included the following variables: age >50 years old, low socioeconomic level, access to social security, current smoker, current illegal drug user, diagnosis of HIV infection previous to hospitalization, HAART for 180 days or more, < 50 viral copies/ml or undetectable viral load, hospital stay (days), current smoking and time of respiratory disease (days).We used the Akaike Information Criterion (AIC) for the final model selection. The model excluded access to social security, hospital stay and time of the respiratory disease. Effect modification and interaction were evaluated but no significant effects were identified using the likelihood ratio test, comparing models with and without multiplicative interaction terms.
For all the study population, for patients who had been diagnosed with HIV infection previous to admission, and for patients with bacterial community acquired pneumonia association between HAART for more than 180 days and all-cause in-hospital mortality was investigated by multivariate unconditional logistic regression. We analysed patients who had been diagnosed with HIV infection prior to admission separately to try to separate the effect that knowledge of patients  HIV status might have on more invasive and informative diagnostic approach or better management for their opportunistic infection. Discharge diagnosis was stratified as a five-level variable (bacterial community-acquired pneumonia; other infectious diseases; PJ pneumonia; mixed; and tuberculosis [reference category]. The logistic regression models were validated by evaluating their suitability, model specificity and multicollinearity. Variables included in the models were those with p-values <=0.20 in the bivariate analysis or with biological plausibility, and covariates were achieved using a hierarchical backward elimination approach. The variable association was expressed as aOR at 95% CI.
With 54 all-cause in-hospital fatalities and 254 surviving patients, the study had 93.4% power at a 5% significance level to test the hypothesis that the proportion of patients receiving HAART for more than 180 days among surviving patients (28.0%) was different from that among all-cause in-hospital fatalities (7.4%).
All analyses were performed using the STATA 13.1 statistical software package (StataCorp LP, College Station, TX, USA).
This study was approved by the Research Ethical Committee of the National Institute for Respiratory Diseases (Instituto Nacional de Enfermedades Respiratorias) (approval number C53-11).