Development and internal validation of a clinical prediction model of the risk of nosocomial bacterial infection in patients with systemic lupus erythematosus

Abstract

IntroductionPatients with systemic lupus erythematosus (SLE) have an increased risk of developing community-acquired infections, as well as those associated with health care. Bacterial infections are the most common and serious while these patients are in hospital. ObjectiveTo develop, and internally validate, a clinical prediction model for the prognosis of the risk of hospital-acquired bacterial infection in SLE patients, using clinical and laboratory data obtained during the first hours of hospital admission. MethodsAn analysis was performed on retrospective cohort of patients with SLE older than 16 years and admitted for reasons other than bacterial infection in two highly complex hospitals in Medellín between 2011 and 2016. The characteristics of the patients who developed a bacterial infection were compared between day 3 and day 15 of hospital admission with those who did not develop one. The significant variables in the bivariate analysis were used for the construction of the model using multivariate logistic regression. ResultsA total of 765 episodes were included, of which 98 (12.8%) presented the outcome of interest. Thirty candidate predictors were considered. The variables incorporated in the final model were: age, neutrophil count, SLEDAI lupus activity score, use of a bladder catheter, use of a central venous catheter in the first 72h, glucocorticoid doses in the previous month, and use of an antimalarial drug in the 3 previous months. The discrimination capacity of the model was acceptable to good (AUC-ROC=0.74; 95% CI, 0.69–0.80). The Hosmer–Lemeshow goodness of fit test (p=.637) suggested adequate calibration. ConclusionA clinical prediction model of prognostic risk of nosocomial bacterial infection in patients with SLE has been developed. This model is made up of simple clinical and laboratory variables available at the time of hospital admission. External validation and clinical impact studies are required before routine implementation.