Value of Propensity Score Matching for Equalizing Comparator Groups in Observational Database Studies: A Case Study in Anti-infectives

PurposePropensity score methodologies can reduce bias and confounding in nonrandomized studies, including pharmaceutical comparative effectiveness studies. An observational case study was developed to demonstrate the impact of propensity score adjustments on outcomes (ie, discharge status) of patients hospitalized for complicated intra-abdominal infections.MethodsTwo cohorts were examined: intensive care unit (ICU) (vs non-ICU) patients and tigecycline-treated patients (vs patients receiving other antibiotics). Discharge status was captured before propensity scoring.FindingsThe impact of propensity scoring on discharge outcome was greater when comparing ICU patients versus non-ICU patients than when comparing tigecycline recipients versus nonrecipients.ImplicationsPropensity scoring should be examined carefully to optimize its effects. Moreover, propensity scoring only addresses bias and confounding in nonrandomized studies that are attributable to variables contained within the dataset (ie, so called “observables”) and not to other variables that may influence the relationship between outcomes and other independent variables.