Impact of socio–economic status on unplanned readmission following injury: A multicenter cohort study

Abstract

BackgroundUnplanned readmissions cost the US economy approximately $17 billion in 2009 with a 30-day incidence of 19.6%. Despite the recognised impact of socio–economic status (SES) on readmission in diagnostic populations such as cardiovascular patients, its impact in trauma patients is unclear. We examined the effect of SES on unplanned readmission following injury in a setting with universal health insurance. We also evaluated whether additional adjustment for SES influenced risk-adjusted readmission rates, used as a quality indicator (QI). Study designWe conducted a multicenter cohort study in an integrated Canadian trauma system involving 56 adult trauma centres using trauma registry and hospital discharge data collected between 2005 and 2010. The main outcome was unplanned 30-day readmission; all cause, due to complications of injury and due to subsequent injury. SES was determined using ecological indices of material and social deprivation. Odds ratios of readmission and 95% confidence intervals adjusted for covariates were generated using multivariable logistic regression with a correction for hospital clusters. We then compared a readmission QI validated previously (original QI) to a QI with additional adjustment for SES (SES-adjusted QI) using the mean absolute difference. ResultsThe cohort consisted of 52,122 trauma admissions of which 6.5% were rehospitalised within 30 days of discharge. Compared to patients in the lowest quintile of social deprivation, those in the highest quintile had a 20% increase in the odds of all-cause unplanned readmission (95% CI=1.06–1.36) and a 27% increase in the odds of readmission due to complications of injury (95% CI=1.04–1.54). No association was observed for material deprivation or for readmissions due to subsequent injuries. We observed a strong agreement between the original and SES-adjusted readmission (mean absolute difference= 0.04%). ConclusionsPatients admitted for traumatic injury who suffer from social deprivation have an increased risk of unplanned rehospitalisation due to complications of injury in the 30 days following discharge. Better discharge planning or follow up for such patients may improve patient outcome and resource use for trauma admissions. Despite observed associations, results suggest that the trauma QI based on unplanned readmission does not require additional adjustment for SES.