Socioeconomic disparity in inpatient mortality after traumatic injury in adults

Abstract

Background: Prior studies have demonstrated that race and insurance status predict inpatient trauma mortality, but have been limited by their inability to adjust for direct measures of socioeconomic status (SES) and comorbidities. Our study aimed to identify whether a relationship exists between SES and inpatient trauma mortality after adjusting for known confounders.

Methods: Trauma patients aged 18-65 years with an Injury Severity Scores (ISS) of ≥9 were identified using the 2003-2009 Nationwide Inpatient Sample. Median household income (MHI) by zip code, available by quartiles, was used to measure SES. Multiple logistic regression analyses were performed to determine odds of inpatient mortality by MHI quartile, adjusting for ISS, type of injury, comorbidities, and patient demographics.

Results: In all, 267,621 patients met inclusion criteria. Patients in lower wealth quartiles had significantly greater unadjusted inpatient mortality compared with the wealthiest quartile. Adjusted odds of death were also higher compared with the wealthiest quartile for Q1 (odds ratio [OR], 1.13; 95% confidence interval [CI], 1.06-1.20), Q2 (OR, 1.09; 95% CI, 1.02-1.17), and Q3 (OR, 1.11; 95% CI, 1.04-1.19).

Conclusion: MHI predicts inpatient mortality after adult trauma, even after adjusting for race, insurance status, and comorbidities. Efforts to mitigate trauma disparities should address SES as an independent predictor of outcomes.

Figure 1

Adjusted odds of inpatient mortality following traumatic injury in adults aged 18–65 with ISS≥9. The reference group is median household income [MHI) quartile 4 [Q4), the wealthiest quartile [75–100%; $67,000+), indicated by the horizontal line at y=l. There are increased odds of mortality for MHI Ql (0–25% quartile; $1–40,999), MHI Q2 (25–50% quartile; $41,000–50,999), and MHI Q3 (50–75% quartile; $51,000–00,999). Vertical bars and values in brackets indicate 95% confidence intervals.

Figure 2

Adjusted odds of inpatient mortality following traumatic injury in adults aged 18–65 with ISS≥9₌ stratified into two year groups. The reference group is median household income (MHI) quartile 4 (Q4), the wealthiest quartile. MHI Q2 and Q3 show decreased odds of mortality in the 2007–2009 group compared to their respective 2003–2006 group odds of mortality values. MHI Q1 shows no difference in the increased odds of mortality between the groups. Vertical bars and values in brackets indicate 95% confidence intervals.