Association between race and age in survival after trauma

Abstract

Importance: Racial disparities in survival after trauma are well described for patients younger than 65 years. Similar information among older patients is lacking because existing trauma databases do not include important patient comorbidity information.

Objective: To determine whether racial disparities in trauma survival persist in patients 65 years or older.

Design, setting, and participants: Trauma patients were identified from the Nationwide Inpatient Sample (January 1, 2003, through December 30, 2010) using International Classification of Diseases, Ninth Revision, Clinical Modification diagnosis codes. Injury severity was ascertained by applying the Trauma Mortality Prediction Model, and patient comorbidities were quantified using the Charlson Comorbidity Index.

Main outcomes and measures: In-hospital mortality after trauma for blacks vs whites for younger (16-64 years of age) and older (≥65 years of age) patients was compared using 3 different statistical methods: univariable logistic regression, multivariable logistic regression with and without clustering for hospital effects, and coarsened exact matching. Model covariates included age, sex, insurance status, type and intent of injury, injury severity, head injury severity, and Charlson Comorbidity Index.

Results: A total of 1,073,195 patients were included (502,167 patients 16-64 years of age and 571,028 patients ≥65 years of age). Most older patients were white (547,325 [95.8%]), female (406 158 [71.1%]), and insured (567,361 [99.4%]) and had Charlson Comorbidity Index scores of 1 or higher (323,741 [56.7%]). The unadjusted odds ratios (ORs) for death in blacks vs whites were 1.35 (95% CI, 1.28-1.42) for patients 16 to 64 years of age and 1.00 (95% CI, 0.93-1.08) for patients 65 years or older. After risk adjustment, racial disparities in survival persisted in the younger black group (OR, 1.21; 95% CI, 1.13-1.30) but were reversed in the older group (OR, 0.83; 95% CI, 0.76-0.90). This finding was consistent across all 3 statistical methods.

Conclusions and relevance: Different racial disparities in survival after trauma exist between white and black patients depending on their age group. Although younger white patients have better outcomes after trauma than younger black patients, older black patients have better outcomes than older white patients. Exploration of this paradoxical finding may lead to a better understanding of the mechanisms that cause disparities in trauma outcomes.

Figure 1. Example of Coarsened Exact Matching on Age

CEM is a statistical means of matching patients based on categorical bins that allows for a greater overall number of successfully matched patients compared to traditional matching while still bounding the degree of model dependence and the average treatment estimation error. The technique involves 4 main steps: 1) The variable of interest (e.g. age) is “coarsened”, meaning that it is assigned categorical bins that are chosen on the reasonable assumption that patients within those bins will behave similarly; 2) Patients from the case (e.g. Black) and Control (e.g. White) groups are matched on the coarsened variable; 3) The patients are assigned back into their group (i.e. Case or Control); and 4) The patients are matched on the next variable.

Figure 2. Odds Ratio for Mortality: Black vs. White by Age Category

There was a higher unadjusted odds of death for Blacks versus Whites for patients < 65 years of age, but not for patients ≥ 65 years of age. After coarsened exact matching (CEM), racial disparities in survival persisted in the younger Black age group, but were reversed in the older age group. These findings were consistent across three different analysis techniques.