Which comorbidities matter most in patients with multiple rib fractures? An analysis of the national inpatient sample

Background: Increased age and number of rib fractures are known to increase the risk of mortality. The impact of comorbidities on the outcomes of patients with rib fractures has not previously been described. We hypothesized that specific medical comorbidities are associated with increased risk of morbidity and mortality following rib fracture. Methods: Patients with multiple rib fractures or flail chest were identified in the National Inpatient Sample by ICD-10 code from the 4th quarter of 2015 through 2016. Comorbidities were categorized into Elixhauser comorbidity groups, and injury severity was estimated using the Injury Severity Score (ISS). The composite adverse outcome was defined as death, pneumonia, tracheostomy, or discharge to a short-term acute care facility. Multivariable logistic regression was performed with covariates chosen through backward selection from the univariate model to determine the relationship of outcomes to demographic variables and comorbidities with alpha set to 0.001. Results: Totally 26,289 patients met inclusion criteria. Composite adverse outcomes occurred in 5,132 (19.5%) patients. Profound ISS (OR 6.013), severe ISS (odds ratio [OR] 2.569), fluid and electrolyte disorder (OR 2.471), and paralysis (OR 2.372) were most associated with adverse outcomes. Within causes of injury, motor vehicle was associated with increased risk of adverse outcome (OR 1.322). Flail chest was also independently associated with adverse outcome (OR 1.816). Conclusion: Morbidity and mortality following rib fracture occurred in approximately one-fifth of patients, especially those with high ISS or associated medical comorbidities. This data can be used for risk stratification and identification of high-risk patients for escalation of care.