United States national trends in comorbidity and outcomes of adult cardiac surgery patients

Background: Comorbidity profiles of cardiac surgery patients are known to have changed over time, but modern national trends in these comorbidities and outcomes are not described. This study describes comorbidity trends over time for common adult cardiac surgery procedures.

Methods: A retrospective, cross-sectional analysis of the National Inpatient Sample was conducted for years 2005-2014. Hospitalizations with coronary artery bypass grafting (CABG), aortic valve replacement (AVR), and mitral valve repair/replacement (MVRR), as well as combined CABG/valve operations, were identified by ICD-9 procedure codes. Comorbidities were defined based on ICD-9 codes to discriminate between comorbidities and complications. Surgical volume, patient age, in-hospital mortality, and length of stay trends over time were evaluated by linear regression.

Results: Incidence increased for AVR, MVRR, and CABG + AVR and declined for CABG and CABG + MVRR (P < .001). The mean number of comorbidities across all surgeries increased from 1.4 to 1.9 (P < .001). Length of stay declined for AVR, CABG + AVR, and CABG + MVRR (P < .001) with an overall decline from 10.1 to 9.7 days (P = .003). In-hospital mortality decreased in all categories over time (P < .001). Overall, in-hospital mortality decreased from 2.9% to 2.3% (P < .001).

Conclusions: Despite increasing comorbidity in cardiac surgery, operations are being conducted with fewer in-hospital mortalities across all types of surgery and decreasing length of stay for most types of surgery, which should inform the frequency of risk model updates and raise questions of the applicability of earlier studies in cardiac surgery to the modern population.