How comorbidities and preoperative expenditures correlate with postoperative adverse outcomes

Objectives: To examine the correlation of preexisting illnesses and preoperative medical expenditures with postoperative major adverse outcomes among geriatric surgical patients. Study Design: Retrospective cohort study using claims from Taiwan's National Health Insurance Research Database. Methods: All geriatric patients aged ≥65 years receiving inpatient surgeries during 2004 to 2007 under universal healthcare coverage were included. Surgical patients aged 55 to 64 years were the reference group. Risk-adjusted 30-day postoperative complication and mortality rates among elderly patients in various age sectors were analyzed and correlated with the preexisting illnesses and preoperative medical expenditures quantitatively. Results: Among 432,614 elderly surgical patients in specific age sectors and 238,802 controls, the prevalence of preexisting illnesses and the riskadjusted postoperative adverse outcome rates were highly age dependent and illness related. When comparing patients aged ≥85 years with patients aged 55 to 64 years, the adjusted odds ratios were 2.74 (95% confidence interval [CI], 2.67-2.82) and 3.56 (95% CI 3.31 -3.84) for incidence of major postoperative complications and mortality after major complications, respectively. Numbers of preexisting illnesses increased in an age-dependent pattern and the preoperative 24-month medical expenditures increased incrementally with the numbers of comorbidities. Postoperative major complications, but not mortality rates, were highly correlated with the numbers of comorbidities and increased parallel with preoperative 24-month comorbidity-related medical expenditures, especially in the younger age group. Conclusions: Adjusting for preexisting covariates, geriatric patients had an age-dependent, illnessrelated, and expenditure-associated pattern of higher postoperative complication and mortality rates. The numbers of comorbidities and preoperative medical expenditures had high predictive value for postoperative adverse outcomes.