Role of patient- and surgery-specific risk in receipt of outpatient preoperative testing

Objective: To determine the independent association of patient- and surgery-specific risk with receipt of outpatient preoperative testing. Methods: Using administrative data from 2010–2013 (Marketscan^® Commercial Claims and Encounters), we constructed a retrospective cohort of 678,368 privately-insured, non-elderly US adults who underwent one of ten operations, including one lower-risk and one higher-risk operation from five surgical specialties. Outcomes were receipt of nine outpatient tests in the 30 days before surgery and cost of those tests. Patient-specific risk was based on Revised Cardiac Risk Index (RCRI) and, alternatively, the Charlson Comorbidity Index (CCI). Surgery-specific risk was based on operation (higher- versus lower-risk within each specialty). Multivariable logistic regression models were constructed to measure the independent association of patient- and surgery-specific risk with the receipt of tests. Results: Receipt of tests ranged from 0.9% (pulmonary function tests) to 46.8% (blood counts), and 65.2% of patients received at least one test. Mean cost per patient for all tests was $124.38. Higher RCRI was strongly associated (Odds Ratio (OR) > 2) with receipt of stress tests and echocardiograms, and more modestly associated [OR < 2] with receipt of most other tests. Undergoing higher-risk operations was strongly associated with receipt of most tests. Results were similar using the CCI for patient-specific risk. Conclusion: Surgery-specific risk is strongly associated with receipt of most preoperative tests, which is consistent with preoperative testing protocols based as much or more on the planned operation as on patient-specific risk factors. Whether this pattern of preoperative testing represents optimal care is uncertain.