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Do Preoperative Consultations Improve Postoperative Clinical Outcomes and for Which Patients?
Major complications occur in 6% of the 64 million surgeries performed in the Unites States (US) each year. To ensure safety for higher risk patients, surgeons sometimes refer their patients for preoperative evaluations by consultants of other medical specialties. Evidence is lacking regarding which surgical patients are most likely to benefit from preoperative consultation. Many healthy patients undergoing low-risk surgeries, including many outpatient surgeries, have consultations that have questionable clinical value, incur substantial resource utilization, and lead to over-diagnosis and treatment.
Objective
To determine the outpatient surgical patient subgroups for whom preoperative consultations are most likely to improve postoperative clinical outcomes.
Data
Medicare claims data for 1.2 million surgeries from 20 preselected outpatient surgical procedures in 2009—the last year that Medicare Part B reimbursed Current Procedural Terminology (CPT) consultation codes before requiring that providers billed consultations using non-distinctive evaluation and management codes. Postoperative outcomes include 30-day mortality, 7-day emergency department visits, and inpatient hospital admissions. We will measure medical risk using claims-based comorbidity measures.
Approach
We will identify causal effects of preoperative consultation on clinical outcomes by instrumenting consultation on the differential distance between patients’ residence and the nearest above- and below-median frequency consulting facilities. We will generate procedure-specific differential distances using ZIP code centroid geocodes of patient residences and facilities where each surgical procedure was delivered. We will estimate interaction effects for individual procedures and medical risk levels.
Implications
This evidence will help develop evidence-based guidelines for preoperative consultations.