A population-based study of anesthesia consultation before major noncardiac surgery

Abstract

Background: In single-center studies, consultation by an anesthesiologist days to weeks before surgery was associated with reduced patient anxiety, case cancellations on the day of surgery, and duration of hospitalization. Nonetheless, the impact of anesthesia consultation on outcomes in the population remains unclear.

Methods: We used population-based, linked, administrative databases to conduct a cohort study of patients, aged 40 years and older, who underwent selected elective intermediate- to high-risk noncardiac surgical procedures in Ontario, Canada, between April 1, 1994, and March 31, 2004. Propensity-score methods were used to construct a matched-pairs cohort that resolved important differences between patients who underwent consultation and those who did not. We then determined the association of consultation (within 60 days before surgery) with hospital length of stay and postoperative mortality (30-day and 1-year) rates within the matched pairs.

Results: Of the 271 082 patients in the entire cohort, 39% (n = 104 716) underwent anesthesia consultation. The proportion of patients who underwent consultation increased from 19% in 1994 to 53% in 2003. Within the matched-pairs (n = 180 254), consultation was associated with reduced mean hospital length of stay (8.17 days vs 8.52 days; difference, -0.35 days; 95% confidence interval [CI], -0.27 to -0.43; P < .001). Consultation was not associated with reduced mortality at 30 days (relative risk, 1.04; 95% CI, 0.96 to 1.13; P = .36) or 1 year (relative risk, 0.98; 95% CI, 0.95 to 1.02; P = .20).

Conclusions: Preoperative anesthesia consultation is associated with reduced length of stay but not with reduced mortality. Future research should evaluate the cost-effectiveness of the increasing use of anesthesia consultation.