Preoperative testing before low-risk surgical procedures

Abstract

Background: There is concern about increasing utilization of low-value health care services, including preoperative testing for low-risk surgical procedures. We investigated temporal trends, explanatory factors, and institutional and regional variation in the utilization of testing before low-risk procedures.

Methods: For this retrospective cohort study, we accessed linked population-based administrative databases from Ontario, Canada. A cohort of 1 546 223 patients 18 years or older underwent a total of 2 224 070 low-risk procedures, including endoscopy and ophthalmologic surgery, from Apr. 1, 2008, to Mar. 31, 2013, at 137 institutions in 14 health regions. We used hierarchical logistic regression models to assess patient- and institution-level factors associated with electrocardiography (ECG), transthoracic echocardiography, cardiac stress test or chest radiography within 60 days before the procedure.

Results: Endoscopy, ophthalmologic surgery and other low-risk procedures accounted for 40.1%, 34.2% and 25.7% of procedures, respectively. ECG and chest radiography were conducted before 31.0% (95% confidence interval [CI] 30.9%-31.1%) and 10.8% (95% CI 10.8%-10.8%) of procedures, respectively, whereas the rates of preoperative echocardiography and stress testing were 2.9% (95% CI 2.9%-2.9%) and 2.1% (95% CI 2.1%-2.1%), respectively. Significant variation was present across institutions, with the frequency of preoperative ECG ranging from 3.4% to 88.8%. Receipt of preoperative ECG and radiography were associated with older age (among patients 66-75 years of age, for ECG, adjusted odds ratio [OR] 18.3, 95% CI 17.6-19.0; for radiography, adjusted OR 2.9, 95% CI 2.8-3.0), preoperative anesthesia consultation (for ECG, adjusted OR 8.7, 95% CI 8.5-8.8; for radiography, adjusted OR 2.2, 95% CI 2.1-2.2) and preoperative medical consultation (for ECG, adjusted OR 6.8, 95% CI 6.7-6.9; for radiography, adjusted OR 3.6, 95% CI 3.5-3.6). The median ORs for receipt of preoperative ECG and radiography were 2.3 and 1.6, respectively.

Interpretation: Despite guideline recommendations to limit testing before low-risk surgical procedures, preoperative ECG and chest radiography were performed frequently. Significant variation across institutions remained after adjustment for patient- and institution-level factors.

Figure 1:

Study flow diagram. Data represent procedures included in the analysis (some patients underwent more than 1 procedure in the study period). CIHI = Canadian Institute for Health Information, DAD = Discharge Abstract Database, LHIN = Local Health Integration Network, OHIP = Ontario Health Insurance Plan, SDS = Same-Day Surgery database.

Figure 2:

Institutional variation in preoperative testing for the 4 preoperative procedures. Each point represents the unadjusted rate of testing for a single institution, with vertical lines representing 95% confidence intervals. The dashed horizontal lines denote mean rates of testing across all institutions. CXR = chest radiography, ECG = electrocardiography, TTE = transthoracic echocardiography.

Figure 3:

Indirect standardized rates of preoperative electrocardiography (ECG). Each point represents the indirect standardized rate of preoperative ECG for a single institution, and the associated vertical line represents the institution’s 95% confidence interval for the testing rate. The dashed horizontal line denotes the mean rate of testing across all institutions.

Figure 4:

Indirect standardized rates of preoperative chest radiography. Each point represents the indirect standardized rate of preoperative chest radiography for a single institution, and the associated vertical line represents the 95% confidence interval for the testing rate. The dashed horizontal line denotes the mean rate of testing across all institutions.