Rates of pulmonary function tests (PFTs) in Ontario, Canada. The vertical dotted line represents the publication of the American College of Physicians guidelines regarding risk assessment for perioperative pulmonary complications. In segmented regression modeling, trends in preoperative testing deceased significantly (P = .006) following publication of these guidelines.
Rates of pulmonary function tests (PFTs) among patients with and without chronic obstructive pulmonary disease (COPD) or asthma. The vertical dotted line represents the publication of the American College of Physicians guidelines regarding risk assessment for perioperative pulmonary complications. In segmented regression modeling, trends in preoperative testing decreased significantly after publication of these guidelines in both the high-risk (P < .001) and low-risk (P = .01) subgroups.
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Sun LY, Gershon AS, Ko DT, et al. Trends in Pulmonary Function Testing Before Noncardiothoracic Surgery. JAMA Intern Med. 2015;175(8):1410–1412. doi:10.1001/jamainternmed.2015.2087
Preoperative pulmonary function tests (PFTs) assess the severity of known pulmonary disease, diagnose causes of respiratory symptoms, and may help identify patients who are at risk for postoperative pulmonary complications. While useful in selected patients, unnecessary testing is costly.1 Few guidelines for the appropriate use of preoperative PFTs exist, with the most recent being the April 2006 American College of Physicians guidelines2 on risk assessment and prevention of postoperative pulmonary complications. We conducted a population-based study in Ontario, Canada, to describe temporal trends in preoperative PFTs and to assess whether the guidelines influenced these trends.
Following research ethics approval from Sunnybrook Health Sciences Centre, we conducted a retrospective cohort study using deidentified data from linked population-based administrative databases. The cohort included individuals who were 40 years or older who underwent elective abdominal aortic aneurysm repair, carotid endarterectomy, peripheral arterial bypass, hip replacement, knee replacement, large-bowel resection, partial liver resection, pancreatoduodenectomy, gastrectomy, esophagectomy, abdominal hysterectomy, radical prostatectomy, nephrectomy, or cystectomy from April 1, 2003, through March 31, 2013.
The outcome of interest was preoperative PFT, defined as physician claims for simple spirometry, flow-volume loop, lung compliance, carbon monoxide diffusion capacity, or bronchial provocative studies within 60 days before surgery. For comparison, we identified nonoperative PFTs, defined as tests conducted from 181 through 365 days before surgery.
After dividing the study into 3-month intervals,3 rates of preoperative and nonoperative PFTs were measured for each interval. Temporal trends in PFT rates were plotted and visually inspected to assess for time points when they changed substantially. We tested for the effect of guidelines on trends using segmented linear regression models.4 These analyses were then repeated within subgroups that were stratified by perioperative pulmonary risk based on the presence or absence of asthma or chronic obstructive pulmonary disease.
Of 511 625 individuals in the cohort, 3.6% underwent preoperative PFTs while 3.3% had nonoperative PFTs. Among high-risk individuals with asthma or chronic obstructive pulmonary disease, the proportions who underwent preoperative and nonoperative testing were similar at 8.3%. Conversely, among individuals without these conditions, 2.0% had preoperative testing while 1.6% had nonoperative testing.
Plotted trends showed that preoperative PFT rates decreased during the study while nonoperative rates remained stable (Figure 1). Trends in preoperative PFT rates appeared to decrease following the American College of Physicians guidelines; this trend was confirmed using segmented regression modeling (P = .006). Qualitatively similar patterns were observed in subgroups with and without risk factors for postoperative pulmonary complications (Figure 2).
Preoperative PFT rates in Ontario, Canada, were low, decreasing from 1 of 23 procedures in 2003 to 1 of 38 procedures in 2013. These trends were qualitatively similar in subgroups stratified by risk for postoperative pulmonary complications. Notably, these decreasing preoperative PFT rates contrast starkly with concurrent increases in rates of other perioperative interventions, such as preoperative anesthesia consultations5 and stress testing.6 While the April 2006 publication of the updated American College of Physicians guidelines was followed by substantial decreases in preoperative PFT rates, these guidelines were unlikely to have been the sole reason for this trend. Specifically, they were not associated with any large-scale promotion projects or changes in provincial health insurance payment schedules. The decline in preoperative PFT rates may, in part, be explained by increased use of bedside spirometry and other alternative pulmonary tests, which are not captured by provincial administrative databases. While less costly and possibly more accessible at some hospitals, these alternative tests have limitations, such as measurement error.7
Given the low overall rate of preoperative PFTs, large-scale efforts to reduce this testing are likely unnecessary. By 2013, preoperative PFTs were performed in less than 8% of Ontario patients with risk factors for pulmonary complications while preoperative testing rates among individuals without known respiratory disease had approached rates seen in the nonoperative setting. These findings indicate the need for more research to identify which surgical patients most benefit from preoperative PFTs.
Corresponding Author: Louise Y. Sun, MD, SM, FRCPC, Division of Cardiac Anesthesiology, University of Ottawa Heart Institute, 40 Ruskin St, Room H2410, Ottawa, ON K1Y 4W7, Canada (email@example.com).
Published Online: June 8, 2015. doi:10.1001/jamainternmed.2015.2087.
Author Contributions: Drs Sun and Wijeysundera had full access to all the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.
Study concept and design: Sun, Beattie, Wijeysundera.
Acquisition, analysis, or interpretation of data: Sun, Gershon, Ko, Thilen, Yun, Wijeysundera.
Drafting of the manuscript: Sun, Beattie, Wijeysundera.
Critical revision of the manuscript for important intellectual content: Sun, Gershon, Ko, Thilen, Yun, Wijeysundera.
Statistical analysis: Sun, Yun, Wijeysundera.
Obtained funding: Wijeysundera.
Administrative, technical, or material support: Beattie, Wijeysundera.
Study supervision: Beattie, Wijeysundera.
Conflict of Interest Disclosures: Dr Gershon reports receiving support through a Physicians’ Services Incorporated Foundation Fellowship in Translational Health Research; Dr Ko, through a Clinician-Scientist Award from the Heart and Stroke Foundation; Drs Beattie and Wijeysundera, through Merit Awards from the University of Toronto Department of Anesthesia; and Dr Wijeysundera, through a Clinician-Scientist Award from the Canadian Institutes of Health Research. Dr Beattie reports being the R. Fraser Elliot Chair of Cardiac Anesthesia at the University Health Network. No other disclosures were reported.
Funding/Support: This study was supported in part by the Institute for Clinical Evaluative Sciences, which is supported in part by the Ontario Ministry of Health and Long-Term Care.
Role of the Funder/Sponsor: The funding sources had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.
Disclaimer: The opinions, results, and conclusions are those of the authors, and no endorsement by the Ontario Ministry of Health and Long-Term Care or the Institute for Clinical Evaluative Sciences is intended or should be inferred.
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