Materials and Methods
Data were obtained from the Truven Health MarketScan Commercial and Medicare Supplemental Databases from 2004 through 2017. These databases contain de-identified records of health services for more than 250 million patients with primary or Medicare supplemental health insurance coverage through employer-based fee-for-service, point-of-service, or capitated plans. The University of Chicago Institutional Review Board (Chicago, Illinois) considered this study exempt from review as there are no patient identifiers in the MarketScan databases (IRB19-1891).
Our analysis included records of patients with an International Classification of Diseases, Ninth Revision–Clinical Modification or International Classification of Diseases, Tenth Revision–Clinical Modification principal procedure code for a major abdominal surgical procedure (Figure 1). We focused on major abdominal procedures as they are a high-risk procedure for major adverse cardiac events as per the Revised Cardiac Risk Index. We did not include intrathoracic and suprainguinal vascular procedures as there may be procedure-specific indications that warranted a resting echocardiogram. Procedures included open or laparoscopic small bowel resections, large bowel resections, gastric resections, pancreatic resections, cystectomies, and nephrectomies from 2005 to 2017 (Supplemental Digital Content table 1, https://links.lww.com/ALN/C688). Subjects were excluded from the analysis if (1) they were under 18 yr old (n = 7,327), (2) the surgery was emergent (identified by correlation with an emergency room service claim from the same date as the surgery; n = 83,227), (3) the surgery was not the first procedure of interest that the patient underwent during the study period (n = 9,476), (4) the subject was not enrolled in an insurance plan for 1 yr before the surgery (n = 132,939), and (5) there was no drug benefit data available in the MarketScan database for the patient (n = 85).
Consolidated Standards of Reporting Trials flow diagram illustrates the organization of the study, including patient record inclusion, exclusion, and classification (Truven Health MarketScan [Truven Health Analytics, USA]).
The primary outcome measure was the presence of a "rarely appropriate" resting echocardiogram performed within 60 days before a major abdominal surgery. A 60-day period was chosen as echocardiograms performed within this time period are likely preoperative tests consistent with previous analyses.[9–11] Outpatient resting transthoracic echocardiograms were identified using Current Procedural Terminology codes (Supplemental Digital Content table 2, https://links.lww.com/ALN/C688). The indications for the preoperative echocardiograms were determined based on the International Classification of Diseases, Ninth Revision–Clinical Modification or International Classification of Diseases, Tenth Revision–Clinical Modification principal or secondary diagnosis code associated with the echocardiography claim. Indications were categorized as "appropriate" if they were clearly specified as "appropriate" in the Appropriate Use Criteria for Echocardiography, such as a resting echocardiogram ordered for dyspnea or acute heart failure (e.g., International Classification of Diseases, Ninth Revision–Clinical Modification code 786.05 or 428.x, respectively; Supplemental Digital Content table 3, https://links.lww.com/ALN/C688). Indications were categorized as "rarely appropriate" if they were specified as "rarely appropriate" in the Appropriate Use Criteria for Echocardiography, such as a resting echocardiogram ordered for chronic heart failure (e.g., International Classification of Diseases, Ninth Revision–Clinical Modification code 428.22) without any additional new symptom identified in a patient with an echocardiogram performed in the previous year, or a resting echocardiogram ordered for coronary atherosclerosis (International Classification of Diseases, Ninth Revision–Clinical Modification code 414.0x). No studies in our cohort were found to be "may be appropriate" as there are very few overall indications that are classified as "may be appropriate" in the Appropriate Use Criteria for Echocardiography, and they could not be correlated to International Classification of Diseases, Ninth Revision–Clinical Modification/International Classification of Diseases, Tenth Revision–Clinical Modification codes. Echocardiograms were considered "unclassifiable" if the indication did not allow appropriateness classification according to the Appropriate Use Criteria for Echocardiography (e.g., heart disease, unspecified). While all the indications for the echocardiograms were based on the 2011 Appropriate Use Criteria for Echocardiography document, the recommended updated classification terminology from the 2013 methodology update was applied. This update did not change the classification of tests from the 2011 document, but rather adjusted the terminology used to describe these classifications in order to more closely reflect their application in practice. In particular, "inappropriate" and "uncertain" indications from the 2011 document are now referred to as "rarely appropriate" and "may be appropriate," respectively, in the 2013 document.
If records of patients included multiple resting echocardiograms, only the claim for the test performed on the date closest to the surgery was analyzed. If records included multiple claims for the same resting echocardiogram with disparate principal diagnosis codes, the claim used for analysis was determined using the following criteria: (1) if there were claims for both physician and facility fees, the claim for the physician fee was analyzed; (2) if claims were paid on different dates, the claim with the earlier paid date was analyzed; and (3) if claims differed only in principal diagnosis, then the claim with the most specific diagnosis code or the code most closely aligned with Appropriate Use Criteria for Echocardiography was analyzed.
Secondary outcomes were major adverse cardiac events that included a diagnosis of myocardial infarction, cardiac arrest, or new heart failure during the inpatient claim associated with the major abdominal surgery. Outcomes were identified using International Classification of Diseases, Ninth Revision–Clinical Modification and International Classification of Diseases, Tenth Revision–Clinical Modification codes and can be found in the Supplemental Digital Content table 4 (https://links.lww.com/ALN/C688). Outcomes were stratified based on the appropriateness classification of the echocardiogram as outlined in the Appropriate Use Criteria for Echocardiography.
Patient characteristics analyzed were age, sex, geographical region, comorbid conditions, and Elixhauser score. Elixhauser comorbidities can be assessed as a single numeric score that summarizes disease burden and is adequately discriminative for in-hospital mortality. Consistent with previous analyses of MarketScan, comorbidity diagnoses were included for cohort subjects if the International Classification of Diseases, Ninth Revision–Clinical Modification and International Classification of Diseases, Tenth Revision–Clinical Modification codes were present at least once in inpatient or outpatient claims from the year before the procedure. Diagnosis codes used to classify comorbidities can be found in the Supplemental Digital Content table 5 (https://links.lww.com/ALN/C688).
Records of patients who underwent nonpreoperative resting echocardiography within 1 yr (i.e., between 61 days and 365 days) of the procedure were also identified, as the Appropriate Use Criteria for Echocardiography specify that a repeat resting echocardiogram is unnecessary within 1 yr of a previous study in the absence of new symptoms or a change in clinical status. This guidance for repeating a resting echocardiogram applies for patients undergoing preoperative evaluation who have had an echocardiogram in the last year.
Other cardiac tests, including exercise or pharmacologic stress tests, myocardial nuclear imaging, stress magnetic resonance imaging, and transesophageal echocardiograms, performed between 61 and 365 days before the procedure were also identified via Current Procedural Terminology codes in outpatient claims (Supplemental Digital Content table 2, https://links.lww.com/ALN/C688). These tests can influence the decision to pursue a preoperative echocardiogram and were included in the analysis.
Data were complete except for region of service (n = 1,576). Apart from this, there were no missing data for any of the variables that were used for the analysis.
The data analysis was completed using SAS software, Version 9.4 (SAS Institute Inc., USA). A data analysis and statistical plan was written after the data were accessed. As this is a retrospective cohort study, the sample size was based on the available data, and no statistical power calculation was conducted. The Cochrane–Armitage test was used to identify any trends in the frequency of "rarely appropriate" echocardiograms throughout the study period. Chi-square and unpaired t tests were used to compare patient characteristics between subjects who underwent preoperative resting echocardiography and those who did not, and chi-square and one-way ANOVA tests were used to compare patient characteristics between subjects who had "appropriate," "rarely appropriate," or "unclassifiable" indications for resting echocardiography and outcomes.
We conducted three sensitivity analyses. The first compared the incidence of "appropriate" resting echocardiograms between the preoperative period and outside of the preoperative period to determine if there was a higher frequency of "rarely appropriate" resting echocardiograms performed in the preoperative period. We applied the Appropriate Use Criteria for Echocardiography in the same manner as resting echocardiograms performed more than 60 days before the operative procedure and compared the appropriateness using a chi-square test. Second, we evaluated the incidence of resting echocardiograms over the 12-month period before surgery in the entire cohort to confirm that resting echocardiograms performed 60 days before the procedure were in response to the upcoming surgical procedure. The third sensitivity analysis evaluated comorbidity burden and cardiac outcomes of patients who underwent a repeat echocardiogram in the 60 days before surgery to evaluate if patients who underwent a repeat echocardiogram had a higher comorbidity burden and higher frequency of major adverse cardiac events. Significance for these analyses was set at P ≤ 0.01 with Bonferroni correction for multiple comparisons and two-tailed hypothesis testing where appropriate.
Anesthesiology. 2021;135(5):854-863. © 2021 American Society of Anesthesiologists | Lippincott Williams & Wilkins