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Figure.  Percentage of 24 694 Patients Undergoing Stress Testing at 217 Facilities
Percentage of 24 694 Patients Undergoing Stress Testing at 217 Facilities
Table.  Baseline Characteristics
Baseline Characteristics
1.
Parfrey  PS, Foley  RN.  The clinical epidemiology of cardiac disease in chronic renal failure.  J Am Soc Nephrol. 1999;10(7):1606-1615.PubMedGoogle Scholar
2.
US Renal Data System Coordinating Center. 2013 Researcher’s Guide to the USRDS Database. https://www.usrds.org/2013/rg/A_intro_sec_1_13.pdf. Accessed April 2, 2019.
3.
Larsen  K, Merlo  J.  Appropriate assessment of neighborhood effects on individual health: integrating random and fixed effects in multilevel logistic regression.  Am J Epidemiol. 2005;161(1):81-88. doi:10.1093/aje/kwi017PubMedGoogle ScholarCrossref
4.
Wennberg  JE.  Unwarranted variations in healthcare delivery: implications for academic medical centres.  BMJ. 2002;325(7370):961-964. doi:10.1136/bmj.325.7370.961PubMedGoogle ScholarCrossref
5.
McFalls  EO, Ward  HB, Moritz  TE,  et al.  Coronary-artery revascularization before elective major vascular surgery.  N Engl J Med. 2004;351(27):2795-2804. doi:10.1056/NEJMoa041905PubMedGoogle ScholarCrossref
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    Research Letter
    May 13, 2019

    Center-Related Variation in Cardiac Stress Testing in the 18 Months Prior to Renal Transplantation

    Author Affiliations
    • 1Cardiovascular Division, Washington University in St Louis, St Louis, Missouri
    • 2Division of Infectious Diseases, Washington University in St Louis, St Louis, Missouri
    • 3Division of Nephrology, Washington University in St Louis, St Louis, Missouri
    JAMA Intern Med. 2019;179(8):1135-1136. doi:10.1001/jamainternmed.2019.0423

    Approximately 40% of patients with end stage renal disease (ESRD) have ischemic heart disease.1 Given this high prevalence, many renal transplant centers assess patients for ischemic heart disease in the pretransplant evaluation. Once accepted as a transplant candidate and placed on the waiting list, there is little guidance regarding subsequent stress testing in asymptomatic individuals. We examined the predictors of and variation in stress testing in the 18 months prior to renal transplantation.

    Methods

    The Washington University Human Research Protection Office exempted this study from institutional review board oversight. From the United States Renal Data System,2 we identified patients with ESRD who underwent a first renal transplant between July 1, 2006, and November 30, 2013, were 40 years or older, and had primary Medicare insurance for at least 18 months prior to the transplant. Patient-level and facility-level characteristics were compared between patients who did and did not undergo stress testing using the t test and Pearson χ2 test for continuous and categorical variables, respectively. Nonnormal and ordinal variables were summarized by the median (first quartile, third quartile) and compared using the Mann-Whitney U test.

    Variables with P < .10 on univariate analysis were entered into a multivariable logistic regression model that included both patient-level and center-level variables. A hierarchical model approach was used with the center as a second-level clustering variable. The median odds ratio (MOR) was determined to describe the likelihood of undergoing a stress test if a patient hypothetically moved from a center with a lower probability of having a stress test to one with a higher probability.3 All analyses were conducted in SAS version 9.3 (SAS Institute Inc), and P < .05 (2-sided) was considered significant. Data were analyzed from June 7, 2017, to February 1, 2019.

    Results

    In 26 694 patients from 217 facilities, the percentage who underwent stress testing in the 18 months prior to renal transplantation by center ranged from 11.1% to 96.2% (median, 60.4%; interquartile range, 31.2%) (Figure). Individuals who underwent stress testing were older with higher percentages of white patients, female patients, recipients of kidneys from living donors, congestive heart failure, valvular disease, peripheral vascular disease, diabetes, hypertension, prior myocardial infarction, and coronary artery disease (Table).

    Independent predictors of stress testing included white race (odds ratio [OR], 1.13; 95% CI, 1.05-1.21), diabetes (OR, 1.14; 95% CI, 1.05-1.24), hypertension (OR, 1.70; 95% CI, 1.55-1.86), coronary artery disease (OR, 2.66; 95% CI, 2.47-2.88), valvular disease (OR, 1.85; 95% CI, 1.66-2.07), peripheral vascular disease (OR, 1.11; 95% CI, 1.03-1.20), and cardiomyopathy (OR, 1.25; 95% CI 1.09-1.43). The MOR was 2.28 (95% CI, 2.04-2.48).

    Discussion

    Our study demonstrates that substantial variability exists among centers in use of stress testing in the 18 months prior to renal transplant. With an MOR of 2.28, transplant center was second only to coronary artery disease in determining the use of stress testing,3 suggesting that the decision to perform a stress test was influenced more strongly by hospital culture than by all other individual patient characteristics, including those associated with coronary artery disease. Although it should be noted that while we accounted for a wide range of patient-level variables in performing our multivariable analysis, we cannot exclude the possibility that unmeasured confounders may have influenced the selection of patients for stress testing at each facility.

    Variation in care is often attributed to differences in disease prevalence or access to care.4 However, neither of those factors is operative in this population of patients, all of whom had ESRD and were on the waiting list for renal transplantation. Rather, the variability in practice among centers suggests that there is no consensus regarding which patients, if any, should undergo stress testing. The lack of consensus may reflect the cognitive dissonance created by the strong association of ischemia on stress testing with adverse outcomes, the absence of data regarding the benefit of stress testing in patients with ESRD awaiting renal transplantation, and the presence of high-quality data that revascularization does not improve outcomes in other high-risk surgical populations.5 Defining the role of surveillance stress testing in patients awaiting renal transplantation requires randomized clinical trials.

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    Article Information

    Accepted for Publication: February 5, 2019.

    Corresponding Author: David L. Brown, MD, Cardiovascular Division, Washington University School of Medicine in St Louis, 660 S Euclid Ave, Campus Box 8086, St Louis, MO 63110 (d.brown@wustl.edu).

    Published Online: May 13, 2019. doi:10.1001/jamainternmed.2019.0423

    Author Contributions: Mr Novak had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

    Concept and design: Shpigel, Saeed, Alhamad, Rich, Brown.

    Acquisition, analysis, or interpretation of data: Shpigel, Saeed, Novak, Rich.

    Drafting of the manuscript: Shpigel, Saeed, Brown.

    Critical revision of the manuscript for important intellectual content: Shpigel, Novak, Alhamad, Rich, Brown.

    Statistical analysis: Shpigel, Saeed, Novak.

    Obtained funding: Brown.

    Administrative, technical, or material support: Brown.

    Supervision: Alhamad, Rich, Brown.

    Conflict of Interest Disclosures: None reported.

    Funding/Support: This work was supported by the Washington University Center for Administrative Data Research, which is supported in part by the Washington University Institute of Clinical and Translational Sciences grant No. UL1 TR002345 from the National Center for Advancing Translational Sciences of the National Institutes of Health and grant No. R24 HS19455 through the Agency for Healthcare Research and Quality.

    Role of the Funder/Sponsor: The funder/sponsor 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 data reported here have been supplied by the US Renal Data System. The interpretation and reporting of these data are the responsibility of the author(s) and in no way should be seen as an official policy or interpretation of the US government.

    References
    1.
    Parfrey  PS, Foley  RN.  The clinical epidemiology of cardiac disease in chronic renal failure.  J Am Soc Nephrol. 1999;10(7):1606-1615.PubMedGoogle Scholar
    2.
    US Renal Data System Coordinating Center. 2013 Researcher’s Guide to the USRDS Database. https://www.usrds.org/2013/rg/A_intro_sec_1_13.pdf. Accessed April 2, 2019.
    3.
    Larsen  K, Merlo  J.  Appropriate assessment of neighborhood effects on individual health: integrating random and fixed effects in multilevel logistic regression.  Am J Epidemiol. 2005;161(1):81-88. doi:10.1093/aje/kwi017PubMedGoogle ScholarCrossref
    4.
    Wennberg  JE.  Unwarranted variations in healthcare delivery: implications for academic medical centres.  BMJ. 2002;325(7370):961-964. doi:10.1136/bmj.325.7370.961PubMedGoogle ScholarCrossref
    5.
    McFalls  EO, Ward  HB, Moritz  TE,  et al.  Coronary-artery revascularization before elective major vascular surgery.  N Engl J Med. 2004;351(27):2795-2804. doi:10.1056/NEJMoa041905PubMedGoogle ScholarCrossref
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