Surgeon Specialty and Operative Mortality With Lung Resection

1. Surgeon Specialty and Operative Mortality With Lung Resection PP Goodney, FL Lucas, TS Stukel, JD Birkmeyer VA Outcomes Group, White River Junction, VT Dartmouth-Hitchcock Medical Center, Lebanon, NH

2. Background • Several studies have reported variation in outcomes according to surgeon specialty • colorectal resection for cancer • Wigmore et al, Ann Surg1999 • carotid endarterectomy • Hannan et al, Stroke2001 • Not all studies have confirmed this finding • Cowan et al, JACS2002

3. Lung resection • Resection for lung cancer • approximately 25,000 cases per year in the U.S. • Performed by: • General surgeons • Cardiothoracic surgeons • Non-cardiac thoracic surgeons www.seer.cancer.gov

4. Research question Does surgeon specialty affect operative mortality in lung resection for lung cancer?

5. Subjects and databases • Study population • All Medicare beneficiaries 1998-1999 • Age 65-99 • Patient selection • Procedure code for lung resection • (pneumonectomy or lobectomy) • Diagnosis code for lung cancer • Unique physician identifier number (UPIN) present on discharge abstract

6. Surgeon Specialty Assignment

7. Surgeon Specialty Assignment American Board of Thoracic Surgery member?

8. Surgeon Specialty Assignment American Board of Thoracic Surgery member? Perform CABG?

9. Surgeon Specialty Assignment American Board of Thoracic Surgery member? Perform CABG?

10. Analysis • Unit of analysis: patient • Main exposure: surgeon specialty • General, cardiothoracic, non-cardiac thoracic • Main outcome measure: operative mortality • Combination of death before discharge or within thirty days of the index procedure

11. Analysis • Using multiple logistic regression models, adjusted for the following: Patient variables: Age, sex, race Comorbidity score Admission acuity Extent of resection Hospital variables: Hospital volume Bed size Teaching status Medical school affiliation ACS-approved cancer center Surgeon variables: Surgeon volume Clustering

12. RESULTS

13. Patient characteristics

14. Hospital characteristics

15. Surgeon characteristics

16. Adjusted operative mortality, by surgeon subspecialty Cardiothoracic Non-cardiac thoracic General p <0.001 between all groups

17. Adjusted operative mortality, by extent of resection Cardio. Cardiothoracic General NCTS General NCTS p <0.001 between all groups

18. Adjusted operative mortality, with high-volume surgeons Cardiothoracic Non-cardiac thoracic General p <0.01 between non-cardiac thoracic surgeons and others

19. Adjusted operative mortality, in high-volume hospitals Cardiothoracic Non-cardiac thoracic General p <0.01 between non-cardiac thoracic surgeons and others

20. Odds ratios of operative mortality

21. Summary • Operative mortality with lung resection varies by surgeon specialty • Risks were lowest for non-cardiac thoracic surgeons • Hospital and surgeon volume account for some, but not all of this effect

22. Limitations • Administrative data for risk adjustment • Error in assignment of surgeon specialty • Bias would tend towards the null

23. Why does performance differ across specialty? • Additional training • Structural differences across specialty • Larger hospitals • Medical school affiliations • ACS-approved cancer programs • Another possibility – • Differences in processes of care • Intensivist-managed ICUs, epidural catheters, pulmonary protocols • Many of these processes are unmeasured in current quality improvement initiatives such as the STS database

24. Do our findings matter? • Although these differences are statistically significant, are they clinically important? • Differences are small (~1%) for lobectomy, but larger (~5%) for pneumonectomy • How much is enough? • Only patients can decide

25. Conclusion • Surgeon specialty impacts operative mortality with lung resection • Some, but not all of this difference can be explained by volume • Further study of these differences may hold potential for improvement

26. Acknowledgement • Scottie Siewers • VA Outcomes Group