surgeon specialty and operative mortality with lung resection pp goodney, fl lucas, ts stukel, jd...
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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
Background
• Several studies have reported variation in outcomes according to surgeon specialty– colorectal resection for cancer
• Wigmore et al, Ann Surg 1999
– carotid endarterectomy• Hannan et al, Stroke 2001
• Not all studies have confirmed this finding• Cowan et al, JACS 2002
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
Research question
Does surgeon specialty affect operative mortality in lung resection for lung
cancer?
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
Unique physicians in lung resection
inpatient filen=4793
Surgeon
Specialty Assignment
Unique physicians in lung resection
inpatient filen=4793
Yesn=2179
Surgeon
Specialty Assignment
American Board of Thoracic Surgery
member?
Non=2614
Unique physicians in lung resection
inpatient filen=4793
Yesn=2179
Cardiothoracic surgeonn=1516
Non-cardiac thoracic surgeon
n=663
Surgeon
Specialty Assignment
American Board of Thoracic Surgery
member?
Perform CABG?
Yes No
Non=2614
Unique physicians in lung resection
inpatient filen=4793
Yesn=2179
Cardiothoracic surgeonn=1516
Non-cardiac thoracic surgeon
n=663
General surgeonn=2614
Surgeon
Specialty Assignment
American Board of Thoracic Surgery
member?
Perform CABG?
Yes No
Non=2614
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
Analysis
• Using multiple logistic regression models, adjusted for the following:
Patient variables:
Age, sex, race
Comorbidity score
Admission acuity
Extent of resection
Surgeon variables:
Surgeon volume
Clustering
Hospital variables:
Hospital volume
Bed size
Teaching status
Medical school affiliation
ACS-approved cancer center
RESULTS
Patient characteristics
General surgeons
Cardiothoracic surgeons
Non-cardiac thoracic
surgeons
No. patients (n) 9,263 9,792 6,490
Age >75 (%) 69.1 69.9 70.4
Female (%) 42.5 42.3 44.8
African American (%) 4.7 4.2 6.0
Charlson score >3 (%) 44.5 46.2 48.4
Pneumonectomy (%) 9.6 11.5 11.5
Hospital characteristics
General surgeons
Cardiothoracic surgeons
Non-cardiac thoracic
surgeons
Bed size 309 433 357
Teaching status (% with residents)
31.0 56.7 58.1
Medical school affiliation (%) 22.4 64.7 57.6
ACS cancer program (%) 53.4 80.7 73.8
>45 lung resections per year (%) 8.4 16.7 13.4
Surgeon characteristics
General surgeons
Cardiothoracic surgeons
Non-cardiac thoracic
surgeons
No. surgeons (n) 2,614 1,516 663
Surgeon age (years) 51.8 51.8 57.9
Years in practice (years) 21.6 21.9 30.5
Average cases/yr, lung resection 3.1 6.5 10.2
>20 lung resections per year (n, %) 71 (2.7%) 65 (4.3%) 87 (13%)
Adjusted operative mortality, by surgeon subspecialty
7.26.4
5.3
0.0
2.0
4.0
6.0
8.0
Surgeon specialty
Gen
eral
Car
diot
hora
cic
Non
-car
diac
th
orac
icp <0.001 between all groups
Adjusted operative mortality, by extent of resection
6.2
16.4
5.4
14.5
4.5
11.9
0.0
5.0
10.0
15.0
20.0
Lobectomy Pneumonectomy
Gen
eral
Car
dio.
NC
TS
Gen
eral
Car
diot
hora
cic
NC
TS
p <0.001 between all groups
Adjusted operative mortality, with high-volume surgeons
6.2 6.1
4.7
0.0
2.0
4.0
6.0
8.0
Surgeon specialty
Gen
eral
Car
diot
hora
cic
Non
-car
diac
th
orac
icp <0.01 between non-cardiac thoracic surgeons and others
Adjusted operative mortality, in high-volume hospitals
5.8 5.9
4.3
0.0
2.0
4.0
6.0
8.0
Surgeon specialty
Gen
eral
Car
diot
hora
cic
Non
-car
diac
th
orac
icp <0.01 between non-cardiac thoracic surgeons and others
Odds ratios of operative mortality
General surgeons
Cardio-thoracic
surgeons
Non-cardiac thoracic
surgeons
Crude 1.00 0.84 0.68
Adjusted for patient characteristics 1.00 0.84 0.68
Patient and hospital characteristics 1.00 0.84 0.68
Patient and hospital characteristics, and hospital volume 1.00 0.87 0.74
Patient and hospital characteristics, hospital and surgeon volume 1.00 0.88 0.76
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
Limitations
• Administrative data for risk adjustment
• Error in assignment of surgeon specialty– Bias would tend towards the null
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
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
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
Acknowledgement
• Scottie Siewers
• VA Outcomes Group