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Supplemental Digital Content
Appendix: Definitions of selected study covariates
Arthroscopic surgery: Patients whose operative CPT codes included:
CPT 29805-29828 (shoulder arthroscopy); CPT 29830-29838 (elbow arthroscopy); CPT 29860-29863
(hip arthroscopy); CPT 29866-29889 (knee arthroscopy)
Abdominal laparoscopy: Patients whose operative CPT codes included:
CPT 44970, CPT 44979 (laparoscopic appendectomy); CPT 44186, CPT 44187 (laparoscopic
jejunostomy for decompression or feeding); CPT 47562-47570 (laparoscopic cholecystectomy); CPT
49650-49659 (laparoscopic hernia surgery); CPT 49320-49329 (diagnostic and other laparoscopy); CPT
58660-58679 (laparoscopy for ovarian surgery); CPT 58541-58554 (laparoscopic hysterectomy)
Current pregnancy: Pregnancy is the process by which a woman carries a developing fetus in her uterus,
beginning at conception and ending in birth, miscarriage or abortion. Male patients with pregnancy
values of “missing” were re-coded to “not pregnant”.
Sapheno-femoral junction surgery: Includes both endovascular great saphenous vein ablation
procedures (radiofrequency ablation, steam ablation, laser ablation, etc) and direct ligation of the
sapheno-femoral junction. Includes CPT codes 36475, 36476, 36478, 36479, 37700, 37722, and 37735.
Venous surgery not involving the great saphenous vein: Includes surgical procedures performed on the
short saphenous vein or perforator/varicose veins (e.g. open ligation, stab phlebectomy). Includes CPT
codes 37500, 37718, 37760, 37765, 37766, 37780, and 37785.
Peripheral vascular disease: includes patients with 1) History of revascularization/amputation for PVD,
such as any type of angioplasty (including stent placement) or revascularization procedure for
atherosclerotic peripheral vascular disease (PVD) (for example, aorta-femoral, femoral-femoral, femoralpopliteal) or a patient who has had any type of amputation procedure for PVD (for example, toe
amputations, transmetatarsal amputations, below the knee or above the knee amputations). Does not
include patients who have had amputation for trauma or a resection of abdominal aortic aneurysms OR 2)
Rest pain/gangrene: Rest pain secondary to occlusive disease occurs at rest and is manifested as a severe,
unrelenting pain aggravated by elevation and often preventing sleep. Gangrene is a marked skin
discoloration and disruption indicative of death and decay of tissues in the extremities due to severe and
prolonged ischemia. This includes patients with ischemic ulceration and/or tissue loss related to
peripheral vascular disease but does not include patients with Fournier’s gangrene.
Chronic obstructive pulmonary disease: chronic obstructive pulmonary disease (such as emphysema
and/or chronic bronchitis) resulting in any one or more of the following: -Functional disability from
COPD (e.g., dyspnea, inability to perform ADLs) -Hospitalization in the past for treatment of COPD Requires chronic bronchodilator therapy with oral or inhaled agents. -An FEV1 of <75% of predicted on
pulmonary function testing. Patients are not included whose only pulmonary disease is asthma, an acute
and chronic inflammatory disease of the airways resulting in bronchospasm. Patients are not included
with diffuse interstitial fibrosis or sarcoidosis.
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Diabetes requiring medication: A patient is not included if diabetes is controlled by diet alone. A
diagnosis of diabetes requiring therapy with an oral hypoglycemic agent or daily insulin therapy.
Congestive heart failure: Only newly diagnosed CHF within the previous 30 days or a diagnosis of
chronic CHF with new signs or symptoms in the 30 days prior to surgery fulfills this definition.
Current smoker: Includes patients who have smoked cigarettes in the year prior to admission to
admission for surgery. Does not include patients who smoke cigars or pipes or use chewing tobacco.
Prior operation within 30 days: The patient has had a major surgical procedure
performed within 30 days prior to the assessed operation that is listed on the CPT
Code Inclusion List. Also include any transplant procedures or trauma procedures if
performed within 30 days prior to the assessed operation.
Renal failure on dialysis: Includes patients with either acute renal failure, defined as the clinical
condition associated with rapid, steadily increasing azotemia (increase in BUN) and a rising creatinine of
above 3 mg/dl, within 24 hours prior to surgery. Additionally includes patients with acute or chronic
renal failure requiring treatment with peritoneal dialysis, hemodialysis, hemofiltration, hemodiafiltration,
or ultrafiltration within 2 weeks prior to surgery.
Active cancer: Includes patients who have cancer that: (1) Has spread to one site or more sites in addition
to the primary site AND (2) In whom the presence of multiple metastases indicates the cancer is
widespread, fulminant, or near terminal OR patients who had chemotherapy for malignancy within 30
days prior to surgery (chemotherapy includes both oral or parenteral treatments but cannot solely be
comprised of hormonal therapy) OR patients who received any radiotherapy (including radiation seed
implantation) for malignancy within 90 days prior to surgery.
Definitions of dependent variables
Deep venous thrombosis: “the identification of a new blood clot or thrombus within the venous system,
which may be coupled with inflammation. This diagnosis is confirmed by a duplex, venogram or CT
scan. The patient must be treated with anticoagulation therapy and/or placement of a vena cava filter or
clipping of the vena cava.”
Pulmonary embolism: “lodging of a blood clot in a pulmonary artery with subsequent obstruction of
blood supply to the lung parenchyma…Enter "YES" if the patient has a V-Q scan interpreted as high
probability of pulmonary embolism or a positive CT spiral exam, pulmonary arteriogram or CT
angiogram.”