Table 1

Documented patient characteristics in the previous studies describing preoperative risk factors for surgical complications

Reference	ASA	Age	Sex	BMI	Alcohol	Smoking	Nutritional status	Functional status	Symptoms/morbidities/medical signs	Type of surgery	Category of surgery
Khuri et al12	Increasing	Increasing	NR	NR	NR	NR	Recent weight loss	Independent/dependent	Albumin, cancer, ascites, BUN, platelets	Emergency	Complexity score,* subspecialty
Daley et al13	Increasing	Increasing	NR	NR	NR	NR	NR	Independent/dependent	Albumin, hematocrite, WBC, COPD, TIA, AFOS, platelets	Emergency	Complexity score*, subspecialty
Anderson et al11	Increasing ASA	Increasing age	NR	NR	NR	NR	NR	Functional status (ACS-NSQUIP grading)	Albumin, hematocrite, INR, BUN, ALP, AST	Emergency	NR
Veltkamp et al14	ASA 2–5	Over 40 years	Male	>27.3	NR	Yes	>10 kg weight loss for 3 months	Independent/dependent	Cardiac/pulmonary disease, HT, DM, renal failure, immunological disorder	Urgent/emergency	Central part of body surgery/major
Dimick et al10	Increasing ASA	NR	NR	Yes	NR	NR	Recent weight loss	Independent/dependent	Diabetes, HT, dyspnoea, albumin, CHF, dialysis	Emergency	NR
Donati et al15	Increasing ASA	Increasing age	Male	NR	NR	NR	NR	NR	Anaemia, NYHA 3–4, HT, diabetes	Emergency/urgent	Increasing severity (major)
Wolters et al19	Increasing ASA	No difference	No	NR	NR	History of smoking	NR	Independent/dependent	Sepsis	Emergency	Severity of operation
Kable et al18	NR	>70 years, frailty	No	NR	Predictive for arthroplasty complications	NR	NR	NR	Anaemia, asthma, cancer, osteoporosis, angina, warfarin-type medication, low albumin	Acute admission	Type and severity of operation
Robinson et al20	NR	All >65 years	No (98% male)	NR	NR	NR	Albumin <3.4 g/dL	Katz Score and >1 falls within 6 months (frailty)	Charlson Index score >3, anaemia, hypoalbuminaemia	NR	NR
Turrentine et al16	Increasing ASA	Increasing age	Male	Yes	NR	current smoker	Recent weight loss	Impairment of ADLs	HT, sepsis, steroids, DM, varices, CHF, ascites, bleeding disorder	Emergency operation	RVU, physician work relative unit
Glasgow et al17	ASA 2–4	Increasing age after 41 years	No	<18.5 and >35.0	NR	current smoker	BMI <18.5	Partially/totally dependent	HT, COPD, steroids, cancer, vascular disease, CHF, bleeding disorder	Inpatient	RVU

*Complexity score of each index operation ranked by groups of subspecialists.
ACS-NSQUIP, American College of Surgeons National Surgical Quality Improvement Program; ADLs, activities of daily living; ALP, alkaline phosphatase; ASA, American Society of Anesthesiologists Physical Status Classification System; AST, aspartate aminotransferase; BMI, body mass index; BUN, blood urea nitrogen; CHF, congestive heart failure; COPD, chronic obstructive pulmonary disease; DM, diabetes mellitus; HT, hypertension; INR, international normalised ratio (blood clotting); NR, not reported; NYHA, New York Heart Association (functional classification of heart failure); RVU, relative value unit by Medicare; TIA, transient ischaemic attack; WBC, white blood cell count.