Table 6 covariates used to adjust statistical models in at least one study
From: Assessing the hospital volume-outcome relationship in surgery: a scoping review
Patient characteristics | Hospital characteristics | Clinical conditions | Severity | Details of the disease | Details of the surgery | Details of the hospital stay | Post-operative events |
|---|---|---|---|---|---|---|---|
Age (patient, donor, recipient, gestational age) | Hospital size (number of beds) | Laboratory results (albumin, anaemia, hyperlipidaemia, natremia, and creatinine) | The All Patient Refined Diagnosis Related Group score | Time to treatment (door-to-balloon time, waiting time, etc.) | Type of procedure and approach (laparoscopic, open, percutaneous, minimally invasive, etc.) | Admission source (nursing facility, home, transfer within hospital, or ambulance) | Adverse effects |
Substance abuse/consumption (alcohol, illicit drugs, tobacco, etc.) | Hospital ownership or type (private or public sector) | Signs of shock on admission (heart rate, hypotension, Glasgow Coma Scale, Japan Coma Scale, hemodynamic instability, ECG) | The Charlson-Comorbidity Index [32] | Tumour characteristics (site, shape, size, stage, grade, differentiation status, histological subgroup, clinical-TNM, pre-therapeutic-TNM, extent, metastasis, distance from critical organs) | Concomitant procedures (additional resections, lymphadenectomy, and valve surgery) | Distance (from home, from previous facility, to the closest high-volume hospital, total distance travelled, etc.) | Resection status (complete resection of positive margins) |
Sex or gender | Hospital teaching status or level (trauma centre, centre of excellence, reference centre, etc.) | Heart disease (atrial fibrillation, LVEF trend, NYHA class [33]) | The Elixhauser score [34] | Injury severity and mechanism, trauma site | Details of anaesthesia (substance used, duration, and local or general) | Cost (total or out-of-pocket) | Complications |
Language | Hospital location (urban, rural, city, state, country, region) | Lung disease (chronic obstructive pulmonary disease, asthma, chronic lung conditions) | The American Society of Anesthesiologists score (ASA) [35] | Multiple and/or synchronous tumours | Treatment modality (resection, laser, stenting, bariatric procedure, etc.) | Admission status (scheduled or emergency) | Post-operative radiotherapy or chemotherapy |
Body mass index (or birthweight or obesity) or body surface area | Number of licensed practical nurses per occupied bed | Liver disease (cirrhosis or failure) | Self-reported comorbidities | Aneurysm characteristics (diameter and rupture) | Risk Adjustment for Congenital Heart Surgery [36] | Discharge type (transfer, recovery unit, nursing home, etc.) | |
Geographic information (city, state, country, zip code, population, density) | Number of registered nurses per occupied bed | Renal disease (chronic or acute renal failure, creatinine, or dialysis) | The modified Kellgren-Lawrence score [37] | Specific scores: International Federation of Gynecology & Obstetrics [38], Furhman [39], Injury Severity Score [40], Kidney Donor Risk Index [41]) | Surgical indication | Length of uninterrupted institutional care (LUIC) | |
Economic status or income (self-reported, zip-code-based, quartiles) | Chronic diseases (diabetes and depression) | The Score for Neonatal Acute Physiology [42] | Lymph node status and lymphadenectomy | Surgeon’s specialty | Period of admission (the year and/or month, on a weekday vs. the weekend) | ||
Educational level (self-reported, parents’ level, zip-code-based) | Pre-operative medical treatment (neo-adjuvant chemotherapy or radiotherapy, immunosuppressive therapy, aspirin, beta blocker, biopsies, statins) | Pre-operative patient-reported outcome measures | Benign or malignant tumours | Time interval between diagnosis and surgery | Total length of stay | ||
Social security status (or primary payer) | Previous surgery (coronary surgery, aortic surgery, total hip/knee replacement, or carotid revascularization) | Diagnosis and/or aetiology | Intraoperative blood volume loss and/or transfusion requirement | Specific length of stay (LUIC, ICU, pre-surgery unit) | |||
Race or ethnicity | Previous or active cancer | Date of diagnosis | Oncological issues (concomitant examination and result, microscopic or macroscopic negative margins) | Ambulatory status | |||
Family history of disease | Number of diagnoses | ICU stay | |||||
Primary tumour site |