Table 3.

List of prognostic variables available for analysis.

Variable	Additional information
Patients’ characteristics
Age (years)	Less than 60 = 1; 60–69 = 2; 70–79 = 3; 80 or older = 4
Gender	Male = 1; female = 0
Marital status	Married = 1; Single = 2; Widowed/divorced = 3
Index of Multiple deprivation 2004	Score range from 2.1 to 79.3 (more deprived); 10 units
Body Mass Index (BMI)	Weight (kg)/height2 (meters); 10 units
Anxiety/depression (EQ-5D-3L 5th question)	Moderate or severe = 1; None = 0
Oxford knee score (OKS) baseline	0 (worst) to 48 (best); right knee
Clinical factors
Pre-operative American Society of Anesthesiologists (ASA) physical function score	Grade 1 = 1, fit and healthy; grade 2 = 2, mild disease; grades 3 and 4 = 3, incapacitating disease and life-threatening disease (grades 3 and 4 were collapsed)
Disease type	Osteoarthritis = 1; rheumatoid arthritis = 0
Disease side (Charnley classification)	One knee = 1; Both knees = 2; General = 3
Knee arthroscopy	Yes = 1; No = 0
Other condition than osteoarthritis or rheumatology arthritis affecting mobility	Yes = 1; No = 0 Lung problems (e.g. asthma), heart conditions (e.g. angina, heart attack), high cholesterol, hypertension, inflammatory joint, back pain, gout, sciatica, osteoporosis, avascular necrosis, polymyositis, polymyalgia, osteomyelitis, psoriatic arthropathy, multiple sclerosis, fibromyalgia, cerebral palsy, Parkinson’s disease, Raynaud’s syndrome, Paget disease, or childhood conditions
Fixed flexion deformity	Yes (knee that is unable to fully extend to 0) = 1; No = 0
State of anterior cruciate ligament (ACL)	Intact (<5 mm) = 0; Damaged (≥5 mm) or Absent = 1