Table 1.

Variables and definitions

Age	Years
Gender	Female/male
Surgical method	Total arthroplasty Hemiarthroplasty Internal fixation with osteosynthesis
American Society of Anaesthesiologists’ (ASA) classification of physical health	I-IV ASA I-no systemic disease ASA II-mild systemic disease ASA III-moderate systemic disease ASA IV-severe systemic disease that is a constant threat to life
Early surgical site infection	a) Development of a superficial or deep infection in the surgical wound any time up to hospital discharge b) Diagnosed by a physician and treated with antibiotics with or without surgical revision
Urinary tract infection, pneumonia and sepsis	Data were extracted from diagnosis codes at discharge from the hospital and based on physician diagnosis and treated with antibiotics Infections were deemed as hospital related if they occurred > 2 days after admission to hospital
Cognitive failure	Including temporary impairment and dementia
Diabetes	Type II: any type of treatment
Pressure ulcer	Norton stage I-IV
Intact skin	Recorded on admission
Time to surgery	Measured from in-hospital diagnosis to surgery dichotomised: < or > 36 h
Housing before hospitalisation	Home or nursing home