Table 2.

Study variables to be requested for individual participant data meta-analysis

Broad classification	Variables
Socio-demographic characteristics	Country in which study was carried out, age, sex, body mass index (weight and height) and smoking status
Past medical/surgical history	Previous hip surgery, other joint surgery and comorbidities (for example, history of diabetes), Charnley classification, Charlson index, ASA grade
Infection characteristics before revision surgery	Duration between index implantation and occurrence/diagnosis of infection, duration between diagnosis of infection and revision surgery
Baseline laboratory data for infection	CRP, ESR, leucocytes, causative organism, neutrophil count, white cell count, synovial fluid white cell count, IL-6
Characteristics of surgical revision	Date of revision, type of re-implantation, type of fixation (cemented or uncemented), use of spacer, type of spacer (static or articulating), use of antibiotics in cement or spacer, time interval between stages for two-stage procedure, diagnosis of re-infection, date of diagnosis of re-infection or date of last follow-up for participants without re-infection, time to re-infection or last follow-up (days or years), antibiotics used and duration of antibiotics
Intervention	One- or two-stage revision

ASA, American Society of Anaesthesiologists; CRP, C-reactive protein; ESR, erythrocyte sedimentation rate; IL-6, interleukin-6.