What are the inpatient and day case costs following primary total hip replacement of patients treated for prosthetic joint infection: a matched cohort study using linked data from the National Joint Registry and Hospital Episode Statistics

BACKGROUND: Prosthetic joint infection (PJI) following total hip replacement (THR) surgery is a serious complication that negatively impacts patients’ lives and is financially burdensome for healthcare providers. As the number of THRs increases, so does this financial burden. This research estimates the economic burden with respect to inpatient and day case hospital admissions for patients receiving revision surgery for PJI following primary THR. METHODS: In this matched cohort study, the National Joint Registry for England, Wales, Northern Ireland and the Isle of Man (NJR) was used to identify patients. Patients revised for PJI with a one- or two-stage revision following THR and patients not revised for PJI were matched on several characteristics using exact and radius matching. Hospital inpatient and day case healthcare records from the English Hospital Episode Statistics database were obtained for 5 years following the identified patient’s primary THR. UK national unit costs were applied to hospital admissions and the 5-year total cost was estimated. A two-part model (Probit and generalised linear model) was employed to estimate the incremental difference in costs between those revised and not revised for PJI. RESULTS: Between 2006 and 2009, 1914 revisions for PJI were identified in the NJR. The matching resulted in 422 patients revised for PJI and 1923 matches not revised for PJI who were included in the analysis. The average cost of inpatient and day case admissions in the 5 years following primary THR was approximately £42,000 for patients revised for PJI and £8000 for patients not revised for PJI. The difference in costs over the 5 years was £33,452 (95% CI £30,828 to £36,077; p < 0.00). CONCLUSIONS: In the 5 years following primary THR, patients who develop PJI and have revision surgery cost approximately £33,000 (over 5-fold) more than patients not revised for PJI based on their hospital inpatient and day case admissions alone. The total burden of PJI is likely to be much higher when also considering outpatient, primary and community care costs. This highlights the need to find both ways to reduce the incidence of PJI following THR and cost-effective treatment strategies if PJI occurs.