Abstract
Two-stage revisions for the infected THA are associated with lower re-infection rates than directexchange (one-stage) revisions, and for this reason are favored in the U.S. However, the twostage approach may result in increased, but poorly quantified, surgical morbidity. We developed a decision analysis to compare direct-exchange revision to the two-stage approach for treating the infected THA.
We performed a systematic literature search for papers that analyzed direct-and two-stage revisions for the treatment of chronic infections after THA, with a > 2 years follow-up. This provided frequencies of the most common postoperative (interim and final) health states. These were converted to monthly probabilities to permit decision analysis. We conducted and previously published two surveys to obtain utility values, one in experienced arthroplasty surgeons and another in patients. Using those probabilities and utilities, we created a Markov cohort modeling the postoperative health states seen during treatment of the infected THA.
Sensitivity analysis was performed for each variable in the tree to verify the models robustness.
Using a 12-month cycle, the Markov model favored direct-exchange revision over the twostage approach, regardless of whether surgeon-or patient-derived utilities were used (0.941 vs. 0.642 expected value (EV), and 0.889 vs. 0.551 EV, for patient-and surgeon-derived utilities, respectively; p< 0.01). These findings were also significant in a lifetime model with a ten-year life expectancy (p< 0.01). The findings were robust in sensitivity analyses using a clinically salient range of input variables.
This decision analysis, which used a systematic review of the literature (for complication and outcome frequencies) and published study-specific survey data from patients and experienced surgeons (for utility values of those health states) found direct-exchange arthroplasty to be superior to the two-stage revision for treating the infected THA. This finding was unexpected, in that this is not our typical approach nor is it favored in this country.
Correspondence should be addressed to Diane Przepiorski at ISTA, PO Box 6564, Auburn, CA 95604, USA. Phone: +1 916-454-9884; Fax: +1 916-454-9882; E-mail: ista@pacbell.net
