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Clinical Effectiveness and Cost-Effectiveness of 2 Management Strategies for Infected Total Hip Arthroplasty in the Elderly

  1. David N. Fisman1,3,
  2. Donald T. Reilly2,
  3. Adolf W. Karchmer1, and
  4. Sue J. Goldie3
  1. 1 Division of Infectious Diseases, Beth Israel Deaconess Medical Center, Boston
  2. 2 Division of Orthopedic Surgery, Beth Israel Deaconess Medical Center, Boston
  3. 3 Harvard Center for Risk Analysis, Harvard School of Public Health, Boston
  1. Reprints or correspondence: Dr. David N. Fisman, Division of Infectious Diseases, Kennedy-6, Beth Israel Deaconess Medical Center, One Deaconess Rd., Boston, MA 02215 (dfisman{at}caregroup.harvard.edu).
 
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Abstract

Optimal management of infected total hip arthroplasty poses a major challenge to clinicians. Exchange arthroplasty is usually advocated but has high rates of surgical morbidity and is expensive. Debridement with prosthesis retention is associated with less morbidity, but high rates of relapsed infection have been described. To estimate the effectiveness and cost-effectiveness of these 2 strategies among older patients, we used a Markov model to simulate patients' projected lifetime clinical course in hypothetical cohorts of 65-year-old and frail 80-year-old men and women. Initial debridement and retention increased life expectancy 2.2–2.6 quality-adjusted life months and had a favorable cost-effectiveness ratio in all cohorts. Results were most sensitive to the annual rate of relapse after debridement and age at initial diagnosis of infection. In the absence of prospective clinical trials, debridement and retention is a reasonable strategy for treatment of older persons with staphylococcal or streptococcal infection and a nonloosened prosthesis.

Total hip arthroplasty (THA) is an important therapeutic modality for persons with arthritis [1, 2]. About 138,000 THAs are done annually in the United States [3]. Infection of the hip prosthesis has been reported in ∼1% of persons undergoing THA [4, 5]. The most common infecting organisms are staphylococci (including Staphylococcus aureus and coagulase-negative staphylococci), which constitute 50%–60% of all isolates, and streptococci, which constitute a further 10%–15% of isolates. Gram-negative bacilli and mixed infections are less common [6–10]. Such infections cause substantial morbidity because of surgical procedures and immobilization and are associated with high medical costs [11, 12].

The standard approach to management of the infected THA is 2-stage exchange arthroplasty [7, 13, 14], which eradicates infection in >80% of patients [7, 10, 15]. This procedure involves surgical removal of the prosthesis, as well as debris and cement, and 6 weeks of subsequent antibiotic therapy. The patient is left without a prosthetic hip for 6 weeks to 1 year before a new prosthesis is reimplanted. This approach requires long periods of immobilization and prolonged rehabilitation, in addition to 2 major surgical procedures. Consequently, there may be some reluctance to recommend 2-stage exchange arthroplasty for frail or elderly patients.

An alternative and less aggressive approach to management is open debridement of the hip with retention of the prosthesis, followed by 6 weeks of antibiotic therapy [4, 16, 17], which may be attempted for patients with staphylococcal or streptococcal infection and a nonloosened prosthesis. Open debridement is a less extensive procedure than 2-stage exchange arthroplasty and requires only a single surgical procedure. In comparison with 2-stage exchange arthroplasty, it is associated with a lower probability of procedure-related morbidity, less immobilization, and consequently less need for rehabilitation. However, most persons will ultimately experience a relapse of infection after debridement and retention, necessitating exchange or resection arthroplasty [4, 16].

In choosing between the 2 major alternative strategies for the management of infected THAs, clinicians and patients are forced to confront a trade-off between short-term surgical morbidity and mortality and long-term relapse of infection. Our objective was to compare the clinical and cost-effectiveness of 2-stage exchange arthroplasty versus debridement and retention among older patients with infected prosthetic hips. We sought to identify how strategy-specific rates of relapse, operative risk, and costs, as well as patient age, sex, and comorbidity, would affect the choice of an optimal management strategy.

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Methods

The model. We constructed a Markov model with use of DATA 3.5 (Treeage Software) [18] to simulate the initial management, clinical course, and later complications of an infected THA. The model was used to evaluate the cost-effectiveness of 2 clinical strategies for managing infected THAs. Markov models such as this one depict the natural history of disease as an evolving sequence of mutually exclusive health states, defined to capture important clinical characteristics, costs, and quality of life. The 4 live health states used to model the clinical course following initial management of infected THA were as follows: functional total hip arthroplasty after debridement and retention, temporary resection arthroplasty, functional total hip arthroplasty after reimplantation of a new prosthesis, and permanent resection arthroplasty. These health states were subdivided to reflect age, comorbidity, and sex.

The model uses transition probabilities to move patients through different health states over time (figure 1). The time horizon of the analysis is divided into equal increments, referred to as Markov cycles, during which patients can transition from one health state to another. To simulate the brief interval between procedures and accommodate the foreshortened life expectancy of an older patient, we used a cycle length of 1 month. In any given month, a patient could remain well or experience a relapse of infection. Patients with relapsed infection would undergo joint resection, thereby transitioning to a temporary resection arthroplasty health state. These patients could subsequently undergo reimplantation of a joint prosthesis. To reflect patient history, unique health states were created to reflect functional arthroplasty after debridement and functional arthroplasty after 2-stage exchange arthroplasty. We assumed that patients with a permanent resection arthroplasty could not undergo joint reimplantation. Patients could die as a result of surgery or other competing causes.

Figure 1
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Figure 1

Overview of Markov model for infected total hip arthroplasty. The model has 5 general health states. Allowed transitions between health states are indicated by arrows: for example, a patient who underwent temporary resection arthroplasty could either remain in the “temporary resection arthroplasty” health state or transition to the “functional prosthesis” health state by undergoing reimplantation of the prosthetic joint. Death may result from surgery or other competing causes.

By following a hypothetical cohort of identical patients through time until they were all dead, we used the model to estimate life expectancy, quality-adjusted life expectancy, and average lifetime costs for each strategy. The comparative performance of debridement and retention was expressed by use of the incremental cost-effectiveness ratio, defined as the additional cost per quality-adjusted life year gained, compared with 2-stage exchange arthroplasty. Because intermediate outcomes are also important to decision makers, we calculated the mean duration of relapse-free survival (defined as time from first operative procedure to relapsed infection or death) and the total lifetime number of surgical procedures associated with each strategy.

The analysis assumed a societal perspective and followed the reference case recommendations of the Panel on Cost-Effectiveness Analysis in Healthcare and Medicine [19]. Future costs and benefits were discounted at a 3% annual rate [19]. Sensitivity analyses were done to determine the robustness of the cost-effectiveness results in the face of reasonable variation in the underlying data assumptions.

Clinical strategies. We assessed 2 competing strategies (figure 1): initial 2-stage exchange arthroplasty, considered to be the status quo or standard of clinical care; and surgical debridement with retention of the prosthesis. We assumed that all patients had an established diagnosis of infected THA, which met proposed criteria for the use of debridement and retention, including duration of symptoms of <1 month, infection with staphylococci or streptococci, no loosening of the prosthesis, and the absence of poor soft tissue integrity as a result of prior surgical procedures [13]. We also assumed that debridement was done promptly after initial presentation [16, 17].

In the 2-stage exchange arthroplasty strategy, patients underwent initial resection of the infected prosthesis, with removal of debris and cement, followed by a 6-week course of appropriate parenteral antibiotic therapy (e.g., oxacillin after identification of a susceptible S. aureus isolate). The planned interval between resection and reimplantation was 2 months, after which patients underwent reimplantation arthroplasty. If relapsed infection occurred, the choice of subsequent therapy depended on whether or not the joint was loose. If the joint was loose, a permanent resection arthroplasty was done. If the joint was not loose, debridement and retention was done, followed by long-term oral antibiotic suppression. Patients who relapsed while being treated with long-term antibiotic suppression underwent permanent resection arthroplasty.

The alternative strategy consisted of surgical debridement and retention of the prosthesis followed by 6 weeks of antibiotic therapy. In the event of relapse, a 2-stage exchange arthroplasty was done. All subsequent care was identical to that provided with the standard care strategy described above.

Study population. The hypothetical cohorts we evaluated were 65-year-old men and women and frail 80-year-old men and women whom we distinguished by age, sex, and comorbidity. We assumed that the 65-year-old cohorts had good functional status and American Society of Anesthesiologists (ASA) scores [20] of 2 (i.e., mild systemic disease). We assumed that the 80-year-old cohorts had impaired functional status and ASA scores of 3 (i.e., more severe systemic disease). Most reported efficacy data pertain to subjects in the 60- to 70-year-old age group, and so 65-year-old men were used in the base-case analysis.

Transition probabilities. Monthly probabilities of relapse after debridement and retention, after exchange arthroplasty, and with suppressive antibiotic therapy were obtained from a formal review of the literature (table 1). A MEDLINE search with the keywords “prosthesis-related infections” and “hip” identified studies published from January 1980 through June 1999. Additional studies were identified through a manual search of references and abstracts from major scientific meetings. Preference was given to studies that documented the presence of infection by use of accepted clinical, pathological, and microbiological criteria [10, 43]; reported the outcomes of different surgical interventions (debridement and 1- and 2-stage exchange arthroplasty) separately; and reported follow-up time, so that it was possible to estimate the rate of relapse of infection from data provided.

Table 1
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Table 1

Variables in the Markov model used to simulate initial management, clinical course, and complications of infected total hip arthroplasty for hypothetical cohorts.

We estimated the 30-day operative mortality rate for procedures of varying complexity by use of regression coefficients derived from the National Veterans Affairs Surgical Risk Study (NVASRS) [38]. The model permitted the estimation of odds of death at 30 days on the basis of such covariates as age, complexity of surgery, functional status, serum albumin level, and ASA score. Because female patients were underreported in the NVASRS data, we estimated their probability of operative mortality by use of the reported differential in the operative mortality rate between male and female patients [39, 40, 44].

We estimated a 2-fold increase in the probability of death during the 3 months after resection arthroplasty on the basis of the persistent excess mortality reported in elderly persons after major orthopedic surgery [40, 45]. All-cause mortality rates adjusted for age, sex, and race were obtained from standardized life tables [46].

Health-related quality of life. Utilities are numerical values assigned to health states, which reflect the desirability of living in a given state. Health state utilities range from perfect health (weighted 1.0) to death (weighted 0). The weights are multiplied by the amount of time spent in each health state, and these products are summed to obtain an estimate of quality-adjusted life expectancy [47].

Preference-based quality weights for patients with hip disease are limited [2, 28, 29]. We used the Health Utilities Index mark 2 to estimate utilities associated with the model's health states. This index permits a summary estimate of quality of life based on the estimation of domain-specific disutilities associated with certain health states [30]. Staff orthopedic surgeons familiar with the management of infected THAs provided estimates of pain, mobility, and self-care associated with each health state. These estimates were used to generate utility estimates through the application of multiattribute utility theory [30, 48, 49]. The significant discomfort and functional limitation associated with temporary and permanent resection arthroplasty [31, 32] resulted in utility estimates for these health states that were lower than the estimates for functional hip arthroplasty health states (0.60 vs. 0.93).

Costs. Selected cost estimates are shown in table 1. Hospital costs associated with resection arthroplasty, reimplantation arthroplasty, and debridement and retention of infected prostheses were derived from Medicare administrative data [33, 50, 51]. Professional and technical costs associated with these procedures were based on Medicare-allowed charges [34]. The costs associated with outpatient parenteral antibiotic therapy were based on the published estimates by Rosen et al. [35], and the costs of long-term oral antibiotics were based on wholesale average prices [36]. Costs of rehabilitation were estimated by use of estimates of rehabilitation costs for persons with hip fracture [37]. We based our estimates of patient time costs on the assumption that patients could not work when immobilized by a resection arthroplasty or during the month of a major surgical procedure. We valued this time by use of published estimates of average weekly 1999 wage rates for persons ⩾65 years of age [52]. Because our estimates of patient time were not based on empirical data, we elected to include these costs in a sensitivity analysis rather than in the base case.

We established the upper and lower bound of the plausible range for each cost by use of alternative sources of data [2, 11, 12, 53]. All costs were converted to 1999 dollars by means of the medical services component of the Consumer Price Index [54].

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Results

Base case. The clinical outcomes of the 2 treatment strategies for each hypothetical cohort are show in table 2. In a cohort of 65-year-old men, relapse-free survival associated with a strategy of initial debridement was 2.5 years, compared with an expected relapse-free survival of 10.7 years for 2-stage exchange arthroplasty. On average, patients who underwent initial debridement had more operative procedures (3.2 vs. 2.4) than did those who underwent initial exchange arthroplasty.

Figure 2
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Figure 2

Sensitivity analysis of the annual rate of relapse after debridement and of quality-adjusted life expectancy. Quality-adjusted life expectancy associated with the strategy of initial debridement and retention varied inversely with the annual rate of relapse after debridement. When the rate of relapse decreased to <19% per year, debridement and retention became a cost-saving strategy. When the relapse rate was >61%, debridement and retention cost more but was associated with lower quality-adjusted life expectancy than was 2-stage exchange arthroplasty, and therefore dominated.

Figure 3
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Figure 3

Sensitivity analysis of age at diagnosis and expected lifetime costs for the non-frail cohorts. When age at initial diagnosis of infected arthroplasty was ⩽79 years, initial debridement and retention was associated with greater total lifetime costs than was 2-stage exchange arthroplasty. When age at initial diagnosis was >79 years, debridement and retention was a cost-saving strategy.

Table 2
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Table 2

Clinical outcomes associated with debridement and 2-stage exchange arthroplasty for 4 hypothetical cohorts.

The undiscounted life expectancy associated with initial exchange arthroplasty exceeded that of initial debridement and retention by 3.6 days. However, the quality-adjusted life expectancy associated with initial debridement and retention exceeded that of initial exchange arthroplasty by 2.8 qualityadjusted life months.

Projected clinical outcomes were similar for the 3 other hypothetical cohorts evaluated (65-year-old women and frail 80-year-old men and women). In all cohorts, a higher rate of relapse-free survival was associated with initial exchange arthroplasty than with the strategy of initial debridement and retention. However, for all cohorts, the quality-adjusted life expectancy associated with the debridement strategy was greater than with 2-stage exchange arthroplasty. Frail 80-year-old men and women had incremental gains in both quality-adjusted and unadjusted life expectancy with the debridement strategy compared with 2-stage exchange arthroplasty.

Cost and cost-effectiveness. The discounted total lifetime costs, life expectancy, quality-adjusted life expectancy, and incremental cost-effectiveness ratios associated with both strategies are shown in table 3. For 65-year-old men, a strategy of debridement and retention increased total lifetime costs by $3600 and increased discounted quality-adjusted life expectancy by 2.2 months, resulting in an incremental cost-effectiveness ratio of $19,700 per QALY gained compared with initial exchange arthroplasty. Results were similar for 65-year-old women, for whom debridement and retention cost $21,800 per QALY gained. For the frail elderly cohorts, a strategy of debridement and retention increased both life expectancy and quality-adjusted life expectancy and total lifetime costs and was associated with an incremental cost-effectiveness ratio of $500 per QALY for men and $8200 per QALY for women compared with 2-stage exchange arthroplasty.

Table 3
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Table 3

Outcomes associated with debridement and 2-stage exchange arthroplasty for 4 hypothetical cohorts.

Sensitivity analyses. The cost-effectiveness of initial debridement and retention was most sensitive to the initial age of the cohort, annual rate of relapse after debridement and retention, and annual rate of relapse after exchange arthroplasty. Results were less sensitive to the cost of debridement, utility estimates, and discount rate. Results were minimally sensitive to the 30-day mortality rate estimate, the median interval between resection and reimplantation, the probability of loosened prosthesis following relapse, the rate of relapse while undergoing long-term antibiotic suppression, and the costs of procedures other than debridement, antibiotics, and rehabilitation. When patient time costs were included in the analysis, debridement and retention became a cost-saving intervention (table 4).

Table 4
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Table 4

Selected univariate sensitivity analyses for a base case of infected total hip arthroplasty in a hypothetical 65-year-old male patient.

As the rate of relapse after debridement and retention increased, the incremental gain in quality-adjusted life-months associated with the debridement and retention strategy decreased, resulting in a higher (less attractive) cost-effectiveness ratio compared with initial exchange arthroplasty. When the annual rate of relapse after debridement was >61%, debridement and retention cost more but provided less qualityadjusted life expectancy compared with a strategy of initial exchange arthroplasty and therefore was dominated. Conversely, as the annual rate of relapse after debridement decreased, the incremental clinical benefits of initial debridement and retention increased, resulting in a lower (more attractive) cost-effectiveness ratio. When the annual rate of relapse after debridement was <19%, initial debridement and retention became cost-saving relative to exchange arthroplasty (figure 2).

A recent study has suggested that extremely low rates of relapse may be attained with 2-stage exchange arthroplasty [15]. To evaluate the impact of these data on the results of our analysis, we decreased the annual rate of relapse after reimplantation arthroplasty to 0.6%. Although there was still greater quality-adjusted life expectancy with the strategy of initial debridement and retention, the incremental cost-effectiveness ratio increased to $430,000 per QALY compared with exchange arthroplasty.

The cost-effectiveness of initial debridement was sensitive to the age at which the infected THA was diagnosed in the non-frail cohorts. For example, if the cohort was 50 years of age when the prosthesis became infected, the incremental cost-effectiveness ratio of initial debridement was $21,200 per QALY gained. The incremental costs associated with initial debridement decreased as age at the time of initial diagnosis of infection increased. In non-frail patients >79 years of age, initial debridement became cost-saving (figure 3).

Because these results were most sensitive to both age and the rate of relapse after initial debridement, we explored the relationship between simultaneous changes in both parameters and the incremental cost-effectiveness of initial debridement and retention (figure 4). Regardless of the cost-effectiveness threshold used ($20,000, $50,000, or $100,000 per QALY), changes in the rate of relapse after debridement had a greater impact on choice of strategy than did changes in age.

Figure 4
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Figure 4

Three-way sensitivity analysis of the annual rate of relapse, age at diagnosis, and acceptable cost-effectiveness threshold for the management strategy of initial debridement and retention. Lines represent incremental cost per quality-adjusted life year (QALY) gained that are necessary to use initial debridement and retention rather than 2-stage exchange arthroplasty ($20,000, $50,000, or $100,000 per QALY). For a given cost-effectiveness threshold, points on or below the line were cost-effective, and points above the line were not cost-effective. Above the uppermost line, debridement and retention cost more but provided less life expectancy than did 2-stage exchange arthroplasty, and therefore dominated. Below the bottom line, debridement and retention was a cost-saving strategy. *Base case.

We assumed that the rate of relapse following 2-stage exchange arthroplasty would be the same whether exchange arthroplasty was done immediately or delayed because of an initial attempt at debridement and retention. Sensitivity analysis demonstrated that the increase in the projected quality-adjusted survival rate with initial debridement and retention persisted when the hazard ratio for relapse after delayed exchange arthroplasty was <1.4. In other words, if the annual rate of relapse after immediate exchange arthroplasty was 3.5%, a strategy of initial debridement and retention, with subsequent delayed exchange arthroplasty, would provide greater quality-adjusted survival rate as long as the rate of relapse after delayed exchange arthroplasty was <4.9%.

We conducted sensitivity analyses for the other 3 hypothetical cohorts (65-year-old women and frail 80-year-old men and women). As in the younger male cohort, results were most sensitive to the annual rate of relapse after debridement and retention. However, in contrast to the younger cohorts, initial debridement and retention remained cost-effective for frail elderly men and women even when the annual relapse rate after exchange arthroplasty was as low as 0.6%. The incremental cost-effectiveness ratio of initial debridement and retention was $9500 per QALY gained for frail elderly men and $38,600 per QALY gained for frail elderly women compared with 2-stage exchange arthroplasty.

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Discussion

Total hip replacement surgery is common in the United States, and the clinical and economic consequences of an infection of the prosthesis are substantial [11, 12, 14]. The choice of optimal therapy to treat elderly patients has been challenging because of a trade-off between the short-term surgical morbidity and mortality associated with prosthesis removal and the long-term higher rates of relapsed infection with prosthesis retention.

Patients who underwent initial exchange arthroplasty, considered the standard of care [6, 13, 14], had an expected duration of relapse-free survival greater than did those who underwent initial debridement and retention. However, a strategy of initial debridement and retention was associated with greater gains in quality-adjusted life expectancy. These results were consistent, regardless of cohort age, health status, and sex. The increase in quality-adjusted life expectancy with initial debridement and retention in the target cohorts ranged from 2.2 to 2.6 quality-adjusted life months. This is similar to the gains in life expectancy associated with chemotherapy for non-small cell lung cancer and the use of β-blockers by men who have survived a myocardial infarction [56].

Given the high rate of relapse associated with initial debridement and retention, the increase in quality-adjusted life expectancy predicted with this strategy may be counterintuitive. However, in older populations, the use of a less aggressive initial surgical procedure might be expected to provide a survival advantage because of decreased initial surgical mortality rates, with patients frequently dying from competing causes of mortality before relapsed infection necessitates further surgery.

For all cohorts, the incremental cost-effectiveness of initial debridement and retention was <$25,000 per QALY gained, ranging from $500 per QALY for frail 80-year-old men to $21,500 per QALY for 65-year-old women, compared with 2-stage exchange arthroplasty. These ratios are more attractive than those for many other well-accepted medical and surgical interventions [57].

The variable with the greatest influence on our results was the rate of relapse after debridement. Increasing the rate of relapse after debridement decreased the expected value of the initial debridement and retention strategy. This is not unexpected, because if the rate of relapse after debridement is high enough, patients will undergo initial debridement only as a prelude to exchange arthroplasty, accruing the risks of an additional procedure with little incremental benefit.

The best available data [4] suggest that the average annual relapse rate after debridement and retention is ∼30%. At this annual relapse rate, initial debridement was cost-effective and was the strategy of choice for all of the cohorts we evaluated. It has been suggested that the use of novel antibiotic combinations, such as ciprofloxacin and rifampin, could further decrease the rate of relapse following debridement among persons with staphylococcal infections of orthopedic devices [21]. If these early observations are borne out by additional studies, the expected increase in the duration of survival with initial debridement and retention would be substantially augmented, and initial debridement would become a cost-saving strategy.

However, we suggest that our analysis be interpreted with caution when applied to persons with S. aureus prosthetic joint infection in whom diagnosis and treatment are delayed. When S. aureus prosthetic joint infection is treated with prompt debridement, the rate of relapse is similar to that used in our base case analysis [16]. However, delay in debridement is associated with relapse rates as high as 80% in the first year [16, 17]. In this situation, we projected that a strategy of initial debridement and retention would be less effective and more costly than exchange arthroplasty and so would not be recommended.

Recently, Brandt et al. [15] reported outcomes associated with a strategy of 2-stage exchange arthroplasty; they reported an annual rate of relapse of 0.6%, substantially lower than the 4%–6% annual rate of relapse reported by others [7–9]. If we assumed this low rate of relapse in the non-frail 65-year-old cohorts, 2-stage exchange arthroplasty became the preferred strategy. However, in frail older patients, initial debridement remained cost-effective, even when the annual rate of relapse after 2-stage exchange was as low as 0.6%. Thus, even the achievement of extremely low rates of relapse after 2-stage exchange arthroplasty would not make this the initial therapy of choice for all age groups when differential surgical mortality rates, competing mortality rates, and quality of life are taken into account.

A strategy of initial debridement and retention will increase total lifetime costs. However, as life expectancy decreases with increasing age, the probability that persons will survive long enough to have a relapse of infection becomes smaller and the strategy ultimately becomes less costly than initial exchange arthroplasty.

This analysis has several limitations. Data are limited on outcomes following treatment for infected total hip arthroplasty, including data on rates of surgical mortality and relapse of infection. There are presently no randomized trials that directly compare different surgical modalities in the treatment of infected total hip arthroplasty. Therefore, systematic differences in patient populations and infecting organisms may complicate the comparison of published rates of relapse after exchange arthroplasty and debridement with retention. We have not included direct exchange arthroplasty as a relevant strategy for this reason. Although results similar to those for 2-stage exchange arthroplasty have been reported [58–61], patients are frequently selected for direct exchange arthroplasty because they are infected with the less virulent organisms (particularly coagulase-negative staphylococci) [61].

Finally, we have assumed that the diagnosis of infection was correct. However, diagnosis of infected total joint arthroplasty is often challenging [62], and the possibility of misdiagnosis might alter the costs and expected survival associated with each therapeutic strategy.

A strategy of initial debridement and retention will provide greater quality-adjusted life expectancy gains than will 2-stage exchange arthroplasty among selected patients with infected THAs. Moreover, this strategy is cost-effective over a broad range of parameter estimates. Although an increased risk of surgical relapse may result in greater overall costs in younger patients, in older persons with lower life expectancy, initial debridement and retention is expected to be a cost-saving intervention. Although existing estimates of relapse rates and surgical mortality rates are not optimal, they constitute the only data available to clinicians and patients faced with this decision. Randomized controlled trials are needed to evaluate alternative strategies for the management of infected THAs. Until such data are available, prompt debridement and retention should be considered for the initial management of patients who are similar to those in our hypothetical cohorts.

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Acknowledgments

We thank Jennifer Daley for her suggestions on the use of the NVASRS surgical mortality regression model.

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Footnotes

  • Financial support: Agency for Healthcare Research and Quality (postdoctoral fellowship to D.N.F.).

  • Received March 9, 2000.
  • Revision received June 26, 2000.
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  1. Clin Infect Dis. (2001) 32 (3): 419-430. doi: 10.1086/318502
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