Copyright © 2009 by The Journal of Bone and Joint Surgery, Inc.
Commentary & Perspective
Commentary & Perspective by
Kevin J. Bozic, MD, MBA*,
University of California San Francisco Medical Center, San Francisco, California
Posted March 2009
The article, "Cost-Effectiveness of Antibiotic-Impregnated Bone Cement Used
in Primary Total Hip Arthroplasty," by Cummins et al., addresses an important
and controversial topic in orthopaedics. Clinicians and health policy-makers
in the United States and other countries have long debated the appropriate indications
for use of antibiotic-impregnated bone cement in total joint arthroplasty. Although
the use of antibiotic-impregnated bone cement for single-stage or two-stage revision
total joint arthroplasty for the treatment of periprosthetic joint infection
is widely accepted and supported by a substantial body of evidence1,2,
the routine use of antibiotic-impregnated bone cement in primary total joint
arthroplasty continues to be a hotly-debated topic among experts in the fields
of orthopaedic surgery, infectious diseases, and health policy. Proponents of
the routine use of antibiotic-impregnated bone cement in total joint arthroplasty
point to evidence from Scandinavian registry studies3,4, which demonstrated
lower rates of revision due to infection or aseptic loosening after total joint
arthroplasty when antibiotic-impregnated bone cement rather than standard bone
cement had been used. Opponents cite the potential risks of the development of
antibiotic-resistant microorganisms, the detrimental effects on the mechanical
properties of the cement, and the higher costs associated with routine use of
antibiotic-impregnated bone cement in primary total joint arthroplasty. The United
States Food and Drug Administration has approved the use of antibiotic-impregnated
bone cement for use only in the management of a suspected or confirmed periprosthetic
infection.
In the study by Cummins et al., the authors used Markov decision-analysis
modeling techniques to evaluate the clinical effectiveness and cost-effectiveness
of antibiotic-impregnated bone cement for routine use in primary total hip arthroplasty.
Some would argue that, in light of the registry3,4 reports of lower
rates of revision due to either infection or aseptic loosening in association
with the use of antibiotic-impregnated bone cement as well as no apparent indication
of an increase in the number of antibiotic-resistant microorganisms, it is difficult
to argue against the widespread use of antibiotic-impregnated bone cement for
primary total joint arthroplasty. However, when considering the adoption of a
technology or intervention that represents a departure from standard clinical
practice, it is important for clinicians and policy-makers to consider these
benefits in light of any potential clinical risks (e.g., the possible development
of antibiotic-resistant microorganisms and potential detrimental effects on the
mechanical properties of bone cement) and economic costs associated with its
use. Decision-analysis techniques are particularly valuable in situations in
which the evaluation of competing treatment strategies requires the simultaneous
consideration of differential risks, benefits, and costs, especially when substantial
uncertainty exists or when the timing of subsequent events are important. Furthermore,
cost-effectiveness analyses are becoming increasingly pertinent in an era of
limited health-care resources and expanding health-care needs. Therefore, decision-analysis
models offer an appropriate tool to assess the risks, costs, and benefits of
routine use of antibiotic-impregnated bone cement for primary total hip arthroplasty.
When interpreting the results of a cost-effectiveness analysis, it is important
to consider the results of the sensitivity analyses rather than just the point
estimate of the incremental cost-effectiveness of the intervention from the base-case
analysis. Because the results of any cost-effectiveness analysis are highly dependent
on the input assumptions, including costs, effectiveness, and clinical outcome
probabilities, these inputs are often associated with a high degree of uncertainty.
Therefore, the cost-effectiveness of any intervention or technology should not
be considered in isolation, but rather in the context of the range of input assumptions
used in the model. Furthermore, although interventions that are associated with
an incremental cost-effectiveness ratio of <$50,000 per quality-adjusted life
year (QALY) gained are often regarded as "cost-effective" by researchers and
health policy-makers, this threshold is somewhat arbitrary and may not be relevant
in modern day policy-making, particularly in the United States, where cost-effectiveness
analyses have not been explicitly considered in policy-making. Instead, clinicians
and policy-makers should consider the threshold costs, effectiveness, and clinical
probabilities that make a particular intervention or technology more or less
cost-effective in comparison with the gold-standard treatment.
In this study, the authors' findings suggest that although routine use of
antibiotic-impregnated bone cement in primary total hip arthroplasty could lead
to a reduction in the number of total hip arthroplasty failures in the United
States, particularly in younger patients, the cost-effectiveness of this strategy
from a societal perspective is questionable. This is because cemented fixation
of total hip prostheses is rarely performed in the United States in patients
who are younger than seventy years (due to the high rates of success and extremely
low revision rates that are associated with cementless fixation in younger patients5 and
because patients who are seventy years of age or older are less likely to benefit
from the potential reduction in total hip revision rates associated with the
use of antibiotic-impregnated bone cement). However, it should be noted that
when the investigators considered all revisions (rather than only revisions due
to infection) as the primary outcome measure, the cost-effectiveness of antibiotic-impregnated
bone cement was evident over a much broader range of parameter estimates. Therefore,
it is possible that antibiotic-impregnated bone cement may play an important
role in reducing total hip arthroplasty failures, and this outcome may become
more apparent as more information is gathered regarding the effect of antibiotic-impregnated
bone cement on failure due to aseptic loosening after total hip arthroplasty.
Recent evidence from large administrative databases suggests that periprosthetic
infection remains one of the most common reasons for revision total joint arthroplasty
in the United States6. This may be due to the fact that, while incremental
changes in implant designs have primarily been aimed at reducing failure rates
associated with the consequences of bearing surface wear and implant loosening,
there is no evidence that the prevalence of periprosthetic infection has decreased
appreciably over the past several decades. Therefore, prophylactic strategies
to minimize periprosthetic infection, including the use of antibiotic-impregnated
bone cement, may become increasingly important in reducing total joint arthroplasty
failures in the years to come. Furthermore, given that acrylic bone cements are
used much more commonly in primary total knee arthroplasty than in primary total
hip arthroplasty in the United States, future studies assessing the clinical
effectiveness and cost-effectiveness of the routine use of antibiotic-impregnated
bone cements in primary total knee arthroplasty may be warranted.
In summary, this well-designed study by Cummins et al. provides a useful framework
for clinicians and policy-makers to consider the role of antibiotic-impregnated
bone cement in primary total hip arthroplasty in the United States. Their finding
that the routine use of antibiotic-impregnated bone cement in primary total hip
arthroplasty could lead to a reduction in total hip arthroplasty revision rates
and a decrease in lifetime costs (depending on patient age at the time of primary
total hip arthroplasty, presumed reductions in failure rates associated with
infection as well as aseptic loosening, and the cost of the antibiotic-impregnated
bone cement) suggests that further investigation into the clinical and policy
ramifications is warranted. Future efforts should be aimed at elucidating the
mechanism by which the use of antibiotic-impregnated bone cement reduces the
rate of revision due to aseptic loosening after total joint arthroplasty in the
United States population; in addition, strategies should be formulated to make
the widespread distribution and use of antibiotic-impregnated bone cement more
economically feasible.
*In support of his research for or preparation of this work, the author received, in any one year, outside funding or grants in excess of $10,000 from the Orthopaedic Research and Education Foundation (OREF). The author or a member of his or her immediate family received, in any one year, payments or other benefits in excess of $10,000 or a commitment or agreement to provide such benefits from a commercial entity (United HealthCare and Blue Cross Blue Shield Association).
References
1. Nelson CL, Evans RP, Blaha JD, Calhoun J, Henry SL, Patzakis MJ. A comparison of gentamicin-impregnated polymethylmethacrylate bead implantation to conventional parenteral antibiotic therapy in infected total hip and knee arthroplasty. Clin Orthop Relat Res. 1993;295:96-101.
2. Hanssen AD, Rand JA, Osmon DR. Treatment of the infected total knee arthroplasty with insertion of another prosthesis. The effect of antibiotic-impregnated bone cement. Clin Orthop Relat Res. 1994;309:44-55.
3. Engesaeter LB, Lie SA, Espehaug B, Furnes O, Vollset SE, Havelin LI. Antibiotic prophylaxis in total hip arthroplasty: effects of antibiotic prophylaxis systemically and in bone cement on the revision rate of 22,170 primary hip replacements followed 0-14 years in the Norwegian Arthroplasty Register. Acta Orthop Scand. 2003;74:644-51.
4. Malchau H, Herberts P, Ahnfelt L. Prognosis of total hip replacement in Sweden. Follow-up of 92,675 operations performed 1978-1990. Acta Orthop Scand. 1993;64:497-506.
5. Mäkelä KT, Eskelinen A, Pulkkinen P, Paavolainen P, Remes V. Total hip arthroplasty for primary osteoarthritis in patients fifty-five years of age or older. An analysis of the Finnish arthroplasty registry. J Bone Joint Surg Am. 2008;90:2160-70.
6. Bozic KJ, Kurtz SM, Lau E, Ong K, Vail TP, Berry DJ. The epidemiology of revision total hip arthroplasty in the United States. J Bone Joint Surg Am. 2009;91:128-33.
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