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(Circulation. 1995;92:2480-2487.)
© 1995 American Heart Association, Inc.

Articles

In-Hospital and One-Year Economic Outcomes After Coronary Stenting or Balloon Angioplasty

Results From a Randomized Clinical Trial

David J. Cohen, MD, MSC; Harlan M. Krumholz, MD, MSC; Craig A. Sukin, MD; Kalon K.L. Ho, MD; Richard B. Siegrist, MS; Michael Cleman, MD; Richard R. Heuser, MD; Jeffrey A. Brinker, MD; Jeffrey W. Moses, MD; Michael P. Savage, MD; Katherine Detre, MD, DRPH; Martin B. Leon, MD; Donald S. Baim, MD; for the Stent Restenosis Study Investigators¹

From the Cardiovascular Division, Beth Israel Hospital, Boston, Mass (D.J.C., C.A.S., K.K.L.H., D.S.B.); the Department of Health Policy and Management, Harvard School of Public Health, Boston, Mass (D.J.C., R.B.S.); Yale School of Medicine, New Haven, Conn (H.M.K., M.C.); Arizona Heart Institute, Phoenix (R.R.H.); Johns Hopkins Hospital, Baltimore, Md (J.A.B.); Lenox Hill Hospital, New York, NY (J.W.M.); Jefferson Medical College, Philadelphia, Pa (M.P.S.); the University of Pittsburgh (Pa) (K.D.); and the Washington (DC) Cardiology Center (M.B.L.).

Correspondence to David J. Cohen, MD, MSc, Cardiovascular Division, Beth Israel Hospital, 330 Brookline Ave, Boston, MA 02215. E-mail djc@hsph.harvard.edu.

	Abstract

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Background Coronary stenting has been shown to improve initial success, reduce angiographic restenosis, and reduce the need for repeat revascularization compared with conventional balloon angioplasty (PTCA). Although previous studies have demonstrated that initial hospital costs for stenting are considerably higher than those for conventional PTCA, the impact of coronary stenting on long-term medical care costs remains unknown.

Methods and Results Between January 1991 and June 1993, 207 consecutive patients with symptomatic coronary disease requiring revascularization of a single coronary lesion were randomized to receive initial treatment by either PTCA (n=105) or Palmaz-Schatz coronary stent implantation (n=102) in the multicenter STRESS trial. Detailed resource utilization and cost data were collected for each patient's initial hospitalization and for any subsequent hospital visits for 1 year after randomization. Compared with conventional angioplasty, coronary stenting resulted in additional catheterization laboratory costs, increased vascular complications, and longer length of stay. Initial hospital costs were thus $2200 higher for stenting than for PTCA ($9738±3248 versus $7505±5015; P<.001). Over the first year of follow-up, however, patients assigned to initial stenting were less likely to require rehospitalization for a cardiac condition and underwent fewer subsequent revascularization procedures. Follow-up medical care costs thus tended to be lower for stenting than for conventional angioplasty ($1918±4841 versus $3359±7100, P=.21). Nonetheless, cumulative 1-year medical care costs remained higher for patients undergoing initial stenting ($11 656±5674 versus $10 865±9073, P<.001). Even after adjustment for the higher incidence of vascular complications in the stent group, total 1-year costs were $300 higher for stenting than for balloon angioplasty.

Conclusions Elective coronary stenting, as performed in the randomized STRESS trial, increased total 1-year medical care costs by $800 per patient compared with conventional angioplasty. Future studies will be necessary to determine whether ongoing refinements in stent design, implantation techniques, and anticoagulation regimens can narrow this cost difference further by reducing stent-related vascular complications or length of stay.

Key Words: stents • angioplasty • trials • cost-benefit analysis • coronary disease

	Introduction

Top Abstract Introduction Methods Results Discussion References

 
Over the past 15 years, technical advances in percutaneous transluminal coronary angioplasty (PTCA) have led to significant improvements in procedural success and safety despite the application of this technique to increasingly challenging lesions.¹ Nonetheless, PTCA remains limited by difficulty in dilating certain types of lesions, abrupt vessel closure, and restenosis that occurs in 30% to 50% of lesions within 6 months of initially successful treatment.^{2 3 4} Recently, coronary stent implantation has emerged as the first new coronary intervention capable of improving 6-month clinical⁵ and angiographic^{5 6} outcomes compared with conventional balloon angioplasty for patients undergoing elective, single-vessel coronary revascularization. Despite these proven benefits, however, the appropriate role of coronary stenting in interventional cardiology remains uncertain, mainly because of concern over its complications and greater cost.^{7 8}

Several single-center observational studies have suggested that hospital costs for coronary stenting may be 50% to 100% higher than for conventional angioplasty, an absolute increase of $2500 to $4000 per patient.^{9 10 11 12 13} These studies suffer from a number of important limitations, however. As observational studies, they may be subject to selection bias; thus, the observed cost differences may partly reflect underlying differences in patient or lesion characteristics rather than the revascularization procedures themselves. Moreover, the results of single-center studies may not be applicable to other institutions or to the healthcare system in general. Finally, the existing studies have focused only on the costs of the initial hospitalization. In practice, cumulative medical care costs during the first year after coronary angioplasty are 40% to 60% higher than those of the initial revascularization procedure itself because of procedural failure or restenosis requiring subsequent bypass surgery or repeat angioplasty.^{14 15 16} Since coronary stenting appears to improve late clinical outcomes compared with conventional balloon angioplasty, it is possible that savings in the cost of follow-up care could partially or completely offset the higher initial cost of the stent procedure. Accordingly, the present study was designed to determine the true costs of coronary stenting and conventional PTCA in the setting of a multicenter, randomized clinical trial. In addition to examining initial hospital costs, we extended clinical and economic follow-up for 1 year after randomization in an attempt to compare the long-term economic impacts of these alternative revascularization procedures.

	Methods

Top Abstract Introduction Methods Results Discussion References

 
Patient Population
Between January 1991 and June 1993, 435 patients were enrolled in the Stent Restenosis Study (STRESS), a randomized trial comparing Palmaz-Schatz coronary stent implantation with conventional balloon angioplasty for patients with symptomatic ischemic heart disease undergoing elective revascularization of a single coronary lesion. Eight of the 13 US clinical sites (see "Appendix") agreed to participate in a voluntary substudy to examine in-hospital and follow-up costs. Of the overall study population, 179 patients were enrolled at non-US sites and were thus ineligible for the economic substudy. An additional 49 patients were enrolled at US sites that declined to participate in the economic substudy. Thus, a total of 207 consecutive patients enrolled at 8 US clinical sites formed the final study population. The study protocol was approved by the institutional review board at each clinical site, and all patients provided informed consent before enrollment.

Entry and exclusion criteria have been described previously.⁶ All patients had symptomatic coronary artery disease requiring revascularization of a single, de novo lesion <15 mm long in a native coronary artery with reference vessel size 3.0 mm. Exclusion criteria included myocardial infarction within 7 days of revascularization, left ventricular ejection fraction <40%, or a contraindication to anticoagulation. In addition, patients with multiple focal lesions, diffuse coronary artery disease, significant left main disease, or severe vessel tortuosity that was thought to make stent implantation difficult were also excluded.

Randomization and Treatment Protocol
As previously described, eligible patients were randomized to undergo either balloon angioplasty or stent implantation using a permuted block design, stratified by enrolling hospital. Revascularization procedures were performed according to a treatment protocol designed to optimize clinical outcomes for each procedure, without specific attention to hospital costs. Balloon angioplasty was performed by standard techniques with a goal of achieving a residual diameter stenosis of 30%. Crossover to stent implantation was permitted only as a "bailout" procedure in the case of abrupt or threatened vessel closure. Palmaz-Schatz coronary stent implantation was performed as previously described using the approved anticoagulation regimen, including aspirin, dipyridamole, dextran, and heparin.¹⁷ After successful stent implantation, heparin was discontinued and vascular access sheaths were removed 4 to 6 hours later. Once hemostasis was obtained, intravenous heparin was resumed and continued until adequate oral anticoagulation (prothrombin time 16 to 18 seconds or international normalized ratio 2.0 to 3.5) was achieved. After hospital discharge, dipyridamole and warfarin were continued for 1 month, and aspirin was continued indefinitely.

All procedural coronary angiograms underwent quantitative analysis at a central core laboratory using a validated edge-detection algorithm as previously described.¹⁸ Angiographic success was defined as achievement of a residual diameter stenosis <50% by quantitative angiography. Clinical success was defined as angiographic success in the absence of a major ischemic complication (death, Q-wave myocardial infarction, bypass surgery, or repeat percutaneous coronary revascularization before hospital discharge). Vascular complications included the need for surgical vascular repair or bleeding requiring transfusion.

Clinical and Angiographic Follow-up
Patients were contacted at 1, 3, 6, and 12 months after randomization to determine their symptomatic status, need for repeat revascularization, and need for hospitalization for any reason. Clinical follow-up was available for 100% of the study population. In addition, patients were required to undergo repeat coronary angiography between 4 and 6 months after study entry. Patients were excluded from angiographic follow-up, however, if they had undergone coronary artery bypass surgery or repeat angioplasty for abrupt closure during the first 2 weeks after initial revascularization.

Determination of Medical Care Costs
Itemized bills were obtained for each patient's initial hospitalization and any subsequent hospitalizations during the 1-year follow-up period. Complete baseline and follow-up economic data were available for 204 of 207 patients (99%); data were incomplete for 1 PTCA and 2 stent patients because of repeat hospitalizations at outside hospitals during follow-up. Hospital admissions that were purely for the purpose of protocol-mandated cardiac catheterization (ie, compulsory 6-month angiographic follow-up) were excluded from the economic analysis unless clinically indicated coronary revascularization (ie, for recurrent chest pain or inducible myocardial ischemia by noninvasive testing) was performed at the time of angiographic follow-up. Determination of which follow-up hospitalizations were excluded from the economic analysis was made by two independent reviewers (C.A.S., K.K.L.H.) blinded to initial treatment assignment.

Cardiac catheterization laboratory costs. The costs of each cardiac catheterization laboratory procedure were determined by standard, "bottom-up" cost-accounting methods.¹⁹ Detailed resource utilization including the number of angioplasty balloons, stents, other devices, guiding catheters, guide wires, and contrast volume were recorded on a standardized data collection form for each procedure, and the costs of each item were estimated on the basis of the mean hospital acquisition costs for the item during the study period. Costs of additional disposable equipment, depreciation and overhead for catheterization laboratory maintenance, and nonphysician personnel were estimated on the basis of the average cost per procedure at Boston's Beth Israel Hospital (one of the study sites) and adjusted for actual procedure duration.¹⁰

Other hospital costs. All other hospital costs were determined by "top-down" cost-accounting methods based on each hospital's annual Medicare Cost Report.²⁰ Hospital room and nursing costs were based on the average per diem cost for the specific patient care unit (eg, coronary care unit, cardiac step-down unit, general medical unit) multiplied by the length of stay on the particular unit. Ancillary costs were obtained by multiplying the number of units of each service used (eg, laboratory tests, x-rays, drugs, blood products) by the average cost per unit. Unit costs were estimated as the hospital charge for the specific item or service multiplied by the cost center–specific cost-to-charge ratio from the hospital's Medicare Cost Report. All costs were converted to 1994 dollars on the basis of the medical care component of the Consumer Price Index.

Professional fees. Physicians' professional fees for percutaneous revascularization and surgical procedures were based on the 1994 Medicare reimbursement levels for each procedure according to the Resource-Based Relative Value Scale.²¹ The angioplasty professional fee was also applied to coronary stenting, because third-party payers did not distinguish between these procedures at the time of this study.

Statistical Analysis
Discrete data are reported as frequencies, while continuous data are reported as mean±SD. Selected cost data are also reported as medians with interquartile ranges. All analyses were based on the intention-to-treat principle. Discrete variables were compared by ² analysis or Fisher's exact test where appropriate. Normally distributed continuous variables were compared by Student's t test. Cost data and other nonnormally distributed data were compared by the Wilcoxon rank-sum test. All analyses were performed with SASversion 6.08 statistical software (SAS Institute). All P values are two-tailed, and a value of P.05 was considered statistically significant.

Relationship With Sponsor
This study was performed according to published guidelines for the conduct of industry-sponsored economic analyses.²² Before initiation of the economic substudy, the data collection instruments and analytic protocol were specified and agreed upon by the study investigators and sponsor. A written agreement was obtained between the sponsor and principal investigators stipulating the right of the investigators to publish the study's findings regardless of their nature. According to this agreement, data collection and analysis were subsequently carried out at the individual study sites and central data coordinating center completely independent of the study sponsor.

	Results

Top Abstract Introduction Methods Results Discussion References

 
Study Population
Between January 1991 and June 1993, 207 consecutive patients were randomized to coronary stent implantation (n=102) or conventional balloon angioplasty (n=105) at eight participating US clinical sites. Baseline patient and target lesion characteristics are described in Table 1. Most patients were men with normal left ventricular ejection fractions and single-vessel coronary disease. The treatment groups were well matched with regard to demographic and clinical characteristics. The patients randomly assigned to stent implantation had slightly longer target lesions than those assigned to PTCA (9.3±3.6 versus 8.4±2.6 mm, P<.05), but there were no other significant angiographic differences between the two treatment groups. The substudy population was generally representative of the overall STRESS study population, except for a higher frequency of multivessel disease. This difference reflects the higher frequency of multivessel disease seen at the US sites (41%) compared with the non-US sites (28%) participating in the STRESS trial.

View this table: [in this window] [in a new window]   Table 1. Baseline Patient and Lesion Characteristics

Initial procedural results and in-hospital complications in our study were similar to those observed in the overall STRESS trial (Table 2). Clinical success, defined as achievement of <50% diameter stenosis without in-hospital ischemic complications, was achieved in 98% of the stent group compared with 91% of the PTCA group (P=.03). Although there were no differences in any of the individual ischemic end points between the treatment groups, patients undergoing initial stenting were somewhat less likely to require either repeat intervention or "relook" coronary angiography before hospital discharge than patients undergoing initial PTCA (2% versus 8%, P=.08). In contrast, the incidence of major vascular complications requiring surgical repair was significantly higher in the stent group than in the PTCA group (7% versus 1%, P=.03).

View this table: [in this window] [in a new window]   Table 2. Initial Procedural Results and Hospital Outcomes

Cardiac Catheterization Laboratory Resource Utilization and Costs
Cardiac catheterization laboratory resource utilization was generally somewhat greater for the stent group than for the PTCA group (Table 3). As expected, patients undergoing initial coronary stenting had significantly more coronary stents implanted than did patients undergoing initial balloon angioplasty (1.1±0.4 versus 0.1±0.4 stents per patient, P<.001). Moreover, patients undergoing initial stenting required more radiographic contrast (265±110 versus 234±123 mL, P=.05) and used more balloon catheters (2.0±0.9 versus 1.7±1.0, P=.03)—excluding the balloon used for stent delivery—compared with the PTCA group, reflecting the frequent need for adjunctive balloon dilation both before and after coronary stent placement. As a result, initial catheterization laboratory resource costs were nearly $1200 higher in the stent group than in the PTCA group ($4691±1156 versus $3505±1505, P<.001).

View this table: [in this window] [in a new window]   Table 3. Initial Catheterization Laboratory Resource Utilization and Costs

Initial Hospital Resource Utilization and Costs
Table 4 summarizes hospital resource utilization and cost data for the initial hospitalization. Mean length of stay was significantly greater for the stent group (7.5±3.4 days overall, 5.8±2.7 days postprocedure) than for the PTCA group (4.8±3.6 days overall, 3.5±3.4 days postprocedure; P<.001 for both comparisons). Initial hospital costs were thus approximately $2200 higher for coronary stenting than for conventional PTCA ($9738±3248 [median $8869] versus $7505±5015 [median $6165]; P<.001). Exclusion of physician professional fees from this analysis decreased the absolute costs of both procedures by approximately $1000 but did not alter the relative difference (stent, $8675±3056; PTCA, $6387±4356; P<.001). On average, $1062 (47%) of this cost increase was due to increased resource utilization in the catheterization laboratory, while the remaining $1171 (53%) was due to increased room/nursing costs and other ancillary services relating primarily to the longer hospital stay after coronary stenting.

View this table: [in this window] [in a new window]   Table 4. Resource Utilization and Costs for Initial Hospitalization

Follow-up Medical Resource Utilization and Costs
During the 1-year follow-up period, patients randomized to initial PTCA were somewhat more likely to require repeat revascularization than were patients assigned to initial stenting (21% versus 15%, P=.24; Table 5). In particular, PTCA patients were more likely to undergo multiple revascularization procedures during follow-up (8% versus 2%, P=.10). As a result, the PTCA group required more repeat revascularization procedures overall (35 versus 19) and more repeat hospitalizations for cardiovascular conditions (43 versus 28) than the stent group. The overall difference in the number of hospitalizations was partially attenuated, however, by an increased need for hospitalizations for noncardiac conditions in the stent group (11 versus 5), related mainly to bleeding complications due to high-dose oral anticoagulation.

View this table: [in this window] [in a new window]   Table 5. 1-Year Clinical Outcomes and Medical Resource Utilization

For the entire 1-year study period, cumulative medical care costs were $800 higher for patients randomized to initial stent implantation compared with initial PTCA ($11 656±5674 [median $10 436] versus $10 865±9073 [median $7172], P<.001; Table 6). Although follow-up medical care costs tended to be lower for the stent group than for the PTCA group ($1918±4841 versus $3359±7100, P=.21), these cost savings were insufficient to fully offset the higher initial cost of stenting. The Figure displays the time course of cumulative medical care costs in the two treatment groups. Although the cost difference at the 6-month time point (ie, before protocol-mandated cardiac catheterization) was >$1200, this difference continued to narrow between months 6 and 12, reflecting the greater need for third and fourth hospital admissions for percutaneous coronary revascularization and late bypass surgery in the group randomized to initial PTCA.

View this table: [in this window] [in a new window]   Table 6. Overall 1-Year Medical Care Costs

View larger version (16K): [in this window] [in a new window]   Figure 1. Plot of cumulative medical care costs in patients randomly assigned to initial percutaneous transluminal coronary angioplasty (PTCA) (n=105) or coronary stenting (n=102). The initial higher cost of stenting was partly offset by $1400 in follow-up cost savings, but 1-year costs remained significantly higher with stenting ($11 656±5674 versus $10 865±9073, P<.001). Of note, the difference in long-term treatment costs continued to narrow between 6 and 12 months after randomization because of additional hospital admissions for percutaneous revascularization and bypass surgery, mainly in the PTCA group. Bracket indicates P<.001.

Since recent studies have suggested that modification of the poststent anticoagulation protocol may reduce the incidence of vascular complications compared with that seen in our study,^{23 24 25} we performed subgroup analyses to examine the impact of vascular complications on the short- and long-term costs of stenting. Among patients randomized to initial stenting, major vascular complications were associated with increased postprocedure length of stay (8.2±2.5 versus 5.6±2.7 days, P=.03) and a $3000 increase in initial hospital costs ($12 516±5810 versus $9436±2726, P=.05). Nevertheless, even in those patients who did not experience a vascular complication, stenting was associated with significantly higher (+$300) 1-year treatment cost than conventional angioplasty ($10 869±3852 versus $10 564±8830, P<.001).

	Discussion

Top Abstract Introduction Methods Results Discussion References

 
The recent publication of the STRESS and Benestent trials has demonstrated that Palmaz-Schatz coronary stenting can decrease angiographic restenosis and reduce the need for late target-vessel revascularization compared with conventional balloon angioplasty. Given the time-limited nature of the restenosis process,^{2 3} the availability of bypass surgery to treat refractory restenosis, and the generally excellent prognosis of patients who undergo percutaneous coronary revascularization, many of whom have single-vessel coronary disease, it seems unlikely that newer coronary interventions will dramatically improve either life expectancy or overall quality of life compared with conventional PTCA.^{26 27} As pressures to contain rising healthcare costs continue to escalate, it is therefore likely that economic considerations will assume an increasingly important role in the evaluation of new coronary interventions.

In this study, we examined medical resource utilization and costs of two alternative revascularization strategies, conventional balloon angioplasty and Palmaz-Schatz coronary stenting, in patients undergoing percutaneous revascularization of a single coronary lesion in a multicenter randomized clinical trial. In accord with previous studies,^{9 10 11 12} we found that the initial hospital costs for coronary stenting were 30% higher than those for conventional PTCA. During the first year after initial revascularization, however, follow-up medical care costs were nearly $1400 lower in the stent group, making the cumulative 1-year cost for coronary stenting only 7% higher than that for conventional PTCA.

Comparison With Previous Studies
Several previous studies have examined in-hospital costs in patients undergoing balloon angioplasty and coronary stenting. Among patients undergoing elective single-vessel coronary revascularization, Dick et al⁹ found that hospital charges were increased by 103% in patients undergoing stenting compared with balloon angioplasty. It is well recognized, however, that hospital charges frequently bear little relation to true costs.¹⁹ More recent single-center observational studies have shown that coronary stenting increased length of stay by 1.9 to 2.5 days and increased medical care resource costs by $2400 to $3000 relative to conventional PTCA.^{10 11} Despite key differences in study design, the results of these observational studies are remarkably similar to those of the present randomized trial.

The results of the present study enhance the findings of previous studies in several important ways. First, by using detailed, resource-based cost-accounting methods in the setting of a randomized clinical trial, our study avoids selection bias and provides the best available estimate of the true in-hospital cost difference between these two procedures. Moreover, while the single-center studies have provided important insights into relative cost differences and patterns of resource consumption, cost-effectiveness analysis from a societal standpoint requires economic data that apply to the overall healthcare system.²⁸ Since we studied costs using a consistent resource-based accounting method across a range of hospital types and locations, our results should be generalizable to the US healthcare system and thus should provide an accurate assessment of the potential impact of such procedures on overall healthcare spending. Finally, our study is the first to compare the long-term medical care costs associated with coronary stenting and conventional angioplasty. Given the potential for improved late clinical outcomes to partially offset the higher initial cost of stenting, this long-term perspective is critical to any assessment of the relative cost-effectiveness of these alternative revascularization procedures.

Clinical Implications
The major finding of the present study is that coronary stenting, as performed in the STRESS trial, failed to reduce long-term medical care costs compared with conventional PTCA. Despite a $1400 reduction in follow-up medical care costs by stenting, cumulative 1-year costs remained nearly $800 higher than those for patients undergoing conventional balloon angioplasty. The savings in the cost of follow-up medical care were thus insufficient to fully offset the $2200 greater initial hospital cost of elective stenting, driven by greater catheterization laboratory resource utilization (ie, additional balloon, stent, and contrast dye use), increased length of stay, and more frequent vascular complications associated with coronary stenting.

Despite its higher long-term costs, coronary stenting may nonetheless be cost-effective. In fact, few modern medical advances are truly cost-saving. Many widespread practices, including bypass surgery for left main disease,²⁹ ß-blocker therapy after acute myocardial infarction,³⁰ and thrombolytic therapy for acute myocardial infarction,³¹ prolong life only at the expense of increased healthcare costs. Nonetheless, such treatments are viewed as cost-effective because their benefits are "worth the additional cost." Thus, in the case of coronary stenting, its cost-effectiveness depends on whether its clinical benefits—mainly a reduction in recurrent angina and the need for repeat revascularization procedures—are sufficient to justify the additional long-term costs of the procedure. While these questions have not been addressed directly in the context of this randomized clinical trial, decision-analytic modeling using population-based utility estimates to reflect patient preferences for various short- and long-term health states suggests that the incremental cost-effectiveness ratio for primary coronary stenting compared with conventional PTCA may be comparable to many other generally accepted medical treatments.³² Of note, the $600-per-patient increase in long-term medical care costs with stenting predicted by this simulation model was very close to the $800 increase observed in the current randomized trial.

Definitive studies to address these issues will ultimately require direct assessment of quality of life and patients' preferences after stenting or conventional angioplasty or, alternatively, contingent valuation of individual "willingness to pay" for the potential clinical benefits of stenting.³³ Until such data become available, however, it is clear that coronary stenting increases overall healthcare costs and that continued efforts to reduce its in-hospital costs are warranted to improve the cost-effectiveness of this promising technology.

Cost-Saving Potential of Coronary Stenting
While present stent technology is clearly more expensive than conventional PTCA, our findings suggest that, with improvements in design and technique, coronary stenting might eventually offer the potential for long-term cost savings relative to conventional angioplasty. Realization of such long-term cost savings will require significant reductions in the initial cost of stenting, however. Although it is tempting to speculate that cost savings could be achieved simply by eliminating stent-related vascular complications—by modification of the poststent anticoagulation protocol^{23 24 25} or by use of a vascular closure device,^{34 35} for example—our study suggests that such changes would be insufficient to render coronary stenting "cost neutral" relative to balloon angioplasty. Even after adjusting for the difference in vascular complication rates between the two procedures, we found that the long-term cost of stenting was still $300 greater than that for PTCA. If recent developments in stent technique, such as the use of ticlopidine,²³ high-pressure postdilation,²⁴ intravascular ultrasound,³⁶ or heparin-coated stents,³⁷ can provide late clinical results comparable to those seen in the present study while simultaneously reducing both vascular complications and length of stay, true long-term cost savings might be possible. Given that stenting reduced follow-up costs by only $1400 in this study, however, any modifications that add significantly to the procedural cost of stenting (already $1200 higher than that for PTCA) could overwhelm this potential for cost savings. On the other hand, if "optimal stent deployment" confers further reductions in restenosis, even greater follow-up cost savings might be possible.

Ultimately, realization of any cost-saving potential of coronary stenting is likely to require a combination of technical, procedural, and operational modifications to limit both catheterization laboratory and ancillary hospital costs. Such modifications may include a reduced stent profile (eliminating the need for routine predilation); use of a single high-pressure balloon for predilation, stent delivery, and postdilation; development of a nonthrombogenic stent that does not require prolonged hospitalization for initiation of oral anticoagulation; or improved manufacturing techniques with resulting reductions in the cost of the stent itself.

Study Limitations
Our study has several limitations. By using cost center–specific, direct cost-to-charge ratios to estimate the costs of ancillary services from itemized hospital bills, we measured average rather than variable costs. As a result, our study may tend to overestimate the true increase in overall healthcare costs that would result from a shift from conventional angioplasty to coronary stenting, at least in the short run. Nonetheless, in the absence of a uniform cost-accounting system across US hospitals, this is the best method currently available for measuring costs in the setting of a multicenter clinical trial.²⁰ To minimize any errors introduced by this method, we measured actual resource utilization and resource costs associated with catheterization laboratory procedures, the single largest component of cost in our study.

An additional limitation of our study is the inclusion of those initial hospital costs incurred before randomization and performance of the index revascularization procedure in our overall cost estimates. As a result, our cost estimates for the initial hospitalization may tend to somewhat overestimate the absolute costs directly attributable to the revascularization procedures themselves. Nonetheless, since preprocedure length of stay was similar for the two treatment groups, the relative cost differences we measured should be valid and unbiased.

Finally, we did not include the costs of outpatient medical care (such as physician visits, outpatient testing, and medications) in our study. Although it is possible that coronary stenting and PTCA might be associated with important differences in outpatient medical resource utilization, in the setting of a clinical trial, most outpatient testing and physician visits are protocol driven and thus unlikely to differ significantly between the two groups. Moreover, although the need for warfarin and associated monitoring is likely to increase the outpatient cost of stenting somewhat, these differences may well be offset by other cost savings and are likely to be small compared with the overall cost of outpatient care during the period of our study.^{38 39} Thus, inclusion of these modest costs in our study would not be expected to change our findings appreciably.

Conclusions
Analysis of the in-hospital and cumulative 1-year costs of elective stenting and conventional balloon angioplasty in the multicenter randomized STRESS trial supports earlier single-center observations and simulation models. The increased in-hospital cost of stenting (+$2200) was only partially offset by the reduction in follow-up medical care costs (-$1400), so that the cumulative 1-year treatment cost remained nearly $800 greater for stenting. In the future, refinements in stent design, implantation techniques, and associated anticoagulation regimens could narrow this cost difference further by reducing stent-related vascular complications or length of stay.

	Acknowledgments

 
This study was supported in part by a grant from Johnson & Johnson Interventional Systems and by an American Heart Association Clinician Scientist Award to Dr Cohen. Dr Ho was supported by a fellowship from the Pfizer Clinical Investigator Training Program.

	Footnotes

 
Johnson & Johnson Interventional Systems provided grant support to partially fund this study.

¹ Additional participants in the STRESS trial are listed in the "Appendix."

The following institutions and investigators participated in the STRESS Economic Substudy.

Arizona Heart Institute, Phoenix, Ariz. Principal investigator, Richard Heuser, MD; coinvestigator, Robert K. Strumpf, MD; research coordinators, Walt Catron, Sue Spooner, RN, Kathy Sniderski, RN.

Beth Israel Hospital, Boston, Mass. Principal investigator, Donald S. Baim, MD; coinvestigators, Daniel Diver, MD, Joseph P. Carrozza, MD; research coordinators, Cindy Senerchia, RN, Paula S. Rooney, RN.

Johns Hopkins Hospital, Baltimore, Md. Principal investigator, Jeffrey Brinker, MD; coinvestigator, Jon Resar, MD; research coordinator, Vicki Coombs, RN.

Lenox Hill Hospital, New York, NY. Principal investigator, Jeffrey Moses, MD; coinvestigator, Alex Shaknovich, MD; research coordinators, Nancy Cohen, Jill Higgins, RN.

Scripps Clinic and Research Foundation, San Diego, Calif. Principal investigator, Richard Schatz, MD; research coordinator, Nancy Morris, RN.

Thomas Jefferson University Hospital, Philadelphia, Pa. Principal investigator, Michael P. Savage, MD; coinvestigators, Sheldon Goldberg, MD, David L. Fischman, MD; research coordinators, Doranne Porter, RN, Sharon Gebhardt, RN.

Washington Cardiology Center, Washington, DC. Principal investigator, Martin B. Leon, MD; research coordinator, Kathi Donovan.

Yale University, New Haven, Conn. Principal investigator, Michael Cleman, MD; coinvestigator, Henry Cabin, MD; research coordinator, Robin Rosen.

Received March 9, 1995; revision received May 22, 1995; accepted May 24, 1995.

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