Cost-Minimization Analysis of Open and Endoscopic Carpal Tunnel Release

Zhang, Steven BA; Vora, Molly; Harris, Alex H.S. PhD; Baker, Laurence PhD; Curtin, Catherine MD; Kamal, Robin N. MD

Journal of Bone & Joint Surgery - American Volume:
doi: 10.2106/JBJS.16.00121
Scientific Articles
Abstract

Background: Carpal tunnel release is the most common upper-limb surgical procedure performed annually in the U.S. There are 2 surgical methods of carpal tunnel release: open or endoscopic. Currently, there is no clear clinical or economic evidence supporting the use of one procedure over the other. We completed a cost-minimization analysis of open and endoscopic carpal tunnel release, testing the null hypothesis that there is no difference between the procedures in terms of cost.

Methods: We conducted a retrospective review using a private-payer and Medicare Advantage database composed of 16 million patient records from 2007 to 2014. The cohort consisted of records with an ICD-9 (International Classification of Diseases, Ninth Revision) diagnosis of carpal tunnel syndrome and a CPT (Current Procedural Terminology) code for carpal tunnel release. Payer fees were used to define cost. We also assessed other associated costs of care, including those of electrodiagnostic studies and occupational therapy. Bivariate comparisons were performed using the chi-square test and the Student t test.

Results: Data showed that 86% of the patients underwent open carpal tunnel release. Reimbursement fees for endoscopic release were significantly higher than for open release. Facility fees were responsible for most of the difference between the procedures in reimbursement: facility fees averaged $1,884 for endoscopic release compared with $1,080 for open release (p < 0.0001). Endoscopic release also demonstrated significantly higher physician fees than open release (an average of $555 compared with $428; p < 0.0001). Occupational therapy fees associated with endoscopic release were less than those associated with open release (an average of $237 per session compared with $272; p = 0.07). The total average annual reimbursement per patient for endoscopic release (facility, surgeon, and occupational therapy fees) was significantly higher than for open release ($2,602 compared with $1,751; p < 0.0001).

Conclusions: Our data showed that the total average fees per patient for endoscopic release were significantly higher than those for open release, although there currently is no strong evidence supporting better clinical outcomes of either technique.

Clinical Relevance: Value-based health-care models that favor delivering high-quality care and improving patient health, while also minimizing costs, may favor open carpal tunnel release.

Author Information

1Stanford University School of Medicine, Stanford, California

2Boston University, Boston, Massachusetts

3Center for Health Care Evaluation, VA Palo Alto Health Care System, Menlo Park, California

4Department of Health Research and Policy, Stanford University, Stanford, California

5Department of Plastic and Reconstructive Surgery, Stanford University School of Medicine, Stanford, California

6Department of Orthopaedic Surgery, Stanford University School of Medicine, Stanford, California

E-mail address for S. Zhang: sezhang@stanford.edu

E-mail address for M. Vora: mollyv@bu.edu

E-mail address for A.H.S. Harris: alexander.harris2@med.va.gov

E-mail address for L. Baker: laurence.baker@stanford.edu

E-mail address for C. Curtin: ccurtin@stanford.edu

E-mail address for R. Kamal: rnkamal@stanford.edu

Article Outline

Carpal tunnel syndrome is the most common nerve compression syndrome of the upper extremity, and carpal tunnel release is the most common hand surgery in the U.S., with approximately 400,000 to 500,000 procedures performed annually1. Carpal tunnel release is extremely effective in reducing carpal tunnel syndrome, with success rates as high as 90% in randomized trials2-4. Current operative procedures for treating carpal tunnel syndrome include a standard open approach and the more recently developed endoscopic approach. Clinically, both types of procedures offer patients certain advantages, although previous studies have not definitively shown one technique to be superior to the other5,6. Some reports have suggested that patients undergoing endoscopic release may possess greater grip strength in the early postoperative period and have less post-surgical pain, tenderness, or scarring7,8. However, meta-analyses have concluded that this advantage does not translate to a faster return to work9,10. Endoscopic release also presents technical challenges and may be associated with greater risk of surgical complications, including incomplete division of the flexor retinaculum and nerve damage, and a higher reoperation rate compared with the open approach6,11-14. It remains unclear which technique represents the best option overall.

The treatment of carpal tunnel syndrome in the U.S. is estimated to cost $2 billion annually1. There are large variations in care, including the utilization of resources such as electromyography (EMG), nerve conduction studies (NCS), magnetic resonance imaging (MRI), ultrasound, and occupational therapy1,15-17. We know of only 1 randomized study, from 2002, to evaluate the outcomes and costs of endoscopic release compared with open release, and that study demonstrated that endoscopic release may provide speedier recovery for patients at no significant difference in costs18. Two meta-analyses of randomized trials comparing patients undergoing endoscopic and open approaches, published in 2005 and 2014, concluded that the endoscopic approach may be financially beneficial to employed patients and their employers9,10. Similarly, previous cost-effectiveness modeling suggested that the endoscopic approach improves post-surgical morbidity; however, that analysis was completed in 199819. Newer surgical technology and techniques have changed the assumptions of these previous efficacy studies. Because neither type of procedure has been shown to offer superior outcomes and both techniques are safe and reliable, the determining factor to use one procedure over the other may lie within their economic benefits, along with patient and provider preference6.

As health-care systems shift from a fee-for-service model to a quality and value-based model, all stakeholders will place increasing scrutiny on the cost incurred to achieve a high-quality outcome. Such analyses will be critical as health systems transition to alternate payment models. This economic analysis, known as cost-minimization analysis, considers the costs of given treatment strategies (i.e., carpal tunnel release surgery) and assumes that the outcomes of treatments exhibit no clinically important differences20. A cost-minimization analysis of the treatment of carpal tunnel syndrome would inform payers and health systems of the incremental cost of alternative treatment methods (e.g., endoscopic release) as well as variations in care that achieve a similar outcome.

We are not aware of any large-scale study evaluating the costs of endoscopic compared with open carpal tunnel release that includes perioperative care, such as diagnostic tests and postoperative therapy. In the current study, we tested the null hypothesis that there is no difference between open and endoscopic carpal tunnel release in terms of cost from the payer and societal perspectives. Secondary analysis included an evaluation of trends in the costs and frequency of diagnostic studies, surgical procedures, and postoperative care in the treatment of carpal tunnel syndrome.

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Materials and Methods

Data

The data for this study were obtained using the PearlDiver patient records database (PearlDiver Technologies) to access the Humana database, which includes both private and Medicare Advantage charge data and reports facility and physician fees for each procedure. The Humana database is composed of 16 million patient records and includes claims data pertaining to diagnoses, procedures, prescriptions, and laboratory testing from the years 2007 to 2014. The billing sources include the facility and physician, and sites of care include inpatient and outpatient care.

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Cohorts

Using the PearlDiver database, we identified patients with records having an ICD-9 (International Classification of Diseases, Ninth Revision) code for carpal tunnel syndrome and a CPT (Current Procedural Terminology) code for carpal tunnel release (Table I). For inclusion, we required that the carpal tunnel release have occurred within 3 years after the diagnosis of carpal tunnel syndrome. No patients were excluded from the study on the basis of age or care setting. Patients were then subdivided into 2 cohorts according to the presence of a CPT code for endoscopic release or open release. Patients who underwent both types of releases, indicated by the presence of CPT codes 64721 and 29848 in their records, were excluded in order to ensure that all fees reflected only a single type of procedure.

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Variables of Interest

The use of EMG and NCS was identified by searching within each cohort for records with CPT codes corresponding to EMG and NCS, as listed in Table I, using a Boolean-type search. For inclusion, EMG and/or NCS must have been conducted within 1 year prior to carpal tunnel release. MRI and ultrasound use were identified similarly using CPT codes corresponding to MRI and ultrasound. Patients who went on to receive hand therapy were identified as those having a record of CPT code 97003 within 3 months after carpal tunnel release. We further assembled a broad list of commonly prescribed therapy activities to capture those used during these therapy sessions that occurred within 3 months after carpal tunnel release, as identified by CPT codes 97039, 97018, 97022, 98960, 90901, 97010, 97014, 97032, 97124, 97760, 97140, 97035, 97530, and 97033.

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Costs

The cost of care was defined as the total of reimbursement fees from the payer perspective—that is, the amount paid to providers by the insurers—and was extrapolated as societal cost, in accordance with previous studies21-28. The cost of care was determined for the type of carpal tunnel release, EMG and NCS utilization, and postoperative occupational therapy.

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Statistical Analysis

Student t test and chi-square analyses were used to compare frequencies and costs for patients who underwent open release with those who underwent endoscopic release. All statistical analyses were performed using R software (version 2.7.0; R Foundation for Statistical Computing).

Because all data were deidentified and anonymous, our study was exempt from institutional review board approval.

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Results

Of the 261,846 patients with a diagnosis of carpal tunnel syndrome, 58,804 (60% female) underwent a carpal tunnel release within 3 years. The most common age group was 65 to 69 years (21%). We subdivided the group of patients who underwent carpal tunnel release into those who underwent open release (n = 50,526) and those who underwent endoscopic release (n = 8,278); most of the patients (86%) underwent open release (Fig. 1-A).

Among the 58,804 patients who underwent carpal tunnel release, 36,133 (61%) had EMG and 44,512 (76%) underwent NCS within 1 year prior to surgery (Fig. 1-B). A total of 27,649 (47%) underwent both EMG and NCS.

An analysis of the frequency of surgery between 2007 and 2014 also revealed that the use of endoscopic release grew 1.6 times faster than the use of open release. The average cost of endoscopic release ($2,439) was significantly higher (62% more) than that of open release ($1,508) (p < 0.0001) (Fig. 2-A). Further analysis showed that facility fees were responsible for most of the difference in costs (an average of $1,884 for endoscopic release compared with $1,080 for open release; p < 0.0001) (Fig. 2-B). Endoscopic release also demonstrated significantly higher physician fees than open release (an average of $555 compared with $428; p < 0.0001). We therefore rejected the null hypothesis that there is no difference between open and endoscopic carpal tunnel release in terms of cost.

Secondary analyses were performed to evaluate the frequency of use of EMG and NCS. We found that patients who underwent endoscopic release were significantly more likely to have undergone NCS within 1 year prior to surgery (74% compared with 71%; p < 0.0001) (Fig. 3-A). However, there was no difference between open and endoscopic release in terms of the rates of patients who received occupational therapy (15% for open compared with 14% for endoscopic; p > 0.05) (Fig. 3-B). Finally, there was a trend toward a difference between open and endoscopic release in reimbursement fees for occupational therapy (an average of $272 per session for open compared with $237 for endoscopic release) (Fig. 3-C). This difference, however, did not achieve significance (p = 0.07).

Finally, we calculated the total average annual reimbursement fees associated with each procedure. This sum was determined on the basis of reimbursements for diagnostic tests (EMG and NCS), surgery, and postoperative occupational therapy. Our data showed that, from 2007 to 2014, the total annual fees associated with the open approach were $11,175,396 and those associated with the endoscopic approach were $2,633,051. After normalizing these fees to the respective cohort size, we found that endoscopic release incurred a significantly higher fee per patient compared with open release ($2,602 compared with $1,751; p < 0.0001).

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Discussion

Carpal tunnel syndrome and its care represent a large cost-generator in the U.S. health-care system. We found that the open approach for carpal tunnel release currently remains, by far, the more common choice of procedure. This is consistent with previous survey data, which showed that more surgeons prefer open carpal tunnel release to endoscopic release29. We found that 14% of the carpal tunnel release procedures were performed endoscopically, but the use of endoscopic release increased at a greater rate than that of open release. We found that the endoscopic approach grew 250% between 2007 and 2014. It is unclear what drove the increase in endoscopic release. It is possible that the cost of endoscopic release was higher because of additional equipment requirements, the type of surgical facility (i.e., surgical center versus hospital), or operative time. However, given the frequency of carpal tunnel release, the comparatively increased cost of the endoscopic approach may be unacceptable for society, payers, and health systems. Our study suggests that the decision for an endoscopic versus an open approach represents potentially unnecessary variation in care, as clinical evidence remains ambiguous in showing the superiority of one procedure over the other6,30.

Our data indicated that 61% of the patients within the Humana database underwent EMG studies and 76% underwent NCS within 1 year prior to carpal tunnel release, which are comparable with levels reported in a recent survey of hand surgeons15. Further analysis showed that patients who underwent the endoscopic approach were significantly more likely to receive NCS prior to surgery; including electrodiagnosis in addition to standard examination may decrease the risk of misdiagnosis of carpal tunnel syndrome and decrease costs from surgical complications31. Although we found a significant difference in usage of NCS, the difference was not robust enough to show a meaningful difference in payer reimbursement cost between our 2 cohorts. Our data also revealed that the use of MRI and ultrasound remained at minimal levels in work-up of carpal tunnel cases. However, clinical evidence has shown that these 2 modalities offer similar, if not equal or higher, sensitivity and specificity compared with electrodiagnostic studies32-35. MRI and ultrasound are likely to grow in relevance and importance as research into these tools advances.

Hand therapy represents a cost of surgery and recovery from it. This is an important aspect to consider as endoscopic carpal tunnel release may have decreased postoperative pain in this study, which perhaps could translate into decreased costs in therapy. Currently, the American Academy of Orthopaedic Surgeons (AAOS) offers no strong recommendation for postoperative occupational therapy following carpal tunnel release due to a lack of evidence demonstrating its benefit, as documented by a recent Cochrane review36. We found that 15% of the patients who underwent open carpal tunnel release and 14% of those who underwent endoscopic release received at least 1 instance of postoperative occupational therapy, representing another potential area of unnecessary variation in care. Further evaluation of therapy use revealed that the patients who received open release were no less likely to have had occupational therapy than their endoscopic counterparts (15% compared 14%; p > 0.05). However, per-patient fees for occupational therapy were higher for those who underwent open release compared with endoscopic release, although this did not achieve significance ($272 compared with $237; p = 0.07) (Fig. 3-C). We hypothesize that the lower cost of therapy after endoscopic release may be secondary to a decrease in scar tissue, tenderness, and pain among those who have undergone endoscopic release37-40. Furthermore, the duration and cost of hand therapy can be influenced by expectations from the patient and the provider. Expectation of a decreased need for hand therapy following endoscopic release, due to smaller surgical incisions, compared with open release can also lead to decreased costs.

For cost-minimization analysis, the overall difference in fees between the 2 approaches was analyzed. To do so, we calculated the total annual fees per patient undergoing carpal tunnel surgery with use of either of the 2 approaches, including diagnostic, surgical, and occupational therapy reimbursements. Our analysis indicated that the total fees per patient who underwent open release ($1,751) remained significantly lower than the total fees per patient who underwent endoscopic release ($2,602). The large driver of these differences in fees was at the reimbursement level, specifically in facility fees, while the differences between open and endoscopic approaches in reimbursement fees for occupational therapy and electrodiagnostic studies were statistically insignificant. Although open release incurred more fees for occupational therapy, they were not enough to negate the higher surgical cost of endoscopic release. However, despite this cost difference, previous studies have shown a faster return to work by an average of 9 days following endoscopic release compared with open release, despite no difference in grip strength at 6 months post-operation10. However, we know of no study to have analyzed the potential economic gain of this advantage and whether it is enough to compensate for the additional cost of endoscopic release. This issue is worth exploring in future studies.

We acknowledge that our study had limitations in scope and granularity. Our data relied on facility and physician fee charges for each procedure, as done previously21-28, which were extrapolated to determine the overall costs of each procedure. We believe that using payer fees to estimate overall health-care cost is appropriate for our study, as previous cost-comparison studies in surgery and other specialties have also extrapolated such fees to determine the economic burden on society21-28. Although we were able to attribute the difference in cost between endoscopic release and open release to facility fees, our methodology does not allow us to further break down this finding. Therefore, we are unable to attribute this increased facility fee for endoscopic release to a particular reason. We suspect that equipment use and geographic location of the facility may play a role in the increased facility fee, as endoscopic carpal tunnel release requires additional endoscopy equipment. Exploring these discrepancies would be worthwhile in future cost-minimization studies. Lastly, the numbers of patients who received each treatment (carpal tunnel release, EMG and NCS, and occupational therapy), may not reflect the actual per-patient numbers due to patient overlap and the inability to isolate patients who received bilateral endoscopic or open releases. The consequence of this potential overlap was largely mitigated by excluding patients who received both open and endoscopic surgery and by specifying a time frame relative to the carpal tunnel release surgery. We believe that we took into account the major procedures associated with carpal tunnel surgery. Only patients who were diagnosed with carpal tunnel syndrome were followed. Doing so limited our search to patients who underwent procedures relevant only to their carpal tunnel syndrome in the limited time frame.

Overall, our study showed that endoscopic carpal tunnel surgery carries more costs to payers and society in treating carpal tunnel syndrome, without established clinical superiority. Our data provide evidence that an increase in the use of an open approach may reduce costs associated with carpal tunnel syndrome and informs payers, physicians, and health systems of this more cost-efficient method41. The decision whether to undergo endoscopic or open carpal tunnel release will ultimately be made by the patient and the provider. Surveys have shown that patients prefer endoscopic release, and this preference should not be ignored42. Additional research is needed into the economic gains of an earlier return to work following endoscopic release. Although our study suggests that endoscopic carpal tunnel release is much costlier than open release, more clinical and economic data are needed to make a definitive recommendation.

Investigation performed at the Stanford University School of Medicine, Stanford, California

A commentary by Wesley P. Phipatanakul, MD, is linked to the online version of this article at jbjs.org.

Disclosure: No external funding was received for this study. On the Disclosure of Potential Conflicts of Interest forms, which are provided with the online version of the article, one or more of the authors checked “yes” to indicate that the author had a relevant financial relationship in the biomedical arena outside the submitted work.

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