Direct economic burden of cubital tunnel surgery in the United States: total payments and components of cost

Abstract

Purpose:

Despite its widespread prevalence, the cost of cubital tunnel syndrome (CuTS) in the United States to patients and insurers is not well understood. The purpose of this study was to quantify the direct payments associated with operative treatment of CuTS. We hypothesized that CuTS represents a substantial cost to the payer in facility fees, surgeon fees and other expenses.

Methods:

Utilizing the MarketScan database of insured patients (commercial and Medicaid), we identified a cohort of 41,777 patients aged 18 to 64 years with surgically treated CuTS from 2006 to 2018. We estimated the median 90-day payments from encounters associated with cubital tunnel release (CuTR) and/or ulnar nerve transposition surgery by summing all payments for claims within 90 days after the index surgery. Published estimates of the annual number of cubital tunnel surgeries were used to calculate the annual expenditure.

Results:

Of 41,777 patients, the median (interquartile range [IQR]) values of total direct payments were $5,522 [$3,426, $9,541]. With an estimated 94,645 cases/year, this leads to an annual payment of more than $522 million. Index facility payments (median [IQR] $2,555 [$1,359, $4,708] were the highest, followed by index provider payments ($1,691 [$1,328, $2,217]). The median index surgeon payment (median [IQR] $905 [$707, $1,184]) represented just over half of the provider payments. Post-operative care had a median [IQR] payment of $377 ($424, $1,987). Limitations of claims databases prevented assessment of other indirect costs associated with cubital tunnel surgery.

Conclusion:

Payments for the surgical treatment of CuTS from the index surgery to 90 days post-operatively have an estimated median of $5,522 per patient, totaling $522 million. Index facility fees are responsible for more than 46% of payments, while index payments to surgeons represent ~16%. Defining this data is critical to understanding one component of the economic impact of CuTS.

Level of Evidence:

Level IV

INTRODUCTION

Cubital tunnel syndrome (CuTS) is the second most common compressive neuropathy after carpal tunnel syndrome (CTS)^1,2 affecting up to 6% of the general population³ and with an incidence of 30 per 100,000 person-years in the United States⁴. It manifests as numbness and tingling about the small and ring finger and may be associated with atrophy of the intrinsic muscles of the hand⁵. Current techniques for surgical treatment include in situ decompression (open or endoscopic) as well as subcutaneous and submuscular transposition to relieve pain and maintain or improve motor and sensory function. A meta-analysis by Wade et al.⁶ reported a combined success rate of 87% in 30 studies documenting results from 2,894 CuTS surgeries using a variety of techniques – validating the results of multiple well-designed clinical trials and meta-analyses that have shown success with a number of different techniques^7–9, although indications for different surgical options may vary by surgeon.

CuTS, like CTS, not only has a high prevalence in the general population, but also demonstrates a peak prevalence in the late working-aged (45–55 years) demographic.^3,10 Theoretically, given the prevalence of compressive neuropathies, the potential need for operative management to address the pathology, and the extensive burden of disease occurring in participants in the work force, both CuTS and CTS have the potential for high direct (evaluation, diagnostic work-up, non-operative, and operative management) and indirect (decreased productivity, time lost contributing to the workforce, etc.) costs to society. While direct and indirect costs of carpal tunnel surgery have been previously evaluated^11–14, the literature regarding the direct cost of cubital tunnel syndrome is more limited. The true cost of this condition would account for both payments to facilities and providers (direct costs of care) as well as the opportunity cost of lost time from work and transportation costs among others (indirect costs of care). To our knowledge, only a single study exists regarding the direct cost of cubital tunnel surgery in the United States and this single institution publication reports relative – rather than actual – direct cost of ulnar nerve decompression, subcutaneous nerve transposition, and submuscular transposition.¹⁵ Therefore, little data exists to quantify the costs of cubital tunnel syndrome to the United States healthcare system. When viewed in context of the high prevalence of CuTS in the general population⁴ and increasing rates of surgical treatment both in the U.S. and internationally^17–21, these cost data are invaluable in understanding the economic impact and burden of disease. Without such data, healthcare providers, policy makers, and funding bodies have little objective data to determine the appropriate allocation of healthcare and research resources to the treatment of cubital tunnel syndrome, which requires knowledge of both costs and efficacy of treatment. The purpose of this study was to focus on a portion of the cost aspect of this calculation by estimating the payments to hospitals and providers associated with the operative treatment of cubital tunnel syndrome in commercially and Medicaid insured populations.

METHODS

We utilized the Merative MarketScan Commercial and Multi-State Medicaid Databases to identify a cohort of adult patients 18–64 years of age with private or Medicaid fee-for-service coverage who underwent surgical treatment for CuTS from 2006–2018 in the United States. Surgical patients were identified by the Current Procedural Terminology (CPT) code 64718. To limit the cohort to true CuTS and minimize the influence of concomitant injuries or additional procedures on overall cost, such as sequelae of flail elbow or traumatic injury, we excluded patients with potentially confounding CPT and International Classification of Diseases, Ninth and Tenth Revisions, Clinical Modification (ICD-CM) diagnosis codes at index surgical admission or if they were not a same-day discharge. If additional procedures were subsequently performed in the 90-day post-operative period, then payments were censored to limit data to only the period prior to the additional procedure (Appendix). Patients were excluded if they had an inpatient stay greater than one day associated with their surgery, underwent concomitant carpal tunnel release at the time of index admission for CuTR, or any procedure with a ICD-9/10 procedure or CPT code matching one of the National Healthcare Safety Network (NHSN) major procedures code list at the time of the index procedure¹⁶. Patients with inpatient admission greater than one day were excluded to capture only outpatient or same-day discharge procedures. Additionally, we excluded procedures if the patient did not have continuous medical insurance from 30 days prior to the index surgery through 90 days post-surgery, to ensure that no costs were missing due to patients changing insurers during the study time frame.

Payments were recorded for all paid claims associated with the index event through 90 days post-surgery including medical, surgical, therapy, and pharmacy claims (except for censored cost data) (Appendix). Index costs specifically define the initial admission/payments associated with facility admission through discharge from surgery regardless of facility type. In contrast, 90-day costs refer to entirety of treatment (index through 90 days post-op). Events in the management of the patient associated with their index surgery were also recorded, using a combination of ICD9/10 and CPT codes to identify any additional procedures or complications related to the index event (Appendix). These events included the utilization of any diagnostic imaging, electrodiagnostic testing, post-operative care, post-operative complications, and additional procedures. Median and ranges of payments were tabulated for CuTR, as well as each claim type of associated costs in the post-index period, as box plots of costs demonstrated that data were not normally distributed (Supplement Figures 1-5). The nonparametric modification of the one-way Analysis of Variance (ANOVA) and Wilcoxon tests were used to compare facility (inpatient, outpatient, ambulatory surgery center (ASC)), provider (all provider, surgeon, surgical specialty), prescription, and total costs by provider specialty and insurance type with alpha set at 0.05. The Dwass, Steel, Critchlow-Fligner multiple comparison procedure was used to compare direct costs by provider specialty. Total estimated direct cost of care was obtained by multiplying the median direct costs per episode of care by the estimated total number of annual cubital tunnel surgeries in the United States. We adjusted payments to 2019 U.S. dollars utilizing the Medical Care component of the Consumer Price Index¹⁷.

RESULTS

A total of 115,089 surgically treated CuTS patients were initially identified; however this pool was narrowed to 41,777 patients after excluding those coded at the index procedure for carpal tunnel release or another major surgical procedure (such as treatment of elbow trauma or other pathology), or with concomitant diagnoses suggestive of elbow trauma, or had a length of hospital stay > 1 day (Figure 1). The mean (standard deviation [SD]) age was 47.2 (±11.6) years and 47.1% of the cohort was female. Geographic data was available for those with commercial insurance with 37.4% of patients from the U.S. South region, 25.8% from the North Central, 14.2% from the Northeast, 12.8% from the West, and 9.8% from unspecified geographic regions. Privately insured patients made up 91.9% of the cohort, while the remaining 8.1% (3,370 patients) had Medicaid fee-for-service coverage.

Figure 1:

CONSORT Diagram of Inclusion / Exclusion

The median [IQR] values of total 90-days payments were $5,522 [$3,426, $9,541]. Based on published estimated surgical rates (~94,645 cases/year in 2021)^17,24, we estimated median direct annual payments of more than $522 million in the U.S. Payments for the index surgical admission had a median [IQR] total of $4,103 [$2,742, $6,494], accounting for 74.3% of total 90-day payments. Among payments associated with the index surgery, facility (median[IQR] $2,555 [$1,359, $4,708] and provider payments ($1,691 [$1,328, $2,217]) were the highest, with the surgeon payment ($905 [$707, $1,184]) representing approximately 22% of the index surgery payments and 16% of the overall treatment payments through 90 days post-index surgery. Post-index event costs including medications, physical and occupational therapy, imaging/diagnostic tests, and treatment of complications had a median [IQR] payment of $377 [$24,$1987] (Table 1). Of the 9,218 (22.1%) patients who received PT/OT post-operatively, 52.8% required more than 1 session with an average duration of 3 sessions within 90 days. Of the patients receiving PT/OT, the median [IQR] post-index PT/OT payment was $172 [96, 341]. Frequencies of facility/provider payments related to post-index events are summarized in Table 2.

Table 1.

Variations in Payments Based on Provider Specialty

	Orthopaedic Surgeon		Plastic Surgeon		Other/Unknown		P-values for Provider Specialty Comparisons†	Total
Payment	Median (IQR)	95% CI	Median (IQR)	95% CI	Median (IQR)	95% CI	P-value	Median (IQR)	95% CI
Index Admission
Facility	$2,396 ($1,307, $4,544)	$2,353, $2,431^	$2,751 ($1,548, $4,847)	$2,530 – $2,964*	$2,867 ($1,500, $4,958)	$2,815 – $2,909*	Orthopaedic v. Plastic: p<0.0001 Orthopaedic v. Other: p<0.0001 Other v. Plastic: p=1.0	$2,555 ($1,359, $4,708)	$2,523 – $2,587
All Providers	$1,714 ($1,379, $2,235)	$1,706 – $1,723^	$1,748 ($1,397, $2,406)	$1,697 – $1,814*	$1,633 ($1,106, $2,164)	$1,614 – $1,648*^	Orthopaedic v. Plastic: p=0.049 Orthopaedic v. Other: p<0.0001 Other v. Plastic: p<0.0001	$1,691 ($1,328, $2,217)	$1,683 – $1,698
Surgeon Only	$896 ($717, $1,145)	$892 – $900	$906 ($710, $1,190)	$884 – $933	$935 ($670, $1,267)	$925 – $942*	Orthopaedic v. Plastic: p=0.49 Orthopaedic v. Other: p=0.0002 Other v. Plastic: p=1.0	$905 ($707, $1,184)	$901 – $909
Total Index	$4,084 ($2,797, $6,433)	$4,045 – $4,129^	$4,331 ($2,987, $6,993)	$4,149 – $4,550*	$4,112 ($2,550, $6,512)	$4,044 – $4,172*^	Orthopaedic v. Plastic: p=0.002 Orthopaedic v. Other: p<0.0001 Other v. Plastic: p<0.0001	$4,103 ($2,742, $6,494)	$4,071 – $4,137
90-day Post-index Period
Medications	$42 ($8, $249)	$40 – $44	$39 ($8, $206)	$33 – $44	$52 ($10, $300)	$48 – $55*^	Orthopaedic v. Plastic: p=0.43 Orthopaedic v. Other: p<0.0001 Other v. Plastic: p=0.005	$43 ($8, $257)	$42 – $45
CuT-Related Events	$293 ($0, $1,557)	$282 – $306	$245 ($0, $1,721)	$196 – $315	$343 ($0, $1,864)	$321 – $364*^	Orthopaedic v. Plastic: p=0.50 Orthopaedic v. Other: p<0.0001 Other v. Plastic: p=0.030	$306 ($0, $1,647)	$294 – $317
Total Post-index	$366 ($23, $1,897)	$350 – $380	$319 ($20, $1,956)	$243 – $398	$415 ($28, $2,240)	$391 – $446*	Orthopaedic v. Plastic: p=0.87 Orthopaedic v. Other: p=0.0004 Other v. Plastic: p=0.18	$377 ($24, $1,987)	$364 – $389
Total Treatment (Index + 90-day Post-op)
Total	$5,472 ($3,456, $9,288)	$5,412 – $5,527^	$5,988 ($3,670, $10,062)	$5,619 – $6,213*	$5,582 ($3,346, $10,002)	$5,503 – $5,675^	Orthopaedic v. Plastic: p=0.008 Orthopaedic v. Other: p=0.95 Other v. Plastic: p=0.013	$5,522 ($3,426, $9,541)	$5,477 – $5,567

IQR=Interquartile Range, CI=confidence interval

^*=statistically significant difference (p<0.05) between Orthopaedic and noted providers

^{^}= statistically significant difference (p<0.05) between Plastic and noted providers

^†=P-values obtained from the Dwass, Steel, Critchlow-Fligner multiple comparison procedure, which is based on pairwise two-sample rankings.

Table 2.

Number and Frequency of Payments Associated with Post-index Events

		Payments	Frequency
Category	Event	N (# of surgeries)	%
Diagnostics	Imaging	1,844	4.41
	EDX	753	1.80
Post-op Care	Pain Management	6,194	14.83
	Provider Visit	1,951	4.67
	PT/OT	9,218	22.06
	Splinting	1,921	4.60
	Prescription Medication	27,919	66.83
Complications	Elbow Contracture	1,287	3.08
	Elbow Instability	229	0.55
	Wound Dehiscence	239	0.57
	Surgical Site Infection	174	0.42
	Hematoma	58	0.14
	Seroma	26	0.06
Procedures	Debridement	298	0.71
	Incision and Drainage	179	0.43
	Repeat CuTR Surgery	1,527	3.66

EDX=electrodiagnostic studies, CuTR=cubital tunnel release

Per our inclusion criteria, 99.96% of surgeries were done on an outpatient basis and 39.9% occurred at an ASC. Only 18 patients were admitted to a facility after surgery. Total payments for the index admission for these admitted patients were 2.4-fold higher on average compared to outpatients, mostly due to increased facility payments (median[IQR] $9,856 [$7,023, $15,161]). Facility payments were lowest for ASCs ($1,566 [$976, $2,883]), representing a 2.2-fold lower payment compared with other outpatient facilities. Surgeries were performed by orthopaedic surgeons in 63.6% of cases, plastic surgeons in 2.6%; 29.6% were listed as other surgeon type, and the provider specialty of the remaining 4.3% was not specified. Payment variations based on provider are presented in Table 2 and insurance type in Table 3. Payments from Medicaid were significantly lower compared to private insurance for median total 90-day and index surgical, but higher for post-index payments; equaling 48.5%, 32.7%, and 126% of those from private insurers, respectively. Index facility (61.1%), all provider (31.9%), and surgeon payments (44.3%) by Medicaid were also significantly less than private insurance.

Table 3.

Medicaid and Private Insurance-based Differences in Payments for Cubital Tunnel Surgery

	Medicaid Insurance		Private Insurance		P-values for Insurance Type Comparisons†
Payment	Median (IQR)	95% CI	Median (IQR)	95% CI	P-value
Index Admission
Facility	$1,609 ($812, $2,999)	$1,520, $1,684	$2,633 ($1,403, $4,857)	$2,598 – $2,674	p<0.0001
All Providers	$559 ($400, $725)	$547 – $569	$1,751 ($1,411, $2,281)	$1,744 – $1,759	p<0.0001
Surgeon Only	$413 ($346, $497)	$406 – $419	$932 ($749, $1,210)	$929 – $936	p<0.0001
Total Index	$1,415 ($780, $2,924)	$1,361 – $1,469	$4,328 ($2,942, $6,768)	$4,294 – $4,360	p<0.0001
90-day Post-index Period
Medications	$133 ($25, $564)	$112 – $149	$40 ($8, $240)	$39 – $42	p<0.0001
CuT-Related Events	$384 ($25, $2,049)	$350 – $431	$299 ($0, $1,621)	$287 – $311	p<0.0001
Total Post-index	$466 ($56, $2,622)	$407 – $515	$370 ($23, $1,937)	$357 – $383	p<0.0001
Total Treatment (Index + 90-day Post-op)
Total	$2,774 ($1,224, $5,954)	$2,624 – $2,913	$5,720 ($3,626, $9,783)	$5,669 – $5,777	p<0.0001

IQR=Interquartile Range, CI=confidence interval

^†=P-values obtained from Mann-Whitney U tests to compare differences in median costs between provider specialties

DISCUSSION

Of the 41,777 surgically treated CuTS patients included in this study, total payments for the surgical treatment of CuTS from the index surgery to 90 days post-op have an estimated median total of $5,522 per patient, totaling approximately $522 million annually in the U.S. based on published estimated surgical rates (~94,645 cases/year for 2021).^{6–7,13–14,17,24} However, given the rising incidence of surgical treatment¹⁸ and relative increase in size of the U.S. population within the typical age demographic, it is likely that our projection slightly underestimates the number of surgical cases and, therefore, the annual cost. Payments for the index surgical admission accounted for around 74% of all direct cost payments. Of the payments for the index surgical admission, facility fees were responsible for 62.3% of index payments. Inpatient admission (<1 day) was associated with a much larger facility fee (median $9,856) compared with those treated in an ASC (median $1,566) or those discharged from an ambulatory surgery facility in a hospital (median $3,4393). Surgeon payment was approximately 22% of the total index surgery cost. In comparison, the direct costs of carpal tunnel surgery have been estimated at just over $3,500¹⁴, a difference which may reflect greater operative time and technical complexity of cubital tunnel release procedures.

To our knowledge only one previous study reports cost data of surgical treatment for CuTS, in a single-center study focused on the relative costs of in situ decompression vs transposition¹⁵. The authors found that, among 121 patients undergoing surgical treatment of CuTS, in situ decompression was the least costly, while cost associated with subcutaneous transposition and submuscular transposition were 1.18 and 1.55-fold higher, respectively. Others have investigated the potential cost-effectiveness of endoscopic treatment, generally concluding higher direct costs, but potential savings overall due to lower indirect costs^19,20. To increase the specificity of our database query, we chose to limit our study to the only specific CPT code (61748) for CuTR, to define the overall cost of surgical treatment of cubital tunnel in the U.S., rather than discerning between techniques. This should increase the general applicability of our results for future cost-effectiveness analyses since multiple well-designed clinical trials and meta-analyses have not shown any one technique to yield superior outcomes^6,7,21.

One cost-saving measure that has shown considerable impact over the years is the transition to outpatient and ambulatory surgery facilities^22–26. Patients admitted to a facility after surgery but discharged on the same day had 5.1-fold higher index admission costs than those treated on an outpatient basis, yet this accounted for only a very small percentage of patients and likely reflects underlying comorbidities or complications rather than standard practice. However, ASC facility fees were 2.2-fold less than other facilities where outpatient surgery was performed. Choice of surgical setting may be influenced by insurers, patient and surgeon preferences, and safety, among other considerations^23–26. With index surgery facility costs representing about 46% of total surgical treatment costs, this represents a potential opportunity for savings. In our comparison of orthopedic, plastic and “other” surgeon total index costs, orthopedic surgeons demonstrated a significantly lower total cost, despite having similar surgeon fees to plastic surgeons and lower fees than “other/unknown” surgeons. This difference appears to be attributable in part to a significantly lower facility fee for orthopedic surgeons, which may reflect a higher rate of usage of ASCs. Even with increased utilization of these facilities for CuTR and other outpatient surgeries, facility fees constitute a large portion of the overall costs. However, it should be noted that plastic surgeons represented only a small percentage of the reported providers, which may represent a lack of accurate coding in the administrative database – presumably the other/unknown surgeons likely represent some proportion of plastics surgeons. Also, the difference in median costs among surgeon types, while statistically significant, represents only a small fraction of the overall costs (around 5%).

Post-operative cubital tunnel related events costs including medications, therapy, diagnostics and treatment of complications had a median cost of $377. Prescription medications made up the second largest portion of post-operative costs and, while these may be indicated, treatment teams should make a coordinated effort to reduce the need for prescription medications when not medically necessary, especially regarding pain control in the post-operative period. Therapy may be a beneficial adjunct to surgery in some cases^27,28, especially when significant muscle weakness is present. However, in the clinical experience of the authors, most patients recover without incident and home exercises may be an appropriate cost-saving alternative to formal therapy for many. In our study, 22% of patients participated in formal physical and/or occupational therapy and half of those (11% of all patients) required more than one session.

One limitation of the study is the inclusion of only privately insured and Medicaid patients in the database. We therefore cannot accurately assess the direct costs for uninsured patients or those with Medicare or workers compensation. Additionally, we excluded patients on managed care Medicaid plans due to lack of payment data and the Medicaid patients included only represent 11 states, due to database limitations. The Medicaid population included only represents those with fee for service plans, as HMO cost data is not reported, leading to an overall underrepresentation of Medicaid patients in this study. Medicaid patients had a total median payment of $2,774, approximately 50% less than those for privately insured patients ($5,720), while index surgical admission payments were nearly 67% lower for Medicaid (Table 3). The relatively low proportion of Medicaid patients in this study and the lower payments likely results in an overestimate of total costs. The published average total payments of index CuTR surgery for Medicare patients are $1,421 for ASCs and $2,371 for hospital-affiliated outpatient surgery centers²⁹. Despite Medicaid expansion under the Affordable Care Act, Medicaid patients have more difficulty obtaining an appointment, longer wait times to surgery, longer travel distances for appointments for hand and other orthopaedic conditions^30–35. Our findings are particularly impactful given that poor reimbursement rates and variation of rates between states and regions are known to hinder access to quality orthopaedic care for these patients^36–38. With a growing proportion of medical providers not willing to accept Medicaid, owing at least in part to poor reimbursement, this is an important area for policymakers to explore to find mechanisms to incentivize providers and expand access to high quality care for Medicaid patients among specialist providers^39,40.

Another limitation of the present study, inherent to administrative data, was the inability to perform detailed chart review and analysis of specific patient characteristics, surgical techniques, and circumstances surrounding complications, or additional costs for individuals. To mitigate this, we used specific inclusion criteria to limit our population to simple CuTS and exclude any potential confounding diagnoses or injuries that could skew our data. This resulted in the exclusion of patients undergoing concomitant release for CTS and CuTS, which may limit the overall generalizability of the data as many patients present with concomitant diagnoses. While this somewhat limits the direct applicability of data in these situations, the purpose of this analysis was only to establish average cost of care for isolated cubital tunnel. Future studies examining specific differences in costs related to specific techniques, equipment and perioperative care practices will help identify additional potential targets for cost-savings, increasing the value of care for patients.

Supplementary Material

Supplement

Administrative database analysis code description with utilized and excluded CPT and ICD codes