Comparative Analysis of Comorbidities and Outcomes in Endoscopic versus Open Treatment of Carpal Tunnel Release in Patients with Rheumatoid Arthritis

Abstract

Background

Rheumatoid arthritis (RA) is a known risk factor for carpal tunnel syndrome, possibly because the inflammation causes compression of the median nerve. Endoscopic and open carpal tunnel release (ECTR and OCTR) have been studied extensively in the general population but less so in patients with RA. The purpose of our study was to analyze outcomes and patient-specific comorbidities associated with ECTR and OCTR in patients with RA.

Materials and Methods

We conducted a retrospective cohort study using the PearlDiver database to identify patients with RA who underwent either ECTR or OCTR between 2010 and 2014. Demographic data, comorbidities, and complication rates were analyzed. We used univariate and multivariable analysis to assess differences between the treatment methods.

Results

Comparing 4,234 patients who underwent OCTR to 683 patients who underwent ECTR, we found no significant differences in medical comorbidities such as hypertension, obesity, chronic kidney disease, hypothyroidism, and diabetes mellitus. Patients who underwent ECTR were significantly more likely to require a repeat procedure within 90 days of the initial procedure. However, this difference was not consistent in multivariate analysis controlling for comorbidities.

Conclusion

Our study found that RA and ECTR were identified as independent risk factors for revision release, with ECTR showing a higher likelihood of repeat procedures within 90 days compared with OCTR. Despite similar demographics and comorbidities in the two study cohorts, use of OCTR outpaced ECTR use in the study period. Future research should explore further characterization of repeat procedures in this higher risk patient subset.

Rheumatoid arthritis (RA) is a known risk factor for carpal tunnel syndrome (CTS), possibly because the inflammation causes compression of the median nerve. ¹ When conservative management fails or symptoms progress, CTS can be managed with carpal tunnel release (CTR) surgery, either open carpal tunnel release (OCTR) or endoscopic carpal tunnel release (ECTR). ²

Both procedures are used routinely, and the differences between them, including differences in outcomes and efficacy, have been well studied. While ECTR and OCTR have been thoroughly analyzed in the general population, there is an absence of literature regarding their efficacy in patients with RA. Although RA is a risk factor for revision release, ³ the literature on RA-specific outcomes is limited—particularly in the context of ECTR versus OCTR.

In the historical context, OCTR was the predominant therapeutic modality. The advent of ECTR can be traced back to the introduction of the two-portal Chow technique in 1989 ⁴ and the single-portal Agee technique in 1992. ⁵ Numerous randomized controlled trials have demonstrated comparable efficacy between open and endoscopic approaches. ^{6 7 8} Noteworthy concerns related to ECTR encompass iatrogenic injuries, ⁹ technical intricacies, ¹⁰ and cost considerations. ¹¹ Nevertheless, empirical evidence substantiates the advantages of ECTR, including expedited return to work, ¹² swifter restoration of grip strength, ¹³ and diminished wound complications. ¹⁴

Despite these merits, OCTR persists as the more prevalent choice for severe CTS cases, ¹⁵ stemming from reservations about ECTR's efficacy in addressing the distal fibers of the transverse carpal ligament. ^{16 17} A notable research gap exists, characterized by a paucity of studies scrutinizing the safety and efficacy of ECTR in cases of CTS, including those with RA, across varying severity levels.

ECTR may be associated with different outcomes, particularly in terms of revision rates, when compared with OCTR. ¹⁸ By exploring these nuances, our study aims to contribute valuable insights into the optimal choice of CTR techniques tailored to the unique characteristics of RA patients.

Materials and Methods

Database

In this retrospective cohort study, we used International Classification of Disease (ICD-9/ICD-10) codes and Current Procedural Terminology (CPT) codes to query a nationally representative deidentified electronic health record database to identify patients with a history of RA who underwent ECTR or OCTR for the treatment of CTS. The database used for our query was PearlDiver (PearlDiver Technologies, Colorado Springs, CO), a commercially available administrative claims database. The PearlDiver database is a comprehensive insurance claims databases containing information billed to all payer types, including commercial insurance, Medicare, Medicaid, and self-pay, capturing data from more than 144 million patients.

Study Cohort

Patients for the study were identified by having a concurrent diagnosis of CTS and RA as defined by ICD and CPT codes. These patients, who subsequently underwent CTR, were split into cohorts of ECTR or OCTR based on the first instance of their surgery as defined by billing codes on the day of the index case (see Supplementary Table S1 , available in the online version only). To exclude acute cases of CTR in the surgical management of fractures, we excluded patients who were diagnosed with a wrist fracture on the same day as the index procedure. In addition, patients with less than 90 days' follow-up were assumed to be lost to follow-up and excluded from our study. Our search identified 683 patients who underwent ECTR and 4,234 who underwent OCTR.

Demographic Characteristics and Outcomes

Data collected for both the ECTR and the OCTR cohorts included demographic information such as age, sex, and Elixhauser Comorbidity Index (ECI). ECI is a method of categorizing comorbidities based on the ICD diagnosis codes found in electronic health records, with each category acting as a dichotomous variable.

The primary outcome of the study was repeat operation, defined as an additional ECTR or OCTR procedure within 90 days of the index procedure. Secondary outcomes included 90-day postoperative medical complications, including readmission, surgical site infection, renal failure, anemia, atrial fibrillation, arrhythmia (without atrial fibrillation), blood transfusion, bleeding complications, cerebrovascular accident, deep vein thrombosis, heart failure, pneumonia, pulmonary embolism, respiratory complications, sepsis, and urinary tract infection.

Statistical Analysis

Statistical analysis was performed using the R software (RStudio Inc., Boston, MA) within PearlDiver. An α level of 0.05 was set as the level of significance. Analysis was conducted using the chi-square ( χ ² ) test for categorical variables and Student's t -test for continuous variables as appropriate. Multivariate logistic regression analysis was conducted to assess for repeat procedures within 90 days of index surgery. To mitigate confounding variables, all comorbidities with p  < 0.20 on univariate analysis were included as independent variables for the multivariable analysis.

Institutional Review Board Statement

This study was conducted using deidentified data from the PearlDiver database, which is exempt from institutional review board approval. Individual informed consent was waived as the study did not involve direct interaction with patients and used retrospective data.

Results

Univariate Analysis of Demographics and Comorbidities

Of the 4,917 patients meeting inclusion criteria, 4,234 underwent OCTR procedures and 683 underwent ECTR procedures ( Table 1 ). Our analysis did not detect significant differences in demographic characteristics between the two groups. No statistical differences were recorded in any comorbidities.

Table 1. Demographic characteristics and comorbidities among patients undergoing carpal tunnel release surgery between 2010 and 2014, by type of surgery.

Characteristic/comorbidity	N (%)		p -Value
	Endoscopic carpal tunnel release ( n  = 683)	Open carpal tunnel release ( n  = 4,234)
Demographics
Age	59 (11.7) a	59 (11.5) a	0.08
Sex
Male	137 (20)	977 (23)	0.09
Female	546 (80)	3,257 (77)
Comorbidities
Alcohol abuse	45 (6.6)	260 (6.1)	0.72
Arrhythmias	223 (32.7)	1,427 (33.7)	0.62
Blood loss anemia	57 (8.3)	308 (7.3)	0.36
Chronic kidney disease	89 (13.0)	610 (14.4)	0.37
Chronic pulmonary disease	340 (49.8)	2,270 (53.6)	0.07
Coagulopathy	114 (16.7)	608 (14.4)	0.12
Congestive heart failure	94 (13.8)	632 (14.9)	0.46
Deficiency anemia	172 (25.2)	1,146 (27.1)	0.33
Depression	374 (54.8)	2,255 (53.3)	0.49
Diabetes mellitus	330 (48.3)	2,084 (49.2)	0.69
Drug abuse	108 (15.8)	573 (13.5)	0.12
Fluid and electrolyte disorders	311 (45.5)	1,949 (46.0)	0.84
Hypertension	563 (82.4)	3,572 (84.4)	0.22
Hypothyroidism	267 (39.1)	1,604 (37.9)	0.58
Liver disease	173 (25.3)	1,031 (24.4)	0.61
Lymphoma	21 (3.1)	106 (2.5)	0.46
Metastatic cancer	44 (6.4)	206 (4.9)	0.10
Nonmetastatic cancer	130 (19.0)	818 (19.3)	0.90
Obesity	339 (49.6)	1,937 (45.7)	0.07
Other neurological disorders	74 (10.8)	520 (12.3)	0.31
Paralysis	21 (3.1)	188 (4.4)	0.12
Peptic ulcer disease	69 (10.1)	424 (10.0)	>0.99
Peripheral vascular disease	197 (28.8)	1,310 (30.9)	0.29
Psychoses	25 (3.7)	209 (4.9)	0.18
Pulmonary circulatory disorders	98 (14.3)	592 (14.0)	0.84
Smoking	371 (54.3)	2,172 (51.3)	0.15
Valvular disease	191 (28.0)	1,239 (29.3)	0.52

^aExpressed as mean (standard deviation).

Univariate Analysis of 90-Day Complications

Within 90 days postoperatively, the ECTR group had higher rates of repeat operations when compared with the OCTR group, 8.6% versus 6.0%, respectively ( p  = 0.01) ( Table 2 ). Rates of other surgical complications such as median nerve injury, wound dehiscence, and surgical site infection were similar between the two cohorts. Rates of medical complications were not statistically significant.

Table 2. Univariate analysis of 90-day outcomes among patients undergoing carpal tunnel release surgery between 2010 and 2014, by type of surgery.

Outcome	N (%)		p -Value
	Endoscopic carpal tunnel release ( n  = 683)	Open carpal tunnel release ( n  = 4,234)
Surgical outcomes
Median nerve injury	0 (0.0)	6 (0.1)	0.80
Repeat operation	59 (8.6)	254 (6.0)	0.01
Surgical site infection	6 (0.9)	56 (1.3)	0.44
Wound dehiscence	3 (0.4)	16 (0.4)	> 0.99
Medical outcomes
Anemia	3 (0.4)	21 (0.5)	> 0.99
Arrhythmia (without AFib)	15 (2.2)	90 (2.1)	> 0.99
Atrial fibrillation	25 (3.7)	162 (3.8)	0.92
Blood transfusion	2 (0.3)	24 (0.6)	0.53
Cerebrovascular accident	7 (1.0)	36 (0.9)	0.82
Deep vein thrombosis	1 (0.1)	3 (0.1)	> 0.99
Heart failure	10 (1.5)	86 (2.0)	0.40
Pneumonia	9 (1.3)	54 (1.3)	> 0.99
Renal failure	4 (0.6)	32 (0.8)	0.81
Respiratory complications	2 (0.3)	17 (0.4)	0.93
Pulmonary embolism	0 (0.0)	18 (0.4)	0.17
Sepsis	2 (0.3)	29 (0.7)	0.35
Urinary tract infection	26 (3.8)	124 (2.9)	0.26

Abbreviation: AFib, atrial fibrillation.

Multivariate Analysis of Repeat Procedures

Comorbidities that met the study criteria for multivariate analysis included chronic pulmonary disease, coagulopathy, drug abuse, metastatic cancer, obesity, paralysis, psychosis, and smoking. Although univariate analysis revealed increased odds of repeat operation in the ECTR group, on multivariate analysis, this difference was not statistically significant after controlling for comorbidities (odds ratio = 2.24; 95% confidence interval, 0.524–6.629; p  = 0.20).

Discussion

Among patients with RA, both those treated with ECTR and those who had OCTR had a high rate of revision surgery compared with rates reported in the general population. ^{19 20} Rates of infection, nerve injury, and wound dehiscence were similar between the groups. Patients in the ECTR group had a significantly higher likelihood of requiring a repeat procedure within 90 days of the initial procedure, but this difference was not statistically significant after controlling for comorbidities.

ECTR has previously been identified as a risk factor for revision CTR. In a retrospective review of 9,417 CTRs (with an overall 1.3% revision rate), initial endoscopic surgery was independently associated with higher odds of revision surgery. ²¹ In another retrospective cohort study examining 1-year revision rates and outcomes of 4,338 patients who underwent ECTR or OCTR, ECTR was associated with a 2.96 times greater likelihood of requiring revision surgery compared with OCTR. ²² Our study found similar trends in univariate analysis, but after controlling for comorbidities within the population with RA, these results were not statistically significant. Increasingly, the literature suggests that the merits of ECTR (including lower rates of postoperative infection and wound dehiscence than OCTR) must be weighed against an increased risk of requiring revision surgery. ²³

Our analysis found very high 90-day revision rates in both the OCTR and the ECTR groups in patients with RA (6.0% and 8.6%, respectively). Previous studies have identified RA as an independent risk factor for revision, although the literature is limited. In a matched case–control analysis, RA and smoking were independently associated with revision CTR, irrespective of initial release method. ²¹ However, in the study by Carroll et al, RA was not associated with a higher rate of revision CTR. ²² High rates of revision in patients with RA may be the result of edema and flexor tenosynovitis in the carpal canal. ²⁴ The inflammation might lead to incomplete release or increased scarring and recurrent symptoms postoperatively. ECTR has inherent limitations when it comes to performing additional procedures such as tenosynovectomy, so it may be more appropriate to utilize the open approach in patients with RA who present with significant synovitis. ¹⁰ OCTR provides direct visualization and the ability to remove inflamed synovial tissue, thereby reducing recurrence risk and potentially improving outcomes.

Altered patterns of median nerve eletromyographic findings are present in CTS in patients with RA, diabetes mellitus, and hypothyroidism (compared with patients with idiopathic CTS) across the range of disease severity, ²⁵ and real-time tissue elastography has shown that median nerve stiffness is increased at baseline in patients with RA. ²⁶ These studies suggest the possibility of an intrinsic difference in the nerve tissue microenvironment that could also be related to a higher rate of revision in patients with RA. There has been debate regarding whether differences between ECTR and OCTR outcomes are impacted by patient selection. ²⁷ In our study, there were no statistically significant differences in rates of common medical comorbidities (such as chronic kidney disease, hypothyroidism, and diabetes mellitus) between the ECTR and OCTR cohorts. Our study demographics resemble those of Devana et al, who used the PearlDiver database to examine demographics and CTR trends in more than 500,000 patients. ²³

Our study has several limitations. With a niche patient population and only a 4-year study window, the sample size is limited. In the future, a larger sample size of this patient population may yield more significant results. We acknowledge the database's limitation in controlling for contralateral CTRs, given the absence of specific CPT codes for sides. However, this constraint is uniform across both ECTR and OCTR groups, suggesting comparable frequencies of contralateral surgeries. Consequently, even if contralateral-sided CPT codes were identified, their occurrence would be expected to be equivalent in the two groups. In addition, we were unable to ascertain specific reasons for revision or intraoperative findings at time of revision. However, the primary strength of the study was the use of the PearlDiver database, which enabled us to isolate a specific patient population that had not been previously examined in depth and to study revision rates, which was noted as a limitation in previous literature. ²³ Future study should prospectively investigate trends and etiologies behind this high rate of revision release in RA patients and substantiate the trend of an increased revision rate in ECTR among RA patients.

Conclusion

This study demonstrates an increased likelihood of 90-day revision procedures in patients with RA who underwent ECTR versus OCTR. There were no significant differences in comorbidities between the two study groups. Future studies should include further evaluation of patient outcomes and reasons for revision within this subset of patients.

Funding Statement

Funding This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.