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Corresponding author: M.C. Jansen, MSc, Department of Plastic, Reconstructive and Hand Surgery, Erasmus Medical Center, s-Gravendijkwal 230, Room EE 15.89, 3015 CE Rotterdam, the Netherlands.
Department of Plastic, Reconstructive and Hand Surgery, Rotterdam, the NetherlandsDepartment of Rehabilitation Medicine, Erasmus Medical Center, Rotterdam, the Netherlands
Department of Plastic, Reconstructive and Hand Surgery, Rotterdam, the NetherlandsDepartment of Rehabilitation Medicine, Erasmus Medical Center, Rotterdam, the Netherlands
Department of Plastic, Reconstructive and Hand Surgery, Rotterdam, the NetherlandsDepartment of Plastic, Reconstructive and Hand Surgery, Xpert Clinic, Rotterdam, the Netherlands
Department of Plastic, Reconstructive and Hand Surgery, Rotterdam, the NetherlandsDepartment of Plastic, Reconstructive and Hand Surgery, Xpert Clinic, Rotterdam, the Netherlands
Department of Plastic, Reconstructive and Hand Surgery, Rotterdam, the NetherlandsDepartment of Plastic, Reconstructive and Hand Surgery, Xpert Clinic, Rotterdam, the Netherlands
Department of Plastic, Reconstructive and Hand Surgery, Rotterdam, the NetherlandsDepartment of Rehabilitation Medicine, Erasmus Medical Center, Rotterdam, the Netherlands
Carpal tunnel release (CTR) is typically offered to symptomatic patients with electrophysiological abnormalities when night orthoses no longer prevent waking with numbness and preferably before there is any static numbness, weakness, or atrophy. The ability to predict the amount of symptom relief after CTR could be beneficial for managing patient expectations and, therefore, improve treatment satisfaction. Therefore, the aim of this study was to identify predictors for symptom relief after CTR and to determine their contribution to symptom relief at 6 months after surgery.
Methods
A total of 1,049 patients who underwent CTR between 2011 and 2015 at 1 of 11 Xpert Clinics in the Netherlands were asked to complete online questionnaires at intake and 3 and 6 months after surgery. Patient demographics, comorbidities, and baseline scores were considered potential predictors for the amount of symptom relief on the Boston Carpal Tunnel Questionnaire (BCTQ) score, which was the primary outcome measure.
Results
A low score on the BCTQ at intake, a codiagnosis of a trigger finger, ulnar nerve neuropathy, trapeziometacarpal joint arthrosis, and instability or arthrosis of the wrist were associated with a smaller improvement in the BCTQ domains after a CTR at 6 months after surgery and accounted for 35% to 42% of the variance on the BCTQ domains in our multivariable regression models.
Conclusions
In this study, we showed that clinical severity of carpal tunnel syndrome at intake is the most important factor in estimating symptom relief after surgical treatment. Furthermore, this study contributes to a more precise understanding of the capabilities of CTR in relieving symptoms for different subgroups of patients. Results of our study can be used to manage patient expectation on symptom relief from CTR.
The Journal of Hand Surgery will contain at least 2 clinically relevant articles selected by the editor to be offered for CME in each issue. For CME credit, the participant must read the articles in print or online and correctly answer all related questions through an online examination. The questions on the test are designed to make the reader think and will occasionally require the reader to go back and scrutinize the article for details.
The JHS CME Activity fee of $15.00 includes the exam questions/answers only and does not include access to the JHS articles referenced.
Statement of Need: This CME activity was developed by the JHS editors as a convenient education tool to help increase or affirm reader’s knowledge. The overall goal of the activity is for participants to evaluate the appropriateness of clinical data and apply it to their practice and the provision of patient care.
Accreditation: The American Society for Surgery of the Hand (ASSH) is accredited by the Accreditation Council for Continuing Medical Education (ACCME) to provide continuing medical education for physicians.
AMA PRA Credit Designation: The ASSH designates this Journal-Based CME activity for a maximum of 1.00 AMA PRA Category 1 Credits™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.
ASSH Disclaimer: The material presented in this CME activity is made available by the ASSH for educational purposes only. This material is not intended to represent the only methods or the best procedures appropriate for the medical situation(s) discussed, but rather it is intended to present an approach, view, statement, or opinion of the authors that may be helpful, or of interest, to other practitioners. Examinees agree to participate in this medical education activity, sponsored by the ASSH, with full knowledge and awareness that they waive any claim they may have against the ASSH for reliance on any information presented. The approval of the US Food and Drug Administration (FDA) is required for procedures and drugs that are considered experimental. Instrumentation systems discussed or reviewed during this educational activity may not yet have received FDA approval.
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Disclosures for this Article
Editors
Jennifer Moriatis Wolf, MD, has no relevant conflicts of interest to disclose.
Authors
All authors of this journal-based CME activity have no relevant conflicts of interest to disclose. In the printed or PDF version of this article, author affiliations can be found at the bottom of the first page.
Planners
Jennifer Moriatis Wolf, MD, has no relevant conflicts of interest to disclose. The editorial and education staff involved with this journal-based CME activity has no relevant conflicts of interest to disclose.
Learning Objectives
Upon completion of this CME activity, the learner should achieve an understanding of:
•
Those factors predictive of outcome after carpal tunnel release
•
Which factors have the greatest impact on how patients function postsurgical carpal tunnel release
Deadline: Each examination purchased in 2018 must be completed by January 31, 2019, to be eligible for CME. A certificate will be issued upon completion of the activity. Estimated time to complete each JHS CME activity is up to one hour.
It has already been shown that surgical treatment for carpal tunnel syndrome (CTS) is generally more effective than nonsurgical treatment (such as orthosis fabrication or corticosteroid injections) in terms of recurrence rate, improvement of symptoms, and hand function.
Although the main goals of carpal tunnel release (CTR) are to resolve symptoms of a sensory disturbance and prevent further progression of disease, some patients continue to have symptoms after surgery.
Although clinical trials can establish whether a treatment is effective on average, further research is needed to improve the predictability of outcomes after surgical treatment for CTS in individual patients.
The ability to predict symptom relief after CTR is desirable because it could help manage patient expectation of the treatment and, therefore, improve self-reported postoperative well-being.
it is at present difficult to predict the outcome after CTR for individual patients with CTS.
Therefore, the aim of this study was to identify those factors that can predict the amount of symptom relief after surgical treatment and to determine the contribution of these factors in predicting the amount of symptom relief for individual patients. By identifying these predictive factors, our goal is to create a risk model to quantify the amount of symptom relief when patients are treated surgically for CTS.
Materials and Methods
Study sample
All patients with CTS who were offered surgical treatment between November 2011 and November 2015 in a hand clinic (Xpert Clinic, The Netherlands) were asked to complete online questionnaires in our Web-based outcome registration system at intake and at 3 and 6 months after surgery. Xpert Clinic is a group of specialized clinics in 11 locations throughout the Netherlands with, at the time of the study, 12 European board-certified hand surgeons performing procedures.
We included patients who received a CTR and had filled-in the Boston Carpal Tunnel Questionnaire
(BCTQ) as part of routine clinical care at intake and at 6 months after surgery. We excluded patients with previous surgical treatment for CTS on the ipsilateral hand. In patients who underwent bilateral CTR, only the first treated hand was included. For this study, we decided not to exclude patients with specific comorbidities or concomitant surgeries because these factors could be potential predictors of symptom relief after CTR. We adhered to the STrengthening the Reporting of OBservational studies in Epidemiology (STROBE) guidelines. Furthermore, the study was approved by the local institutional review board and written informed consent was obtained from all patients.
Treatment
All patients underwent an open CTR. Subsequently, all patients received standard postoperative care, which consisted of 3 to 5 days of bandages and a sling around the operated hand. After this, standardized hand therapy, consisting of nerve and tendon gliding exercises, was started by a hand therapist. Patients were seen at our outpatient clinic within 14 days after surgery to monitor progress and to remove sutures.
Measurements
Baseline characteristics
We collected sociodemographic data before surgery from all patients including age, sex, hand dominance, duration of symptoms, body mass index, occupation, and smoking and alcohol usage. Patients were diagnosed with CTS by a physician based on a combination of symptoms, physical examination findings, and electrodiagnostic testing. In addition, information on the presence of comorbidities was retrieved from the medical record. Comorbidities were diagnosed by a physician based on the medical history, physical examination, radiographic imaging, or electrodiagnostic testing. We defined that comorbidities and concomitant procedures needed a minimum of 10 cases, within the sample, to be included in the analyses. Moreover, the comorbidities ulnocarpal impingement, scaphoid nonunion collapse wrist, pisotriquetral arthrosis, distal radioulnar arthrosis, and scapholunate dissociation were grouped under the variable “instability and/or arthrosis of the wrist.” Cubital tunnel syndrome, Guyon canal syndrome, and unspecified ulnar nerve neuropathy were also grouped under a separate “ulnar nerve neuropathy” variable.
Primary outcome measurement: BCTQ
To assess the symptom intensity of CTS, patients filled out the BCTQ (Dutch Language Version
: 1, no complaints; 5, maximum complaints possible) at baseline and 3 and 6 months after surgery. The BCTQ covers 2 domains; the symptom severity scale (SSS) and the functional status scale (FSS), including 11 and 8 items, respectively.
Complications
Complications were registered during a 6-month period after surgery. These included infections treated with antibiotics, wound dehiscence, iatrogenic median nerve injury, and postoperative bleeding.
Statistical analysis
A proportion of the data from the included patients had missing values owing to nonresponse. At baseline, there was a proportion of nonresponse for the following variables: body mass index (33% missing), duration of symptoms (18% missing), smoking status (33% missing), and alcohol intake (33% missing). Nonresponse for all other baseline characteristics was 0% to 3%. Regarding the outcome measurements, there was a nonresponse of 0%, 8%, and 0% for the BCTQ at baseline, 3 months, and 6 months, respectively. Because information on the presence of comorbidities and concomitant surgery was retrieved from the medical record for every patient, we had no missing data for these variables. However, it should be noted that some information might not have been well documented within the medical records.
Because of the proportion of missing values and to check for selection bias in our inclusion criteria, a nonresponder analysis for baseline variables was performed (Table E1, available on the Journal’s Web site at www.jhandsurg.org). This analysis was done by conducting analyses of variance, chi-square statistics, and unpaired t tests. After Bonferroni correction for multiple testing, we concluded that the missing data were independent of both observable and unobservable variables and could, therefore, be classified as missing completely at random.
was used to impute the missing values at baseline and follow-up 10 times. The collected data were used as auxiliary variables in our imputation model. Auxiliary variables are variables that are not imputed during the imputation process but are used to impute the missing values.
Bivariable analyses were done to identify potential predictive baseline factors for clinical outcome, defined as the difference between scores at baseline and at 6 months after surgery on the SSS score, the FSS score, and the total BCTQ score. From these bivariable analyses, all associated variables with a significance of P less than .20 were considered for a backward multivariable regression analysis. Subsequently, variables with a pooled significance level of less than .05 were used in the final multivariable models.
Because the convergent pattern of the postoperative courses of the different subgroups of patients presented in Figure 1 might be partly explained by regression to the mean, a correction for regression to the mean was done to adjust the postoperative scores of the SSS, FSS, and BCTQ-total by using the method suggested by Kelly and Price.
Figure 1A Postoperative course of the BCTQ-SSS, B BCTQ-FSS, and C the BCTQ-Total score of subgroups of patients grouped on their score at intake, corrected for regression to the mean. The error bars represent the standard error of the mean.
Between November 2011 and November 2015, 2,748 patients underwent a primary CTR. After exclusions, the cohort consisted of 1,049 patients (Fig. 2). Baseline characteristics of the included patients can be found in Table 1.
Figure 3 shows a significant mean improvement on all primary and secondary outcomes at 6 months after surgery and shows the distributions of these outcomes at intake and 6 months after surgery. After 6 months, 985 patients (93.8%) showed improvement on the BCTQ-total score with a mean improvement of 1.15 points (± 0.63). However, 64 patients showed a deterioration on the BCTQ-total score at 6 months with a mean increase of 0.31 (± 0.26). Furthermore, there were 21 complications in 20 patients, consisting of 14 infections and 6 wound dehiscences. One patient had an infection and a wound dehiscence. All 20 patients with a complication did not show deterioration on the BCTQ-total score at 6 months after surgery.
Figure 3Pre- and postoperative distributions of the A BCTQ-FSS, B the BCTQ-SSS, and C the BCTQ-total score within the study population at intake and 6 months after surgery, with the y axis representing the frequency of the different scores situating on the x axis. Values in the right upper corner represent t test P values and the deltas for the mean differences between the intake and 6 month postoperative score with the corresponding SD.
Several potential predictive factors were identified from our bivariable analyses (Table 2). Subsequently, these potential predictive factors were used in creating our multivariable models (Table 3). The multivariable models could explain 42%, 38%, and 35% of the variance in the model for the change score of the BCTQ-SSS, BCTQ-FSS, and BCTQ-total score, respectively, at 6 months. Generally, a more severe score at intake was predictive for a greater improvement on the score at 6 months for the BCTQ-SSS score, whereas the presence of trapeziometacarpal joint arthrosis, a trigger finger, ulnar nerve neuropathy on the ipsilateral hand and a high BCTQ-FSS score at intake were predictive for a smaller improvement on the BCTQ-SSS score at 6 months after surgery. Likewise, a more severe score at intake and a more physically demanding job were predictive for greater improvement at 6 months on the BCTQ-FSS score, whereas the presence of trapeziometacarpal joint arthrosis, a trigger finger, and instability or arthrosis of the ipsilateral hand were predictive for a smaller improvement on the BCTQ-FSS score at 6 months after surgery. For the BCTQ-total score at 6 months, a more severe score at intake for the BCTQ-SSS and the BCTQ-FSS were predictive for a greater improvement, whereas the presence of a trigger finger or trapeziometacarpal joint arthrosis was predictive for a smaller improvement compared with the score at intake.
Table 2Bivariable Analyses With Correlation Coefficients Representing the Relation Between Baseline Variables and Surgical Effect on the BCTQ Domains
Table 3Multivariable Regression Analysis With Beta Coefficients Representing the Relation Between Baseline Variables and the Surgical Effect on the BCTQ Domains
Figure 1 further illustrates that the clinical severity of CTS at intake is the most important factor in estimating the effect of surgical treatment. This figure shows the effect of surgery on the BCTQ scores after 3 and 6 months for subgroups of patients defined by their score at intake, corrected for regression to the mean. This figure also indicates that patients with severe CTS symptoms at baseline have approximately the same level of residual symptoms at 6 months after surgery as those with less severe CTS symptoms at baseline.
Discussion
In this study, we showed that clinical severity of CTS at intake is the most important factor in estimating the symptom relief after surgical treatment because patients with more severe CTS at intake experienced greater effect of CTR on the BCTQ. Although the amount of symptom relief after CTR is higher for patients with more severe CTS, these patients might also have more residual symptoms. However, Figure 1 shows that the amount of residual symptoms at 6 months after surgery in patients with severe CTS symptoms at baseline is close to the amount of residual symptoms at 6 months after surgery of patients with less severe CTS symptoms at baseline. By using multivariable models, we could explain 37% to 41% of the variation in treatment effect on the BCTQ. This means that the majority of the variation between the outcomes of different patients cannot be explained by the variables included in the present study.
This study confirms that surgical treatment of CTS is, on average, effective for improving function and symptom intensity.
However, our study also shows that mean improvement might not be a relevant measure for individual patients because of the wide variation in symptom relief between individual patients. Our study also shows that the BCTQ score might be influenced by the presence of other, unrelated conditions. The presence of comorbidities might, therefore, not be predictive for the response to CTR because patients with these comorbidities might also have been responding to the BCTQ for their persistent symptoms related to these comorbidities. This could mean that the BCTQ is an insensitive outcome measure because it does not only reflect median nerve dysfunction. Therefore, patients with multiple comorbidities of the hand should also be clearly counseled that they have symptoms related to more than 1 etiology and that CTR is meant to address only the symptoms related to the median nerve compression. This information could be of importance in adjusting the individual patient’s expectations of surgical treatment for CTS.
Although we tested 28 variables, only a few variables were found to have predictive value for the effect of surgery on the BCTQ-score. At present, few and relatively small studies have performed similar analyses. Conzen et al
found similar results in the way that the amount of improvement after CTR is largely independent of sociodemographic characteristics. Moreover, our study is in line with that of Burke et al
who found that patients with more severe symptoms, as determined by patient self-assessment at intake, have a greater improvement in the symptom severity and hand function after surgery. However, this finding might also be explained as a characteristic of the imperfect measurement scales of the BCTQ.
The lack of predictive value of most of our evaluated baseline characteristics, as well as the approximately 60% unexplained variance, may indicate that other variables that were not examined play a role. For example, multiple studies have shown that mental health plays an important role when evaluating treatment effect on self-reported upper extremity health.
In addition, preoperative expectations influence postoperative patient-reported outcomes and could be of importance when predicting success of CTR in an individual.
Furthermore, it could be that the BCTQ shows a relatively small change because of other comorbidities that are not treated by the CTR influencing its score. Therefore, patient expectations of the effect of CTR on other comorbidities of the hand should be addressed before surgery. Future research should focus on the role of nonphysical factors in predicting treatment outcome after CTR as well as on developing more valid and sensitive outcome measures of CTS.
Several limitations of our study should be considered. First, some comorbidities present within our study sample could have been missed by the physician and, therefore, remained undiagnosed. Second, because the completion of our questionnaires in daily clinical practice was voluntary, we have a high amount of missing data. Because of the amount of missing data, we could not conduct a complete case analysis and only identified 40% of our CTS patients as eligible for inclusion. Because of this missing data, our study sample might not be a valid representation of our CTS patient population and imputing the data could then give misleading results.
However, a nonresponder analysis indicated that the missing data pattern was at random and that there were no differences between included and excluded patients at baseline. We therefore assumed that our study sample is a valid representation of our CTS patient population. Third, our study lacked information on nerve conduction study results. At Xpert Clinic, all patients receive electrodiagnostic testing as a part of routine practice for CTS. However, the outcomes of electrodiagnostic testing were not reported in a consistent and standardized format. Therefore, this information was of insufficient quality to be included in our analyses. Although the predictive value of electrodiagnostic measurements in predicting surgical outcome after CTR is heavily debated in the literature and does not seem to be of additional value in predicting surgical outcome,
information on median nerve conduction might have improved the explained variance of our model. Fourth, information on chronic pain and centralized pain conditions such as fibromyalgia and complex regional pain syndrome was also not accessible in a consistent and accessible format. Fifth, CTR procedures in our cohort were performed by specialists highly trained in hand surgery and that may lead to a larger effect on the BCTQ than procedures performed by other medical specialists. However, because CTR is considered a relative simple procedure, this is not likely to influence the generalizability of the results of our study. Sixth, the BCTQ might not be able to distinguish between symptoms that are permanent, such as static numbness, from those that are correctable, such as intermittent numbness. Also, caution should be advised for patients who have asymptomatic median nerve entrapment. In addition, although Figure 1 is corrected for regression to the mean, the postoperative course of the BCTQ scores of subgroups of patients might be influenced by ceiling and floor effects of the BCTQ.
In conclusion, this study contributes to a more precise understanding of the capabilities of surgical treatment in relieving symptoms and improving function for different subgroups of patients as well as the management of expectations. However, a significant proportion of the variability in symptom relief remains unexplained. Furthermore, our study shows that the BCTQ might be an insensitive outcome measure because it may not only reflect median nerve dysfunction. We suggest that future research on predictive factors focus more on nonphysical factors such as mental health, preoperative expectations, and disease awareness. This way, patients at risk for a low postoperative satisfaction can be identified and targeted for expectation management. In addition, future research should focus on developing more valid measures so that the evaluation of outcomes in CTS patients is less influenced by unrelated comorbidities of the hand.
Acknowledgments
We want to thank the patients and physicians that participated in this study.
Appendix
Table E1Nonresponder Analysis for Completing the BCTQ With the Variables Representing Patient Characteristics at Intake
Baseline Characteristics
Nonresponder Analyses (n = 2,748)
Responders at Intake and 6 Mo (n = 1,049)
Responders at Intake and Nonresponders at 6 Mo (n = 942)
Nonresponders at Intake and Responders at 6 Mo (n = 93)
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