Study Population
This retrospective study was conducted after obtaining approval from our institutional review board. Between May 2004 and May 2007, 282 patients with the diagnosis of carpal tunnel syndrome without a known cause were recommended for carpal tunnel release by a single hand surgeon (H.S.G.) at an urban, tertiary referral hospital. We excluded patients who had associated diseases, including cervical radiculopathy, cubital tunnel syndrome, diabetes mellitus, hypothyroidism, chronic renal failure, other peripheral neuropathies, arthritis, and Buerger disease. The average duration of symptoms prior to surgery was greater than thirty months. Surgery was recommended when the clinical symptoms of tingling, pain, or weakness did not improve following at least two months of conservative treatment consisting of splinting and the use of nonsteroidal anti-inflammatory drugs and/or corticosteroid injections. We used a rigid brace to hold the wrist in a neutral position. We did not routinely recommend corticosteroid injections unless a patient refused surgery and asked for a second-best choice or temporary relief, or when the diagnosis was unclear because of multiple sites of nerve compression. Electrodiagnostic studies confirmed the diagnosis in all patients.
During discussions, the operating surgeon briefly explained that (1) the surgical procedure consisted of an open carpal tunnel release performed under local anesthesia on an outpatient basis, (2) there would be three to four days of postoperative splint immobilization and no formal physiotherapy, (3) functional outcomes should include some degree of symptom relief, and (4) complications could include transient weakness, scar, or pillar pain, and, rarely, symptom recurrence and nerve damage. Patients with bilateral involvement were offered a choice of staged or simultaneous surgery. Patients were also given a brochure on carpal tunnel syndrome, and informed consent was obtained when patients decided to undergo surgery.
Of the 282 patients, thirty-six (13%) canceled the scheduled operation during the waiting period, which averaged four weeks. These thirty-six patients were all female homemakers, and none had a Workers' Compensation issue. These thirty-six patients were then contacted by mail and were asked to complete the questionnaire. Three were considered ineligible because they had undergone surgery at other hospitals, and eighteen (55%) of thirty-three returned completed questionnaires, which is slightly lower than the average survey response rate of 60% for patients that has been reported in other medical studies20. Of the 246 patients who underwent surgery, seventy female homemakers were randomly selected as controls and were contacted by mail and asked to complete the survey; thirty-eight (54%) of them returned completed questionnaires. The average time interval between the day when the patient enlisted for surgery and the date of the follow-up questionnaire was thirty months (range, seventeen to forty-two months) for the group that had an operation and thirty-two months (range, sixteen to forty-four months) for the cancellation group. Responses from members of these two groups were analyzed to identify the reasons for choosing to undergo or avoid surgery.
Survey Design
The survey was composed of four parts. In part one, patients answered questions concerning the reasons for choosing or canceling surgery; the questions were "I chose surgery because of the following reasons… " for the operation group, and "I canceled surgery because of the following reasons… " for the cancellation group. Each question was rated by the patient on a 5-point Likert scale (with 1 indicating strong disagreement; 2, disagreement; 3, neutral; 4, agreement; and 5, strong agreement). In part two, the patients were asked to answer questions regarding demographic characteristics, including marital status, experience with surgery, response to nonsteroidal anti-inflammatory treatment or corticosteroid injection, the existence of a caregiver, the distance between home and hospital, annual income, and educational status, and whether they had private health-care insurance that would reimburse medical bills associated with surgery. (In South Korea, all patients are partially covered by the national health system and are personally responsible for approximately 30% of the total medical cost. Patients with private medical insurance can claim a portion or all of the remaining costs from insurance companies.)
In part three of the questionnaire, the questions were based on a questionnaire designed by Trousdale et al.16 regarding preoperative concerns of patients related to total hip and total knee arthroplasty. Patients responded using a 4-point descriptive scale (with 1 indicating he or she was not concerned; 2, somewhat concerned; 3, very concerned; and 4, extremely concerned). Part four investigated current functional status, and patients were requested to complete two validated outcome surveys, the Boston carpal tunnel questionnaire21 and the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire22,23, which also had been completed when the patients first enlisted for surgery. The Boston carpal tunnel questionnaire is a disease-specific status scale that incorporates a symptom severity scale and a functional scale. The symptom severity scale is composed of eleven items that address severity, frequency, and duration of symptoms, whereas the functional status scale is composed of eight questions that assess the difficulty of performing eight daily tasks. Each question offers five possible responses of increasing severity, which are scored from 1 (none) to 5 (most severe); the mean values of all of the items in the Boston carpal tunnel questionnaire were calculated. The DASH quantifies general disabilities related to the upper extremity. The questionnaire contains thirty items; twenty-one concern difficulties with specific tasks, five evaluate symptoms, and one each evaluates social function, work function, sleep, and confidence. The DASH scores are scaled between 0 and 100, with higher scores representing more disability of the upper extremity.
Data Analysis
In part one of the survey, ranks of items associated with the decision to undergo or not to undergo surgery were identified. In part two, sociodemographic characteristics were compared with use of Mann-Whitney U tests for continuous variables and with use of chi-square and Fisher exact tests for categorical variables. In part three, patient concerns were ranked and compared between the groups with use of the Mann-Whitney U test. Finally, in part four, the functional status of the patient was assessed with use of the Boston carpal tunnel21 and DASH questionnaire scores22,23. These scores were compared between the groups and between the time of first enrollment for surgery and the time of the survey, with use of the Mann-Whitney U test and the Wilcoxon signed-rank test. Significance was set at p < 0.05.
For the purpose of retrospective power analysis, a prespecified effect size and the observed variance were used and the power for comparison of the follow-up DASH scores was calculated. The estimate of the pooled standard deviation of the follow-up DASH scores was 9.8. With eighteen patients in the cancellation group and thirty-six patients in the operation group, there was 93% power to detect a difference of 10 points in the DASH scores between the groups. Inasmuch as a 10-point difference in the DASH scores represents a meaningful change (10% of the total score of 100) in clinical outcome status, a difference of 10 points detectable with 93% power provides good assurance that clinically meaningful differences were not missed because of low power.
An assessment of internal consistency among the responses was made to determine whether the responses were sufficiently stable to be considered reliable. The Cronbach alpha coefficient was 0.78 for the symptom domain and 0.81 for the function domain on the Boston carpal tunnel questionnaire and 0.91 for the tasks domain and 0.71 for the symptom domain on the DASH questionnaire. As all coefficient values exceeded 0.6, there was evidence of acceptable internal consistency for the instrument.
Source of Funding
We received no funds to do this study.
In this study, we identified factors that affect the willingness of patients with carpal tunnel syndrome without a known cause to undergo carpal tunnel release. This was done in an attempt to understand the decision-making process from the patient's perspective. Previous studies have identified factors that patients consider when they are deciding to undergo total joint arthroplasty, e.g., future expectation of pain relief, improved walking, restoration of quality of life16,25, fear of surgery26,27, arthritis severity, risks of surgery, the opinions of others14,15, past negative experience with surgery or unwanted treatment, and the advice or apathy shown by health professionals toward surgery19. In the present study, subjective symptoms were found to be the most important reason for undergoing surgery from the patient's perspective. Electrodiagnostic findings tend to affect a physician's choice of treatment9,28,29, but they were not found to be compelling reasons for undergoing surgery from the patient's perspective.
We also compared sociodemographic characteristics, treatment histories, electrodiagnostic findings, and functional status, as assessed by the Boston carpal tunnel and DASH scores, and found no significant difference between the study groups. Previous studies have shown that older people have more unexpressed concerns about orthopaedic surgery30 and are less willing to undergo total joint replacement. Furthermore, the perceptions of the benefits of total joint replacement were less positive among those with a low socioeconomic status, women15, and black Americans as opposed to white Americans31-33. In a study on factors that affect treatment decisions in life-threatening illnesses such as breast cancer, patients who did not accept their physician's treatment recommendations were found to be better educated and more likely to be risk takers34. The present study was composed entirely of Korean women, and thus we were unable to investigate ethnic or sex differences. We speculate that the reason why no differences in patient characteristics were observed in the present study is that carpal tunnel release is perceived as a relatively minor procedure compared with total joint replacement or cancer treatment.
Starting at the greatest concern and going to lesser concerns among those that were significantly different between the groups (Table III), patients who canceled surgery were most concerned about transient weakness of the hand followed by the inability to take care of family, the inability to take care of the home, the inability to pay bills, the family's financial burden, and persistent scar or pillar pain. These findings indicate that patients have financial concerns although they did not rank economic burden as the major reason for cancellation. It should also be noted that patient concerns can be influenced by differences among health-care organizations, as was shown by a study in the United Kingdom, which found that financial considerations had little effect on the decision to cancel surgery17. Regardless of the given health-care system, we believe that, by understanding a patient's concerns, the physician can provide more patient-oriented consultation and enhance the quality of health care17,19.
The Boston carpal tunnel and DASH scores improved in both study groups, and those who canceled or underwent surgery had similar self-reported outcome scores, whereas our expectation was that the two groups would have quite different functional status. We are uncertain whether this similarity was due to real disease improvement because outcome assessments were subjective, and no objective data, such as follow-up electrophysiological studies or physical examinations of muscle atrophy and sensibility, were available. Furthermore, this finding does not mean that all patients who canceled surgery would show improvement; in fact, three of the thirty-six patients who canceled surgery underwent surgery at other hospitals and those with improved function may have been more inclined to complete and return questionnaires. In addition, patients who have symptoms such as night pain and severe tingling sensation often have a diminution in symptoms over time as chronic nerve damage progresses11. Another possible explanation is that those who avoided surgery may have rejected the medicalization of carpal tunnel syndrome or adapted to their disability after realizing that carpal tunnel syndrome is neither life-threatening nor likely to result in progressive paralysis of the upper extremity. A similar pattern of surgery avoidance was observed in a study on total joint surgery, in which patients referred to their arthritic conditions as age normative19. Nevertheless, the finding that the majority of patients who canceled surgery demonstrated no subjective symptomatic or functional deterioration and reported improvements in outcome scores suggests that recommendations for surgery on the basis of patient symptoms is reasonable from the patient's perspective.
This study has several limitations. The first and most notable was that our sample was subject to selection bias; that is, patients who canceled surgery had actually chosen initially to undergo an operation, and thus they may not represent all those who are unwilling to receive operative treatment, such as those who initially refuse surgery. Second, our sample was also subject to responder bias, as those with improved function may have been more inclined to complete and return questionnaires. Third, conservative treatment of only two months before recommending surgery was short, and treatment protocols including injections were not the same for all patients. Fourth, our sample was small and our patients were all female Korean homemakers who had no possibility of claiming compensation, and thus they do not represent the general population with carpal tunnel syndrome. Furthermore, we acknowledge that restricting our investigation to homemakers could weaken the merits of the study, although it may well have reduced the effects of some confounding factors. Fifth, the study was retrospective, and thus it may not accurately provide the true reasons for choosing to undergo or cancel surgery or the real concerns of patients at the time of decision-making. Furthermore, we relied on a restricted number of questions, which may not have embraced all reasons and concerns. Sixth, this study was based on patients treated by one physician, and the use of different indications for surgery and methods of consultation might have resulted in different patient responses. Finally, the Korean language version of the Boston carpal tunnel questionnaire still requires validation in terms of its reliability, responsiveness, and consistency.
Given these limitations, our study showed that subjective symptoms were the most important decision-making consideration for patients with carpal tunnel syndrome. Furthermore, those who canceled the operation had self-reported functional scores that were similar to those who had undergone surgery. 