Carpal tunnel decompression in the super-elderly

Patients and Methods

A prospectively compiled database of patients undergoing carpal tunnel decompression was examined retrospectively to identify the study cohort. The study centre is the sole provider of hand services to a population of approximately 360 000.¹⁵ Between 2005 and 2012, 1398 consecutive patients were diagnosed with carpal tunnel syndrome. The diagnosis was made by a trained member of the hand service team, using a combination of clinical assessment and nerve conduction studies. Surgical decompression was only offered after failure of conservative measures, which included wrist splints and steroid injection(s). All carpal tunnel decompressions were performed as an open procedure, with most undertaken under local anaesthetic as a day case. Immediate mobilisation was encouraged and patients were reviewed at two weeks for removal of sutures.

Patient demographics, comorbidities, smoking status, clinical signs (Phalen’s test, Tinel’s sign and thenar muscle atrophy¹⁶), nerve conduction studies and limb-specific function (QuickDASH¹⁷) were recorded pre-operatively. Nerve conduction studies were performed by a specialist technician using a Dantec Keypoint Portable Nerve Conduction / EMG machine (Dantec Dynamics, Bristol, United Kingdom). These were reported by a consultant neurophysiologist and conduction defects were classified as mild, moderate or, severe as described by Jenkins et al.¹⁸ The QuickDASH score is a patient-reported outcome measure that consists of 11 self-assessment questions.¹⁷ The resulting score is reported on a scale of 0 to 100, where 0 represents no disability and 100 represents total disability. QuickDASH has demonstrated good reliability, validity and responsiveness when used for patients with upper limb disorders.¹⁹

Patients were then asked to complete a further QuickDASH questionnaire at one year using a postal survey. The absolute change in the score relative to the pre-operative score was calculated, where a positive score (> 0) indicated that a patient’s symptoms had improved and a negative score that their symptoms had worsened. They were also asked to record their level of satisfaction with their surgery using a visual analogue scale (VAS) of 0 to 100, where 0 signified not satisfied and 100 was very satisfied. Patients who defined their level of satisfaction as ≥ 50 were categorised as being satisfied and those reporting a level of satisfaction <  50 were categorised as dissatisfied. This method has previously been used to report the level of patient satisfaction with hip and knee replacement.^20,21

During the study period, pre-operative data were compiled for 1398 carpal tunnel decompressions. However, 642 (45.9%) of these did not have linked outcome assessments at one year recorded and were lost to follow-up. There was no significant difference shown in the case-mix variables between those patients lost to one-year follow-up and those with recorded one-year outcome data (Table I). The study cohort consisted of 756 patients with a mean age of 59 years (24 to 96) and included 579 (77%) women and 177 (23%) men.

Results

There were 97 patients in the super-elderly group with a mean age of 83.7 years (80 to 96, sd 3.4) and 659 patients in the control group with a mean age of 56.0 years (24 to 79, sd 12.2), with similar case-mix variables (Table II). However, super-elderly patients were significantly more likely to suffer with ischaemic heart disease (OR 2.28, 95% CI 1.12 to 4.66) and osteoarthritis (OA) (OR 2.50, 95% CI 1.61 to 3.89) and to have thenar muscle atrophy on examination (OR 9.2, 95% CI 5.8 to 14.6). In contrast, there was a lower rate of smoking (OR 0.17, 95% CI 0.07 to 0.42) in the super-elderly group, who were also less likely to have undergone nerve conduction studies (OR 0.2, 95% CI 0.1 to 0.4). When nerve conduction studies were performed, the super-elderly patients were significantly more likely to have a severe conduction deficit (OR 12.4, 95% CI 3.0 to 51.3).

The mean pre-operative QuickDASH score was 55.4 (0 to 100, sd 20.0), which improved to a mean of 22.2 (0 to 100, sd 22.5) at one year, an overall improvement of 32.1 points (95% CI 30.1 to 34.0; p < 0.001). Both groups were found to show a significant improvement in their QuickDASH scores at one year (Table III). There were, however, no significant differences between the super-elderly and the younger control group in the mean values of QuickDASH scores for pre-operative (difference 0.7, 95% CI –3.6 to 5.0; p = 0.76) and post-operative scores (difference 3.8, 95% CI –1.0 to 8.6; p = 0.12) or for the change between them (difference 3.1, 95% CI –2.4 to 8.7; p = 0.27). Multivariate linear regression was used to control for confounding variables between the groups, and an adjusted difference in the pre-operative, post-operative and change in the QuickDASH score was calculated (Table III). This confirmed that there was no significant difference in the QuickDASH scores between the two groups at any time point, and that the real difference after adjusting for case-mix variables was smaller than that illustrated on univariate analysis.

In all, 21 patients (3%) did not complete the satisfaction question at one year, which left 735 patients who were assessed for level of satisfaction. A total of 631 (86%) patients were satisfied with their outcome, but the remaining 104 (14%) were dissatisfied. The rate of satisfaction was lower in the super-elderly group (84%) compared with the control cohort (86%), but this did not achieve statistical significance (OR 0.82, 95% CI 0.43 to 1.54; p = 0.53). Logistic regression analysis confirmed that, after adjusting for confounding variables, the rate of satisfaction was not significantly different between the two groups (OR 0.78, 95% CI 0.34 to 1.58, p = 0.49).

Discussion

This study shows that the functional outcome and rate of satisfaction in super-elderly patients after carpal tunnel decompression are equal to those of their younger counterparts. There was, however, a greater rate of comorbidity in the super-elderly group and they were more likely to have thenar muscle atrophy. The super-elderly were also less likely to be investigated with nerve conduction studies, and when these were performed, they were more likely to have a severe conduction deficit.

There was a trend towards a greater proportion of women in the super-elderly group, as well as a significantly greater rate of OA and ischaemic heart disease. The higher proportion of women in this group probably reflects the fact that women form a greater proportion of the population with increasing age.²² It is also unsurprising that OA and ischaemic heart disease were more prevalent in the super-elderly, as they are more prevalent in the general population with increasing age.^23,24 By contrast, there was no difference in the rate of diabetes mellitus, thyroid disease or rheumatoid arthritis between the super-elderly and the younger control group, although it might have been expected that these comorbidities would have been more prevalent in the younger group, as they are associated risk factors for carpal tunnel syndrome.²⁵ Hence, it would seem that although diabetes mellitus, thyroid disease and rheumatoid arthritis are risk factors for carpal tunnel syndrome, they do not predispose a patient to an earlier need for carpal tunnel decompression.

Super-elderly patients enjoyed a functional outcome and level of satisfaction equal to those of the younger control group, despite a greater rate of thenar muscle atrophy and severe nerve conduction deficits. Bland²⁶ showed that the outcome was worse for patients with a severe pre-operative nerve conduction deficit: only 47% of his patients described their outcome as successful. In his discussion, Bland²⁶ went on to state that those patients with the most severe conduction deficits were elderly, and that this accounted for their poorer outcome. Although our study supports a greater rate of more severe nerve conduction deficits in the elderly, we found no difference in the level of satisfaction in the super-elderly group compared with that of the younger control group. Townshend, Taylor and Gwynne-Jones²⁷ also found that a more severe nerve conduction deficit was associated with a less complete recovery and persistence of symptoms post-operatively. However, they also illustrated a high level of patient satisfaction despite the persistent symptoms. Our study supports the conclusion of Townshend et al²⁷ and shows a high level of patient satisfaction, despite a greater rate of severe nerve conduction deficits. We have also shown that the functional outcome of the super-elderly is equal to that of younger patients with a less severe nerve conduction deficit. With this evidence, it can be argued that waiting for nerve conduction studies to confirm the severity of the carpal tunnel syndrome will only delay the time to surgical decompression as most patients will have a severe conduction deficit. Consequently, it is now the policy in our unit to list symptomatic super-elderly patients with clinical signs consistent with carpal tunnel syndrome for decompression without nerve conduction studies.

Super-elderly patients showed a significant improvement in their QuickDASH score after carpal tunnel decompression; however, a mean post-operative score of 25.5 one year after operation signifies that there is persistent upper limb disability. This persistent disability was also shown by Atroshi et al,²⁸ who observed a mean post-operative QuickDASH of 23.7 after carpal tunnel decompression in their cohort of 308 patients with a mean age of 55 years, which they attributed to co-existing upper limb conditions. Dowrick et al²⁹ reported that the DASH score also measured disability in patients with lower limb dysfunction, which may have influenced the post-operative QuickDASH score as it includes some items that relate to lower limb function, such as the ability to ‘Carry the shopping bag or briefcase’.¹⁷ A recent study has shown that the QuickDASH score increases (increased disability) with age, and that the mean post-operative score of 25.5 (sd 21.0) that we identified in our super-elderly population is approximately what would be observed in a normal population of the same age (a mean score of 36 for women and 23 for men).³⁰ This suggests that super-elderly patients return to their expected pre-operative ‘normal’ functional status after carpal tunnel decompression. In contrast, the younger control group, with a mean age of 56 years, had a mean post-operative QuickDASH score of 21.7 (sd 22.7), which is more than that expected in a normal population (a predicted score of 16 for women and 12 for men aged between 50 and 59 years).³⁰ It would seem that although these younger patients also have a significant improvement in their function after carpal tunnel decompression, they do not return to their expected population-based normal pre-operative functional status.

This study shows that the rate of satisfaction in the super-elderly patients is equal to that of their younger counterparts. Porter et al¹⁰ found that with increasing age, patients were less likely to be satisfied, finding a satisfaction rate of 66% in patients > 60 years compared with 87% in those patients aged ≤ 60 years. Their study was, however, based on 87 patients, with only 41 of those in the older group, and may have been subject to type I statistical error. Hobby, Venkatesh and Motkur³¹ also showed a lower rate of patient satisfaction with increasing age, and patients > 70 years were significantly less likely to be satisfied, but once again this was based on only 14 patients. More recently, Roushdi et al¹³ have described a satisfaction rate of 58% in a group of patients aged ≥ 80 years, but again this was based on a relatively small cohort of 24 super-elderly patients.

Contrary to these smaller studies, we have shown an equivocal rate of satisfaction of 84% in super-elderly patients. This rate is consistent with that reported by Weber and Rude¹⁴ of 90% for patients aged ≥ 65 years seen in their cohort of 92 carpal tunnel decompressions. Leit, Weiser and Tomaino³² also reported a similar finding for patients aged ≥ 70 years, with a satisfaction rate of 92%. These differing rates of satisfaction in elderly and super-elderly patients may be related to the case-mix variables reported in these studies, such as gender, comorbidity, muscle atrophy and the severity of nerve conduction deficit, which are known to influence the rate of patient satisfaction.⁸ In our study, we adjusted for these confounding variables and believe that the results presented reflect an accurate satisfaction rate for super-elderly patients. It is also interesting to note that Katz et al⁹ did not find age to be a predictor of post-operative satisfaction when adjusting for such confounding variables, which further supports our conclusions.

The retrospective design is a major limitation of this study and may have resulted in a selection bias of the defined super-elderly cohort. Potentially, not all super-elderly patients may have been offered surgical decompression, owing to associated comorbidities or general frailty and conservative measures may have been used. However, surgical decompression was routinely offered to these patients when they were referred to our unit during the study period. A second limitation was the rate of loss at follow-up, with 45.9% of patients lost at one-year functional review. However, no significant difference was identified between those lost at follow-up and the study cohort for patient demographics or pre-operative QuickDASH score. Despite this loss, the reported cohort is the largest in the literature and the demographics are similar to those reported by other authors and support the general applicability of the reported results.^28,33

In conclusion, this study shows that, after carpal tunnel decompression, super-elderly patients enjoy a functional outcome and satisfaction rate equal to those of their younger counterparts. However, super-elderly patients are more likely to have thenar muscle atrophy and a severe nerve conduction deficit at presentation, and for these reasons may warrant decompression on a relatively urgent basis.