STRONG RECOMMENDATION There were ten high and five moderate quality studies supporting the use of either the CTS-6, NCV/EMG, and ultrasonography for the diagnosis of carpal tunnel syndrome (High-Quality: Wong 2004, Draghici 2020, Martikkala 2021, Falsetti 2022, Fu 2015, Moran 2009, Fowler 2014, Graham 2008, Wang 2020, Chen 2021) (Moderate-Quality: Mehrpour 2016, Mallouhi 2006, Naranjo 2007, Abdel Ghaffar 2012, Kanagasabai 2022). Although there was heterogeneity in the patient populations and comparisons for different studies there was strong and consistent evidence supporting these tools in diagnosing carpal tunnel syndrome. For example, Fowler 2014 studied ultrasonography versus NCV/EMG using CTS-6 as a reference standard (a tool that encompasses signs and symptoms used by clinicians to diagnose carpal tunnel syndrome) and found a positive predictive value of ultrasound and NCV/EMG of 94% and 89% respectively, and a negative predictive value of 82% and 80% respectively. In Fu 2015, the authors used clinical diagnosis of carpal tunnel along with NCV/EMG to test the use of ultrasonography and found a sensitivity and specificity of 91% and 93% respectively. In Graham 2008, NCV/EMG confirmation of carpal tunnel syndrome was used as the reference standard to test the correlation of the pre-test probability of having carpal tunnel syndrome using the CTS-6. The correlation of having carpal tunnel syndrome by using the CTS-6 compared to NCV/EMG diagnosis was as high as 0.9. There was no strong evidence demonstrating clinical superiority between diagnostic tools in this review, therefore we do not propose superiority of one test over the other, however, we highlight the use of CTS-6 as a diagnostic tool and/or screening tool, and the utilization of ultrasound or NCV/EMG as diagnostic tests when the positive predictive value when using the CTS-6 is low.
Benefits/Harms of Implementation
There is no specific research focused on the benefits/harms of the various modalities used to diagnose carpal tunnel syndrome that were found in this review. Roe (2022) found that from a shared decision-making perspective, patients want decision making for the testing for carpal tunnel diagnosis (ultrasound or NCV/EMG) to be equally collaborative. Harms of utilization of NCV/EMG include the unpleasant and invasive experience of the test, in addition to delays in treatment and costs. Similar harms related to delays and costs may be present for the utilization of ultrasound.
Outcome Importance
There was no evidence from this review that provided guidance for how the diagnostic tool used affected clinical outcomes.
Cost Effectiveness/Resource Utilization
While not the purpose of this systematic review, the guideline informs how future studies assess the cost effectiveness of testing for carpal tunnel syndrome.
Future Research
Future investigation can focus on differences in cost and patient outcomes based on diagnostic tools used.
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