Effects of Varying Case Definition on Carpal Tunnel Syndrome Prevalence Estimates in a Pooled Cohort

ObjectiveTo analyze differences in carpal tunnel syndrome (CTS) prevalence using a combination of electrodiagnostic studies (EDSs) and symptoms using EDS criteria varied across a range of cutpoints and compared with symptoms in both ≥1 and ≥2 median nerve-served digits.DesignPooled data from 5 prospective cohorts.SettingHand-intensive industrial settings, including manufacturing, assembly, production, service, construction, and health care.ParticipantsEmployed, working-age participants who are able to provide consent and undergo EDS testing (N=3130).InterventionsNone.Main outcome measuresCTS prevalence was estimated while varying the thresholds for median sensory latency, median motor latency, and transcarpal delta latency difference. EDS criteria examined included the following: median sensory latency of 3.3 to 4.1 milliseconds, median motor latency of 4.1 to 4.9 milliseconds, and median-ulnar sensory difference of 0.4 to 1.2 milliseconds. EDS criteria were combined with symptoms in ≥1 or ≥2 median nerve-served digits. EDS criteria from other published studies were applied to allow for comparison.ResultsCTS prevalence ranged from 6.3% to 11.7%. CTS prevalence estimates changed most per millisecond of sensory latency compared with motor latency or transcarpal delta. CTS prevalence decreased by 0.9% to 2.0% if the criteria required symptoms in 2 digits instead of 1.ConclusionsThere are meaningful differences in CTS prevalence when different EDS criteria are applied. The digital sensory latency criteria result in the largest variance in prevalence