The CTS-2T: An Assessment of a Modified, Telephone-Based Version of the CTS-6 in the Evaluation of Carpal Tunnel Syndrome.

PURPOSE

Preconsultation electrodiagnostic studies (EDS) are used frequently by hand surgeons. However, EDS can increase health care expenditures and delay access to subspeciality care. Our purpose was to assess the validity of a modified, telephone-based versions of the CTS-6 (the "CTS-3T" and "CTS-2T") in determining a preconsultation diagnosis of carpal tunnel syndrome (CTS).

METHODS

Adult patients scheduled via telephone for an outpatient upper extremity visit were administered the telephone screening instrument by a clinic scheduler. Patients were asked the 2 history components of the CTS-6 (subjective numbness and nocturnal symptoms) and instructed on how to perform the Phalen test. Points assigned to individual phone questions were the same as in the CTS-6. The CTS-6 data from a prior study were used to determine diagnostic thresholds for phone instruments. The 2-item CTS-2T consisted of both history questions and the 3-item CTS-3T also included the Phalen test. Following telephone administration by a clinic scheduler, 1 of 3 hand surgeons administered the CTS-6 during clinic, which served as the reference standard. Sensitivity (Sn), specificity (Sp) and agreement (Cohen's κ) for the CTS-2T and 3T were calculated.

RESULTS

A total of 178 patients were included and 36% had CTS based on the results of the CTS-6. The CTS-2T had a Sn/Sp of 78%/88% whereas for the CTS-3T it was 77%/83%, respectively. Agreement between schedulers and surgeons for diagnosis of CTS was moderate (κ = 0.59; 95% confidence interval, 0.47-0.71) for CTS-3T and substantial for CTS-2T (κ = 0.68; 95% confidence interval, 0.54-0.77). Agreement for the Phalen test was the lowest of the 3 items (κ = 0.18, slight).

CONCLUSIONS

The CTS-2T demonstrated a Sn/Sp of 78%/88% with substantial agreement for the diagnosis of CTS. With high Sn/Sp, surgeons who routinely require preconsultations EDS should consider incorporating the CTS-2T into scheduling pathways, as this telephone screening instrument can accurately identify patients with suspected CTS.

TYPE OF STUDY/LEVEL OF EVIDENCE: Diagnostic II.