Ultrasound as a First-line Test in the Diagnosis of Carpal Tunnel Syndrome: A Cost-effectiveness Analysis

Abstract

Background The American Academy of Orthopaedic Surgeons (AAOS) recommends that surgeons obtain a confirmatory test in patients for whom carpal tunnel surgery is being considered. The AAOS, however, does not specify a preferred test. Ultrasound reportedly causes less patient discomfort and takes less time to perform, while maintaining comparable sensitivity and specificity to electrodiagnostic testing (EDX). Questions/purposes We determined whether ultrasound as a first-line diagnostic test is more cost-effective than using EDX alone or using ultrasound alone: (1) when used by a general practitioner; and (2) when used by a specialist. Methods A fictional population of patients was created and each patient was randomly assigned a probability of having true-positive, false-positive, true-negative, and truepositive ultrasound and EDX tests over an expected range of sensitivity and specificity values using Monte Carlo methods. Charges were assigned based on Medicare charges for diagnostic tests and estimates of missed time from work. Results The average charge for the use of ultrasound as a first-line diagnostic test followed by EDX for confirmation of a negative ultrasound test was $562.90 per patient in the general practitioner scenario and $369.50 per patient in the specialist scenario, compared with $400.30 and $428.30 for EDX alone, respectively. Conclusions The use of diagnostic ultrasound as a firstline test for confirmation of a clinical diagnosis of carpal tunnel syndrome is a more cost-effective strategy in the specialist population and results in improved false-negative rates in the generalist population despite increased cost. Level of Evidence Level III, economic and decision analyses. See the Guidelines for Authors for a complete description of levels of evidence.

Sonography in carpal tunnel syndrome with normal nerve conduction studies

“…The cardinal diagnostic feature is absolute or relative enlargement of the median nerve proximal to the edge of the flexor retinaculum; anatomic variants and space‐occupying lesions (e.g., ganglion cysts or aberrant muscles) may also be visualized . Some investigators have proposed HRUS as a first‐line study, replacing NCS, as it is painless and possibly less expensive . Still, the technique is less well standardized, and consensus regarding optimal criteria for abnormality is insufficient …”

Baseline Characteristics of the Median Nerve on Ultrasound Examination

“…4 In addition, the use of ultrasound as a firstline test in the diagnostic algorithm is a more cost-effective approach than use of electrodiagnostic testing alone. 3 The determination of normal baseline values is critical for the use of ultrasound for the diagnosis of CTS. Much of the literature is based on relatively small series that lack significant power to accurately define baseline values within a narrow confidence interval.…”

Carpal tunnel syndrome – current controversies

“…However, it has been recommended by the American Academy of Orthopaedic Surgeons (AAOS) that a confirmatory test be used prior to CTD. 7 EDT remains the traditional investigation of choice in diagnosing CTS. It has a high sensitivity and specificity but is uncomfortable for patients and is time-consuming.…”

“…7 Results were based on average USA Medicare tariffs of the upper extremity ($367.80) compared with EDT ($428.30) in either a general practice or specialist setting. The need for the study was rationalized by the relatively comparable sensitivity and specificity rates of US and EDT accompanied by approximately 10e20% false-negative rates for each modality.…”