Reliability and validity of the elevated arm stress test in the diagnosis of neurogenic thoracic outlet syndrome.

OBJECTIVES: The objective of this retrospective analysis of prospectively collected data was to assess the test-retest reliability and validity of the elevated arm stress test (EAST) as measured by the duration in a cohort of patients with suspected neurogenic thoracic outlet syndrome (NTOS). METHODS: Patients evaluated for NTOS between January 2017 and September 2018 were identified. Test-retest reliability by the intraclass correlation coefficient was determined for duration of the EAST. For the validity analysis, patients were classified in a proven NTOS group or a symptomatic control group without NTOS using the Society for Vascular Surgery reporting standards and the outcome of thoracic outlet decompression surgery. A receiver operating characteristic curve was made for the duration of EAST. The area under the curve, and positive and negative predictive values were calculated for the EAST. RESULTS: In total, 428 patients with suspected NTOS were retrospectively analyzed. Of these patients, 61 were excluded because no EAST data was available. Another 101 patients were excluded because of inconclusive reporting standards, arterial or venous TOS, or because thoracic outlet decompression surgery was not performed or had a negative result. The validity analysis in the remaining 266 patients showed an area under the curve for the duration of the EAST of 0.62 (95% confidence interval, 0.55-0.69). The positive predictive value of the duration ranged between 65% and 66%, and the negative predictive value between 53% and 58%. For the test-retest reliability analysis, 118 patients were excluded because they performed only one measurement in a 100-day time period. Analysis in the remaining 148 patients showed an intraclass correlation coefficient value of 0.65 (95% confidence interval, 0.55-0.74) for duration. CONCLUSIONS: The EAST measured by the duration showed a moderate test-retest reliability, but the discriminative value was low in the diagnosis of NTOS. The outcome of the EAST measured by the duration should be used with caution.

Reliability and validity of the standardized elevated arm stress test in the diagnosis of neurogenic thoracic outlet syndrome.

OBJECTIVE: We developed a standardized elevated arm stress test (sEAST) meter to standardize patients' posture and measure additional grip and fatigue parameters. In the present prospective cohort study, we aimed to determine the reliability and validity of the sEAST in the diagnosis of neurogenic thoracic outlet syndrome (NTOS). METHODS: Patients evaluated for NTOS between October 2018 and February 2020 were included and performed the sEAST. The patients were classified into a proven NTOS group or a symptomatic control group using the reporting standards for NTOS and the outcome of thoracic outlet decompression surgery. Healthy persons were recruited as an asymptomatic control group. The test-retest reliability, area under the receiver operating characteristic curve, and positive and negative predictive values were calculated for each sEAST parameter. RESULTS: A total of 426 patients with suspected NTOS and 147 healthy controls had performed the sEAST. The validity analysis was performed with data from 111 patients with proven NTOS, 94 symptomatic controls, and 147 asymptomatic controls. The reporting standards were inconclusive for 116 patients; 77 patients had been excluded because thoracic outlet decompression surgery had not been performed or was unsuccessful, and 28 because they had arterial or venous thoracic outlet syndrome. The area under the receiver operating characteristic curve for the proven NTOS group compared with the asymptomatic control and symptomatic control groups ranged from 0.59 to 0.77 and 0.54 to 0.63, respectively. The positive predictive value ranged from 46% to 65% and the negative predictive value from 51% to 66%. The test-retest reliability analysis for 80 patients with multiple sEAST measurements showed moderate to good (0.52-0.87) intraclass correlation coefficient values for the duration and grip strength parameters. However, the grip fatigue parameters demonstrated poor (0.46-0.16) intraclass correlation coefficient values. CONCLUSIONS: The sEAST showed good test-retest reliability for the duration and grip strength parameters. However, the discriminative value of all sEAST parameters was low for NTOS diagnostics. The good test-retest reliability of the sEAST parameters indicates that they could be valuable outcome measures for comparison in a diagnostic care pathway.