Construct validity of the Single Arm Military Press (SAMP) test for upper limb function in patients with neck pain.

Background: Neck pain (NP) is often associated with upper limb disability (ULD). A clinically feasible measure to evaluate ULD in NP patients is necessary. The Single Arm Military Press (SAMP) is a ULD performance-based measure, specifically for NP patients. The validity of the SAMP in patients is still unknown.

Objective: To explore the construct validity (hypotheses testing) of the SAMP in NP patients.

Methods: A total of 210 NP patients and 81 controls were recruited. The SAMP; Disability of the Arm, Shoulder, and Hand (DASH); and Neck Disability Index (NDI) were completed at baseline and 4-7 days later. The Visual Analogue Scale (VAS) was used to measure NP and ULD severity pre-testing in both occasions. Patients were divided into 4-subgroups based on their NDI score. Convergent validity was examined using Pearson correlation. The t-test and analysis of variance (ANOVA) were used to evaluate discriminant and known groups' validity. To determine SAMP cut-off scores, the sensitivity and specificity were explored.

Results: A negative correlation between the SAMP and DASH/NDI scores was found in the patient group (r = -0.91 and -0.87, p < 0.01). The t-test revealed substantial differences (t = -23.96) in score between patients and controls. Also, ANOVA revealed substantial differences (f = 20.86) between the patients' subgroups. The area under the curve (AUC) for patients and controls exceeded 0.90 when sensitivity and specificity were at equal importance.

Conclusion: The SAMP can distinguish between NP patients and controls, and between different NP disability levels. The responsiveness of the SAMP needs to be investigated.