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

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.

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

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.

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.

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