Interrater and intrarater reliability of the single arm military press (SAMP) test for upper limb function in patients with non-specific neck pain

Background: Performance measures that assess the upper limb disability (ULD) in patients with neck pain can provide useful information for making clinical decisions regarding the optimal management of those patients. The Single Arm Military Press (SAMP) test is a performance based ULD measure developed specifically for populations with neck pain. In this test, patients are asked to lift a 1 kg weight repetitively overhead for 30 s with repetitions counting as the score. Whilst the test has been shown to be acceptable and feasible for use by clinicians and patients, its reliability in a patient group is still unknown. Objective: To assess the interrater, intrarater reliability and measurement error of the SAMP test in patients with non-specific neck pain (NSNP). Methods: A total of 210 patients with NSNP and 81 healthy subjects were recruited for this study. The Disabilities of the Arm, Shoulder and Hand (DASH) and the Neck Disability Index (NDI) were assessed at baseline to ensure eligibility of the participants. The SAMP test was assessed at baseline and repeated 4-7 days later. A VAS symptom score was used to establish the stability of the participants across time. Interrater, intrarater reliability and measurement error were evaluated using Interclass Correlation Coefficient (ICC2,1) and the standard error of measurement (SEM). Results: The ICCs for interrater and intrarater reliability for the SAMP test ranged from 0.993 to 0.996 in the patient group. The SEM was <= 1 and smaller than the Smallest Detectable Change (SDC) and Bland-Altman plot indicated that the test is accurate. Conclusion: The almost perfect interrater and intrarater reliability and low levels of measurement error indicate that the 1 kg SAMP test has potential for evaluating upper limb functional capacity in female patients with NSNP. Before the test can be fully recommended, further studies are required to evaluate the validity and responsiveness of the SAMP test in population with NSNP and other neck disorders.