Background and purpose: Outcome measures must be repeatable over time to judge changes as a result of treatment. It is unknown whether the presence of neck pain can affect measurement reliability over a time period when some change could be expected as a result of an intervention. The present study investigated the reliability of two measures, active cervical range of movement (AROM) and pressure pain thresholds (PPTs), in symptomatic and asymptomatic subjects.
Method: A repeated-measures study design with one week between testing sessions was used. Nineteen healthy asymptomatic subjects and 19 subjects with chronic neck pain participated in the study. The neck movements measured were: flexion, extension, right and left lateral flexion, and axial rotation. PPTs were measured over six bilateral sites, both local and remote to the cervical spine.
Results: The between-week intra-class correlation coefficients (ICCs2,1) for AROM ranged from 0.67 to 0.93 (asymptomatic group) and from 0.64 to 0.88 (chronic neck pain group). Standard error of measurement (SEM) was similar in both groups, from 2.66 degrees to 5.59 degrees (asymptomatic group) and from 2.36 degrees to 6.72 degrees (chronic neck pain group). ICCs2,1 for PPTs ranged from 0.70 to 0.91 (asymptomatic group) and from 0.69 to 0.92 (chronic neck pain group). SEM ranged from 11.14 to 87.71 kPa (asymptomatic group) and from 14.25 to 102.95 kPa (chronic neck pain group).
Conclusions: The findings of moderate to very high between-week reliability of measures of AROM and PPTs in both asymptomatic and chronic neck pain subjects suggest the presence of symptomatology does not adversely affect reliability of these measures. The results support the use of these measures for monitoring change in chronic neck pain conditions.