Long-Term Stability and Minimal Detectable Change of the Cervical Flexion-Rotation Test

Abstract

Reliability of clinical measurements over time. To determine the long-term stability and minimal detectable change (MDC) of the flexion-rotation test (FRT) measurements over days in subjects with cervicogenic headache (CGH). The FRT is used by physical therapists to assist in identifying upper cervical movement impairment, as well as to gauge treatment effectiveness. Test-retest reliability for the FRT has been reported, but the stability of range-of-motion measures taken during the FRT over time and the MDC have not been investigated. Fifteen subjects with CGH were evaluated on headache-free days using the FRT by a blinded examiner at baseline, 2, 4, and 14 days later. An additional 10 asymptomatic subjects were included for blinding purposes. On each occasion, the examiner measured range of motion and determined whether the FRT was positive or negative. For subjects with CGH, there was no significant change in FRT range of motion over days (P>.05). Intraclass correlation coefficients for intratester reliability were 0.95 (95% CI: 0.90 to 0.98) and 0.97 (95% CI: 0.94 to 0.99) for right and left rotation, respectively. MDC90 was 4.7 degrees for right rotation and 7 degrees for left rotation. Examiner interpretation of the FRT was consistent over time, with kappa = 0.92. This study provides evidence that FRT measurements are stable over time, and the MDC90 indicates that a change in FRT range of motion of at least 7 degrees is required to be confident that a change has occurred due to an intervention rather than measurement error.