Reliability, Validity, and Responsiveness of the Craniocervical Flexion Test in People Who Are Asymptomatic and Patients with Nonspecific Neck Pain: a Systematic Review and Meta-Analysis

Objective: Among the tests designed to evaluate neck neuromuscular function, the Craniocervical Flexion Test (CCFT) assesses the function of the deep cervical flexor muscles (DCFs). The purpose of this study was to conduct a review and meta-analysis of published articles about all measurement properties of the different CCFT versions (CCFT Activation Score [CCFT-AS], CCFT Performance Index [CCFT-PI], CCFT Cumulative Performance Index [CCFT-CPI], and CCFT alternative procedures for measuring activation level (CCFT1) or endurance (CCFT2) in people who were asymptomatic and people with nonspecific neck pain. Methods: PubMed Central, MEDLINE, CINAHL, Scopus, Web of Science, and Google Scholar were searched from inception to June 30, 2020. Studies were selected if they reported data on reliability, validity, and/or responsiveness of the CCFT in adults who were asymptomatic or who had nonspecific neck pain. Two reviewers independently selected the studies, conducted quality assessment, and extracted the results. All meta-analyses used a random-effects model. Results: Twenty-one studies met the inclusion criteria. The rating of interrater reliability (assessed for CCFT-AS and CCFT-CPI) was positive only for using the test at a group level. The same rating was ascribed to the intrarater reliability of CCFT-AS, CCFT1, and CCFT2, whereas CCFT-PI and CCFT-CPI showed positive intrarater reliability for assessment of individuals as well. CCFT validity was rated as positive for expressly assessing DCF action when measuring DCF activation through electromyography-not through ultrasonography-or craniocervical flexion motion and for differentiating patients who were asymptomatic and patients who had nonspecific neck pain (only the AS version) and was rated as negative for investigating the CCFT performance correlation with the severity of nonspecific neck pain. CCFT responsiveness was rated as negative. Conclusions: The CCFT is a potentially useful tool for detecting impairment in DCF control and identifying patients who have nonspecific neck pain and who would benefit from a targeted intervention. However, the limited reliability affects its suitability for that purpose. Further research on the reliability of different CCFT versions in which the raters are thoroughly trained is strongly recommended.