Purpose: Neck pain is a common cause of disability. This study investigated the psychometric properties of the cervical nonorganic signs (CNOS), a tool for assessing abnormal illness behaviors in patients with neck pain.
Methods: The CNOS was administered on patients with neck pain. Reliability and validity analyses were used to evaluate the psychometric properties. Exploratory factor analysis was used to investigate the dimensionality. Correlations with the Short Form-36 were used to investigate the convergent validity.
Results: The results supported the reliability (inter-rater reliability intra-class correlation: 0.920), validity (correlated with body pain (|ρ|=0.31) and vitality (|ρ| =0.30), and two-factor dimensionality (χ2= 5.904, p= 0.66; χ2/df = 0.738; RMSEA< 0.001; CFI = 1.000; TLI = 1.024; SRMR = 0.047) of the scale. The two factors were pain (severe pain) and vitality (poor vitality) expressed by the patients.
Conclusion: The CNOS is a reliable and valid instrument for assessing pain and vitality problems. It helps patients to express severe pain and lack of vitality. The rehabilitation discipline could use the scale to understand pain expression and to design proper rehabilitation programs. Implications for Rehabilitation The cervical nonorganic signs has two domains (pain and vitality). The scale is reliable and valid for patients with neck pain. Patients with high scores on the pain domain have severe body pain that may interfere with normal social activities. Clinicians should understand their suffering and try to help them to alleviate the pain.
Keywords: Neck pain; exploratory factor analysis; pain expression; psychometric properties.