Development of a patient-reported outcome: the Neck OutcOme Score (NOOS)--Content and construct validity

To develop a patient-reported outcome evaluating the impact of neck pain. The results of item generation and reduction and subscale structure in support of the content and construct validity of the measure are reported.

Items were generated from the literature and through focus groups including patients with neck pain and healthcare professionals, respectively. Item reduction was based on focus groups and field-tested questionnaire data. Construct validity was assessed using exploratory factor analysis.

Focus groups containing 24 patients (mean age 57.2 (standard deviation (SD) 15.9) years, range 24-85 years); 19 women) and 12 healthcare professionals were conducted before data saturation was achieved. A total of 196 patients with neck pain (mean age 47.8 (SD 13.7) years), range 18-89 years; 146 women) completed the preliminary questionnaire. Overall 35 items were removed from the original 69. A multidimensional questionnaire, divided into five subscales, was developed from the remaining 34 items: mobility; symptoms; sleep disturbance; everyday activity and pain; and participation in everyday life. Exploratory factor analysis supported a 5-subscale structure.

The Neck OutcOme Score has excellent content validity and preliminary results support a 5-subscale structure. Additional work is needed to assess the reliability, further construct validity and responsiveness.