Psychometric properties of the MOS sleep scale in Turkish patients with knee osteoarthritis: A methodological validation study

ObjectiveTo investigate if the Medical Outcomes Study (MOS) sleep scale was reliable, valid, and responsiveness to treatment in Turkish patients with knee osteoarthritis (OA).Patients and MethodsThis is a methodological validation study. One hundred patients with knee OA and 75 healthy controls were included. The MOS sleep scale was administered to two groups to assess sleep status. The reliability of the questionnaire was assessed using reproducibility and internal consistency (Cronbach's alpha and item-total correlation). To assess reproducibility, the questionnaire was administered twice at 3-day intervals before treatment. It was also administered to patients at the end of treatment to investigate responsiveness to treatment. To assess concurrent validity, correlations with the NHP (Nottingham Health Profile) and the WOMAC (Western Ontario and McMaster Universities Osteoarthritis Index) were examined.ResultsThe MOS sleep scale all scores were significantly lower in patients with knee OA than in controls (p < 0.05). After the treatment, a significant improvement was observed in all MOS sleep scale scores of the patients (p < 0.05). The Turkish version of the MOS sleep scale was reliable with strong internal consistency (Cronbach alpha: 0.74-0.85 and Item-total correlation:0.50-0.89) and good reproducibility (intra-reader correlation:0.47-0.83, inter-reader correlation:0.43-0.84) in patients with knee OA. When assessing concurrent validity of the scale, it was determined that its correlations with WOMAC and NHP scores were moderate and good levels (r = -0.21-0.50, p = 0.03-0.0001).ConclusionOur study showed that the MOS sleep questionnaire is a valid, reliable, and treatment-responsive scale in Turkish patients with knee OA.