Development and psychometric analysis of the Japanese version of the Nottingham Health Profile: Cross-cultural adaptation

Objective To adapt the Nottingham Health Profile (NHP) for Japanese and to describe the results of the assessment of its psychometric properties. Methods Assessments included test-retest reliability over approximately a 2-week interval, internal consistency and construct validity in 133 patients with COPD. Results The distribution of scores indicated that most of the NHP sections exhibited a floor effect, although this is greatly reduced with the NHP-Distress scale. The test-retest reliability was above 0.8 for all sections when patients reporting any change in their health status rating were excluded. Cronbach's alpha coefficients reflected the number of items contained in each section. The internal consistency of the emotional reactions section at one timepoint and the physical mobility section at both timepoints were lower than expected to be higher. All sections except the pain section could be used to distinguish patients who reported their health status to be good or fair from those who rated it to be poor or very poor. Conclusion The adaptation of the NHP for Japanese was successful. Most sections showed reasonable test-retest reliability, indicating that they produced acceptable levels of random measurement error. The internal consistency of the sections was confirmed, although the alpha values of the emotional reactions and physical mobility sections were lower than might be expected for scales of their length. Different sections of the Japanese NHP were shown to have known group validity.