The Developed Patient Healthy Questionnaire-8 with a Greater Impact on Quality of Life Compared with the Somatic Symptom Scale-8 in Functional Dyspepsia

Abstract Background: To adapt insufficiencies of the Somatic Symptom Scale-8 (SSS-8) measuring somatization in functional dyspepsia (FD) to develop PHQ-8, of which reliability, validity and the effects of somatization evaluated by the developed PHQ-8 on quality of life (QoL) were further assessed.Methods: 612 FD patients completed a 25 items questionnaire. 8 items were selected from 25 items to constitute the PHQ-8 by discrete degree, correlation coefficient, factor analysis and Cronbach coefficient four methods. Reliability and validity for the PHQ-8 and the SSS-8 were compared by principal component and confirmatory factor analysis. The effects of somatization, depression and anxiety on the Nepean Dyspepsia Index (NDI) for QoL were explored by Pearson correlation coefficient and linear regression analysis.Results: Cronbach’s α coefficients for the PHQ-8 and the SSS-8 were 0.601, 0.553, and cumulative contribution rates of three extracted factors were 55.103%, 51.666%, respectively. Somatization evaluated by the PHQ-8(r=0.309, P<0.001) and the SSS-8 (r=0.281, P<0.001) were related to the NDI. The model for the PHQ-8 showed χ2=31.247, RMR=0.01, RMSEA=0.042, GFI=0.984. Linear regression analysis showed that somatization measured by the PHQ-8 (β=0.270, P<0.001), anxiety (β=0.163, P<0.001) and depression (β=0.136, P=0.003) were determinants of the NDI; somatization measured by the SSS-8 (β=0.250, P<0.001), anxiety (β=0.156, P<0.001) and depression (β=0.155, P =0.001) were determinants of the NDI.Conclusions: The developed PHQ-8 had a better reliability and validity, which assessing somatization appeared to have a greater impact on QoL than that of the SSS-8. These results suggested that the developed PHQ-8 might improve to study the effects of somatization on QoL instead of the SSS-8 in specific FD patients.