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

Abstract

Background: To develop the Patient Healthy Questionnaire-8 (PHQ-8), as a more reliable approach compared with the Somatic Symptom Scale-8 (SSS-8), evaluating somatization in patients with functional dyspepsia (FD), in which the effects of somatization assessed by these two approaches on quality of life (QoL) of FD patients were further compared. Methods: Herein, 612 FD patients completed a questionnaire involving 25 items. 8 out of 25 items were selected to develop the PHQ-8 by four methods of discrete degree, correlation coefficient, factor analysis, and Cronbach’s α coefficient. Reliability and validity of the PHQ-8 and the SSS-8 were compared by principal component and confirmatory factor analyses. The effects of somatization, depression, and anxiety on the Nepean Dyspepsia Index (NDI) for QoL were explored by Pearson’s correlation coefficient and linear regression analysis. Results: The Cronbach’s α coefficient for the PHQ-8 and the SSS-8 was 0.601 and 0.553, respectively, and the cumulative contribution rate of three extracted factors for the developed PHQ-8 and SSS-8 was 55.103% and 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) was found to be correlated with the NDI. The model used for the PHQ-8 showed that the values of chi-squared (χ2), root mean square residual (RMR), root mean square error of approximation (RMSEA), goodness-of-fit index (GFI), and adjusted GFI (AGFI) were 31.247, 0.01, 0.042, 0.984, and 0.967, respectively. Linear regression analysis unveiled that somatization (β=0.270, P<0.001), anxiety (β=0.163, P<0.001), and depression (β=0.136, P=0.003) assessed by the PHQ-8 were correlated with the NDI; besides, somatization (β=0.250, P<0.001), anxiety (β=0.156, P<0.001), and depression (β=0.155, P =0.001) evaluated by the SSS-8 were correlated with the NDI.Conclusions: The developed PHQ-8 showed to have a superior reliability and validity, and somatization assessed by the developed PHQ-8 showed have a greater influence on QoL of FD patients compared with the SSS-8. Our findings suggested that the developed PHQ-8 may improve fast assessment of the effects of somatization on FD patients in lieu of the SSS-8.