Validation of the Chinese version of the PHQ-15 in a tertiary hospital

BACKGROUND

This study aimed to investigate the reliability and validity of the Chinese version of the Patient Health Questionnaire (PHQ-15) in a tertiary hospital.

METHODS

Using a cross-sectional study design, the Chinese version of the PHQ-15 was administered to a total of 1329 inpatients. To examine the discriminant validity of this questionnaire, we investigated the correlation of the PHQ-15 score with sociodemographic data and the PHQ-9 and GAD-7 scale scores. Exploratory factor analysis was performed to assess the internal consistency of the PHQ-15. To evaluate the consistency of this questionnaire with item response theory (IRT), IRT analysis was performed.

RESULTS

The Chinese version of the PHQ-15 showed good reliability (Cronbach's alpha = 0.83). The correlations of the PHQ-15 scores with the PHQ-9 depression scale scores (r = 0.565) and the GAD-7 anxiety scale scores (r = 0.512) were moderate; these results suggested that the PHQ-15 had discriminant validity. We identified three factors, referred to as "cardiopulmonary," "gastrointestinal," and "pain/neurological," which explained 56 % of the total variance. A second-order factor analysis including these three factors produced an acceptable model. Several items (4, 8 and 11) displayed extreme floor effects. Additionally, item 4 displayed a very small variance of 0.35 and showed very small differences in its thresholds based on IRT analysis.

CONCLUSIONS

The PHQ-15 scale had good reliability and high validity to detect patients with high somatic symptom severity in a Chinese tertiary hospital. Several of the current findings were consistent with previous research on the PHQ-15 in Western countries and in China. To improve the diagnostic quality of this questionnaire, items 4, 8 and 11 can be omitted.

The Hordaland Health Study (HUSK)

OBJECTIVE

The Whiteley Index (WI) is a widely used screening instrument for health anxiety/hypochondriasis. Several studies have previously explored the psychometric properties of the WI, but with mixed findings concerning both item composition and factor structure. The main aim of the current study was to examine different factor structures as identified from previous studies using data from a large general population based study. We also wanted to provide gender specific norms.

METHODS

Data were taken from a large population-based study in Norway, the Hordaland Health Study (HUSK N=7274). Confirmatory factor analysis (CFA) of several models of the WI was conducted. Item response theory (IRT) analysis was performed on the model with the best goodness-of-fit.

RESULTS

CFA of all previously proposed factor models of the WI revealed clearly inadequate model fits. The IRT analysis suggested that a six-item model best described the data, and CFA confirmed an adequate goodness-of-fit across indices.

CONCLUSION

The current study found evidence for a six-item, single-factor model of the WI. Our findings suggest that this abbreviated version has the best factor structure compared to previously proposed factor models. We recommend that the factor structure identified in this study should be investigated further in independent samples.