Evaluation of reliability and validity of the Patient Health Questionnaire-9 in patients with acne

To evaluate the reliability and validity of the Patient Health Questionnaire-9 (PHQ-9) in patients with acne. Three hundred acne patients were enrolled from January 2019 to December 2019. PHQ-9 and Hamilton Depression Scale(HAMD) survey was conducted to evaluate their depression status. Cronbach's alpha coefficient and test-retest reliability after 1 week were used to analyze the reliability of PHQ-9. Factor analysis, Spearman correlation analysis, receiver operating characteristic curve (ROC curve) were used for validity analysis of the PHQ-9.The screening validity was analyzed in different subgroups. Two hundred fifty-eight patients with acne completed the questionnaire. Forty-seven were diagnosed with depressive disorder. The best cut-off point for the PHQ-9 score is 9 points, with a sensitivity of 95.7%,a specificity of 88.6% and the area under the ROC curve(AUC) of 0.973.In validity analysis, the correlation coefficient between the total score of PHQ-9 and HAMD was 0.766,the kappa value was 0.530.Factor analysis revealed two common factors (cognitive-affective factor and somatic symptom factor),which explained 65.52% of the total variances. In reliability analysis, the Cronbach's alpha coefficient of the PHQ-9 was 0.851,the test-retest reliability value was 0.824.The time to complete the PHQ-9 was significantly less than the time to complete HAMD (P< .001).The PHQ-9 shows good reliability and validity for the diagnosis of depression in patients with acne, and can be used for preliminary screening of depression.