A new PHQ-2 for Chinese adolescents: identifying core items of the PHQ-9 by network analysis

The importance of preventing and treating adolescent depression has been gradually recognized in Chinese society, especially in the context of the COVID-19 pandemic. Early screening is the first step. The Patient Health Questionnaire-9 (PHQ-9) is a leading scale in the field of depression screening. To improve screening efficiency in large-scale screening, an even shorten scale is desirable. The PHQ-2, which only included two items measuring anhedonia and depressed mood, is an ultra-form of the PHQ-9. However, emerging evidence suggests that there may be a better short form for the PHQ-9, especially for adolescents. Therefore, using two large samples of Chinese adolescents, this study aimed to identify the core items of the PHQ-9 and examine the short form consisting of core items.

Surveys were conducted among primary and middle school students in two Chinese cities with different economic levels during the COVID-19 pandemic. Two gender-balanced samples aged 10 to 17 (n_{Sample 1} = 67281, n_{Sample 2} = 16726) were collected. Network analysis was used to identify the core items of the PHQ-9, which were extracted to combine a short version. Reliability, concurrent validity, and the receiver operating characteristic curve (ROC) of the short form were examined. Analyses were gender-stratified.

Network analysis identified fatigue and depressed mood as core items in the PHQ-9 among Chinese adolescents. Items measuring Fatigue and Mood were combined to be a new PHQ-2 (PHQ-2 N). The PHQ-2 N displayed satisfactory internal consistency and current validity. Taking the PHQ-9 as a reference, the PHQ-2 N showed higher ROC areas and better sensitivity and specificity than the PHQ-2. The optimal cutoff score for the PHQ-2 N was 2 or 3.

Fatigue and depressed mood are the central symptoms of the depressive symptom network. The PHQ-2 N has satisfactory psychometric properties and can be used in rapid depression screening among Chinese adolescents.