Other PHQ-9 item pairings are better than the PHQ-2: A machine learning analysis

The Patient Health Questionnaire-2 (PHQ-2) is the most commonly used ultra-brief depressive symptomatology pre-screening instrument. However, this analysis demonstrated the PHQ-2 is not superior to other PHQ-9 item pairings in this sample. 12 out of the 36 pairings had an equal or higher cross-validation area under the receiver operating characteristic curve than the PHQ-2. The two pairings of phq2&4 and phq2&8 performed best and suggest low energy or psychomotor retardation or agitation may be more discriminatory symptoms than anhedonia. Pairings were combined with machine learning models which are not restricted to the summation and greater-than-or-equal-to logic of the PHQ-2 thresholds.