Experienced, bothered by, or both: People differ in how they understand the Patient Health Questionnaire (PHQ) items

Importance: The Patient Health Questionnaire (PHQ) is the leading assessment tool for depression in both research and in clinical practice. However, important questions remain about its validity, specifically about whether participants respond according to the frequency they experience symptoms or the frequency with which they are bothered by the symptoms.Objective: To investigate how participants understand and respond to the PHQ, which asks participants “how often have you been bothered by any of the following problems”, but then only emphasizes frequency (from ‘not at all’ to ‘nearly every day’) in the response options.Design, Setting, and Participants: The study used data from a general population sample collected via MTurk (N=503, Mage=40.63, SD=13.62) and from a clinical sample with medium to high depression collected within the OPTIMA study (N=349, Mage=33.48, SD=12.13). Data were collected between 2022-2023.Main Outcome(s) and Measure(s): After completing the PHQ, participants’ interpretation of PHQ instructions was assessed via three questions: 1) How they would respond to the PHQ sleep item in a hypothetical scenario where they overslept nearly every day but were comfortable with oversleeping; 2) Whether they had based their earlier PHQ responses on frequency of their symptoms, the frequency with which the symptoms bothered them, or taking both into consideration; 3) How they would answer the PHQ in the future (based on these same three options). Results: In the hypothetical oversleeping scenario, only 54.7% (MTurk) and 15.5% (OPTIMA) of participants interpreted the PHQ correctly (the frequency with which the problems bothered them). When asked how they responded to the PHQ, only 21.3% and 11.5% of participants interpreted the PHQ correctly, and only 22.3% and 10.0% reported they would do so in the future, indicating stability in their interpretation.Conclusions and Relevance: Our findings raise serious concerns that the majority of participants in general and clinical population samples might not be adhering to PHQ instructions to score how often symptoms bothered them. This highlights key concerns regarding the validity and accuracy of this tool in diagnosing and quantifying depression.