Interpretation Issues With the Patient Health Questionnaire Instructions

Area of Science:

• Psychological assessment
• Mental health research methodology

Background:

• Patient Health Questionnaire (PHQ) versions (PHQ-2, PHQ-8, PHQ-9) are widely used for depression assessment in research and clinical settings.
• Concerns exist regarding the validity of PHQ instruments, specifically whether responses reflect symptom frequency or the degree to which symptoms are bothersome.

Purpose of the Study:

• To investigate how participants interpret the instructions of the PHQ, which are intended to measure symptom severity based on bothersomeness.
• To assess if participants focus on symptom frequency or bothersomeness when completing the PHQ.

Main Methods:

• Utilized data from a general population sample (Amazon Mechanical Turk, n=503) and a clinical sample with moderate to severe depression (OPTIMA study, n=349).
• Assessed participants' interpretation of PHQ-8 instructions using three post-completion questions, including a hypothetical scenario and self-reported interpretation basis (frequency vs. bothersomeness).
• Collected data between 2022 and 2023.

Main Results:

• A significant majority of participants across both samples misinterpreted the PHQ instructions, with only 54.7% (MTurk) and 15.5% (OPTIMA) correctly understanding the 'bothered by' aspect in a hypothetical scenario.
• Fewer participants reported basing their PHQ responses on symptom bothersomeness (21.3% MTurk, 11.7% OPTIMA) or intended to do so in the future (22.3% MTurk, 9.9% OPTIMA).
• The validity of the PHQ-8 was found to vary based on participants' interpretation of its instructions.

Conclusions:

• Widespread misinterpretation of PHQ instructions was identified in both community and clinical samples.
• These findings raise significant concerns about the validity of the PHQ for both research purposes and clinical decision-making.
• Revising PHQ instructions or assessment methods may be necessary to ensure accurate depression measurement.