Objectives: Our aims were to investigate discrepancies between depressed patients' GlobalRating of Change (GRC) and scores on the Patient Health Questionnaire depression module (PHQ-9). Our objectives were to ascertain patients' views on the source and meaning of mismatches and assess their clinical significance.
Design: Qualitative study nested within a cohort, in a programme investigating the indications for prescribing antidepressants that will lead to a clinical benefit.
Setting: Primary care practices in north-west England.
Participants: We invited 32 adults with a recent diagnosis of depression and evidence of mismatch between GRC and PHQ-9 Scores to participate. Of these, 29 completed our interviews; most were women, identified as white British, had high school education or higher, were employed or retired and had been depressed for a long time.
Main measures: We conducted semistructured interviews with a topic guide, focusing on experiences of depression; treatment experiences and expectations; effectiveness of the questionnaires; reasons for the mismatch; and social factors. Interviews were transcribed and subjected to interpretative phenomenological analysis.
Results: We identified four themes as explanations for mismatch between GRC and PHQ-9: perceptions that GRC provided a more accurate assessment of current mental state than PHQ-9; impact of recent negative or positive life events on either measure; personal understanding of depression as normally fluctuating, and tendency to underscore on PHQ-9 as a means of self-motivation; and lack of recall.
Conclusions: The combined used of the PHQ-9 and a more open question better captures the patient's unique experiences of mental health. This approach ascertains the relevance of symptoms to the individual's experience and influences treatment decisions.
Study registration: This study was an element of NIHR Programme Grant RP-PG 0610 10048.
Keywords: PHQ-9; PRIMARY CARE; depression; diagnosis; mismatch; patient perspectives.
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