Emoqol-100: Development and validation of a single question for low mood in primary care. A retrospective audit.

Background: Patients with depression need to be diagnosed and managed effectively in primary care. However, current inventories for case-finding low mood are time-consuming when considering the limited time available during appointments. Aim: To validate the diagnostic accuracy of a single question on the emotional quality of life (Emoqol-100) as a measure of depression in symptomatic patients. Design & setting: A retrospective clinical audit, validating the Emoqol-100 compared with the 9-item Patient Health Questionnaire (PHQ-9) and Burns Depression Scale Today (BDST) in South Auckland, New Zealand. Method: Consecutive patients with suspected low mood, seen over 22 months in a single primary care clinic by one of the authors, were eligible for this retrospective audit (n = 160). The index test was the verbally asked Emoqol-100: 'How is your emotional quality of life now, with 100 being perfect and 0 being the worst imaginable?' The reference standard was the PHQ-9 (n = 426 visits) with a cut-off point of ≥10 or BDST (n = 513 visits) with a cut-off point of ≥6. Results: The Emoqol-100 range 0–20 had a likelihood ratio (LR) of 25.2 for low mood compared with the BDST as the reference standard; and for Emoqol-100 scores of 21–40, 41–60, 61–80, and 81–100 the LRs were 3.6, 1.7, 0.35, and 0.09, respectively. For the PHQ-9, these were 10.1, 2.9, 1.3, 0.40, and 0.2, respectively. Any score ≤60 was associated with a low mood. Conclusion: The Emoqol-100 appears to have high validity, so when it is low (≤60), it is suggestive of a high PHQ-9 or BDST score, and a mood issue probably exists. Emoqol-100 could be helpful for busy primary care professionals and other clinicians.