IASP 2022 Poster Presentation


This is a research poster presented at the International Association for the Study of Pain (IASP) World Congress in Toronto, September 2022. An abstract can be found below along with Brendan’s details and links to other publications.

Poster Presentation Abstract

Background and aims: It is well established that chronic pain is influenced by a myriad of psychological factors. As such, psychological screening for depressive symptoms is a component of guideline care for the treatment of pain. It is assumed that screening, and subsequent psychological treatment for those with clinically important depression, improves mood outcomes. However, whether the act of screening with a depression scale influences depression itself has not been explored. The Patient Health Questionnaire – 9 (PHQ-9), a nine-item questionnaire, is commonly used to screen for depression symptoms. The PHQ-9 has established cut-offs to trigger referral to specialist psychological care. Here, we aimed to determine whether screening for depression with the PHQ-9, compared to no PHQ-9 screening, influences depression six months later. We also explored whether referral for psychological care and receipt of psychological care mediated this effect.

Methods: We used clinical audit data from seven clinics in Australia, USA, and the UK, of patients with chronic pain (>3 months) presenting to primary care. At baseline, participants were randomised to either complete (n=893) or not complete (n=886) the PHQ-9. A single item mood numeric rating scale (mNRS) that asked, ‘How would you rate your general mood this past week?’, with anchors of 0 = ‘very bad, as depressed as I could be’ and 10 = ‘excellent’ was used to assess depression at 6-month follow up. Prior to analysis, the mNRS was determined to have a strong correlation with the PHQ-9 (Spearman’s rank-order correlation =0.83, p<0.01). For analysis, the mNRS scale was flipped to match the direction of PHQ-9 scores, i.e., low scores = mild depression, high scores = severe depression. Causal mediation analysis was used to estimate the direct effect of screening on depression at 6-months by blocking the effect of referral for and attendance to psychological care.

Results: Participants with persisting pain [n = 1779; Female = 1183 (66%); mean age (SD) = 42.8 ± 15.7 years; mean pain duration (SD) = 51.9 ± 22.3 months] were recruited and randomly allocated to be screened with the PHQ-9 at baseline. Screened participants had greater depression (11-point mNRS) at 6-month follow up compared to those who were not screened (0.48 points, 95% CI 0.34 to 0.79). When attendance (n = 466; 26%) and referral (n = 645; 36%) for psychological care were treated as the mediator, the direct effect remained significant at 0.41 points (95% CI 0.23 to 0.57) and 0.46 points (95% CI 0.32 to 0.60) respectively. Sensitivity analyses suggested that the direct effects were robust to potential mediator-outcome confounding.

Conclusions: These data suggest that screening for depression using the PHQ-9 may paradoxically increase depression for people with chronic pain, regardless of psychological referral or attendance. These findings suggest the effect is minimal, but, notably, there seems to be no benefit of screening using the PHQ-9 and providing referral for psychological care in this cohort. Future research is needed to assess the generalisability of these results.

Source of financial support: BM & GLM are supported by a Leadership Investigator Grant from the National Health & Medical Research Council of Australia to GLM (ID 1178444). HL is funded by the National Health and Medical Research Council (NHMRC ID APP1126767); National Institute for Health Research (NIHR) Collaboration for Leadership in Applied Health Research and Care Oxford at Oxford Health NHS Foundation Trust. TRS is supported by a National Health & Medical Research Council of Australia Career Development Fellowship (ID1141735). LS is supported by the National Institutes of Health. FAB is supported by the John Stuart Colville Fellowship (Arthritis Foundation of South Australia).

Relevance for patient care: People with persisting pain are often also affected by depression. Thus, it is sensible that clinicians screen for depression to optimise care for people with pain. However, in a large dataset of people with pain we found a surprising effect – screening with a widely used depression scale (the PHQ-9) increased depression six months later, regardless of psychological follow-up. Although the effect was small, this finding raises questions about the way in which depression is screened in people with pain.

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IASP 2022 Poster Presentation
Brendan Mouatt