Exploring the association between patient-drawn pain diagrams and psychological and physical health variables: A large-scale study of patients with low back pain.

Background: Despite the use of Patient-Drawn Pain Drawings (PDPDs) in clinical settings, their validity as indicators of psychological distress remains debated. We aimed to assess the association between PDPD areas and physical health and psychological variables.

Methods: This study analysed digitally-drawn PDPDs from 15,345 chronic low back pain (LBP) patients at a Danish outpatient hospital unit. We employed a novel quantitative approach to calculate four log-transformed geometric pain areas for each PDPD. We assessed six psychological constructs and seven physical health variables. Associations were modelled using multivariable linear regression.

Results: Increasing leg pain intensity (estimates from 0.12 to 0.25), disability (estimates from 0.3 to 0.14), and pain duration (estimates from 0.10 to 0.33) had the strongest associations with increasing pain areas. Conversely, increasing fear of movement (estimates from -0.02 to -0.05) and catastrophizing (estimates from -0.02 to -0.03) were associated with slight reductions in pain areas. Anxiety and depression had the weakest and most uncertain relationships to pain area size.

Conclusions: Increasing levels of leg pain intensity, pain duration, and pain-related disability were consistently associated with larger geometric pain areas in PDPDs. Conversely, the associations between the psychological constructs and the geometric pain areas exhibited varying directions and were notably weaker. Clinicians are encouraged to focus on the association of PDPDs with physical symptoms rather than psychological conditions during clinical assessments.

Significance statement: This large-scale study demonstrates that extensive pain areas in pain drawings drawn by LBP patients do not signify psychological distress. Our findings reveal that these pain representations are more closely linked to increased pain intensity, pain duration, and disability rather than being independently associated with psychological factors. Clinicians are encouraged to focus on the association of extensive pain areas with physical symptoms rather than psychological distress during clinical assessments.