Categorisation of children’s lower limb pain conditions as chronic primary and secondary musculoskeletal pain: a modified Delphi study

Background Chronic lower limb pain is common and often disabling for children. Classification of chronic pain changed with the release of the International Classification of Diseases 11 (ICD-11), describing ‘chronic primary musculoskeletal pain’ – as chronic pain in muscles, bones, joints, or tendons associated with emotional distress, functional disability, and not explained by another diagnosis. Existing terminology for paediatric chronic lower limb pain may be better described within the new classification or considered under these broad parent terms. This study aimed to categorise children’s lower limb pain conditions as chronic primary or secondary musculoskeletal pain using expert consensus. Methods An international panel completed a three-round Delphi survey. Participants were presented with 124 conditions resulting in chronic lower limb pain, selecting whether each could be categorised as either chronic primary musculoskeletal pain or chronic secondary musculoskeletal pain. Conditions achieving > 70% agreement reached consensus for categorisation, while conditions achieving 50–69% agreement progressed to the following round for re-rating. Conditions achieving < 50% agreement were excluded. Results There were 21 expert health professionals who categorised four conditions as chronic primary musculoskeletal pain: ‘growing pains’, ‘musculoskeletal pain’, ‘persistent lower limb pain in the presence of restless leg syndrome’ and ‘persistent lower limb pain in the presence of functional neurological disorder’. There were 117 conditions categorised as chronic secondary musculoskeletal pain. Conclusions Conditions categorised as chronic primary musculoskeletal pain share features of persistent lower limb pain without clear underlying pathophysiology, or historically being diagnoses of exclusion. Considering these under the umbrella of ‘chronic primary musculoskeletal pain’ may provide opportunity for developing shared clinical guidance to reduce unnecessary variation in care. Trial registration N/A, this research is not a clinical trial