Identification of patterns of foot and ankle pain in the community: Cross-sectional findings from the clinical assessment study of the foot.

OBJECTIVES: To investigate patterns of foot and ankle pain locations and symptoms, socio-demographic and comorbid characteristics to examine whether there are distinct foot and ankle pain phenotypes. METHODS: Adults aged ≥50 years registered with four general practices in North Staffordshire were mailed a Health Survey questionnaire. Participants reporting foot pain in the last month indicated foot pain location on a foot manikin. Foot and ankle pain patterns were investigated by latent class analysis. Associations between the classes with foot pain symptoms, socio-demographic and comorbid characteristics were assessed. RESULTS: Four thousand four hundred fifty-five participants with complete foot pain and manikin data were included in this analysis (mean age 65 years [SD 9.8], 49% male). Of those with foot and ankle pain (n = 1356), 90% had pain in more than one region. Six distinct classes of foot and ankle pain were identified: no pain (71%), bilateral forefoot/midfoot pain (4%), bilateral hindfoot pain (5%), left forefoot/midfoot pain (8%), right forefoot/midfoot pain (5%) and bilateral widespread foot and ankle pain (6%). People with bilateral widespread foot and ankle pain were more likely to be female, obese, depressed, anxious, have/had a manual occupation, have comorbidities, lower SF-12 scores and greater foot-specific disability. Age did not differ between classes. CONCLUSIONS: Six distinct classes of foot and ankle pain locations were identified, and those with bilateral widespread foot and ankle pain had distinct characteristics. Further investigation of these individuals is required to determine if they have poorer outcomes over time and whether they would benefit from earlier identification and treatment.