Spinal and sacroiliac involvement in SAPHO syndrome: A single center study of a cohort of 354 patients

OBJECTIVE:SAPHO syndrome is a highly heterogeneous disease with distinct treatment response. We report the largest cohort of SAPHO syndrome and explore its clinical classification with special interest in spinal and sacroiliac involvement. METHODS:A total of 354 patients with SAPHO syndrome were recruited in Peking Union Medical College Hospital. The demographic, clinical and imaging data were collected at baseline. Spinal and sacroiliac involvement was determined by the co-existence of related symptoms and imaging evidence of lesions in the spine or sacroiliac joints on either bone scintigraphy, CT or MRI. RESULTS:A total of 197 (55.6%) patients were identified to have spinal or sacroiliac involvement. Compared to those without spinal or sacroiliac lesions, these patients were significantly older at onset (38 ± 12 vs 35 ± 10 years old, p = 0.019) but had comparable duration of disease. Therapeutically, patients with spinal or sacroiliac involvement had been treated more aggressively with more frequently prescribed NSAIDs, glucocorticoids, DMARDs, TNF-α inhibitors, and bisphosphonates (all p ≤ 0.001). Nonetheless, greater disease activity was observed for these patients at baseline, supported by both inflammatory markers (ESR and hs-CRP) and visual analog scale (VAS) for pain (all p < 0.001). CONCLUSIONS:SAPHO patients with spinal or sacroiliac involvement are older at onset and have greater disease activity despite of more aggressive treatments compared to those without. Stratified management is in urgent need for this rare disease.