Compromised bone health is recognized as an important source of morbidity among children with glucocorticoid (GC)-treated rheumatic diseases (RD). The aims of this study were to determine the frequency and characteristics of incident vertebral fractures (VF) 12 months after GC initiation in a prospectively-followed cohort of children with RD, and to examine clinical factors associated with their development.
Children (< 17 years) initiating GC for treatment of RD between January 2005 and December 2007 in ten participating Canadian tertiary pediatric centers were enrolled in the Steroid-Associated Osteoporosis in the Pediatric Population (STOPP) study. Enrolled patients had baseline (within 30 days of initiating GC) and 6- monthly spine areal (a) BMD studies. Additionally, radiographs of the thoracolumbar spine at baseline and 12 months (m) were evaluated using the Genant semi-quantitative method. Fractures present at baseline (prevalent VFs) were documented. An incident VF was defined as a new VF or worsening of an existing fracture. Patients also had baseline and 3 monthly assessment of GC exposure, clinical status including disease activity (measured on a 10 cm visual analogue scale by the patient’s rheumatologist), and questionnaires to determine physical activity and vitamin D/calcium intake.
Of 135 patients enrolled, data were available on 118 (64% female, median age 10.8 years) at 12 m. Diagnoses included juvenile dermatomyositis (JDM) (23%), juvenile idiopathic arthritis (JIA) (36 %), systemic lupus (SLE) and related conditions (18%), systemic vasculitis (14%), and other ( 9%). At 12 m, 7 patients (6%) had 12 incident VFs (3 SLE, 2 JDM, 1 vasculitis, 1 overlap). All incident VFs were new fractures; 5 patients had a single VF, one had 2 VFs and one had 5 VFs. Three patients had mild and 4 had moderate VFs. Nine (75%) of the incident VFs were thoracic and 11 (92%) had wedge morphology. Patients with and without incident VFs were similar for age, gender, pubertal status, disease activity, physical activity, vitamin D/calcium intake and presence of back pain. The decrease in spine aBMD and increase in BMI in the first 6 months was larger in those with incident VFs (Δ spine aBMD Z-score mean -0.8, SD 0.4; Δ BMI Z-score +1.7, SD 1.0) versus those without (Δ spine aBMD Z-score -0.4, SD 0.5; Δ BMI Z-score +0.5 SD 0.8). Cumulative GC dose (g/m2) was almost double in those with incident VFs (median 9.3 g/m2, range 3.0-12.5) versus those without (median 5.4, range 0.01-27.5); with the greatest difference in GC dose seen within the first 6m. None of the 9 children with baseline prevalent VFs had incident fractures. In 8 of these 9 patients, spine status had improved overall at 12 m.
Incident VFs occurred in a small proportion of our cohort (6%); however one patient was more severely affected. Children with incident VFs received almost twice as much GC therapy as those without, had a greater decline in spine BMD, and manifested greater increases in BMI. Back pain and baseline prevalent VFs did not appear to be associated with incident VFs. Funded by CIHR.
Bianca A. Lang: None; Celia Rodd: None; Timothy Ramsay: None; David A. Cabral: None; Peter B. Dent: Roche , 6; Janet E. Ellsworth: None; Kristin M. Houghton: None; Adam Huber: None; Roman Jurencak: None; Maggie Larché: None; Claire M.A. LeBlanc: None; Brian Lentle: None; MaryAnn Matzinger: None; Paivi M. Miettunen: None; Kiem Oen: None; Johannes Roth: None; Claire Saint-Cyr: None; Rosie Scuccimarri: None; Nazih Shenouda: None; Leanne M. Ward: None; and the Canadian STOPP Consortium: None.