Incident vertebral fractures and risk factors in the first three years following glucocorticoid initiation among pediatric patients with rheumatic disorders

Authors

Claire M.A. LeBlanc, School of Medicine
Jinhui Ma, University of Ottawa
Monica Taljaard, University of Ottawa
Johannes Roth, University of Ottawa
Rosie Scuccimarri, School of Medicine
Paivi Miettunen, University of Calgary
Bianca Lang, Dalhousie University, Faculty of Medicine
Adam M. Huber, Dalhousie University, Faculty of Medicine
Kristin Houghton, The University of British Columbia
Jacob L. Jaremko, University of Alberta
Josephine Ho, University of Calgary
Nazih Shenouda, University of Ottawa
Mary Ann Matzinger, University of Ottawa
Brian Lentle, The University of British Columbia
Robert Stein, Western UniversityFollow
Anne Marie Sbrocchi, School of Medicine
Kiem Oen, University of Manitoba
Celia Rodd, University of Manitoba
Roman Jurencak, University of Ottawa
Elizabeth A. Cummings, Dalhousie University, Faculty of Medicine
Robert Couch, University of Alberta, Faculty of Medicine and Dentistry
David A. Cabral, The University of British Columbia
Stephanie Atkinson, McMaster University
Nathalie Alos, University of Montreal
Frank Rauch, School of Medicine
Kerry Siminoski, University of Alberta

Document Type

Article

Publication Date

9-1-2015

Journal

Journal of Bone and Mineral Research

Volume

30

Issue

9

First Page

1667

Last Page

1675

URL with Digital Object Identifier

10.1002/jbmr.2511

Abstract

Vertebral fractures are an important yet underrecognized manifestation of osteoporosis in children with chronic, glucocorticoid-treated illnesses. Our goal was to determine the incidence and clinical predictors of vertebral fractures in the 3 years following glucocorticoid initiation among pediatric patients with rheumatic disorders. Incident vertebral fractures were evaluated according to the Genant semiquantitative method on lateral radiographs at baseline and then annually in the 3 years following glucocorticoid initiation. Extended Cox models were used to assess the association between vertebral fractures and clinical risk predictors. A total of 134 children with rheumatic disorders were enrolled in the study (mean ± standard deviation (SD) age 9.9 ± 4.4 years; 65% girls). The unadjusted vertebral fracture incidence rate was 4.4 per 100 person-years, with a 3-year incidence proportion of 12.4%. The highest annual incidence occurred in the first year (6.0%; 95% confidence interval (CI) 2.9% to 11.7%). Almost one-half of the patients with fractures were asymptomatic. Every 0.5 mg/kg increase in average daily glucocorticoid (prednisone equivalents) dose was associated with a twofold increased fracture risk (hazard ratio (HR) 2.0; 95% CI 1.1 to 3.5). Other predictors of increased vertebral fracture risk included: (1) increases in disease severity scores between baseline and 12 months; (2) increases in body mass index Z-scores in the first 6 months of each 12-month period preceding the annual fracture assessment; and (3) decreases in lumbar spine bone mineral density Z-scores in the first 6 months of glucocorticoid therapy. As such, we observed that a clinically significant number of children with rheumatic disorders developed incident vertebral fractures in the 3 years following glucocorticoid initiation. Almost one-half of the children were asymptomatic and thereby would have been undiagnosed in the absence of radiographic monitoring. In addition, discrete clinical predictors of incident vertebral fractures were evident early in the course of glucocorticoid therapy.