Automated determination of bone age and bone mineral density in patients with juvenile idiopathic arthritis: a feasibility study
1 Department of Pediatrics/Pediatric Rheumatology, Sophia Children’s Hospital, Erasmus MC, Rotterdam, The Netherlands
2 Department of Radiology, Academic Medical Center, Amsterdam, The Netherlands
3 Department of Pediatric Hematology, Immunology, Rheumatology and Infectious Disease, Emma Children’s Hospital, Academic Medical Center, Amsterdam, The Netherlands
4 Department of Pediatric Rheumatology, Reade location Jan van Breemen, Amsterdam, The Netherlands
Arthritis Research & Therapy 2014, 16:424 doi:10.1186/s13075-014-0424-1Published: 27 August 2014
IntroductionChronic inflammation combined with glucocorticoid treatment and immobilization puts juvenile idiopathic arthritis (JIA) patients at risk of impaired growth and reduced bone mineral density (BMD). Conventional methods for evaluating bone age and BMD are time consuming, or come with additional costs and radiation exposure. In addition, an automated measurement of bone age and BMD is likely to be more consistent than visual evaluation. This study aimed to evaluate feasibility of an automated method for determination of bone age and (cortical) bone mineral density (cBMD) in severely affected juvenile idiopathic arthritis (JIA) patients. A secondary objective was to describe bone age and cBMD in this specific JIA population, eligible for biologic treatment.MethodsIn total, 69 patients with standard hand radiographs at start of etanercept treatment and of calendar age within the reliability ranges (2.5 to 17?years for boys and 2 to 15?years for girls) were extracted from the Dutch Arthritis and Biologicals in Children register. Radiographs were analyzed with the BoneXpert method, automatically determining bone age and cBMD expressed as bone health index (BHI). Agreement between measurements of the left and right hand radiographs and a repeated measurement of the left hand was assessed with the intraclass correlation coefficient (ICC). Regression analysis was used to identify variables associated with Z-scores of bone age and BHI.ResultsBoneXpert reliably evaluated radiographs of 67 patients (radiographs of two patients were rejected due to poor image quality). Agreement between left-right hand radiographs (ICC 0.838 to 0.996) and repeated measurements (ICC 0.999 to 1.000) was good. Mean Z-scores of bone age (?0.36, P?=?0.051) and BHI (?0.85, P?<?0.001) were lower compared with the healthy population. Glucocorticoid use was associated with delayed bone age (0.79 standard deviation (SD), P?=?0.028) and male gender was associated with a lower Z-score of BHI (0.65 SD, P?=?0.021).ConclusionsBoneXpert is an easy-to-use method for assessing bone age and cBMD in patients with JIA, provided that radiographs are of reasonable quality and patients? bone age lies within the age ranges of the program. The population investigated had delayed bone maturation and lower cBMD than healthy children.