Osteoporosis prognosis concerns raised for childhood SLE
MedWire News: Children with systemic lupus erythematosus (SLE) are at significant risk for osteoporosis, say researchers who have identified important markers for deteriorating bone health.
The Canadian team says that combining pubertal status at diagnosis, accumulative steroid dose, and serial z-score measurements allows clinicians to assess pediatric SLE patients for long-term risk for low lumbar spine bone mineral density (BMD).
"If these prognostic predictors are confirmed in future studies, we will be able to select those at highest risk of a deteriorating BMD trajectory for future pre-emptive interventions," write Earl Silverman and co-authors, from the Hospital for Sick Children in Toronto, Ontario.
Overall, 68 patients, aged a median of 13.1 years, with a new diagnosis of SLE underwent annual dual-energy X-ray absorptiometry examinations (DEXAs) over 3 years. Their BMD results were collated with information on disease activity and treatment.
The researchers found that the average lumbar spine BMD z-scores decreased over the study, from -0.42 at baseline to -1.02 and -1.11 at years 2 and 3, respectively. Low BMD was defined as a z-score of -2.00 or below; 9% of patients met this criteria in their baseline DEXA, increasing to 19% by year 3.
In all, 35% of patients showed a decline in their BMD category between their first and last DEXA, and 41% of patients with a normal score at baseline had a low or low-normal score by year 3.
Indeed, there was a general deterioration of lumbar spine BMD, at a rate of -0.06 z-score per year from diagnosis, after adjusting for height-for-age z score, the team reports in the Annals of the Rheumatic Diseases.
Analysis revealed that BMD trajectory showed a greater decline for patients who were in puberty at time of diagnosis compared with their prepubertal counterparts. The rate of deterioration also increased with greater cumulative steroid dose, but fell with increasing weight z-score.
"One would have predicted less impact in pubertal patients as higher physiological bone mass accrual might offset the effects of detrimental factors," Silverman et al comment. "This unexpected result could be due to the complex interaction of the hormonal milieu during puberty with other factors regulating bone physiology."
They conclude: "Interval cumulative steroid dose represents an important target that clinicians may modify to ameliorate deteriorating BMD trajectory over time."
By Lynda Williams