Association of bone mineral density with incidental renal stone in long-term survivors of childhood acute lymphoblastic leukemia.

Abstract

9527 Background: With 5-year survival of childhood acute lymphoblastic leukemia (ALL) now exceeding 90%, long term morbidities are of growing concern. Both low bone mineral density (BMD) and renal dysfunction have been reported in ALL survivors. Our objective was to evaluate the association between low BMD and incidental renal stones, a known predictor of renal dysfunction. Methods: Adult participants who were 10+ year survivors of childhood ALL and members of St. Jude Lifetime Cohort study were recruited between 12/2007 and 3/2011. During their risk-based medical evaluations they underwent quantitative computed tomography (QCT) to evaluate BMD. Incidental renal stones were identified by radiologists’ review of axial QCT source images. Demographic information was abstracted from responses to health surveys and dietary intake from a Block food frequency questionnaire. Association between BMD and renal stones was evaluated in a multivariable logistic regression model. Confounding variables were selected using directed acyclic graphs and change in effect estimates strategy. Results: At a median of 26.1 years from diagnosis, BMD Z score of > 1 standard deviation (SD) was detected in 77/662 (11.6%) and renal stones in 73/662 (11%) participants. In a multivariable model adjusted for age, dietary vitamin D and renal radiation, when compared to BMD Z score > 1 SD, the risk of renal stones increased with a decrease in BMD Z-score; 1 to 0 SD (Odds Ratio (OR), 1.93; 95% confidence interval (CI), 0.69 to 5.41), 0 to -1 SD (OR, 1.46; 95% CI, 0.52 to 4.05), -1 to -2 SD (OR, 2.72; 95% CI, 0.81 to 6.41), and ≤ -2 SD (OR, 4.96; 95% CI, 1.43 to 17.13). Older age (45-54 vs.18-24 y; OR, 3.66; 95% CI, 1.10 to 12.15), renal radiation (OR, 1.97; 95% CI, 0.59 to 6.50) and > 141.5 IU intake of vitamin D (OR, 1.65; 95% CI, 0.98 to 2.77) were also associated with renal stone formation. Conclusions: Our results not only help us recognize survivors at risk, but also informs radiologists to be vigilant of incidental renal stones among older ALL survivors with low BMD.