Medication adherence and growth in children with CKD

Abstract

Background and objectives: Poor growth is a consequence of CKD, but can often be partially or fully prevented or corrected with the use of a number of medications. The extent of nonadherence with medications used to treat or mitigate growth failure in CKD has not been examined prospectively in children with CKD.

Design, setting, participants, & measurements: The prevalence of both prescription of and nonadherence to recombinant human growth hormone (rhGH), phosphate binders, alkali, active vitamin D, nutritional vitamin D, iron, and erythrocyte-stimulating agents was summarized over the first seven visits of the Chronic Kidney Disease in Children cohort study. The association between self-reported nonadherence to each medication group and the mean annual change in age- and sex-specific height z score was quantified using seven separate linear regression models with generalized estimating equations.

Results: Of 834 participants, 597 reported use of at least one of these medication groups and had adherence data available. Nonadherence ranged from 4% over all visits for erythrocyte-stimulating agents to 22% over all visits for nutritional vitamin D. Of the study participants, 451 contributed data to at least one of the analyses of adherence and changes in height z score. Children nonadherent to rhGH had no change in height z score, whereas those adherent to rhGH had a significant improvement of 0.16 SDs (95% confidence interval, 0.05 to 0.27); the effect size was slightly larger and remained significant after adjustment. Among participants with height≤3rd percentile and after adjustment, adherence to rhGH was associated with a 0.33 SD (95% confidence interval, 0.10 to 0.56) greater change in height z score. Nonadherence with other medication groups was not significantly associated with a change in height z score.

Conclusions: Self-reported nonadherence to rhGH was associated with poorer growth velocity in children with CKD, suggesting an opportunity for intervention and improved patient outcome.

Keywords: CKD; children; pediatric nephrology.

Copyright © 2014 by the American Society of Nephrology.

Figures

Figure 1.

Medication use at the first seven visits of the CKiD study. Medication use increased per visit as follows: active vitamin D, 7.5% (P<0.001); iron supplement, 3.9% (P=0.004); alkali therapy, 4.8% (P=0.002); phosphate binder, 7.9% (P<0.001); nutritional vitamin D, 17.6% (P<0.001); ESA, 2.6% (P=0.34); and rhGH, 3.1% (P=0.32). CKiD, Chronic Kidney Disease in Children; ESA, erythrocyte-stimulating agent; rhGH, recombinant human growth hormone.

Figure 2.

Prevalence of nonadherence by medication group at each of the first seven visits of the CKiD study. The number of children reporting medication with adherence data available (i.e., the denominator of the percentage plotted) is given at the bottom of the figure for each of the medication groups. The percentages of medication nonadherence over all seven visits are as follows: nonadherence to any medication group, 24%; active vitamin D, 13%; iron supplements, 15%; alkali therapy, 16%; phosphate binders, 21%; nutritional vitamin D, 22%; ESA, 4%; and rhGH, 17%. NA, nonadherence.