Short stature in advanced pediatric CKD is associated with faster time to reduced kidney function after transplant

Abstract

Background: Among children who receive a kidney transplant, short stature is associated with a more complicated post-transplant course and increased mortality. Short stature prior to transplant may reflect the accumulated risk of multiple factors during chronic kidney disease (CKD); however, its relationship with post-transplant kidney function has not been well characterized.

Methods: In the Chronic Kidney Disease in Children (CKiD) cohort restricted to children who received a kidney transplant, short stature (i.e., growth failure) was defined as age-sex-specific height < 3rd percentile. The outcome was time to estimated glomerular filtration rate (eGFR) < 45 ml/min/1.73 m2 after transplant. Parametric survival models, including adjustment for disease severity, socioeconomic status (SES), and parental height by inverse probability weighting, described the relative times to eGFR< 45 ml/min/1.73 m2.

Results: Of 138 children (median CKD duration at transplant: 13 years), 20% (28) had short stature before the transplant. The median time to eGFR < 45 ml/min/1.73 m2 after kidney transplantation was 6.6 years and those with short stature had a significantly faster time to the poor outcome (log-rank p value 0.004). Children with short stature tended to have lower SES, nephrotic proteinuria, higher blood pressure, and lower mid-parental height before transplant. After adjusting for these variables, children with growth failure had 40% shorter time to eGFR < 45 ml/min/1.73 m2 than those with normal stature (relative time 0.60, 95%CI 0.32, 1.03).

Conclusions: Short stature was associated with a faster time to low kidney function after transplant. SES, disease severity, and parental height partially explained the association. Clinicians should be aware of the implications of growth failure on the outcome of this unique population, while continued attempts are made to define modifiable factors that contribute to this association.

Keywords: GFR; Graft loss; Growth failure; Kidney transplantation; Pediatrics.

Conflict of interest statement

Conflict of Interest: The authors declare that they have no conflict of interest.

Figures

Figure 1.

Unweighted (left panel) and inverse probability weighted (right panel) step functions of the time to eGFR 2 after kidney transplant, by short stature (N=138). Cumulative incidence curves were based on parametric survival models with log-normal distribution for each group with location (β) and scale σ and denoted as LN(β,σ).