The effect of abnormal birth history on ambulatory blood pressure and disease progression in children with chronic kidney disease

Abstract

Objective: To examine the associations between abnormal birth history (birth weight <2500 g, gestational age <36 weeks, or small for gestational age), blood pressure (BP), and renal function among 332 participants (97 with abnormal and 235 with normal birth history) in the Chronic Kidney Disease in Children Study, a cohort of children with chronic kidney disease (CKD).

Study design: Casual and 24-hour ambulatory BP were obtained. Glomerular filtration rate (GFR) was determined by iohexol disappearance. Confounders (birth and maternal characteristics, socioeconomic status) were used to generate predicted probabilities of abnormal birth history for propensity score matching. Weighted linear and logistic regression models with adjustment for quintiles of propensity scores and CKD diagnosis were used to assess the impact of birth history on BP and GFR.

Results: Age at enrollment, percent with glomerular disease, and baseline GFR were similar between the groups. Those with abnormal birth history were more likely to be female, of Black race or Hispanic ethnicity, to have low household income, or part of a multiple birth. Unadjusted BP measurements, baseline GFR, and change in GFR did not differ significantly between the groups; no differences were seen after adjusting for confounders by propensity score matching.

Conclusions: Abnormal birth history does not appear to have exerted a significant influence on BP or GFR in this cohort of children with CKD. The absence of an observed association is likely secondary to the dominant effects of underlying CKD and its treatment.

Figure 1

Distribution of propensity scores, by BH status and matched data with weighting, based on full constrained matching. The box plots represent the distribution of propensity scores (predicted probabilities) by BH (abnormal and normal) based on the logistic regression model described in the Methods. The unmatched data points are not included in the final analysis. The matched data points are included in the final analysis. All matched subjects with an abnormal BH have a weight equal to 1, matched subjects with a normal BH are represented by a dot size proportional to the weight based on the matching algorithm. The discontinuous boxplots represent the weighted distributions of propensity scores.