¹Department of Pediatrics, Karolinska University Hospital, Huddinge, Sweden

Correspondence: Rafael T. Krmar, Department of Pediatrics, Karolinska University Hospital, Huddinge, S-141 86 Stockholm, Sweden E-mail: rafael.krmar@klinvet.ki.se

^*This work was partially supported by grants (to R.T.K. and U.B.B.) from the Freemason's Stockholm Foundation for Children's Welfare, the Samariten Foundation, and the Research Foundation of Karolinska Institute, and from the Swedish Medical Research Foundation (grant no. 6864), respectively.

Received 25 January 2005; Revised 6 May 2005; Accepted 10 May 2005.

Abstract

Background: The aim of this study was to evaluate, in stable pediatric renal transplant recipients, the long-term reproducibility of average office and ambulatory blood pressure (BP) readings and day-to-night BP variability under similar clinical conditions.

Methods: The study involved 18 pediatric kidney transplant recipients who had repeated routine office and 24-h ambulatory BP monitoring (ABPM) in three visits, 12 months apart, over a 2-year period. Reproducibility of office and ambulatory BP averages between pairwise measurements were analyzed by calculating the mean difference and the standard deviation of the difference (SDD). Nondippers were arbitrarily defined by applying both a pediatric and an adult definition, respectively.

Results: Throughout the 2-year period, there were no significant differences in mean office, 24-h, daytime, night-time systolic, and diastolic BP values. Overall, SDD were lower for ambulatory BP recordings than for office BP measurements indicating a better long-term reproducibility for ABPM compared with office BP readings. The SDD for systolic and diastolic BP ranged from 12.4 to 13.7 and 6.3 to 9.5 for office BP and from 6.2 to 7.3 and 5.1 to 5.6 for 24-h BP, respectively. Regardless of the definition applied to define dipper and nondipper status, only half of the study group showed consistency in their circadian BP variability when comparing the three ABPMs.

Conclusions: The present study demonstrates that long-term reproducibility of ABPM is superior to that for office measurements. Day-to-night BP variability, however, appears to change over time, making it questionable to classify a recipient as a dipper or nondipper during a single ABPM recording.