Sex and age as determinants for high blood pressure in pediatric renal transplant recipients: a longitudinal analysis of the CERTAIN Registry

Physical activity and its impact on cardiovascular health in pediatric kidney transplant recipients

BACKGROUND

Cardiovascular (CV) morbidity after kidney transplantation (KTx) in childhood is of increasing importance. In light of a high prevalence of CV risk factors, protective measures such as physical activity (PA) come into focus. Our aim was to comprehensively assess PA in pediatric KTx recipients and evaluate its impact on CV health.

METHODS

Forty-eight patients were assessed for frequency, duration, intensity, and setting of PA using the "Motorik-Modul" PA questionnaire. Walking-based activity was measured by accelerometer in a subgroup (n = 23). CV risk factors and subclinical CV organ damage were determined. The impact of PA on CV parameters was analyzed using linear regression models.

RESULTS

Fifty-two percent of pediatric KTx recipients did not reach WHO recommended PA level; 54% did not engage in PA with vigorous intensity (VPA). Twenty-nine percent indicated an extremely inactive lifestyle (< 120 min/week of moderate to vigorous intensity PA, MVPA). Compared to the healthy German KiGGS cohort, KTx recipients specifically lacked engagement in sport activities (KTx: 129 min/week; 95%CI, 97-162 vs. KiGGS, 242 min/week; 95%CI, 230-253). VPA was associated with lower systolic blood pressure (p = 0.024) and resting heart rate (p = 0.005), MVPA with fewer components of the post-transplant metabolic syndrome (p = 0.037), and better left ventricular diastolic function (p = 0.006).

CONCLUSIONS

A considerable lack of PA, especially VPA, exists in young KTx recipients. PA was positively associated with important parameters of CV health. While long-term CV protection through PA seems promising in pediatric KTx recipients, specific educational approaches are most likely needed to increase patients' engagement in sport activities.

Hypertension in Pediatric Solid Organ Transplant Recipients

PURPOSE OF REVIEW

To review the current literature regarding hypertension (HTN) following pediatric solid organ transplant (SOTx), including definition, prevalence, risk factors, outcomes, and treatment.

RECENT FINDINGS

In recent years several new guidelines for the definition, monitoring, and management of pediatric HTN have been published, but with no specific recommendations regarding SOTx recipients. HTN remains highly prevalent, yet underdiagnosed and undertreated in kidney transplant (KTx) recipients, especially when ambulatory blood pressure monitoring (ABPM) is utilized. There are little data regarding its prevalence in other SOTx recipients. HTN in this population is multifactorial and is associated with HTN status prior to Tx, demographic factors (age, sex, and race), weight status, and immunosuppression protocol. HTN is associated with subclinical cardiovascular (CV) end-organ damage, including left ventricular hypertrophy (LVH) and arterial stiffness, yet there are no recent data regarding its long-term outcomes. There are also no updated recommendations regarding the optimal management of HTN in this population. Given its high prevalence and the young age of this population facing years at increased CV risk, post-Tx HTN requires more clinical attention (routine monitoring, frequent application of ABPM, better BP control). Additional research is needed for a better understanding of its long-term outcomes as well as its treatment and treatment goals. Much more research is needed regarding HTN in other pediatric SOTx populations.

The significance of central blood pressure for cardiovascular target organ damage in children and adolescents after kidney transplantation

BACKGROUND

Cardiovascular (CV) complications are important causes of morbidity and mortality in children after kidney transplantation (KTx). In adults, central blood pressure (cBP) is an accepted predictor of CV sequelae. We aimed to assess the prognostic value of cBP over peripheral blood pressure (pBP) for existing CV damage.

METHODS

We measured cBP and pBP in 48 pediatric KTx recipients (mean age: 13.5 ± 4.2 years). Assessment of left ventricular mass index (LVMI) and aortic pulse wave velocity (PWV) allowed detection of CV target organ damage. LVMI and PWV were used as endpoints in multivariable linear regression models, in which cBP and pBP were compared for their predictive value.

RESULTS

Using cBP z-scores, we identified a larger number of patients with uncontrolled or untreated hypertension compared to pBP (36% vs. 7%). Central systolic blood pressure (cSBP) was a significant independent predictor of LVMI, while peripheral systolic blood pressure (pSBP) was not. Comparing central (cDBP) and peripheral (pDBP) diastolic blood pressure for their predictive value on PWV revealed a greater estimate for cDBP (0.035 vs. 0.026 for pDBP) along with a slightly better model fit for cDBP.

CONCLUSIONS

Our data in a small group of patients provide first evidence that cBP measurements in pediatric KTx recipients might be helpful in identifying patients at risk for the development of CV sequelae. Investigating a larger patient number, ideally repeatedly, is needed to create further evidence supporting our findings. In light of available devices measuring cBP noninvasively, the implementation of such clinical studies post-KTx care should be feasible. A higher resolution version of the Graphical abstract is available as Supplementary information.

Arterial stiffness and blood pressure increase in pediatric kidney transplant recipients

BACKGROUND

Pulse wave velocity (PWV) is a measure of arterial stiffness. We investigated PWV and blood pressure (BP) to determine to what extent BP changes contribute to arterial stiffness, and secondly, to identify influencing factors on BP in children after kidney transplantation.

METHODS

Seventy children ≥ 2.5 years post-transplantation with at least two PWV measurements were included. Changes of systolic (Δ SBP) and diastolic BP (Δ DBP) were classified into "stable/decreasing," "1-10 mmHg increase," and " > 10 mmHg increase." Linear mixed modeling for PWV z-score (PWVz) adjusted either for Δ SBP or Δ DBP was performed. An extended dataset with monthly entries of BP, immunosuppression, and creatinine was obtained in 35 participants over a median of 74 months to perform linear mixed modeling for SBP and DBP.

RESULTS

PWVz increased with a rate of 0.11/year (95% CI 0.054 to 0.16). Compared to participants with stable BP, those with 1-10-mmHg SBP and DBP increase showed a higher PWVz of 0.59 (95% CI 0.046 to 1.13) and 0.86 (95% CI 0.43 to 1.30), respectively. A > 10-mmHg BP increase was associated with an even higher PWVz (SBP β = 0.78, 95% CI 0.22 to 1.34; DBP β = 1.37, 95% CI 0.80 to 1.94). Female sex and participants with lower eGFR showed higher PWVz. In the extended analysis, DBP was positively associated with cyclosporin A and everolimus trough levels.

CONCLUSIONS

A higher increase of PWV is seen in patients with greater BP increase, with higher cyclosporin A and everolimus trough levels associated with higher BP. This emphasizes the role of BP as a modifiable risk factor for the improvement of cardiovascular outcome after transplantation. A higher resolution version of the Graphical abstract is available as Supplementary information.

The Association of Midday Napping With Hypertension Among Chinese Adults Older Than 45 Years: Cross-sectional Study

BACKGROUND

Hypertension is one of the main public health issues around worldwide, and midday napping is a popular habit. The association between the two remains to be explored.

OBJECTIVE

The goal of the research was to explore the association of midday napping with hypertension.

METHODS

This study separately selected 11,439, 12,689, and 9464 Chinese respondents aged over 45 years from the China Health and Retirement Longitudinal Study 2011, 2015, and 2018 data sets. Binary logistic regression was used to explore the association of midday napping with hypertension, and the 3-step method was used to test the mediation effect of BMI.

RESULTS

Among all respondents, the prevalence rates of hypertension were 24.6% (2818/11439) in 2011, 21.1% (2683/12689) in 2015, and 22.1% (2092/9464) in 2018. Midday napping was positively correlated with hypertension. In 2011 and 2015, napping 60 to 90 minutes had the greatest odds ratios [OR] (OR₂₀₁₁ 1.705, OR₂₀₁₅ 1.494). In 2018, the biggest OR came from the group napping 30 to 60 minutes (OR 1.223), and ORs of different napping durations decreased from 2011 to 2018. In addition, BMI had a partial mediation effect in 2015 and 2018.

CONCLUSIONS

Midday napping is a potential risk factor for hypertension with BMI acting as a mediator. To prevent hypertension, avoiding prolonged duration of midday napping and taking action to maintain a normal BMI level are recommended.

Impact of Sex and Obesity on Echocardiographic Parameters in Children and Adolescents

Subclinical alterations in left ventricular structure and function are detectable in adolescents with hypertension or obesity. However, data on early echocardiographic abnormalities in seemingly healthy children are lacking. Sex differences in cardiac structure and function have been previously reported, but sex-specific reference values are not available. Specifically, the potential interaction of sex and overweight has not been addressed at all. Anthropometric data, blood pressure and exercise tests were obtained in 356 healthy children. Echocardiographic parameters comprised peak early (E) and late (A) mitral inflow Doppler velocities, E/A ratio, tissue Doppler peak velocities of early (e') and late diastolic (a') excursion of mitral/septal annulus and isovolumetric relaxation time (IVRT). Left ventricular mass index (LVMI) and LVMI z-score were calculated. Interaction terms between BMI and sex and stratification by sex were used for analysis. We provide values for echocardiographic parameters for children of two age groups separated by BMI. Overweight/obese children had a significant higher LVMI, lower E/A ratio, higher E/e' ratios and a longer IVRT. For a given BMI in the upper ranges we demonstrated a higher LVMI in girls than in boys, the IVRT extended significantly more in girls than in boys with increasing BMI. There are sex differences in structural and functional echocardiographic parameters in children and adolescents. Our data not only confirms the importance of overweight and obesity, but demonstrates important interactions between sex and overweight. The greater susceptibility of overweight girls toward echocardiographic changes associated with potential long-term functional impairment needs further exploration and follow-up.Trial registration number DRKS00012371; Date 18.08.2017.

Insights from the 4C-T Study suggest increased cardiovascular burden in girls with end stage kidney disease before and after kidney transplantation

Mortality in children with kidney failure is higher in girls than boys with cardiovascular complications representing the most common causes of death. Pulse wave velocity (PWV), a measure of vascular stiffness, predicts cardiovascular mortality in adults. Here, PWV in children with kidney failure undergoing kidney replacement therapy was investigated to determine sex differences and potential contributing factors. Two-hundred-thirty-five children (80 girls; 34%) undergoing transplantation (150 pre-emptive, 85 with prior dialysis) having at least one PWV measurement pre- and/or post-transplantation from a prospective cohort were analyzed. Longitudinal analyses (median/maximum follow-up time of 6/9 years) were performed for PWV z-scores (PWVz) using linear mixed regression models and further stratified by the categories of time: pre-kidney replacement therapy and post-transplantation. PWVz significantly increased by 0.094 per year and was significantly higher in girls (PWVz +0.295) compared to boys, independent of the underlying kidney disease. During pre-kidney replacement therapy, an average estimated GFR decline of 4ml/min/1.73m² per year was associated with a PWVz increase of 0.16 in girls only. Higher diastolic blood pressure and low density lipoprotein were independently associated with higher PWVz during pre-kidney replacement therapy in both sexes. In girls post-transplantation, an estimated GFR decline of 4ml/min/1.73m² per year pre-kidney replacement therapy and a longer time (over 12 months) to transplantation were significantly associated with higher PWVz of 0.22 and of 0.57, respectively. PWVz increased further after transplantation and was positively associated with time on dialysis and diastolic blood pressure in both sexes. Thus, our findings demonstrate that girls with advanced chronic kidney disease are more susceptible to develop vascular stiffening compared to boys, this difference persist after transplantation and might contribute to higher mortality rates seen in girls with kidney failure.

Acute rejection and growth outcomes in paediatric kidney allograft recipients treated with a corticosteroid minimisation immunosuppressive protocol

BACKGROUND

Corticosteroid minimisation immunosuppressive protocols (CMP) for children are an approach to safely reduce unwanted medication side effects associated with long-term exposure following kidney transplantation. Here, we provide data regarding the incidence of acute rejection and growth over an extended follow-up in children receiving the CMP used in our centre.

METHODS

We retrospectively analysed all children treated with a CMP who received a kidney transplant and had follow-up care in our centre between 2009 and 2019. Data were compared to 5 control groups from recent studies.

RESULTS

Ninety-nine kidney allograft recipients were included in the study (mean follow-up 4.4 years). There was no difference in the cumulative frequency of acute rejection in CMP-treated graft recipients compared to controls. Graft function at latest follow-up was significantly lower in graft recipients experiencing acute rejection compared to those without acute rejection (53.7 mL/min/1.73 m² vs. 66.8 mL/min/1.73 m², p = 0.021). Children experiencing >1 acute rejection episode had a greatly elevated risk of graft failure (p = 0.0009, OR 68.25). At latest follow-up, 64/90 (71.1%) graft recipients had a normal height, and younger graft recipients demonstrated greater catch up growth than older children. CMP-treated graft recipients showed a reduced rate of height deficit (28.9% vs. 55.1%, p = 0.0025), less obesity (12.2% vs. 23.9%, p = 0.031), and reduced rates of hypertension (35.4% vs. 68.2%, p< 0.0001).

CONCLUSIONS

Children treated with a CMP show greater height attainment, lower frequency of obesity, and reduced rates of hypertension, without an increased risk of acute rejection. Graphical abstract.