Childhood Vascular Risk Factors and Retinal Vessel Caliber

Influence of secondhand smoke exposure on the retinal vasculature of children in Hong Kong

BACKGROUND

A recent prospective demonstrated that cardiovascular risk factors in early childhood were associated with later cardiovascular events. However, the impact of secondhand smoke (SHS) on children is unclear. The aims of this study is to determine the effects of SHS exposure on the retinal vasculature of children.

METHODS

This is a population-based cross-sectional study of children aged 6 to 8 years. All participants received comprehensive ophthalmic examinations and retinal photography. Data on SHS exposure was derived from a validated questionnaire. A validated deep-learning system was used to automatically estimate retinal arteriolar and venular calibers from retinal photographs. Associations of quantitative retinal vessel caliber values with SHS exposure, number of smokers in the household, and total number of cigarettes smoked were determined by analyses of covariance (ANCOVA) after adjusting for potential confounders. Test of trend was determined by treating categorical risk factors as continuous ordinal variables.

RESULTS

Here we show children exposed to SHS have wider retinal arteriolar (CRAE 152.1 µm vs. 151.3 µm, p < 0.001) and venular (CRVE 216.7 µm vs. 215.5 µm, p < 0.001) calibers compared to those in smoke-free homes, after adjustment for different factors. Wider arteriolar and venular calibers are also associated with increasing number of smokers in the family (p trend < 0.001) and more cigarettes smoked among family smokers (p trend<0.001).

CONCLUSIONS

Exposure to SHS at home is associated with changes in retinal vasculature among children. This reinforces the adverse effect of secondhand smoking around children though further research incorporating comprehensive assessment of potential confounders is necessary.

Smoking in pregnancy is associated with increased adiposity and retinal arteriolar wall-to-lumen ratio in adolescence: The Copenhagen Child Cohort Study 2000

PURPOSE

To investigate the association between prenatal exposures and anthropometric data and cardiovascular risk factors including retinal arteriolar wall-to-lumen ratio in adolescence.

METHODS

This longitudinal observational study included all 1445 adolescents from the Copenhagen Child Cohort 2000 who attended the 2016-2017 examination. Outcome measures included retinal arteriolar wall-to-lumen ratio, height, body mass index, waist-to-hip ratio, body composition measured by bioimpedance, and blood pressure. Information on prenatal exposures (birth weight, gestational age, maternal smoking during pregnancy) as well as sex, parental age, household income and parental educational levels were obtained from national registries. Associations between exposures and outcome measures were analyzed using general linear models.

RESULTS

Maternal smoking during pregnancy was associated with a higher retinal arteriolar wall-to-lumen ratio (0.004 or 1.9%, P = 0.009) at age 16/17 years, an association driven exclusively by the female participants (0.008 or 3.7%, P < 0.0001). Maternal smoking during pregnancy was also associated to higher body-mass index (1.43 kg/m², P < 0.0001), waist-to-hip ratio (0.02, P < 0.0001) and fat mass index (0.93 kg/m², P < 0.0001). Birth weight, gestational age, and parental age had no detectable impact on retinal arteriolar wall-to-lumen ratios.

CONCLUSION

Prenatal exposure to tobacco smoking is associated with a higher risk of obesity and, predominantly in girls, to a greater retinal arteriolar wall thickness, which suggests that maternal smoking may induce an unfavorable cardiovascular and metabolic risk profile in the child.

Systematic review on retinal microvasculature, physical activity, sedentary behaviour and adiposity in children and adolescents

AIM

As retinal microvasculature (RMV) can be assessed non-invasively, it presents an opportunity to examine the health and disease of the human microcirculation, as RMV alterations have been recognised as one of the earliest signs of cardiovascular risk. This review summarises current literature on the associations between physical activity (PA), sedentary behaviour (SB) and/or adiposity and RMV in children and adolescents aged 0-18 years.

METHODS

Six databases were searched (MEDLINE, Scopus, Web of Science, ScienceDirect, PsycINFO and CINAHL), through to December 11, 2019. English, Portuguese, French, Spanish or Dutch were the languages searched. Meta-analyses were performed using the meta-analyst software.

RESULTS

A total of 6796 studies were screened, and 26 studies were included, representing 24 448 participants, from 12 different countries. Studies reporting results on weight status were twenty-three, PA was assessed in six studies, and SB was assessed in three studies. Four studies examined weight status and PA/SB. Meta-analysis was performed for two studies and showed that children with obesity have smaller retinal arterioles (-2.38 µm difference, 95% CI 0.62, 4.15 µm) and larger retinal venules (2.74 µm difference, 95% CI -4.78, -0.72 µm) than children without obesity.

CONCLUSION

Results showed that adiposity was associated with microvascular alterations in children and adolescents. Increased adiposity, lack of PA and high levels of SB were negatively correlated with vessel width parameters.

The impact of maternal asthma during pregnancy on offspring retinal microvascular structure and its relationship to placental growth factor production in utero

Asthma is a common chronic disease in pregnancy that affects placental function and fetal growth and associated with cardio-metabolic disorders in the offspring but the mechanisms are unknown. This study explored whether maternal asthma in pregnancy is associated with the development of offspring microvascular structure and whether it was related to biomarkers of angiogenesis in utero. Children aged 4 to 6 years, born to either asthmatic mothers (n = 38) or healthy controls (n = 25), had their retinal microvascular structure examined. Maternal plasma PlGF concentrations at 18 and 36 weeks' gestation were measured. There was a significant global difference in all retinal microvascular measures between children of asthmatic mothers relative to controls and increased retinal venular tortuosity in children born to asthmatic mothers (7.1 (95% CI 0.7-13.5); P = .031). A rise in plasma PlGF from 18 to 36 weeks' gestation was observed in the control population which was significantly lower in the asthma group by 190.9 pg/mL. PlGF concentrations were correlated with microvascular structure including arteriolar branching and venular tortuosity. These exploratory findings indicate that exposure to maternal asthma during pregnancy is associated with persistent changes in microvascular structure in childhood that may be driven by alterations to angiogenic mechanisms in utero.

Obesity, High Blood Pressure, and Physical Activity Determine Vascular Phenotype in Young Children

Cardiovascular disease often develops during childhood, but the determinants of vascular health and disease in young children remain unclear. The study aimed to investigate the association of obesity and hypertension, as well as physical fitness with retinal microvascular health and large artery stiffness, in children. In this cross-sectional study, 1171 primary school children (aged 7.2±0.4 years) were screened for central retinal arteriolar equivalent (CRAE) and central retinal venular equivalent (CRVE) diameters, pulse wave velocity (PWV), body mass index, blood pressure (BP), and cardiorespiratory fitness by standardized procedures for children. BP was categorized according to the reference values of the population-based German KiGGS study (Kinder- und Jugendgesundheitssurvey [Children- and Adolescents Health Survey]) and the American Academy of Pediatrics guidelines. Overweight (mean [95% CI]: CRAE, 200.5 [197.9-203.2] µm; CRVE, 231.4 [228.6-234.2] µm; PWV, 4.46 [4.41-4.52] m/s) and obese children (CRAE, 200.5 [196.4-204.7] µm; CRVE, 233.3 [229.0-237.7] µm; PWV, 4.51 [4.43-4.60] m/s) had narrower CRAE, wider CRVE, and higher PWV compared with normal-weight children (CRAE: 203.3 [202.5-204.1] µm, P<0.001; CRVE: 230.1 [229.1-230.9] µm, P=0.07; PWV: 4.33 [4.31-4.35] m/s, P<0.001). Children with high-normal BP (CRAE, 202.5 [200.0-205.0] µm; PWV, 4.44 [4.39-4.49] m/s) and BP in the hypertensive range (CRAE, 198.8 [196.7-201.0] µm; PWV, 4.56 [4.51-4.60] m/s) showed narrower CRAE, as well as higher PWV, compared with normotensive peers (CRAE: 203.7 [202.9-204.6] µm, P<0.001; PWV: 4.30 [4.28-4.32] m/s, P<0.001). With each unit increase of body mass index and systolic BP, CRAE decreased and PWV increased significantly. Children with the highest cardiorespiratory fitness had wider CRAE, narrower CRVE, and lower PWV compared with least fit children. Childhood obesity and hypertension, even at preclinical stages, are associated with microvascular and macrovascular impairments in young children. Primary prevention programs targeting physical activity behavior may have the potential to counteract development of small and large vessel disease early in life. Clinical Trial Registration- URL: http://www.clinicaltrials.gov . Unique identifier: NCT02853747.

Retinal microvasculature: population epidemiology and concordance in Australian children aged 11-12 years and their parents

OBJECTIVES

To describe distributions and concordance of retinal microvasculature measurements in a population-based sample of Australian parent-child dyads at child age 11-12 years.

DESIGN

Cross-sectional Child Health CheckPoint study, between waves 6 and 7 of the national population-based Longitudinal Study of Australian Children (LSAC).

SETTING

Assessment centres in seven Australian cities, February 2015-March 2016.

PARTICIPANTS

Of the 1874 participating families, 1288 children (51% girls) and 1264 parents (87% mothers, mean age 43.7) were analysed. Diabetic participants and non-biological pairs were excluded from concordance analyses.

OUTCOME MEASURES

Retinal photographs were taken by non-mydriatic fundus camera. Trained graders scored vascular calibre using semi-automated software, yielding estimates of central retinal arteriolar equivalent (CRAE) and central retinal venular equivalent (CRVE) and arteriolar-venular ratio (AVR). Pearson's correlation coefficients and multivariable linear regression models assessed parent-child concordance. Survey weights and methods accounted for LSAC's complex sampling, stratification and clustering within postcodes.

RESULTS

Mean (SD) of CRAE and CRVE were larger in children (159.5 (11.8) and 231.1 (16.5) μm, respectively) than parents (151.5 (14.0) and 220.6 (19.0) μm), yielding similar AVR (children 0.69 (0.05), parents 0.69 (0.06)). Correlation coefficients for parent-child pairs were 0.22 (95% CI 0.16 to 0.27) for CRAE, 0.23 (95% CI 0.17 to 0.28) for CRVE and 0.18 (95% CI 0.13 to 0.24) for AVR. Mother-child and father-child values were similar (0.20 and 0.32 for CRAE, 0.22 and 0.29 for CRVE, respectively). Relationships attenuated slightly on adjustment for age, sex, blood pressure, diabetes and body mass index. Percentiles and concordance are presented for the whole sample and by sex.

CONCLUSIONS

Arteriolar and venular calibre were similar to previously documented measures in midlife adult and late childhood populations. Population parent-child concordance values align with moderate polygenic heritability reported in smaller studies.

Obesity, Blood Pressure, and Retinal Vessels: A Meta-analysis

CONTEXT

Retinal vessel imaging is a noninvasive diagnostic tool used to evaluate cardiovascular risk. Childhood obesity and elevated blood pressure (BP) are associated with retinal microvascular alterations.

OBJECTIVE

To systematically review and meta-analyze associations between obesity, BP, and physical activity with retinal vessel diameters in children.

DATA SOURCES

We conducted a literature search through the databases of PubMed, Embase, Ovid, Web of Science, and the Cochrane Register of Controlled Trials.

STUDY SELECTION

School- and population-based cross-sectional data.

DATA EXTRACTION

General information, study design, participants, exposure, and outcomes.

RESULTS

A total of 1751 studies were found, and 30 full-text articles were analyzed for eligibility. Twenty-two articles (18 865 children and adolescents) were used for further assessment and reflection. Eleven articles were finally included in the meta-analysis. We found that a higher BMI is associated with narrower retinal arteriolar (pooled estimate effect size -0.37 [95% confidence interval (CI): -0.50 to -0.24]) and wider venular diameters (0.35 [95% CI: 0.07 to 0.63]). Systolic and diastolic BP are associated with retinal arteriolar narrowing (systolic BP: -0.63 [95% CI: -0.92 to -0.34]; diastolic BP: -0.60 [95% CI -0.95 to -0.25]). Increased physical activity and fitness are associated with favorable retinal vessel diameters.

LIMITATIONS

Long-term studies are needed to substantiate the prognostic relevance of retinal vessel diameters for cardiovascular risk in children.

CONCLUSIONS

Our results indicate that childhood obesity, BP, and physical inactivity are associated with retinal microvascular abnormalities. Retinal vessel diameters seem to be sensitive microvascular biomarkers for cardiovascular risk stratification in children.