Lipoprotein a level and its correlates, in children and adolescents of Saurashtra region in India: Cross sectional study

Aim: To generate data on serum Lipoprotein(a) levels and look for its correlation with different factors/ characteristics in children and adolescents (6-15 years) years from Saurashtra region of India

Available data depicts significant ethnic variation in the Lp(a) levels.  South Asian population are at high risk of ASCVD and have been found to exhibit high median Lp(a) level. However, data on normal levels/ range of Lp(a) levels in Indian children is scarce and exhibit significant variation due to lack of standardization and harmonization of Lp (a) assays. To the best of our knowledge there is no data on correlation/ association of Lp(a) levels with demographic, anthropometric and biochemical characteristics in children from our country. It needs to be emphasized that we still do not have any evidence-based Lp(a) cut off points for ascertaining risk in primary prevention settings for ASCVD.

Given the lacunae in literature, the objective of the study is to estimate the levels of Lp(a) and assess the correlation of  serum Lp(a) level to various risk factors of ASCVD in children and adolescents in a Saurashtra region, in Gujarat.

Study design: Cross sectional Observational study

Methodology:

The study participants meeting  eligibility criteria (inclusion/exclusion) will be recruited after written/verbal assent and parental consent as applicable for the age. Children presenting with acute illness during the first visit shall be assessed for meeting eligibility criteria in their follow up visit post the illness (2 weeks after illness subsides).

A pre-structured case detail performa shall be used to collect their demographic details, medical history, dietary history (24 hour recall method), socioeconomic history (Modified Kuppuswamy scale). Their physical activity (minutes/week; classified as <300 mins/week & >300 mins/week), screen time (hours/day & days/week; classified as <120 mins/day & >120 mins/day) will be noted as reported. Their birth weight will be noted and categorised as <1500 gms, <2500 gms, 2500-4100 gms, >4100 gms.

Data related to the family history of risk factors of atherosclerotic cardiovascular disease [(a) high blood pressure or stroke before age 50, b) heart attack or angina before the age of 50, c) high blood cholesterol or on lipid lowering medicines at any age, d) diabetes at any age] will be collected.

Anthropometry of the child (Height, Weight, Waist circumference, Hip Circumference) will be done by standard techniques . Standing height will be measured to the nearest 1mm by calibrated scale (Secca wall mounted stadiometer), weight to the nearest 0.1 kg using calibrated digital scale, and waist and hip circumference to the nearest 1mm using calibrated non stretchable anthropometric tape. Waist circumference (W.C) will be measured at the midpoint of the lowest rib cage and the iliac crest, in standing position during end-tidal expiration  and Hip circumference (H.C) at the maximum diameter of buttocks in standing position. Waist circumference will be classified as <70th centile/>70th centile for age and sex as per Indian charts (Khadilkar). Waist circumference height (WHt) ratio will be calculated (<0.5, >0.5).

Arterial blood pressure measurement will be done on the left arm of the child kept at the level of the heart in sitting position.  Two readings will be taken at 10-min intervals using an Omron  blood pressure monitor. Average readings of more than 90th percentile will be verified by auscultatory method. A systolic and/or diastolic blood pressure ≥90th percentile  as per the age, sex and height centile as per American task force on hypertension charts 2020, will be classified as hypertension risk.

Pubertal stage will be determined based on Tanner’s criteria: prepubertal (1–2 Tanner stage), pubertal (3–4 Tanner stage) and post pubertal (5 Tanner stage).

Acanthosis nigricans will be noted on the back of the neck, as a skin indicator of insulin resistance. Acanthosis will be rated for severity on a scale of 0 to 4 points as per Burke’s scale, with a score of 0 indicating absence and a score of 1, 2, 3, or 4 indicating presence (1, least severe barely visible, 2- limited till base of neck, 3- extending laterally on neck, 4, most severe extending anteriorly). Other significant general physical and systemic examination findings will also be noted.

Body composition analysis will be done by impedance analysis method, using the Inbody 770 equipment. The participants will be requested to stand on the equipment with bare feet, ensuring that the soles of their feet are in contact with the metal impressions on the foot platform. Additionally, participants will be asked to hold the hand device with both hands, keeping their arms abducted at a 90-degree angle. This procedure typically takes approximately 2 minutes to complete.

Blood samples will be obtained for assessing serum Lp(a) levels and other biochemical parameters viz Lipid profile, fasting glucose, creatinine, SGPT/OT, CRP (1 plain vial (4mL and 1 fluoridated vial (1mL)). The Lp(a) concentrations will be measured using an uniformly, calibrated immunoturbidimetric assay in concordance with WHO/IFCC reference standards. The samples will be processed on the day of collection and data will be kept confidential.

The study participants will be informed about the results of the investigations if requested or if any abnormality is detected in the biochemical parameters, in which case relevant standard of care shall be offered to them.

Scope of the project-

The generated data will provide important information about normative data of Lp(a) levels in Indian children. The generated data may facilitate future large scale epidemiological studies. It might provide supportive evidence for policy-makers to introduce the estimation of Lp(a) for universal/ selective screening, particularly at a younger age. This will facilitate early adoption of lifestyle interventions in meticulously managing the ASCVD risk factors over the life course, viz avoiding smoking, managing weight, adopting physical exercise and diet modulation. It might also aid in clinical decision-making regarding the introduction, modification, or initiation of lipid-lowering therapies in children with concurrent high LDL cholesterol. Identification of individuals who might gain from upcoming targeted therapies is another consideration.