Apolipoprotein screening in Australian children: feasibility and the effect of age, sex, and ethnicity

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Abstract
Objectives (i) To evaluate the feasibility of detecting adverse lipid profiles in schoolchildren by measuring capillary dried blood spot apolipoprotein levels, and (ii) to assess the effect of age, sex and ethnicity on apolipoprotein levels. Design We measured capillary dried blood spot apolipoproteins B and A‐l (apo B and apo A‐l); assessed levels in relation to age, sex and ethnicity; and recalled children with elevated levels for a full lipid profile measurement. Participants and setting 6992 children (3501 boys and 3491 girls), aged 5‐13 years, from schools in eastern Sydney, 1991‐1995. Main outcome measures Capillary blood levels of apolipoproteins B and A‐l, and serum total cholesterol level. Results Of the 6951 children who provided an adequate fingerprick blood sample, we recalled 1465 children (21.1%) (640 boys [43.7%] and 825 girls [56.3%]) with elevated apo B levels and/or apo B: apo A‐l ratios for further testing, either by us or by their family doctor (overall estimated compliance rate up to 70%). Among the 458 children who returned to us, there was a 90% positive predictive value for a total cholesterol level of over 4.5 mmol/L in those with both elevated apo B levels and high apo B: apo A‐l ratios. Girls had higher apo B levels and apo B: apo A‐l ratios than boys (P<0.00001 for both), and in both sexes there was a trend downwards for apo B and upwards for apo B: apo A‐l ratio over the age range tested, but levels were relatively stable between the ages of 6 and 10 years. Indian children (1.5% of the screened population) had the highest apo B levels, followed by white children (71.1%); Asian children (9.2%) had the lowest (P<0.00001 compared with Indian and white children). Conclusions The high positive predictive value of capillary blood apolipoprotein levels for an adverse lipid profile in children suggests that measuring apolipoprotein levels by this method is a useful initial approach to cardiovascular risk assessment.