30 Lipid ranges in an irish population

Introduction Dyslipidemia is recognised as one of the most important modifiable risk factors for cardiovascular disease. The distribution of lipid parameters for certain populations, most notably in the United States, has been previously characterised in numerous studies, however there has never been a detailed evaluation of lipid distributions in an Irish cohort. Methods 110,620 serum lipid profile requests and result sets in an Irish population between 2004 and 2017 were analysed in relation to changes in age and sex-specific lipid distributions. This group was sub selected from a much larger database to include only first-time requests from primary care and taking precautions to have an untreated population. From this database we calculated age- and sex-related reference intervals for every 5 years of life from the age of 10 years to greater than 90 years for total cholesterol, triglycerides (TG), HDL cholesterol and LDL cholesterol (LDL-C). Results There are notable differences between the sexes and across different age groups in lipid profiles. Figure 1 shows the mean values for LDL-C for our population. The differences appear before the 20-year-old group and show that LDL-C levels rise at a younger age in men and peak at the ages of 40–50 years. In women peak values occur in the older age groups and women have higher mean values than men over the age of 50 years. Total cholesterol distributions follow a similar pattern to that of LDL-C. (Figure 2) The distribution of triglyceride levels for both males and females show a distinct positive skew from childhood through to old age. The positive skew is particularly marked in adult males up to the 60-year age group. In middle age median triglycerides are 0.5 mmol/l higher in males than females, with the sex difference widening to about 2.2 mmol/l amongst those individuals towards the 97.5 percentile of the distribution. Above 65 years triglyceride levels tend to fall or plateau in both sexes. Distributions in an Irish population are similar to international temporal and geographical comparisons, however the elderly Irish population tend to have lower total cholesterol levels than international comparators. Conclusions These distributions should be constructive in epidemiological and public health initiatives, providing data for temporal and geographical comparisons with other similar studies. For healthcare professionals advising individual patients it provides useful age-related reference intervals for the interpretation of significant dyslipidaemias.