Examination of the precision of the Cholestech LDX® point-of-care testing device for lipid profiling

Introduction: This study examines the precision of the Cholestech LDX® point-of-care testing (POCT) device. This device provides a full lipid profile from a capillary blood sample and is currently used in primary care in the Republic of Ireland and the UK for the screening for cardiovascular disease. Methodology: Ethical approval for this project was sought and granted. 55 staff members of University College Cork (UCC), Ireland were offered a free health screen, part of which involved two measurements of their lipid profile using the Cholestech LDX® POCT device. The capillary blood samples used for analysis were taken consecutively from different digits on the same hand. The lipid profile results were then analysed to see if there were any statistical or clinical differences between the two measurements. Data analysis were performed using Predictive Analytics Soft- Ware Statistics (PASW) (SPSS Inc. Chicago, Ill.) version 18.0 for statistical analysis Results: There was very good correlation between the two measurements for total cholesterol (TC) (r = 0.959, p < 0.0005, n = 52), the mean difference between the measurements was 0.16 ± 0.30mmol /L between the measurements (95%CI 0.07-0.24 mmol/L, p < 0.0005). A Kappa test of agreement demonstrated only moderate agreement between the two measurements (k = 0.69, p < 0.0005). There were also statistically significant differences between measurements for Triglycerides (TG) (0.13 ± 0.38 mmol/L, 95%CI 0.03-0.24 mmol/L, n = 50, p < 0.016) and Low Density Lipoprotein Cholesterol (LDL-C) (0.09 ± 0.27 mmol/L, 95%CI 0.01-0.17 mmol/ L, n = 46, p < 0.031). High Density Lipoprotein Cholesterol (HDL-C) showed no statistical or clinical differences between measurements (0.01 ± 0.17mmol/L, n = 49, p < 0.824). A Kappa test of agreement demonstrated almost perfect agreement between the measurements for HDL-C (k = 1, p < 0.0005). Conclusion: The Cholestech LDX® was shown to be imprecise for TC, TG and LDL-C. Caution must be used when using POCT devices for screening and monitoring cardiovascular disease. The Cholestech LDX® POCT device should not be used for diagnosis of dyslipidaemia.