A systematic review of lipoprotein(a) reporting in Australia: variability in availability, measurement, and clinical recommendations

Background/introduction Lipoprotein(a) [Lp(a)] is an established risk factor for atherosclerotic cardiovascular disease (ASCVD). While guidelines recommend Lp(a) should be measured at least once in a person’s lifetime, very few Lp(a) tests are ordered. Hesitancy to order Lp(a) tests may be due to the inability to modify elevated levels if they are detected, but may also relate to a lack of access to the testing facilities and their out-of-pocket costs for patients. Purpose We aimed to characterise the variability in availability of lipoprotein(a) [Lp(a)] testing and reporting format amongst Australian pathology providers. Methods A cross-sectional national review was conducted through interviews and de-identified Lp(a) reports from Australian public and private laboratories accredited by the Royal College of Pathologists of Australasia (covering >90% of pathology services in Australia). Data were extracted on Lp(a) test availability, pricing, measurement units, threshold values for clinical decision-making, the inclusion of interpretative comments and management recommendations, and relevant guidelines referenced. Results Fourteen of the fifteen laboratory networks contacted provided data. Four were state-wide centralised public pathology networks, and three were national private pathology networks. Lp(a) testing was available on-site in nine laboratory networks, and available as a send-away test in the remaining five. Testing costs to patients ranged from no charge to $75. All measurements were in nmol/L. Among networks that conducted in-laboratory testing, a reference interval of <32nmol/L was used in three networks and <72nmol/L in five networks. One network did not provide a reference interval. Interpretative comments varied, with two networks citing a threshold of >75 nmol/L, two citing >90 nmol/L, two citing >100 nmol/L, and one citing >125 nmol/L for elevated risk of cardiovascular events. Clinical recommendation for familial screening was utilised by one reporting network. Six different guidelines were referenced among the nine networks performing Lp(a) measurements. Conclusion Significant heterogeneity in Lp(a) reporting exists and may lead to confusion around result interpretation. Many labs still do not have access to on-site testing which likely contributes to an increased cost for testing. As interest in Lp(a) continues to grow with the advent of targeted therapies, access and harmonisation of reporting will be increasingly important.