Lipoprotein(a) testing in Norway: trends and perspectives from primary care

Abstract Background There is a growing focus on the role of lipoprotein(a) Lp(a) in cardiovascular disease (CVD) development. Despite its clinical relevance, Lp(a) testing remains uncommon worldwide. However, Norway stands out with a relatively high test frequency over the past 20 years, probably due to Lp(a) being discovered by the Norwegian scientist Kåre Berg in 1963, and the simplicity of requesting a test. The majority of Lp(a) tests in Norway are conducted by the general practitioners (GPs). Aims We aimed to investigate the prevalence of Lp(a) testing in Norway in the primary care and hospital settings between 2000-2023. We also aimed to identify the clinical indications and consequences associated with its use among GPs. Methods Trends of Lp(a) testing were analyzed based on data from the Norwegian Control and Payment of Health Reimbursement Database (KUHR) and national laboratory data from Fürst Medical Laboratory (Fürst) between 2000-2023, where the measurements are mainly ordered by the GPs from the primary care. Data from Lp(a) testing among GPs were collected in May 2024 through an online questionnaire. The sample consisted of 100 Norwegian GPs. Results 64,875 Lp(a) measurements were performed in 2023 in Norway (1.5% of the population above 18 yrs). 75% of the Lp(a) measurements in 2023 were analyzed at Fürst. 45% of the tests at Fürst were repeated measurements. We estimate that ~15% of the Norwegian population above 18 years of age had an Lp(a) test between 2000 and 2023. The number of Lp(a) tests at Fürst increased by 329% from 11,362 tests in 2000 to 48,795 tests in 2023. The test frequency was similar in women and men throughout the period, with the highest test frequency in age group 50-60 years. 63% of the GPs in the questionnaire answered that they have tested for Lp(a) at least once. When asked about tests they usually request for cardiovascular risk assessment, 9% of GPs indicated testing Lp(a) in patients without CVD, 16% indicated testing in patients with established CVD, and 19% in both groups, while 56% indicated not testing Lp(a) in this context. Among the 63% of GPs that had tested for Lp(a) at least once, the most common reason for testing Lp(a) was a family history of CVD (68% and 73% for patients with and without CVD, respectively) and the most common impact of an elevated Lp(a) test was intensification of preventive treatment for other risk factors (68% and 71% in patients with and without CVD). Conclusion ~15% of the total Norwegian population above 18 years was tested for Lp(a) between 2000 and 2023, which makes Norway one of the countries with the highest testing rates of Lp(a) worldwide. The annual testing rate for Lp(a) was 1.5% of the Norwegian population in 2023, and the tests are primarily requested by GPs. A family history of premature CVD was reported to be the major motivation for testing.