Prognosis of hypercholesterolemic patients taking pravastatin for five years: the Chiba Lipid Intervention Program (CLIP) Study

Discontinuation versus continuation of statins: A systematic review

BACKGROUND

Clinicians and patients often face a decision to continue or discontinue statins. We examined the impact of discontinuation of statins compared with continuation on clinical outcomes (all-cause mortality, cardiovascular [CV] mortality, CV events, and quality of life).

METHODS

We conducted a systematic review. Randomized controlled trials (RCTs), cohort studies, case-control studies, and quasi-randomized studies among people ≥18 years were eligible. We searched MEDLINE, Embase, and Cochrane Central Registry (inception to August 2023). Two independent reviewers performed screening and extracted data. Quality assessment was performed by one author and verified by another. We summarized results narratively, performed meta-analysis for a subset of studies, and used GRADE to assess certainty of evidence. We summarized findings in the subgroup of persons ≥75 years.

RESULTS

We retrieved 8369 titles/abstracts; 37 reports from 36 studies were eligible. This comprised 35 non-randomized studies (n = 1,708,684) and 1 RCT (n = 381). The 1 RCT was conducted among persons with life expectancy <1 year and showed there is probably no difference in 60-day mortality (risk difference = 3.5%, 90% CI -3.5 to 10.5) for statin discontinuation compared with continuation. Non-randomized studies varied in terms of population and setting, but consistently suggested that statin discontinuation might be associated with a relative increased risk of mortality (hazard ratio (HR) 1.92, 95% CI 1.52 to 2.44, nine studies), CV mortality (HR 1.63, 95% CI 1.27 to 2.10, five reports), and CV events (HR 1.31, 95% CI 1.23 to 1.39, eight reports). Findings in people ≥75 years were consistent with main results. There was a high degree of uncertainty in findings from non-randomized studies due to methodological limitations.

CONCLUSIONS

Statin discontinuation does not appear to affect short-term mortality near end-of-life based on one RCT. Outside of this population, findings from non-randomized studies consistently suggested statin discontinuation may be associated with worse outcomes, though this is uncertain.

Prevalence of statin intolerance: a meta-analysis

AIMS

Statin intolerance (SI) represents a significant public health problem for which precise estimates of prevalence are needed. Statin intolerance remains an important clinical challenge, and it is associated with an increased risk of cardiovascular events. This meta-analysis estimates the overall prevalence of SI, the prevalence according to different diagnostic criteria and in different disease settings, and identifies possible risk factors/conditions that might increase the risk of SI.

METHODS AND RESULTS

We searched several databases up to 31 May 2021, for studies that reported the prevalence of SI. The primary endpoint was overall prevalence and prevalence according to a range of diagnostic criteria [National Lipid Association (NLA), International Lipid Expert Panel (ILEP), and European Atherosclerosis Society (EAS)] and in different disease settings. The secondary endpoint was to identify possible risk factors for SI. A random-effects model was applied to estimate the overall pooled prevalence. A total of 176 studies [112 randomized controlled trials (RCTs); 64 cohort studies] with 4 143 517 patients were ultimately included in the analysis. The overall prevalence of SI was 9.1% (95% confidence interval 8.0-10%). The prevalence was similar when defined using NLA, ILEP, and EAS criteria [7.0% (6.0-8.0%), 6.7% (5.0-8.0%), 5.9% (4.0-7.0%), respectively]. The prevalence of SI in RCTs was significantly lower compared with cohort studies [4.9% (4.0-6.0%) vs. 17% (14-19%)]. The prevalence of SI in studies including both primary and secondary prevention patients was much higher than when primary or secondary prevention patients were analysed separately [18% (14-21%), 8.2% (6.0-10%), 9.1% (6.0-11%), respectively]. Statin lipid solubility did not affect the prevalence of SI [4.0% (2.0-5.0%) vs. 5.0% (4.0-6.0%)]. Age [odds ratio (OR) 1.33, P = 0.04], female gender (OR 1.47, P = 0.007), Asian and Black race (P < 0.05 for both), obesity (OR 1.30, P = 0.02), diabetes mellitus (OR 1.26, P = 0.02), hypothyroidism (OR 1.37, P = 0.01), chronic liver, and renal failure (P < 0.05 for both) were significantly associated with SI in the meta-regression model. Antiarrhythmic agents, calcium channel blockers, alcohol use, and increased statin dose were also associated with a higher risk of SI.

CONCLUSION

Based on the present analysis of >4 million patients, the prevalence of SI is low when diagnosed according to international definitions. These results support the concept that the prevalence of complete SI might often be overestimated and highlight the need for the careful assessment of patients with potential symptoms related to SI.

Statin intolerance: an updated, narrative review mainly focusing on muscle adverse effects

INTRODUCTION

Statins have been established as the standard of care for dyslipidemia and preventing cardiovascular diseases while posing few safety concerns. However, misconceptions about statin intolerance lead to their underuse, indicating a need to improve the understanding of the safety of this treatment.

AREAS COVERED

We searched PubMed and reviewed literatures related to statin intolerance published between February 2015 and February 2020. Important large-scale or landmark studies published before 2015 were also cited as key evidence.

EXPERT OPINION

Optimal lowering of low-density lipoprotein cholesterol with statins substantially reduces the risk of cardiovascular events. Muscle adverse events (AEs) were the most frequently reported AEs by statin users in clinical practice, but they usually occurred at a similar rate with statins and placebo in randomized controlled trials and had a spurious causal relationship with statin treatment. We proposed a rigorous definition for identifying true statin intolerance and present the criteria for defining different forms of muscle AEs and an algorithm for their management. True statin intolerance is uncommon, and every effort should be made to exclude false statin intolerance and ensure optimal use of statins. For the management of statin intolerance, statin-based approaches should be prioritized over non-statin approaches.

Serum cystatin C is associated with large cerebral artery stenosis in acute ischemic stroke

Large cerebral artery stenosis is a major cause of acute ischemic stroke (AIS); however, the correlation between serum cystatin C (CysC) and the stenosis of large cerebral arteries in patients with AIS has not been established. We performed a retrospective review of acute ischemic stroke patients, who were examined by cerebral digital subtraction angiography(DSA). Participants (252 cases) included 131 patients without stenosis and 121 patients with large cerebral artery stenosis. Serum CysC levels in patients with large cerebral artery stenosis were much higher than that of control subjects (p<0.001). However, serum CysC levels were not related to the location of stenosis. Further, logistic regression analyses showed that increased serum CysC was an independent risk factor of large cerebral artery stenosis in patients with acute ischemic stroke. Total participants were subdivided into quintiles based on serum CysC levels. Compared with the first quintile, the odds ratios of risk for large cerebral artery stenosis in the fourth and the fifth quintile were 1.26 (p<0.05) and 4.71(p<0.05) respectively, after the adjustment for age, sex, and smoking, hypertension, type 2 diabetes mellitus(DM), dyslipidemia, creatinine(Cr), urea, uric acid, and C reactive protein(CRP). Therefore, a significant positive correlation was observed between elevated serum CysC levels and large cerebral artery stenosis in patients with acute ischemic stroke. In summary, our findings provide new insights into the correlation between increased serum CysC and large cerebral artery stenosis in patients with acute ischemic stroke.

Cystatin C-Adiponectin Complex in Plasma Associates with Coronary Plaque Instability

Aim: Adiponectin (APN) is an adipocyte-derived bioactive molecule with antiatherogenic properties. We previously reported that cystatin C (CysC) abolished the anti-atherogenic effects of APN. We aimed to elucidate the clinical significance of CysC–APN complex in patients with coronary artery disease (CAD).

Methods: We enrolled 43 stable CAD male patients to examine the relationship between CysC–APN complex and coronary plaque characteristics. Serum was immunoprecipitated by the anti-APN antibody and immunoblotted by the anti-CysC antibody to demonstrate the presence of CysC–APN complexes in vivo. To confirm their binding in vitro, HEK293T cell lysates overexpressing myc-APN and FLAG-CysC were immunoprecipitated with an anti-myc or anti-FLAG antibody, followed by immunoblotting with an anti-APN or anti-CysC antibody.

Results: CysC was identified as a specific co-immunoprecipitant with APN by the anti-APN antibody in human serum. In vitro, FLAG-CysC was co-immunoprecipitated with myc-APN by the antimyc antibody and myc-APN was co-immunoprecipitated with FLAG-CysC by the anti-FLAG antibody. Among CAD patients, serum CysC–APN complex levels negatively correlated with fibrotic components of coronary plaques and positively correlated with either necrotic or lipidic plus necrotic components. Plaque burden negatively correlated with serum APN levels but not serum CysC–APN complex levels. Serum CysC levels had no association with plaque characteristics. In multivariate analysis, CysC–APN complex levels were identified as the strongest negative factor for fibrotic components and the strongest positive factor for both necrotic and lipidic plus necrotic components.

Conclusion: Measuring serum CysC–APN complex levels is helpful for evaluating coronary plaque instability in CAD patients.

Optimal strategies for monitoring lipid levels in patients at risk or with cardiovascular disease: a systematic review with statistical and cost-effectiveness modelling

BACKGROUND

Various lipid measurements in monitoring/screening programmes can be used, alone or in cardiovascular risk scores, to guide treatment for prevention of cardiovascular disease (CVD). Because some changes in lipids are due to variability rather than true change, the value of lipid-monitoring strategies needs evaluation.

OBJECTIVE

To determine clinical value and cost-effectiveness of different monitoring intervals and different lipid measures for primary and secondary prevention of CVD.

DATA SOURCES

We searched databases and clinical trials registers from 2007 (including the Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, the Clinical Trials Register, the Current Controlled Trials register, and the Cumulative Index to Nursing and Allied Health Literature) to update and extend previous systematic reviews. Patient-level data from the Clinical Practice Research Datalink and St Luke's Hospital, Japan, were used in statistical modelling. Utilities and health-care costs were drawn from the literature.

METHODS

In two meta-analyses, we used prospective studies to examine associations of lipids with CVD and mortality, and randomised controlled trials to estimate lipid-lowering effects of atorvastatin doses. Patient-level data were used to estimate progression and variability of lipid measurements over time, and hence to model lipid-monitoring strategies. Results are expressed as rates of true-/false-positive and true-/false-negative tests for high lipid or high CVD risk. We estimated incremental costs per quality-adjusted life-year.

RESULTS

A total of 115 publications reported strength of association between different lipid measures and CVD events in 138 data sets. The summary adjusted hazard ratio per standard deviation of total cholesterol (TC) to high-density lipoprotein (HDL) cholesterol ratio was 1.25 (95% confidence interval 1.15 to 1.35) for CVD in a primary prevention population but heterogeneity was high (I(2) = 98%); similar results were observed for non-HDL cholesterol, apolipoprotein B and other ratio measures. Associations were smaller for other single lipid measures. Across 10 trials, low-dose atorvastatin (10 and 20 mg) effects ranged from a TC reduction of 0.92 mmol/l to 2.07 mmol/l, and low-density lipoprotein reduction of between 0.88 mmol/l and 1.86 mmol/l. Effects of 40 mg and 80 mg were reported by one trial each. For primary prevention, over a 3-year period, we estimate annual monitoring would unnecessarily treat 9 per 1000 more men (28 vs. 19 per 1000) and 5 per 1000 more women (17 vs. 12 per 1000) than monitoring every 3 years. However, annual monitoring would also undertreat 9 per 1000 fewer men (7 vs. 16 per 1000) and 4 per 1000 fewer women (7 vs. 11 per 1000) than monitoring at 3-year intervals. For secondary prevention, over a 3-year period, annual monitoring would increase unnecessary treatment changes by 66 per 1000 men and 31 per 1000 women, and decrease undertreatment by 29 per 1000 men and 28 per 1000 men, compared with monitoring every 3 years. In cost-effectiveness, strategies with increased screening/monitoring dominate. Exploratory analyses found that any unknown harms of statins would need utility decrements as large as 0.08 (men) to 0.11 (women) per statin user to reverse this finding in primary prevention.

LIMITATION

Heterogeneity in meta-analyses.

CONCLUSIONS

While acknowledging known and potential unknown harms of statins, we find that more frequent monitoring strategies are cost-effective compared with others. Regular lipid monitoring in those with and without CVD is likely to be beneficial to patients and to the health service. Future research should include trials of the benefits and harms of atorvastatin 40 and 80 mg, large-scale surveillance of statin safety, and investigation of the effect of monitoring on medication adherence.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42013003727.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Statins for the primary prevention of cardiovascular disease

BACKGROUND

Reducing high blood cholesterol, a risk factor for cardiovascular disease (CVD) events in people with and without a past history of CVD is an important goal of pharmacotherapy. Statins are the first-choice agents. Previous reviews of the effects of statins have highlighted their benefits in people with CVD. The case for primary prevention was uncertain when the last version of this review was published (2011) and in light of new data an update of this review is required.

OBJECTIVES

To assess the effects, both harms and benefits, of statins in people with no history of CVD.

SEARCH METHODS

To avoid duplication of effort, we checked reference lists of previous systematic reviews. The searches conducted in 2007 were updated in January 2012. We searched the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library (2022, Issue 4), MEDLINE OVID (1950 to December Week 4 2011) and EMBASE OVID (1980 to 2012 Week 1).There were no language restrictions.

SELECTION CRITERIA

We included randomised controlled trials of statins versus placebo or usual care control with minimum treatment duration of one year and follow-up of six months, in adults with no restrictions on total, low density lipoprotein (LDL) or high density lipoprotein (HDL) cholesterol levels, and where 10% or less had a history of CVD.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies for inclusion and extracted data. Outcomes included all-cause mortality, fatal and non-fatal CHD, CVD and stroke events, combined endpoints (fatal and non-fatal CHD, CVD and stroke events), revascularisation, change in total and LDL cholesterol concentrations, adverse events, quality of life and costs. Odds ratios (OR) and risk ratios (RR) were calculated for dichotomous data, and for continuous data, pooled mean differences (MD) (with 95% confidence intervals (CI)) were calculated. We contacted trial authors to obtain missing data.

MAIN RESULTS

The latest search found four new trials and updated follow-up data on three trials included in the original review. Eighteen randomised control trials (19 trial arms; 56,934 participants) were included. Fourteen trials recruited patients with specific conditions (raised lipids, diabetes, hypertension, microalbuminuria). All-cause mortality was reduced by statins (OR 0.86, 95% CI 0.79 to 0.94); as was combined fatal and non-fatal CVD RR 0.75 (95% CI 0.70 to 0.81), combined fatal and non-fatal CHD events RR 0.73 (95% CI 0.67 to 0.80) and combined fatal and non-fatal stroke (RR 0.78, 95% CI 0.68 to 0.89). Reduction of revascularisation rates (RR 0.62, 95% CI 0.54 to 0.72) was also seen. Total cholesterol and LDL cholesterol were reduced in all trials but there was evidence of heterogeneity of effects. There was no evidence of any serious harm caused by statin prescription. Evidence available to date showed that primary prevention with statins is likely to be cost-effective and may improve patient quality of life. Recent findings from the Cholesterol Treatment Trialists study using individual patient data meta-analysis indicate that these benefits are similar in people at lower (< 1% per year) risk of a major cardiovascular event.

AUTHORS' CONCLUSIONS

Reductions in all-cause mortality, major vascular events and revascularisations were found with no excess of adverse events among people without evidence of CVD treated with statins.

An assessment of risk factors for the complexity of coronary artery disease using the SYNTAX score

In 2005, the SYNTAX score was reported as "an angiographic tool grading the complexity of coronary artery disease". We investigated risk factors for the complexity of coronary artery disease (CAD) using SYNTAX scores in patients with new-onset CAD. The subjects were 359 consecutive cases that underwent de novo percutaneous coronary intervention (PCI) or coronary artery bypass graft surgery without previous PCI history. Acute myocardial infarction was excluded. The SYNTAX scores were obtained from coronary angiographies performed before PCI. On multivariate linear regression analysis of risk factors for the SYNTAX scores, aging, being a male and having diabetes mellitus were identified as significant independent risk factors (age: multiple regression coefficient 0.27, p = 0.001; male: 4.91, p = 0.004; diabetes: 4.53, p = 0.001). Other coronary risk factors such as hypertension, hypercholesterolemia, smoking and reduced renal function were not identified as significant independent risk factors. In patients undergoing PCI, aging, being a male and having diabetes mellitus are considered to be independent risk factors for the complexity of CAD. Therefore, when patients with CAD have these factors, we expect the CAD of the patient to be more complex and that it will be necessary to provide more careful medical care.

Statins for the primary prevention of cardiovascular disease

BACKGROUND

Reducing high blood cholesterol, a risk factor for cardiovascular disease (CVD) events in people with and without a past history of coronary heart disease (CHD) is an important goal of pharmacotherapy. Statins are the first-choice agents. Previous reviews of the effects of statins have highlighted their benefits in people with coronary artery disease. The case for primary prevention, however, is less clear.

OBJECTIVES

To assess the effects, both harms and benefits, of statins in people with no history of CVD.

SEARCH STRATEGY

To avoid duplication of effort, we checked reference lists of previous systematic reviews. We searched the Cochrane Central Register of Controlled Trials (Issue 1, 2007), MEDLINE (2001 to March 2007) and EMBASE (2003 to March 2007). There were no language restrictions.

SELECTION CRITERIA

Randomised controlled trials of statins with minimum duration of one year and follow-up of six months, in adults with no restrictions on their total low density lipoprotein (LDL) or high density lipoprotein (HDL) cholesterol levels, and where 10% or less had a history of CVD, were included.

DATA COLLECTION AND ANALYSIS

Two authors independently selected studies for inclusion and extracted data. Outcomes included all cause mortality, fatal and non-fatal CHD, CVD and stroke events, combined endpoints (fatal and non-fatal CHD, CVD and stroke events), change in blood total cholesterol concentration, revascularisation, adverse events, quality of life and costs. Relative risk (RR) was calculated for dichotomous data, and for continuous data pooled weighted mean differences (with 95% confidence intervals) were calculated.

MAIN RESULTS

Fourteen randomised control trials (16 trial arms; 34,272 participants) were included. Eleven trials recruited patients with specific conditions (raised lipids, diabetes, hypertension, microalbuminuria). All-cause mortality was reduced by statins (RR 0.83, 95% CI 0.73 to 0.95) as was combined fatal and non-fatal CVD endpoints (RR 0.70, 95% CI 0.61 to 0.79). Benefits were also seen in the reduction of revascularisation rates (RR 0.66, 95% CI 0.53 to 0.83). Total cholesterol and LDL cholesterol were reduced in all trials but there was evidence of heterogeneity of effects. There was no clear evidence of any significant harm caused by statin prescription or of effects on patient quality of life.

AUTHORS' CONCLUSIONS

Although reductions in all-cause mortality, composite endpoints and revascularisations were found with no excess of adverse events, there was evidence of selective reporting of outcomes, failure to report adverse events and inclusion of people with cardiovascular disease. Only limited evidence showed that primary prevention with statins may be cost effective and improve patient quality of life. Caution should be taken in prescribing statins for primary prevention among people at low cardiovascular risk.

Safety and efficacy of statins in Asians

Asian patients frequently have heightened responses to therapeutic drugs. As a consequence, the recommended drug doses are often lower in Asian countries than in Western countries. This practice extends to the use of cardiovascular drugs, including statins for the treatment of dyslipidemia. Pharmacokinetic investigations have noted higher plasma levels of statins in Asians compared with Caucasians, although postmarketing data for all statins have not identified any particular safety issues, even when statins are given at equivalent doses. The potential mechanisms of heightened response to statins in Asians are related to genetically based differences in the metabolism of statins at the level of hepatic enzymes and drug transporters. Studies indicate that lower statin doses achieve lipid improvements in Asian patients comparable with those observed with higher doses in Caucasians. In conclusion, prescribing lower starting doses of statins in Asians appears warranted while research on this subject continues.

Effects of pravastatin on the in vitro phagocytic function and hydrogen peroxide production by monocytes of healthy individuals

Macrophages play a part in pathogenesis of atherosclerosis, oxidizing LDL-cholesterol and transforming themselves in foam cells and producing free radicals of oxygen that may also oxidize LDL-cholesterol. HMG-CoA reductase inhibitors are very efficient in long-term control of atherogenesis acting by different mechanisms not fully established. Thus, we investigated the in vitro influence of pravastatin on phagocytosis and hydrogen peroxide production by monocytes of healthy individuals. Phagocytosis of Saccharomyces erevisiae by peripheral blood monocytes of 20 healthy individuals was assessed in the absence or presence of pravastatin. Hydrogen peroxide production was assessed based on the horseradish peroxidase-dependent oxidation of phenol red method. Pravastatin had no influence on phagocytosis through scavenger receptors, while it decreased by 20% the mean+/-SD phagocytic index of monocytes through complement receptors, from 141+/-77 to 113+/-56 (p=0.017), due to a decrease in the number of particles ingested by monocytes, from 2.1+/-0.5 to 1.7+/-0.3 (p=0.003). This statin also decreased the baseline production of hydrogen peroxide, by 7.7%, from 0.098+/-0.013 to 0.091+/-0.013 (OD by 2x10(5) monocytes per hour) (p=0.025). Pravastatin was able to decrease the phagocytosis through complement receptors and caused a decrease in the production of hydrogen peroxide by monocytes. It is possible this statin may directly inhibit the development of atherosclerotic plaque and its instability dependent on phagocytosis and the presence of reactive species of oxygen.

Clearance rates of cerivastatin metabolites in a patient with cerivastatin-induced rhabdomyolysis

We report on a patient who developed acute rhabdomyolysis after taking cerivastatin. A 74-year-old hypercholestrerolaemic woman taking cerivastatin (0.15 mg/day) for 22 days complained of general muscle weakness and muscle pain. Her serum creatinine phosphokinase level was 19,190 IU/L. Serum myoglobin was over 3000 ng/mL. Serum concentration of cerivastatin at 6 h after taking the last dose (0.15 mg) was 8062.5 ng/L, which was almost 5.7 times higher than that of normal persons. The serum concentration of cerivastatin showed that the half-life of cerivastatin in this patient was 22.4 h, compared with 2.4 h for normal controls. Cerivastatin is catabolized by cytochrome P450, 3A4 and 2C8 to M-1, and by 2C8 to M-23. The ratio of M-23 to M-1 in her serum was much lower than that of control persons (0.64 vs. 2.08). She had previously taken simvastatin which is metabolized by CYP3A4, without any sign and symptoms of rhabdomyolysis. These results suggest that the slowed clearance of cerivastatin in this patient might have been compounded by cytochrome P450, 2C8 dysfunction.

Obesity as the core of the metabolic syndrome and the management of coronary heart disease

The global burden of coronary heart disease (CHD) has led to the introduction of international guidelines to minimize the morbidity and mortality that result from this condition. These guidelines recognize the contribution of multiple risk factors to the development of CHD and advocate a multifaceted approach to treatment. Obesity, particularly visceral adiposity, contributes to the clustering of many other risk factors, such as hypertension, insulin resistance/type 2 diabetes and dyslipidemia, within individual patients. The molecular mechanisms underlying the metabolic abnormalities induced by visceral adiposity have yet to be fully elucidated; however, adipocytokines such as adiponectin, tumor necrosis factor-alpha and resistin seem to play an important role in this process. Obesity is a major modifiable CHD risk factor, and the benefits of weight loss are numerous, leading to improvements in several co-morbidities. Guidelines advocate lifestyle changes to correct excess bodyweight and improve the CHD risk factor profile. In addition, pharmacologic therapy is recommended for the management of other risk factors, such as hypertension and dyslipidemia, which may not be adequately controlled by lifestyle changes alone. Lowering low-density lipoprotein cholesterol (LDL-C) levels is the primary target for drug therapy for CHD prevention, and statins are first-line lipid-modifying therapy. The introduction of more efficacious statins with favorable effects on the lipid profile will optimize the control of dyslipidemia. Combining these new treatments with lifestyle changes and drug therapies for managing other CHD risk factors, as part of a multifaceted approach to treatment, will have benefits for CHD prevention.

Improvement in Japanese Clinical Laboratory Measurements of Total Cholesterol and HDL-cholesterol by the US Cholesterol Reference Method Laboratory Network

BACKGROUND

Accurate and precise measurements of total cholesterol (TC) and HDL-cholesterol (HDL-C) are necessary for effective diagnosis and treatment of lipid disorders. We studied the impact of TC certification and HDL-C evaluation in Japanese clinical laboratories to standardize their measurements.

METHODS

We selected 78 laboratories participated at least twice for TC and 46 laboratories participated twice for HDL-C in the standardization protocols developed by the Cholesterol Reference Method Laboratory Network (CRMLN). We compared the initial and subsequent results using the performance guidelines established by US National Cholesterol Education Program (NCEP).

RESULTS

For TC, mean percentage bias of all participants was -0.93% and -0.49% for the initial and second rounds, respectively. Mean within-sample CV was 0.72% and 0.69% for the initial and second rounds, respectively. For HDL-C, mean percentage bias of all participants was -1.86% and -0.06% for the initial and second events, respectively. Mean among-run CV was 1.56% and 1.58% for the initial and second events, respectively.

CONCLUSIONS

TC accuracy in the second round than the initial round tended to improvement although statistically not significant, however in the five years follow-up, mean absolute percentage bias was reduced over time. HDL-C accuracy was statistically improved in the second event than the initial event. The precision for both TC and HDL-C did not change. This study shows CRMLN protocols contribute effectively to improvement of TC and HDL-C performance.