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Dive into the research topics where Michael Clearfield is active.

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Featured researches published by Michael Clearfield.


The New England Journal of Medicine | 2001

Measurement of C-Reactive Protein for the Targeting of Statin Therapy in the Primary Prevention of Acute Coronary Events

Paul M. Ridker; Nader Rifai; Michael Clearfield; John R. Downs; Stephen E. Weis; J. Shawn Miles; Antonio M. Gotto

Background Elevated levels of C-reactive protein, even in the absence of hyperlipidemia, are associated with an increased risk of coronary events. Statin therapy reduces the level of C-reactive protein independently of its effect on lipid levels. We hypothesized that statins might prevent coronary events in persons with elevated C-reactive protein levels who did not have overt hyperlipidemia. Methods The level of C-reactive protein was measured at base line and after one year in 5742 participants in a five-year randomized trial of lovastatin for the primary prevention of acute coronary events. Results The rates of coronary events increased significantly with increases in the base-line levels of C-reactive protein. Lovastatin therapy reduced the C-reactive protein level by 14.8 percent (P<0.001), an effect not explained by lovastatin-induced changes in the lipid profile. As expected, lovastatin was effective in preventing coronary events in participants whose base-line ratio of total cholesterol to high-de...


The Lancet | 2010

Statins and risk of incident diabetes: a collaborative meta-analysis of randomised statin trials

Naveed Sattar; David Preiss; Heather Murray; Paul Welsh; Brendan M. Buckley; Anton J. M. de Craen; Sreenivasa Rao Kondapally Seshasai; John J.V. McMurray; Dilys J. Freeman; J. Wouter Jukema; Peter W. Macfarlane; Chris J. Packard; David J. Stott; Rudi G. J. Westendorp; James Shepherd; Barry R. Davis; Sara L. Pressel; Roberto Marchioli; Rosa Maria Marfisi; Aldo P. Maggioni; Luigi Tavazzi; Gianni Tognoni; John Kjekshus; Terje R. Pedersen; Thomas J. Cook; Antonio M. Gotto; Michael Clearfield; John R. Downs; Haruo Nakamura; Yasuo Ohashi

BACKGROUND Trials of statin therapy have had conflicting findings on the risk of development of diabetes mellitus in patients given statins. We aimed to establish by a meta-analysis of published and unpublished data whether any relation exists between statin use and development of diabetes. METHODS We searched Medline, Embase, and the Cochrane Central Register of Controlled Trials from 1994 to 2009, for randomised controlled endpoint trials of statins. We included only trials with more than 1000 patients, with identical follow-up in both groups and duration of more than 1 year. We excluded trials of patients with organ transplants or who needed haemodialysis. We used the I(2) statistic to measure heterogeneity between trials and calculated risk estimates for incident diabetes with random-effect meta-analysis. FINDINGS We identified 13 statin trials with 91 140 participants, of whom 4278 (2226 assigned statins and 2052 assigned control treatment) developed diabetes during a mean of 4 years. Statin therapy was associated with a 9% increased risk for incident diabetes (odds ratio [OR] 1.09; 95% CI 1.02-1.17), with little heterogeneity (I(2)=11%) between trials. Meta-regression showed that risk of development of diabetes with statins was highest in trials with older participants, but neither baseline body-mass index nor change in LDL-cholesterol concentrations accounted for residual variation in risk. Treatment of 255 (95% CI 150-852) patients with statins for 4 years resulted in one extra case of diabetes. INTERPRETATION Statin therapy is associated with a slightly increased risk of development of diabetes, but the risk is low both in absolute terms and when compared with the reduction in coronary events. Clinical practice in patients with moderate or high cardiovascular risk or existing cardiovascular disease should not change. FUNDING None.


Circulation | 2000

Relation Between Baseline and On-Treatment Lipid Parameters and First Acute Major Coronary Events in the Air Force/Texas Coronary Atherosclerosis Prevention Study (AFCAPS/TexCAPS)

Antonio M. Gotto; Edwin J. Whitney; Evan A. Stein; Deborah R. Shapiro; Michael Clearfield; Stephen E. Weis; Jesse Y. Jou; Alexandra Langendorfer; Polly A. Beere; Douglas J. Watson; John R. Downs; John S. de Cani

BACKGROUND The Air Force/Texas Coronary Atherosclerosis Prevention Study (AFCAPS/TexCAPS) is the first primary-prevention study in a cohort with average total cholesterol (TC) and LDL cholesterol (LDL-C) and below-average HDL cholesterol (HDL-C). Treatment with lovastatin (20 to 40 mg/d) resulted in a 25% reduction in LDL-C and a 6% increase in HDL-C, as well as a 37% reduction in risk for first acute major coronary event (AMCE), defined as fatal or nonfatal myocardial infarction, unstable angina, or sudden cardiac death. This article describes the relation between baseline and on-treatment lipid and apolipoprotein (apo) parameters and subsequent risk for AMCEs. METHODS AND RESULTS With all available data from the entire 6605-patient cohort, a prespecified Cox backward stepwise regression model identified outcome predictors, and logistic regression models examined the relation between lipid variables and AMCE risk. Baseline LDL-C, HDL-C, and apoB were significant predictors of AMCE; only on-treatment apoB and the ratio of apoB to apoAI were predictive of subsequent risk; on-treatment LDL-C was not. When event rates were examined across tertiles of baseline lipids, a consistent benefit of treatment with lovastatin was observed. CONCLUSIONS Persons with average TC and LDL-C levels and below-average HDL-C may obtain significant clinical benefit from primary-prevention lipid modification. On-treatment apoB, especially when combined with apoAI to form the apoB/AI ratio, may be a more accurate predictor than LDL-C of risk for first AMCE.


JAMA | 2012

Association of LDL Cholesterol, Non–HDL Cholesterol, and Apolipoprotein B Levels With Risk of Cardiovascular Events Among Patients Treated With Statins: A Meta-analysis

S. Matthijs Boekholdt; Benoit J. Arsenault; Samia Mora; Terje R. Pedersen; John C. LaRosa; Paul J. Nestel; R. John Simes; Paul N. Durrington; Graham A. Hitman; K. M. A. Welch; David A. DeMicco; Aeilko H. Zwinderman; Michael Clearfield; John R. Downs; Andrew Tonkin; Helen M. Colhoun; Antonio M. Gotto; Paul M. Ridker; John J. P. Kastelein

CONTEXT The associations of low-density lipoprotein cholesterol (LDL-C), non-high-density lipoprotein cholesterol (non-HDL-C), and apolipoprotein B (apoB) levels with the risk of cardiovascular events among patients treated with statin therapy have not been reliably documented. OBJECTIVE To evaluate the relative strength of the associations of LDL-C, non-HDL-C, and apoB with cardiovascular risk among patients treated with statin therapy. DESIGN Meta-analysis of individual patient data from randomized controlled statin trials in which conventional lipids and apolipoproteins were determined in all study participants at baseline and at 1-year follow-up. DATA SOURCES Relevant trials were identified by a literature search updated through December 31, 2011. Investigators were contacted and individual patient data were requested and obtained for 62,154 patients enrolled in 8 trials published between 1994 and 2008. DATA EXTRACTION Hazard ratios (HRs) and corresponding 95% CIs for risk of major cardiovascular events adjusted for established risk factors by 1-SD increase in LDL-C, non-HDL-C, and apoB. RESULTS Among 38,153 patients allocated to statin therapy, 158 fatal myocardial infarctions, 1678 nonfatal myocardial infarctions, 615 fatal events from other coronary artery disease, 2806 hospitalizations for unstable angina, and 1029 fatal or nonfatal strokes occurred during follow-up. The adjusted HRs for major cardiovascular events per 1-SD increase were 1.13 (95% CI, 1.10-1.17) for LDL-C, 1.16 (95% CI, 1.12-1.19) for non-HDL-C, and 1.14 (95% CI, 1.11-1.18) for apoB. These HRs were significantly higher for non-HDL-C than LDL-C (P = .002) and apoB (P = .02). There was no significant difference between apoB and LDL-C (P = .21). CONCLUSION Among statin-treated patients, on-treatment levels of LDL-C, non-HDL-C, and apoB were each associated with risk of future major cardiovascular events, but the strength of this association was greater for non-HDL-C than for LDL-C and apoB.


American Heart Journal | 2013

Rationale and design of the Cardiovascular Inflammation Reduction Trial: a test of the inflammatory hypothesis of atherothrombosis.

Brendan M. Everett; Aruna D. Pradhan; Daniel H. Solomon; Nina P. Paynter; Jean G. MacFadyen; Elaine Zaharris; Milan Gupta; Michael Clearfield; Peter Libby; Ahmed Hasan; Robert J. Glynn; Paul M. Ridker

BACKGROUND Inflammation plays a fundamental role in atherothrombosis. Yet, whether direct inhibition of inflammation will reduce the occurrence of adverse cardiovascular outcomes is not known. DESIGN The Cardiovascular Inflammation Reduction Trial (CIRT) (ClinicalTrials.govNCT01594333) will randomly allocate 7,000 patients with prior myocardial infarction (MI) and either type 2 diabetes or the metabolic syndrome to low-dose methotrexate (target dose 15-20 mg/wk) or placebo over an average follow-up period of 3 to 5 years. Low-dose methotrexate is a commonly used anti-inflammatory regimen for the treatment of rheumatoid arthritis and lacks significant effects on lipid levels, blood pressure, or platelet function. Both observational and mechanistic studies suggest that low-dose methotrexate has clinically relevant antiatherothrombotic effects. The CIRT primary end point is a composite of nonfatal MI, nonfatal stroke, and cardiovascular death. Secondary end points are all-cause mortality, coronary revascularization plus the primary end point, hospitalization for congestive heart failure plus the primary end point, all-cause mortality plus coronary revascularization plus congestive heart failure plus the primary end point, incident type 2 diabetes, and net clinical benefit or harm. CIRT will use standardized central methodology designed to ensure consistent performance of all dose adjustments and safety interventions at each clinical site in a manner that protects the blinding to treatment but maintains safety for enrolled participants. SUMMARY CIRT aims to test the inflammatory hypothesis of atherothrombosis in patients with prior MI and either type 2 diabetes or metabolic syndrome, conditions associated with persistent inflammation. If low-dose methotrexate reduces cardiovascular events, CIRT would provide a novel therapeutic approach for the secondary prevention of heart attack, stroke, and cardiovascular death.


Journal of the American College of Cardiology | 2014

Very low levels of atherogenic lipoproteins and the risk for cardiovascular events: a meta-analysis of statin trials.

S. Matthijs Boekholdt; G. Kees Hovingh; Samia Mora; Benoit J. Arsenault; Pierre Amarenco; Terje R. Pedersen; John C. LaRosa; David D. Waters; David A. DeMicco; R. John Simes; Antony C. Keech; David Colquhoun; Graham A. Hitman; D. John Betteridge; Michael Clearfield; John R. Downs; Helen M. Colhoun; Antonio M. Gotto; Paul M. Ridker; Scott M. Grundy; John J. P. Kastelein

BACKGROUND Levels of atherogenic lipoproteins achieved with statin therapy are highly variable, but the consequence of this variability for cardiovascular disease risk is not well-documented. OBJECTIVES The aim of this meta-analysis was to evaluate: 1) the interindividual variability of reductions in low-density lipoprotein cholesterol (LDL-C), non-high-density lipoprotein cholesterol (non-HDL-C), or apolipoprotein B (apoB) levels achieved with statin therapy; 2) the proportion of patients not reaching guideline-recommended lipid levels on high-dose statin therapy; and 3) the association between very low levels of atherogenic lipoproteins achieved with statin therapy and cardiovascular disease risk. METHODS This meta-analysis used individual patient data from 8 randomized controlled statin trials, in which conventional lipids and apolipoproteins were determined in all study participants at baseline and at 1-year follow-up. RESULTS Among 38,153 patients allocated to statin therapy, a total of 6,286 major cardiovascular events occurred in 5,387 study participants during follow-up. There was large interindividual variability in the reductions of LDL-C, non-HDL-C, and apoB achieved with a fixed statin dose. More than 40% of trial participants assigned to high-dose statin therapy did not reach an LDL-C target <70 mg/dl. Compared with patients who achieved an LDL-C >175 mg/dl, those who reached an LDL-C 75 to <100 mg/dl, 50 to <75 mg/dl, and <50 mg/dl had adjusted hazard ratios for major cardiovascular events of 0.56 (95% confidence interval [CI]: 0.46 to 0.67), 0.51 (95% CI: 0.42 to 0.62), and 0.44 (95% CI: 0.35 to 0.55), respectively. Similar associations were observed for non-HDL-C and apoB. CONCLUSIONS The reductions of LDL-C, non-HDL-C, and apoB levels achieved with statin therapy displayed large interindividual variation. Among trial participants treated with high-dose statin therapy, >40% did not reach an LDL-C target <70 mg/dl. Patients who achieve very low LDL-C levels have a lower risk for major cardiovascular events than do those achieving moderately low levels.


American Journal of Cardiology | 2001

Air force/texas coronary atherosclerosis prevention study (afcaps/texcaps): Additional perspectives on tolerability of long-term treatment with lovastatin

John R. Downs; Michael Clearfield; H. Alfred Tyroler; Edwin J. Whitney; William Kruyer; Alexandra Langendorfer; Vladimir Zagrebelsky; Stephen E. Weis; Deborah R. Shapiro; Polly A. Beere; Antonio M. Gotto

This study presents the long-term safety data from AFCAPS/TexCAPS, the first primary prevention trial to demonstrate that men and women with average levels of low-density lipoprotein cholesterol (LDL-C) and below average levels of high-density lipoprotein cholesterol (HDL-C) can significantly benefit from long-term treatment to lower LDL-C; lovastatin 20 to 40 mg/day reduced the risk of a first acute major coronary event (fatal or nonfatal myocardial infarction, unstable angina, or sudden death) by 37% (p = 0.00008). This double-blind randomized, placebo-controlled trial, in 6,605 generally healthy middle-aged and older men and women, had prespecified end point and cancer analyses. All analyses were intention-to-treat. Safety monitoring included history, physical examination, and laboratory studies (including hepatic transaminases and creatine phosphokinase [CPK]). All participants, even those who discontinued treatment, were contacted annually for vital status, cardiovascular events, and cancer history. After an average of 5.2 years of follow-up, there were 157 deaths (80 receiving lovastatin and 77 receiving placebo; relative risk [RR] 1.04; 95% confidence interval [CI] 0.76 to 1.42; p = 0.82); of which 115 were noncardiovascular (RR 1.21; CI 0.84 to 1.74; p = 0.31), and of these, 82 were due to cancer (RR 1.41; CI 0.91 to 2.19; p = 0.13). There were no significant differences between treatment groups in overall cancer rates, discontinuations for noncardiovascular adverse experiences, or clinically important elevations of hepatic transaminases or CPK. Among those who used cytochrome P450 isoform (CYP3A4) inhibitors, there were no treatment group differences in the frequency of clinically important muscle-related adverse events. Treatment with lovastatin 20 to 40 mg daily for primary prevention of coronary heart disease was well tolerated and reduced the risk of first acute coronary events without increasing the risk of either noncardiovascular mortality or cancer.


Circulation | 2013

Levels and Changes of HDL Cholesterol and Apolipoprotein A-I in Relation to Risk of Cardiovascular Events Among Statin-Treated Patients: A Meta-Analysis

S. Matthijs Boekholdt; Benoit J. Arsenault; G. Kees Hovingh; Samia Mora; Terje R. Pedersen; John C. LaRosa; K M Welch; Pierre Amarenco; David A. DeMicco; Andrew Tonkin; David R. Sullivan; Adrienne Kirby; Helen M. Colhoun; Graham H Hitman; D. John Betteridge; Paul N. Durrington; Michael Clearfield; John R. Downs; Antonio M. Gotto; Paul M. Ridker; John J. P. Kastelein

Background— It is unclear whether levels of high-density lipoprotein cholesterol (HDL-C) or apolipoprotein A-I (apoA-I) remain inversely associated with cardiovascular risk among patients who achieve very low levels of low-density lipoprotein cholesterol on statin therapy. It is also unknown whether a rise in HDL-C or apoA-I after initiation of statin therapy is associated with a reduced cardiovascular risk. Methods and Results— We performed a meta-analysis of 8 statin trials in which lipids and apolipoproteins were determined in all study participants at baseline and at 1-year follow-up. Individual patient data were obtained for 38 153 trial participants allocated to statin therapy, of whom 5387 suffered a major cardiovascular event. HDL-C levels were associated with a reduced risk of major cardiovascular events (adjusted hazard ratio [HR], 0.83; 95% confidence interval [CI], 0.81–0.86 per 1 standard deviation increment), as were apoA-I levels (HR, 0.79; 95% CI, 0.72–0.82). This association was also observed among patients achieving on-statin low-density lipoprotein cholesterol levels <50 mg/dL. An increase of HDL-C was not associated with reduced cardiovascular risk (HR, 0.98; 95% CI, 0.94–1.01 per 1 standard deviation increment), whereas a rise in apoA-I was (HR, 0.93; 95% CI, 0.90–0.97). Conclusions— Among patients treated with statin therapy, HDL-C and apoA-I levels were strongly associated with a reduced cardiovascular risk, even among those achieving very low low-density lipoprotein cholesterol. An apoA-I increase was associated with a reduced risk of major cardiovascular events, whereas for HDL-C this was not the case. These findings suggest that therapies that increase apoA-I concentration require further exploration with regard to cardiovascular risk reduction.


American Journal of Cardiology | 1997

Design & Rationale of the Air Force/Texas Coronary Atherosclerosis Prevention Study (AFCAPS/TexCAPS)

John R. Downs; Polly A. Beere; Edwin J. Whitney; Michael Clearfield; Stephen E. Weis; Jeffrey Rochen; Evan A. Stein; Deborah R. Shapiro; Alexandra Langendorfer; Antonio M Gotto

The Air Force/Texas Coronary Atherosclerosis Prevention Study (AFCAPS/TexCAPS) is a randomized, double-blind, placebo-controlled primary prevention trial. It is designed to test the hypothesis that in addition to a lipid-lowering diet, treatment with lovastatin is more effective than placebo in reducing acute major coronary events (i.e., sudden cardiac death, fatal and nonfatal myocardial infarction, and unstable angina) in a cohort with normal to mildly elevated total (180 to 264 mg/dl) and low-density lipoprotein (LDL) cholesterol (130 to 190 mg/dl) and low high-density lipoprotein (HDL) cholesterol (< or =45 mg/dl for men and < or =47 mg/dl for women). Two sites in Texas, Lackland Air Force Base in San Antonio and the University of North Texas Health Science Center in Fort Worth, will conduct the study. After at least 12 weeks of an American Heart Association Step 1 diet and 2 weeks placebo run-in, 6,605 men and women, ages 45 to 73 and 55 to 73 years, respectively, without clinical evidence of coronary heart disease, are randomized in equal numbers to either lovastatin (20 mg/day) or placebo. Study procedures maintain the blind, allowing titration of lovastatin from 20 to 40 mg/day to achieve an LDL cholesterol goal of < or = 110 mg/dl. All participants are followed until study completion, when 320 participants have had a primary end point or a minimum of 5 years after the last participant is randomized, whichever occurs last. All end points are adjudicated by an independent committee using prespecified criteria. Unique features of this trial are (1) the inclusion of unstable angina in the primary end point to reflect the increasing trend to treat coronary heart disease aggressively before a myocardial infarction has occurred, (2) aggressive pharmacologic intervention, with titration, to attain an LDL cholesterol goal less than the current National Cholesterol Education Panel guidelines for primary prevention, and (3) a cohort that includes women, the elderly, and those with mild to moderate hyperlipidemia and low HDL cholesterol. Compared with earlier studies, results will be applicable to a broader population and may help clarify the role of aggressive LDL cholesterol reduction measures in primary prevention. Treatment of this population is likely to realize the greatest cumulative long-term benefit in the prevention of acute major coronary events.


Trials | 2006

Comparison of the efficacy and safety of rosuvastatin 10 mg and atorvastatin 20 mg in high-risk patients with hypercholesterolemia--Prospective study to evaluate the Use of Low doses of the Statins Atorvastatin and Rosuvastatin (PULSAR).

Michael Clearfield; John Amerena; Jean-Pierre Bassand; Hugo R Hernández García; Sam S Miller; Froukje Sosef; Michael Palmer; Brian Bryzinski

BackgroundMany patients at high risk of cardiovascular disease do not achieve recommended low-density lipoprotein cholesterol (LDL-C) goals. This study compared the efficacy and safety of low doses of rosuvastatin (10 mg) and atorvastatin (20 mg) in high-risk patients with hypercholesterolemia.MethodsA total of 996 patients with hypercholesterolemia (LDL-C ≥ 3.4 and < 5.7 mmol/L [130 and 220 mg/dL]) and coronary heart disease (CHD), atherosclerosis, or a CHD-risk equivalent were randomized to once-daily rosuvastatin 10 mg or atorvastatin 20 mg. The primary endpoint was the percentage change from baseline in LDL-C levels at 6 weeks. Secondary endpoints included LDL-C goal achievement (National Cholesterol Education Program Adult Treatment Panel III [NCEP ATP III] goal < 100 mg/dL; 2003 European goal < 2.5 mmol/L for patients with atherosclerotic disease, type 2 diabetes, or at high risk of cardiovascular events, as assessed by a Systematic COronary Risk Evaluation (SCORE) risk ≥ 5% or 3.0 mmol/L for all other patients), changes in other lipids and lipoproteins, cost-effectiveness, and safety.ResultsRosuvastatin 10 mg reduced LDL-C levels significantly more than atorvastatin 20 mg at week 6 (44.6% vs. 42.7%, p < 0.05). Significantly more patients achieved NCEP ATP III and 2003 European LDL-C goals with rosuvastatin 10 mg compared with atorvastatin 20 mg (68.8% vs. 62.5%, p < 0.05; 68.0% vs. 63.3%, p < 0.05, respectively). High-density lipoprotein cholesterol was increased significantly with rosuvastatin 10 mg versus atorvastatin 20 mg (6.4% vs. 3.1%, p < 0.001). Lipid ratios and levels of apolipoprotein A-I also improved more with rosuvastatin 10 mg than with atorvastatin 20 mg. The use of rosuvastatin 10 mg was also cost-effective compared with atorvastatin 20 mg in both a US and a UK setting. Both treatments were well tolerated, with a similar incidence of adverse events (rosuvastatin 10 mg, 27.5%; atorvastatin 20 mg, 26.1%). No cases of rhabdomyolysis, liver, or renal insufficiency were recorded.ConclusionIn high-risk patients with hypercholesterolemia, rosuvastatin 10 mg was more efficacious than atorvastatin 20 mg at reducing LDL-C, enabling LDL-C goal achievement and improving other lipid parameters. Both treatments were well tolerated.

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John R. Downs

University of Texas Health Science Center at San Antonio

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Stephen E. Weis

University of North Texas Health Science Center

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Paul M. Ridker

Brigham and Women's Hospital

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Edwin J. Whitney

University of Texas at San Antonio

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Evan A. Stein

University of Cincinnati

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