Are high-density lipoprotein and triglyceride levels important in secondary prevention: impressions from the BIP and VA-HIT trials

Is In-Stent Restenosis After a Successful Coronary Stent Implantation Due to Stable Angina Associated With TG/HDL-C Ratio?

We examined the impact of the preprocedural triglyceride (TG)/high-density lipoprotein cholesterol (HDL-C) ratio on risk of in-stent restenosis (ISR). Patients with typical anginal symptoms and/or positive treadmill or myocardial perfusion scintigraphy test results who underwent successful coronary stent implantation due to stable angina were examined; 1341 patients were enrolled. The hospital files of the patients were used to gather data. Cox regression analysis showed that the TG/HDL-C ratio was independently associated with the presence of ISR ( P < .001). Moreover, diabetes mellitus ( P = .007), smaller stent diameter ( P = .046), and smoking status ( P = .001) were also independently associated with the presence of ISR. Using a cutoff of 3.8, the TG/HDL-C ratio predicted the presence of ISR with a sensitivity of 71% and a specificity of 68%. Also, the highest quartile of TG/HDL-C ratio had the highest rate of ISR ( P < .001). Measuring preprocedural TG/HDL-C ratio, in fasting or nonfasting samples, could be beneficial for the risk assessment of ISR. However, further large-scale prospective studies are required to establish the exact role of this simple, easily calculated, and reproducible parameter in the pathogenesis of ISR.

Lentil Sprouts Effect On Serum Lipids of Overweight and Obese Patients with Type 2 Diabetes

Background: The present study aimed to determine the effect of lentil sprouts [LS] on lipid profiles in overweight and obese patients with type 2 diabetes.

Methods: Forty- eight overweight and obese type 2 diabetic patients, September and November2013, 30-65 years, participated in this clinical trial and randomly divided into two groups; LS group and controls. Patients in control group received conventional drug therapy, while patients in LS group received 60 g LS daily during 8 weeks along with routine medication. Significant differences among and between the groups were determined by independent t-test and paired sample t-test using SPSS software. The patients were blinded for the treatment. In this trial the effect of LS on serum lipid profiles were inves-tigated.

Results: Thirty-nine patients completed the study. After 8 weeks, serum levels of HDL-C was higher in the LS group compared to control group (48.3 ±1.9 vs. 42.8±1.7, P<0.03). TG and ox-LDL were lower in the LS group compared to controls [(127±13.4 vs. 170± 12.4.P<0.01) and (83.3±29.1 vs. 98.7±28.2.P<0.6)].

Conclusions: LS consumption could have favorable effect on serum lipid profiles.

Origin and therapy for hypertriglyceridaemia in type 2 diabetes

Hypertriglyceridaemia (HTG) is a risk factor for cardiovascular disease (CVD) in type 2 diabetes and is caused by the interaction of genes and non-genetic factors, specifically poor glycaemic control and obesity. In spite of statin treatment, residual risk of CVD remains high in type 2 diabetes, and this may relate to HTG and atherogenic dyslipidemia. Treatment of HTG emphasises correcting secondary factors and adverse lifestyles, in particular, diet and exercise. Pharmacotherapy is also required in most type 2 diabetic patients. Statins are the first-line therapy to achieve recommended therapeutic targets of plasma low-density lipoprotein cholesterol and non-high-density lipoprotein cholesterol. Fibrates, ezetimibe and n-3 fatty acids are adjunctive treatment options for residual and persistent HTG. Evidence for the use of niacin has been challenged by non-significant CVD outcomes in two recent large clinical trials. Further investigation is required to clarify the use of incretin-based therapies for HTG in type 2 diabetes. Extreme HTG, with risk of pancreatitis, may require insulin infusion therapy or apheresis. New therapies targeting HTG in diabetes need to be tested in clinical endpoint trials. The purpose of this review is to examine the current evidence and provide practical guidance on the management of HTG in type 2 diabetes.

Safety, tolerance, and efficacy of extended-release niacin monotherapy for treating dyslipidemia risks in persons with chronic tetraplegia: a randomized multicenter controlled trial

OBJECTIVE

To test the safety, tolerance, and efficacy of extended-release niacin monotherapy on dyslipidemia in persons with chronic tetraplegia.

DESIGN

Placebo-controlled, blinded, multicenter, randomized controlled trial.

SETTING

Three spinal cord injury research/rehabilitation centers.

PARTICIPANTS

Persons with chronic tetraplegia (N=54) and low plasma high-density lipoprotein cholesterol (HDL-C) levels.

INTERVENTION

Extended-release niacin monotherapy (48 weeks; n=31) on a dose-titration schedule versus matched placebo (n=23).

MAIN OUTCOME MEASURES

Safety was assessed by using percentages of treatment-emergent adverse events and increased levels of hepatic transaminases, uric acid, glycosylated hemoglobin, and fasting glucose. Tolerance was assessed by using participant reports for frequency and intensity of adverse effects of extended-release niacin. Primary effectiveness outcomes were fasting HDL-C level and plasma total cholesterol (TC)/HDL-C ratio. Secondary outcomes included plasma low-density lipoprotein cholesterol (LDL-C) and TC levels and LDL-C/HDL-C ratio.

RESULTS

Significant increases in fasting HDL-C levels (24.5%) were accompanied by decreases in TC/HDL-C and LDL-C/HDL-C ratios, LDL-C levels, and TC levels (all P<.05). No evidence of sustained hepatotoxicity or hyperglycemia was observed. Treatment-emergent withdrawals (12.9%) accompanied flushing (n=1), hypotension/presyncope (n=1), and diarrhea (n=2). One subject experienced transient hyperuricemia. Other drug-reported symptoms did not differ from those for placebo.

CONCLUSIONS

Extended-release niacin monotherapy is safe, tolerated, and effective for most persons with chronic tetraplegia. Special precautions for changes in bowel habits and postadministration hypotension should be observed.

Association between dyslipidemia and vascular events in patients treated with statins: report from the UK General Practice Research Database

OBJECTIVE

A retrospective cohort study was conducted to evaluate the association between low high-density lipoprotein cholesterol (HDL-C) and/or elevated triglycerides (TG) and cardiovascular (CV) and/or cerebrovascular (CB) events among patients with elevated low-density lipoprotein cholesterol (LDL-C) despite statin treatment.

METHODS

Patient demographics, clinical characteristics, laboratory data, and CV/CB events, were collected from the UK General Practice Research Database. Abnormal lipid levels were defined using US and European clinical guidelines. The association between the frequency of CV/CB events among patients with HDL-C/TG abnormalities versus patients with isolated low LDL-C was estimated using multivariate Cox proportional hazards regression.

RESULTS

Of 19,843 statin-treated patients, 6823 had elevated LDL-C despite therapy for a mean follow-up of 1.99+/-1.06 years. Among these patients, 3115 (45.7%) also had HDL-C/TG abnormalities. A total of 715 patients (10.5%) experienced CV/CB events. In statin-treated patients not at LDL-C goal, the relative risk of a vascular event was 24% higher in patients with HDL-C/TG abnormalities (HR=1.24, 95% CI: 1.06-1.46, p=0.006) than in patients without HDL-C/TG abnormalities. Additional variables that were associated with a significantly increased risk of CV/CB events included age (p<0.0001), gender (p=0.027), and medication possession ratio (p<0.0001), while diabetes mellitus (p<0.0001), hypertension (p<0.0001), 10-year Framingham risk score>30% (p=0.005), statin dose (p<0.0001), and LDL-C level at baseline (p<0.0001) were associated with a significantly decreased risk of CV/CB events.

CONCLUSION

Among statin-treated patients with elevated LDL-C from UK clinical practices, reduced HDL-C and/or elevated TGs were associated with a significantly increased relative risk of CV/CB events.

Triglyceride/HDL-cholesterol ratio is an independent predictor for coronary heart disease in a population of Iranian men

BACKGROUND AND AIMS

To determine whether triglyceride/high-density lipoprotein cholesterol ratio (TG/HDL-C), which has been shown to be an indicator of the metabolic syndrome (MetS) and insulin resistance, can predict coronary heart disease (CHD) independently of total cholesterol (TC) and other risk factors in an Iranian population with a high prevalence of MetS and low HDL-C.

METHODS AND RESULTS

Between February 1999 and August 2001, 1824 men > or =40 years old, free of clinical cardiovascular diseases at baseline, were followed. Baseline measurements included serum level of TC, HDL-C, TG and risk factors for CHD including age, systolic and diastolic blood pressure, body mass index, waist circumference, diabetes, smoking and a family history of premature cardiovascular diseases. During a median follow up of 6.5 years until March 2007 (11,316 person-years at risk), a total of 163 new CHD events (27 fatal and 136 nonfatal) occurred. The prevalence of MetS in subjects with TG/HDL-C > or =6.9 (top quartile) reached 63.6% versus 3.0% in those with TG/HDL-C <2.8 (low quartile). According to a stepwise Cox proportional hazard model, including TG and TG/HDL-C quartiles, with TC and other risk factors, men in the top quartile of TG/HDL-C relative to the first quartile had a significant hazard ratio (HR) of 1.75 (95% CI, 1.02-3.00), while TG did not remain in the model.

CONCLUSION

The evaluation of TG/HDL-C ratio should be considered for CHD risk prediction in our male population with a high prevalence of MetS.

Niacin and fibrate use among patients with high triglycerides and low high-density lipoprotein cholesterol

BACKGROUND

National guidelines recommend treating low HDL and/or high triglycerides (TG) with adjunctive therapy that supplements statin monotherapy in patients with multiple cardiovascular disease (CVD) risk factors. Niacin and fibrates have been shown in clinical trials to be effective as adjunctive therapy for these lipid abnormalities.

OBJECTIVE

To evaluate the pharmacologic treatment of low HDL and high TG in real-world practice by assessing a large managed-care population with CVD risk factors enrolled in a commercial health plan.

RESEARCH DESIGN AND METHODS

Complete lipid panel results (LDL, HDL, TG) obtained between 1/1/2006 and 12/31/2006 (index lab) were available for all participants. Subjects were observed 180 days pre-index to determine which CVD risk factors were present (male aged 45+, female 55+, coronary heart disease, hypertension, diabetes mellitus). Patients whose LDL was at goal but who had low HDL and high TG were assessed for lipid treatment status by evaluating outpatient pharmacy claims 6 months pre- and post-index.

RESULTS

Treatment with any lipid therapy increased for all risk groups, and by total risk factors, from pre-index to post-index. Use of fibrates and niacin, alone or in combination with a statin, also increased for all risk groups, and by total risk factors as well, but was below expectations based on guideline recommendations. For example, among patients with 4 risk factors, <20% of patients with low HDL/high TG received niacin and/or a fibrate post-index date.

CONCLUSIONS

Our results indicate that in actual clinical practice, niacin and fibrates are underutilized in the treatment of low HDL and high TG. The findings of this study must be considered within the limitations of database analysis as claims data are collected for the purpose of payment and not research.

HDL-cholesterol modulation and its impact on the management of cardiovascular risk

There is strong epidemiological evidence that HDL-cholesterol (HDL-C) is an independent cardiovascular risk factor. A low HDL-C is a common finding in the general population, and is a feature of metabolic syndrome, the prevalence of which is increasing globally. The importance of HDL-C as a coronary risk factor is generally accepted, and has been incorporated into most of the commonly applied risk engines. There are several causes of a low HDL-C, including rare genetic abnormalities, and more common conditions associated with lifestyle and drug therapy. Not all of these are associated with an increased risk of coronary disease. A better understanding of HDL metabolism and the mechanisms by which it may exert its protective effects has revealed why this may be the case. New therapeutic targets have also been identified that may allow HDL-C to be raised in patients with low levels. However, good clinical endpoint studies are still required to enable the setting of absolute target values for HDL-C in patients at high cardiovascular risk.

Who needs to care about small, dense low-density lipoproteins?

BACKGROUND

Increasing evidence suggest that the 'quality' rather than only the 'quantity' of low-density lipoprotein (LDL) exerts a great influence on the cardiovascular risk. Small, dense LDL seem to be an important predictor of cardiovascular events and progression of coronary artery disease (CAD) and their predominance has been accepted as an emerging cardiovascular risk factor by the National Cholesterol Education Program Adult Treatment Panel III.

DISCUSSION

Some studies showed in past years that small, dense LDL are usually elevated in patients at very high cardiovascular risk, such as those with CAD and type 2 diabetes. More recently elevated levels of these particles have been found in other categories of patients at high cardiovascular risk, such as those with non-coronary forms of atherosclerosis (e.g. with carotid artery disease, aortic abdominal aneurysm and peripheral arterial disease) and metabolic diseases (with polycystic ovary syndrome and growth hormone deficiency); notably, in most of them, the predominance of small, dense LDL characterised their type of dyslipidaemia, alone or in combination with elevated triglycerides and reduced high-density lipoproteins cholesterol concentrations.

CONCLUSIONS

The therapeutical modulation of small, dense LDL have been shown to significantly reduce cardiovascular risk and weight reduction and increased physical activity may constitute first-line therapy. In addition, lipid-lowering drugs are able to favourably alter these particles and fibrates and nicotinic acid seem to be the most effective agents. Promising data are also available with the use of rosuvastatin, the latest statin introduced in the market, and ezetimibe, a cholesterol absorption inhibitor.

Endothelial function, arterial stiffness and lipid lowering drugs

The endothelium is a dynamic organ that plays a pivotal role in cardiovascular homeostasis. Alteration in endothelial function precedes the development of atherosclerosis and contributes to its initiation, perpetuation and clinical manifestations. It has been suggested that the assessment of endothelial function could represent a barometer of vascular health that could be used to gauge cardiovascular risk. This review summarises the various methods used to assess endothelium-dependent vasodilatation and their potential prognostic implications. In addition, the techniques used to evaluate arterial stiffness are discussed. The latter is to some extent controlled by the endothelium and has been the subject of considerable research in recent years. This paper also discusses the effects of lipid lowering treatment on both endothelial function and arterial stiffness.

The clinical significance of the size of low-density-lipoproteins and the modulation of subclasses by fibrates

BACKGROUND

Beyond total low-density-lipoproteins (LDL) levels, increasing evidence suggests that the 'quality' of LDL exerts a great influence on the cardiovascular risk. Several studies have also shown that the therapeutic modulation of LDL size is of benefit in reducing the risk of cardiovascular events. Hypolipidaemic treatment is able to alter LDL subclass distribution but strong variations have been noticed among different agents. Fibrates have a major impact on triglyceride metabolism and in modulating LDL size and subclasses, but variations exist among the different molecules.

METHODOLOGY

A literature search (by Medline and Scopus) was performed using the following headings: 'small dense LDL', 'LDL size', 'LDL subfractions', 'LDL subclasses', 'LDL distribution' and 'fenofibrate', 'bezafibrate', 'ciprofibrate' and 'gemfibrozil' up to 20 January 2007. The authors also manually reviewed the references of selected articles for any pertinent material.

RESULTS

Analysis of all published studies revealed that treatment with fenofibrate, ciprofibrate, bezafibrate and gemfibrozil is usually beneficial, and fenofibrate may be more efficacious than the other molecules. This is supported by using all the available techniques in subjects with a very wide range of lipid alterations.

CONCLUSION

Among the different agents, fenofibrate has been found to be particularly effective in modulating LDL size and subclasses in patients at higher cardiovascular risk, such as those with type 2 diabetes or the metabolic syndrome.

Clinical importance and therapeutic modulation of small dense low-density lipoprotein particles

The National Cholesterol Education Programme Adult Treatment Panel III accepted the predominance of small dense low-density lipoprotein (sdLDL) as an emerging cardiovascular disease (CVD) risk factor. Most studies suggest that measuring low-density lipoprotein (LDL) particle size, sdLDL cholesterol content and LDL particle number provides additional assessment of CVD risk. Therapeutic modulation of small LDL size, number and distribution may decrease CVD risk; however, no definitive causal relationship is established, probably due to the close association between sdLDL and triglycerides and other risk factors (e.g., high-density lipoprotein, insulin resistance and diabetes). This review addresses the formation and measurement of sdLDL, as well as the relationship between sdLDL particles and CVD. The effect of hypolipidaemic (statins, fibrates and ezetimibe) and hypoglycaemic (glitazones) agents on LDL size and distribution is also discussed.

Fibrates in the prevention of cardiovascular disease in patients with type 2 diabetes mellitus: meta-analysis of randomised controlled trials

OBJECTIVE

To assess the impact of lipid lowering treatment with fibrates on cardiovascular endpoints in patients with type 2 diabetes mellitus.

METHODS

MEDLINE (from inception to November 2005) and the Cochrane Controlled Trials Register (including Issue 3, 2005) were searched for randomised controlled trials comparing therapy with fibrates to placebo in patients with type 2 diabetes mellitus. Electronic searches were supplemented by manual searching of reference lists, reviews, conference abstracts and specialist journals. Incidence rate ratios (IRRs) were estimated using a fixed effects model. The primary endpoint was the IRR for coronary heart disease (CHD) events (a combination of non fatal myocardial infarction and death due to CHD). Secondary endpoints included: (1) death due to CHD; (2) fatal and non fatal myocardial infarction; and (3) fatal and non fatal stroke.

RESULTS

Eight trials and 12 249 patients with type 2 diabetes were included in the analyses. A total of 924 CHD events (418 and 506 in the treatment and placebo groups, respectively) occurred during a follow up of 60 395 person-years (30 106 and 30 289 in treatment and placebo groups). The combined IRR for CHD events was 0.84 (95% confidence interval [CI] 0.74-0.96, p = 0.008). The numbers needed to treat (NNTs) to prevent one CHD event over 10 years were nine and 26 for patients with and without pre-existing CHD, respectively. IRRs for death due to CHD, myocardial infarction and stroke were 0.96 (95% CI 0.77-1.20, p = 0.73), 0.88 (95% CI 0.69-1.12, p = 0.30) and 0.87 (95% CI 0.73-1.05, p = 0.14), respectively. Larger benefits were found when restricting the analysis to trials that were not confounded by unequal provision of additional lipid-lowering therapy.

CONCLUSIONS

Fibrates are associated with a substantial reduction of CHD events, but their exact role in lipid lowering treatment of patients with type 2 diabetes mellitus remains to be defined.

Fenofibrate: a novel formulation (Triglide) in the treatment of lipid disorders: a review

Cardiovascular disease is the major cause of mortality worldwide and accounts for approximately 40% of all deaths. Dyslipidemia is one of the primary causes of atherosclerosis and effective interventions to correct dyslipidemia should form an integral component of any strategy aimed at preventing cardiovascular disease. Fibrates have played a major role in the treatment of hyperlipidemia for more than two decades. Fenofibrate is one of the most commonly used fibrates worldwide. Since fenofibrate was first introduced in clinical practice, a major drawback has been its low bioavailability when taken under fasting conditions. Insoluble Drug Delivery-Microparticle fenofibrate is a new formulation that has an equivalent extent of absorption under fed or fasting conditions. In this review, we will discuss the clinical pharmacology of fenofibrate, with particular emphasis on this novel formulation, as well as its lipid-modulating and pleiotropic actions. We will also analyze the major trial that evaluated fibrates for primary and secondary prevention of cardiovascular disease, the safety and efficacy profile of fibrate-statin combination treatment, and the current recommendations regarding the use of fibrates in clinical practice.

Fenofibrate Intervention and Event Lowering in Diabetes (FIELD) study: baseline characteristics and short-term effects of fenofibrate [ISRCTN64783481]

OBJECTIVE

The Fenofibrate Intervention and Event Lowering in Diabetes (FIELD) Study is examining the effects of long-term fibrate therapy on coronary heart disease (CHD) event rates in patients with diabetes mellitus. This article describes the trial's run-in phase and patients' baseline characteristics.

RESEARCH DESIGN AND METHODS

FIELD is a double-blind, placebo-controlled trial in 63 centres in 3 countries evaluating the effects of fenofibrate versus placebo on CHD morbidity and mortality in 9795 patients with type 2 diabetes mellitus. Patients were to have no indication for lipid-lowering therapy on randomization, but could start these or other drugs at any time after randomization. Follow-up in the study was to be for a median duration of not less than 5 years and until 500 major coronary events (fatal coronary heart disease plus nonfatal myocardial infarction) had occurred.

RESULTS

About 2100 patients (22%) had some manifestation of cardiovascular disease (CVD) at baseline and thus high risk status. Less than 25% of patients without CVD had a (UKPDS determined) calculated 5-year CHD risk of <5%, but nearly all had a 5-year stroke risk of <10%. Despite this, half of the cohort were obese (BMI > 30), most were men, two-thirds were aged over 60 years, and substantial proportions had NCEP ATP III features of the metabolic syndrome independent of their diabetes, including low HDL (60%), high blood pressure measurement (41%), high waist measurement (65%), and raised triglycerides (52%). After a 6-week run-in period before randomisation with all participants receiving 200 mg comicronized fenofibrate, there were declines in total and LDL cholesterol (10%) and triglycerides (26%) and an increase in HDL cholesterol (6.5%).

CONCLUSION

The study will show the effect of PPAR-alpha agonist action on CHD and other vascular outcomes in patients with type 2 diabetes including substantial numbers with low to moderate CVD risk but with the various components of the metabolic syndrome. The main results of the study will be reported in late 2005.

HDL cholesterol and protective factors in atherosclerosis

A low level of high-density lipoprotein cholesterol (HDL-C) is an important risk factor for cardiovascular disease. Epidemiological and clinical studies provide evidence that HDL-C levels are linked to rates of coronary events. The cardioprotective effects of HDL-C have been attributed to its role in reverse cholesterol transport, its effects on endothelial cells, and its antioxidant activity. Although some clinical trials suggest a benefit of raising HDL-C to reduce risk, further studies are needed, and HDL-C is still not considered a primary target of therapy in the National Cholesterol Education Program guidelines. However, HDL-C should be considered as part of the patient's overall profile of established risk factors in determining treatment strategies.

Postprandial hypertriglyceridaemia in patients with Tangier disease

BACKGROUND

Tangier disease (TD) is the phenotypic expression of rare familial syndromes with mutations in the ABCA1 transporter. TD results in extremely low high density lipoprotein (HDL) cholesterol and reduced low density lipoprotein cholesterol, with normal or mildly increased fasting triglyceride (TG) concentrations. Although there is a close relation between HDL cholesterol values and atherogenesis, the risk of coronary artery disease is variable in TD. Raised fasting or postprandial TG values frequently accompany low HDL cholesterol and can add to the risk of a vascular event.

AIMS

To investigate the postprandial TG response in TD.

PATIENTS AND METHODS

Five patients (three homozygotes (HTD) and two heterozygotes (hTD)) from one family were studied. One was defined by DNA analysis as homozygous for a new mutation (C2033A) resulting in truncation of the ABCA1 protein. Their TG concentrations were measured before and four, six, and eight hours after a standardised fat load and compared with a control group.

RESULTS

Two patients with HTD had high fasting TG concentrations. The third patient with HTD, the two with hTD, and the control group had TG concentrations within the reference range. The patients with HTD had increased postprandial peak TG values when compared with those with hTD and controls.

CONCLUSION

Patients with HTD, with or without fasting hypertriglyceridaemia, may have an increased TG response to a fatty meal. The small number of patients does not allow definitive conclusions to be made. However, postprandial hypertriglyceridaemia could be a reason why some patients with TD develop premature atherosclerosis.

Statin-fibrate combination: therapy for hyperlipidemia: a review

Statins and fibrates are well-established treatments for hyperlipidaemias and the prevention of vascular events. However, fibrate + statin therapy has been restricted following early reports of rhabdomyolysis that mainly involved gemfibrozil, originally with bovastatin, and recently, with cerivastatin. Despite this limitation, several reports describing combination therapy have been published. This review considers these studies and the relevant indications and contraindications. Statin + fibrate therapy should be considered if monotherapy or adding other drugs (e.g. cholesterol absorption inhibitors, omega-3 fatty acids ornicotinic acid) did not achieve lipid targets or is impractical. Combination therapy should be hospital-based and reserved for high-risk patients with a mixed hyperlipidaemia characterised by low density lipoprotein cholesterol (LDL) >2.6 mmol/l(100 mg/dl, high density lipoprotein cholesterol (HDL) <1.0 mmol/l (40 mg/dl) and/or triglycerides> 5.6 mmol/l (500 mg/dl. These three 'goals' are individually mentioned in guidelines. Patients should have normal renal, liver and thyroid function tests and should not be receiving therapy with cyclosporine, protease inhibitors or drugs metabolised through cytochrome P450 (especially 3A4). Combination therapy is probably best conducted using drugs with short plasma half-lives; fibrates should be prescribed in the morning and statins at night to minimise peak dose interactions. Both drug classes should be progressively titated from low doses. Regular (3-monthly) monitoring of liver function and creatine kinase is required. In conclusion, fibrate + statin therapy remains an option in high-risk patents. However, long-term studies involving safety monitoring and vascular endpoints are required to demonstrate the efficacy of this regimen.