Biomedical subjects

Steven M Snapinn

Publications and source records attributed to Steven M Snapinn.

At least 19 recordsLinked to original sources

PubMed2006

Sex-based short- and long-term survival in patients following complicated myocardial infarction.

AIMS: Mortality in women following an acute myocardial infarction (AMI) is higher than in men, in that women are older and have more co-morbidity at the time of AMI. We evaluated short- and long-term sex-related differences in management and prognosis among high-risk patients following AMI. METHODS AND RESULTS: A total of 1575 women and 3902 men with AMI and heart failure, left ventricular dysfunction, or anterior Q waves, were recruited for participation in the OPTIMAAL trial and followed for 2.7+/-0.9 years in seven European countries. Symptomatic heart failure was more common in women when compared with men. Women were older, with more hypertension and diabetes mellitus. Fewer women were treated with thrombolytics (P<0.001 in all cases). Women had a 1.37-fold higher risks of death (P<0.001) during follow-up, but no differences were observed after adjusting for age. However, in-hospital mortality was significantly higher in women (4.89 vs. 2.54%; P<0.001) and a 1.57-fold higher risk of in-hospital death (P=0.006) persisted after adjusting for age and co-morbidities. CONCLUSION: Among high-risk patients with AMI, age-adjusted long-term survival was similar between sexes. However, adjusted in-hospital mortality was significantly higher in women. Higher short-term risk may warrant more rapid and appropriate management of women with AMI.

Adult↗

PubMed2006

Impact of diabetes mellitus on regression of electrocardiographic left ventricular hypertrophy and the prediction of outcome during antihypertensive therapy: the Losartan Intervention For Endpoint (LIFE) Reduction in Hypertension Study.

BACKGROUND: Diabetes mellitus is associated with increased cardiovascular (CV) morbidity and mortality and with greater ECG left ventricular hypertrophy (LVH); however, it is unclear whether diabetes attenuates regression of hypertensive LVH and whether regression of ECG LVH has similar prognostic value in diabetic and nondiabetic hypertensive individuals. METHODS AND RESULTS: A total of 9193 hypertensive patients (1195 with diabetes) in the Losartan Intervention For Endpoint (LIFE) Reduction in Hypertension Study were treated with losartan- or atenolol-based regimens and followed up with serial ECG and blood pressure determinations at baseline and 6 months and then yearly until death or study end. ECG LVH was defined with gender-adjusted Cornell voltage-duration product (CP) criteria >2440 mm . ms. After a mean follow-up of 4.8+/-0.9 years, patients with diabetes had less regression of CP LVH (-138+/-866 versus -204+/-854 mm . ms, P<0.001), remained more likely to have LVH by CP (56.0% versus 48.1%, P<0.001), and had higher rates of CV death, myocardial infarction, stroke, and all-cause mortality and of the LIFE composite end point of CV death, myocardial infarction, or stroke. In multivariable Cox proportional hazards models, in-treatment regression or absence of ECG LVH by CP was associated with between 17% and 35% reductions in event rates in patients without diabetes but did not significantly predict outcome in patients with diabetes. CONCLUSIONS: Hypertensive patients with diabetes have less regression of CP LVH in response to antihypertensive therapy than patients without diabetes, and regression of ECG LVH is less useful as a surrogate marker of outcomes in hypertensive patients with diabetes. These findings may in part explain the higher CV morbidity and mortality in hypertensive patients with diabetes, and the absence of a demonstrable improvement in prognosis in diabetic patients in response to regression of ECG LVH suggests a more complex interrelation between underlying LV structural and functional abnormalities and outcome in these patients.

Aged↗

PubMed2006

Does albuminuria predict cardiovascular outcomes on treatment with losartan versus atenolol in patients with diabetes, hypertension, and left ventricular hypertrophy? The LIFE study.

OBJECTIVE: Our current aims were to investigate whether 1) baseline urinary albumin-to-creatinine ratio (UACR) predicted cardiovascular outcomes, 2) changes in UACR differed between treatments, 3) benefits of losartan were related to its influence on UACR, and 4) reduction in albuminuria reduced cardiovascular events. RESEARCH DESIGN AND METHODS: In 1,063 patients with diabetes, hypertension, and left ventricular hypertrophy, UACR was measured for a mean of 4.7 years. The primary composite end point included cardiovascular death, myocardial infarction, and stroke. Cox models were run including and excluding baseline and time-varying UACR. RESULTS: Increasing baseline albuminuria related to increased risk for cardiovascular events. Reductions in UACR at years 1 and 2 were approximately 33% for losartan vs. 15% for atenolol (P < 0.001). Benefits of losartan seem to be most prominent in patients with the highest level of baseline UACR, although treatment by albuminuria interaction was only significant for total mortality. Approximately one-fifth of the superiority of losartan was explained by the greater reduction of albuminuria. Risk of the primary end point was related to the in-treatment UACR. CONCLUSIONS: Lowering of albuminuria in patients with hypertension and diabetes appears to be beneficial and should be the subject of additional study in future clinical trials.

Aged↗

PubMed2005

Hospitalizations for new heart failure among subjects with diabetes mellitus in the RENAAL and LIFE studies.

We sought to study the risk factors for heart failure (HF) and the relation between antihypertensive treatment with losartan and the first hospitalization for HF in patients with diabetes mellitus in the Losartan Intervention For Endpoint reduction in hypertension (LIFE) and Reduction of Endpoints in NIDDM with the Angiotensin II Antagonist Losartan (RENAAL) studies. We evaluated 1,195 patients with hypertension, left ventricular hypertrophy, and diabetes from the LIFE study and 1,513 patients with type 2 diabetes and nephropathy from the RENAAL study. The comparative treatments were atenolol in the LIFE study and placebo in the RENAAL study. Patients with a history of HF were excluded from this analysis. Losartan significantly reduced the incidence of first hospitalizations for HF versus placebo in the RENAAL study (hazard ratio 0.74, p=0.037) and versus atenolol in the LIFE study (hazard ratio 0.57, p=0.019). Patients enrolled in the RENAAL study were at a higher risk of developing HF (hazard ratio for RENAAL vs LIFE diabetics 3.0, p<0.0001). The significant, independent baseline risk factors for the development of HF in the RENAAL study were urinary albumin/creatinine ratio, age, peripheral vascular disease, the Cornell product, body mass index, and previous angina; in the LIFE study they were the Cornell product, previous myocardial infarction, peripheral vascular disease, baseline atrial fibrillation, alcohol use (inverse relation), and urinary albumin/creatinine ratio. The beneficial effect of losartan on the reduction of risk for hospitalization for new HF was demonstrated in patients who were at high renal and/or high cardiovascular risk.

Adrenergic beta-Antagonists↗

PubMed2005

The effect of losartan versus atenolol on cardiovascular morbidity and mortality in patients with hypertension taking aspirin: the Losartan Intervention for Endpoint Reduction in hypertension (LIFE) study.

OBJECTIVES: We conducted a subgroup analysis in the Losartan Intervention For Endpoint reduction in hypertension (LIFE) study to determine whether aspirin interacted with the properties of losartan, an angiotensin-II receptor antagonist. BACKGROUND: Negative interactions between angiotensin-converting enzyme inhibitors and aspirin have been reported. There are no data reported from clinical trials about possible interactions between angiotensin-II receptor antagonists and aspirin. METHODS: The LIFE study assigned 9,193 patients with hypertension and left ventricular hypertrophy (LVH) to losartan- or atenolol-based therapy for a mean of 4.7 years, with 1,970 (21.4%) taking aspirin at baseline. The primary composite end point (CEP) included cardiovascular death, stroke, and myocardial infarction (MI). The present cohort was stratified by aspirin use at baseline. RESULTS: Blood pressures were reduced similarly in the losartan with aspirin (n = 1,004) and atenolol with aspirin (n = 966) groups. The CEP was reduced by 32% (95% confidence interval 0.55 to 0.86, p = 0.001) with losartan with aspirin compared to atenolol with aspirin, adjusted for Framingham risk score and LVH. The test for treatment versus aspirin interaction, excluding other covariates, was significant for the CEP (p = 0.016) and MI (p = 0.037). CONCLUSIONS: There was a statistical interaction between treatment and aspirin in the LIFE study, with significantly greater reductions for the CEP and MI with losartan in patients using aspirin than in patients not using aspirin at baseline. Further studies are needed to clarify whether this represents a pharmacologic interaction or a selection by aspirin use of patients more likely to respond to losartan treatment.

Adrenergic beta-Antagonists↗

PubMed2005

Importance of baseline distribution of proteinuria in renal outcomes trials: lessons from the reduction of endpoints in NIDDM with the angiotensin II antagonist losartan (RENAAL) study.

A key issue in the analysis of outcome trials is the adjustment for baseline covariates that influence the primary outcome. Imbalance of an important covariate between treatment groups at baseline is of considerable concern if one treatment group is favored over another with respect to the hypothesis testing outcome. With the use of the Reduction of Endpoints in NIDDM with the Angiotensin II Antagonist Losartan (RENAAL) study database as an example, the influence of baseline proteinuria on the primary composite endpoint, ESRD, and ESRD or death after adjusting for baseline proteinuria as a continuous covariate was examined. Increasing baseline proteinuria was associated with increased risk for renal events, confirming that proteinuria is an important covariate for renal outcomes. When the randomization was stratified according proteinuria <2000 mg/g or >/=2000 mg/g, within the higher proteinuria stratum (>/=2000 mg/g), patients in the losartan group had a higher baseline mean proteinuria value. When the imbalance was adjusted, an increase in the magnitude and the significance of the risk reduction with losartan for each outcome was observed. No apparent interaction between treatment effect and baseline proteinuria was found, and there was no heterogeneity in the treatment response in patients with different baseline proteinuria levels. After proteinuria was adjusted as a continuous variable, greater treatment effects were observed in the RENAAL study. This effect was due solely to the imbalance in baseline proteinuria. Considering the importance of proteinuria as a risk factor, adjustment for baseline proteinuria as a continuous covariate should be prespecified in the design and analysis of clinical trials involving renal outcomes, even when patients are stratified on the basis of level of proteinuria.

Adult↗

PubMed2005

Analysis of bleeding complications associated with glycoprotein IIb/IIIa receptors blockade in patients with high-risk acute coronary syndromes: insights from the PRISM-PLUS study.

We aim to characterize the hemorrhagic complications and predictors of increased bleeding risk in a population of patients with high-risk acute coronary syndromes (ACS), enrolled in the PRISM-PLUS study. Patients treated with heparin plus tirofiban had more bleeding events compared to patients treated with heparin alone. No significant increase in major bleeding, thrombocytopenia, blood loss and blood products transfusions was observed among the patients who received the combination therapy. Several clinical variables were independently associated with increased risk of bleeding for both treatment groups: advanced age, lower body weight, female gender, decreased creatinine clearance (<30 ml/min). Females, patients with impaired renal function, patients requiring percutaneous coronary intervention (PCI), especially prolonged PCI (>100 min duration) or coronary artery bypass surgery (CABG) were at risk for increased major bleeding complications. Increased blood loss was also found in females, patients with elevated diastolic blood pressure, PCI, duration of PCI>100 min or CABG. No incremental risk was detected with the addition of tirofiban to heparin in patients at risk for major bleeding or increased blood loss. We concluded that identification of patients with high-risk ACS, at risk for bleeding complications and blood loss can be done with specific clinical variables. Tirofiban added to heparin increased minor hemorrhagic complications. Although there was no significant increase in major bleeding, thrombocytopenia and blood transfusions with the combination of tirofiban plus heparin, the power to detect a statistically significant difference in these endpoints was limited by the small number of events.

Aged↗

PubMed2005

Correlation between the TIMI risk score and high-risk angiographic findings in non-ST-elevation acute coronary syndromes: observations from the Platelet Receptor Inhibition in Ischemic Syndrome Management in Patients Limited by Unstable Signs and Symptoms (PRISM-PLUS) trial.

BACKGROUND: The TIMI risk score for unstable angina and non-ST elevation myocardial infarction is an effective tool for predicting the risk of death and ischemic events among patients with non-ST elevation acute coronary syndromes, as well as for identifying those who are likely to benefit most from low-molecular-weight heparin and glycoprotein IIb/IIIa inhibition. METHODS: To explore the pathobiologic basis for this interaction, we evaluated the relationship between the risk score, assessed at presentation, and angiographic findings among patients with non-ST elevation acute coronary syndromes. Angiographic data regarding thrombus, epicardial flow, and lesion severity were available for 1491 patients from the angiographic substudy of PRISM-PLUS. RESULTS: Patients with risk scores of 5 to 7 (N = 435) were more likely to have a severe culprit stenosis (81% vs 58%, P < .001) and multivessel disease (80% vs 43%, P < .001) compared to those with scores of 0 to 2 (N = 220). The probability of left main disease (P = .01), visible thrombus, and impaired flow in the culprit lesion also increased progressively with rising risk scores (P < .001). Of the risk indicators that comprise the score, history of coronary disease, advanced age, and ST changes showed the strongest association with severe epicardial disease. Positive biomarkers of necrosis, ST changes, and prior aspirin use emerged as stronger correlates of visible thrombus and/or impaired culprit artery flow. CONCLUSIONS: The TIMI risk score identifies patients who are more likely to have intracoronary thrombus, impaired flow, and increased burden of coronary atherosclerosis. These findings likely explain in part the particular benefit of potent antithrombin and antiplatelet agents among patients with higher risk scores.

Aged↗

PubMed2005

The effects of losartan compared to atenolol on stroke in patients with isolated systolic hypertension and left ventricular hypertrophy. The LIFE study.

The Losartan Intervention For Endpoint reduction in hypertension (LIFE) study reported that a losartan-based antihypertensive regimen reduced cardiovascular morbidity and mortality (composite of cardiovascular death, stroke, and myocardial infarction) more than therapy based on atenolol in patients with left ventricular hypertrophy and isolated systolic hypertension (ISH). Patients aged 55-80 years with blood pressures 160-200/<90 mm Hg were followed for a mean of 4.7 years. Blood pressure was similarly reduced in the losartan (n=660) and atenolol (n=666) ISH groups. There were 88 (6.6%) patients who experienced a stroke, 18 of which were fatal. Of patients experiencing strokes, 72.7% had an ischemic stroke. ISH patients in LIFE compared to the non-ISH group had a higher incidence of any stroke and embolic stroke, and similar incidences of fatal, atherosclerotic, and hemorrhagic/other strokes. The incidence of any stroke (40% risk reduction [RR], p=0.02), fatal stroke (70% RR, p=0.035), and atherothrombotic stroke (45% RR, p=0.022) was significantly lower in losartan-treated compared to the atenolol-treated patients. The 36% RR for embolic strokes in the losartan group was not statistically significantly (p=0.33) different from the atenolol group. These data suggest that losartan-based treatment is more effective than an atenolol-based treatment for patients with ISH and a high risk for stroke.

Aged↗

PubMed2005

Pulse pressure and effects of losartan or atenolol in patients with hypertension and left ventricular hypertrophy.

In the Losartan Intervention For Endpoint reduction in hypertension (LIFE) study, the primary composite end point of cardiovascular death, stroke, and myocardial infarction was reduced by losartan versus atenolol in patients with hypertension and left ventricular hypertrophy. The objective of this post hoc analysis was to determine the influence of pulse pressure on outcome. Patients were divided into quartiles of baseline pulse pressure. Cox regression, including baseline Framingham risk score as a covariate, was used to compare risk in the quartiles. In the atenolol group, there were significantly higher risks in the highest versus lowest quartile for the composite end point 28% (confidence interval [CI], 2% to 62%; P=0.035), stroke 84% (CI, 32% to 157%; P<0.001), and total mortality 41% (CI, 7% to 84%; P=0.013). Risk for myocardial infarction was 44% higher (CI, -5% to 120%; P=0.089). The risks in the losartan group also increased with increasing quartile, but were lower than in the atenolol group, and differences between the highest and lowest quartiles were not significant: composite end point 12% (CI, -13% to 44%; P>0.2), stroke -5% (CI, -34% to 37%; P>0.2), myocardial infarction 30% (CI, -13% to 94%; P>0.2), and total mortality 32% (CI, -1% to 76%; P=0.062). In patients with hypertension and left ventricular hypertrophy in the LIFE study, there were significantly higher risks, adjusted for the Framingham risk score, for the primary composite end point, stroke, and total mortality in the highest versus lowest quartile of pulse pressure with atenolol-based treatment. The risks in the losartan group also increased with increasing pulse pressure quartile, but were lower than those in the atenolol group, and were not significant.

Aged↗

PubMed2004

Stroke reduction in hypertensive adults with cardiac hypertrophy randomized to losartan versus atenolol: the Losartan Intervention For Endpoint reduction in hypertension study.

The Losartan Intervention For Endpoint reduction in hypertension (LIFE) study showed that treatment with the angiotensin II type-1 receptor antagonist losartan reduces overall stroke risk compared with conventional therapy with the beta-blocker atenolol. We conducted secondary analyses in LIFE to determine the extent to which the cerebrovascular benefits of losartan apply to different clinical subgroups and stroke subtypes and to assess the dependence of these benefits on baseline and time-varying covariates. Among 9193 hypertensive patients with electrocardiographic evidence of left ventricular hypertrophy, random allocation to losartan-based treatment lowered the risk of fatal (hazard ratio [HR], 0.65; 95% confidence interval [CI], 0.43 to 0.96; P=0.032) and atherothrombotic stroke (HR, 0.72; 95% CI, 0.59 to 0.88; P=0.001) compared with atenolol-based therapy. Although comparable risk reductions occurred for hemorrhagic and embolic stroke, these were not statistically significant. The number of neurological deficits per stroke was similar, but there were fewer strokes in the losartan group for nearly every level of stroke severity. Effects were consistent in all clinical subgroups except for those defined by age and ethnicity. The benefits of losartan on all strokes were independent of baseline and time-varying risk factors, including blood pressure. The number needed to treat for 5 years to prevent 1 stroke was 54 for the average participant, declining to 25, 24, and 9 for patients with cerebrovascular disease, isolated systolic hypertension, and atrial fibrillation, respectively. In conclusion, substantial cerebrovascular benefit could be realized with the institution of losartan-based therapy over conventional therapy among hypertensive patients with left ventricular hypertrophy across the spectrum of cardiovascular risk.

Aged↗

PubMed2004

Safety and efficacy of enoxaparin vs unfractionated heparin in patients with non-ST-segment elevation acute coronary syndromes who receive tirofiban and aspirin: a randomized controlled trial.

CONTEXT: Enoxaparin or the combination of glycoprotein IIb/IIIa inhibitor tirofiban with unfractionated heparin independently have shown superior efficacy over unfractionated heparin alone in patients with non-ST-elevation acute coronary syndromes (ACS). It is not clear if combining enoxaparin with glycoprotein IIb/IIIa inhibitors is as safe or as effective as the current standard combination of unfractionated heparin with glycoprotein IIb/IIIa inhibitors. OBJECTIVE: To assess efficacy and safety of the combination of enoxaparin and tirofiban compared with unfractionated heparin and tirofiban in patients with non-ST-elevation ACS. DESIGN, SETTING, AND PARTICIPANTS: A prospective, international, open-label, randomized, noninferiority trial of 1 mg/kg of enoxaparin every 12 hours (n = 2026) compared with weight-adjusted intravenous unfractionated heparin (n = 1961) in patients with non-ST-elevation ACS receiving tirofiban and aspirin. Phase A of the A to Z trial was conducted between December 1999 and May 2002. MAIN OUTCOME MEASURES: Death, recurrent myocardial infarction, or refractory ischemia at 7 days in the intent-to-treat population with boundaries set for superiority and noninferiority. Safety based on measures of bleeding using the Thrombolysis in Myocardial Infarction (TIMI) classification system. RESULTS: A total of 169 (8.4%) of 2018 patients randomized to enoxaparin experienced death, myocardial infarction, or refractory ischemia at 7 days compared with 184 (9.4%) of 1952 patients randomized to unfractionated heparin (hazard ratio [HR], 0.88; 95% confidence interval [CI], 0.71-1.08). This met the prespecified criterion for noninferiority. All components of the composite primary and secondary end points favored enoxaparin except death, which occurred in only 1% of patients (23 for enoxaparin and 17 for unfractionated heparin). Rates for any TIMI grade bleeding were low (3.0% for enoxaparin and 2.2% for unfractionated heparin; P =.13). Using a worst-case approach that combined 2 independent bleeding evaluations, use of enoxaparin was associated with 1 additional TIMI major bleeding episode for each 200 patients treated. CONCLUSIONS: In patients receiving tirofiban and aspirin, enoxaparin is a suitable alternative to unfractionated heparin for treatment of non-ST-elevation ACS. The 12% relative and 1% absolute reductions in the primary end point in favor of enoxaparin met criterion for noninferiority and are consistent with prior trials performed without the use of glycoprotein IIb/IIIa inhibitors.

Aged↗

PubMed2004

Informative noncompliance in endpoint trials.

Noncompliance with study medications is an important issue in the design of endpoint clinical trials. Including noncompliant patient data in an intention-to-treat analysis could seriously decrease study power. Standard methods for calculating sample size account for noncompliance, but all assume that noncompliance is noninformative, i.e., that the risk of discontinuation is independent of the risk of experiencing a study endpoint. Using data from several published clinical trials (OPTIMAAL, LIFE, RENAAL, SOLVD-Prevention and SOLVD-Treatment), we demonstrate that this assumption is often untrue, and we discuss the effect of informative noncompliance on power and sample size.

Journal Article↗

PubMed2004

Tirofiban therapy for patients with acute coronary syndromes and prior coronary artery bypass grafting in the PRISM-PLUS trial.

The role of glycoprotein IIb/IIIa platelet receptor antagonist therapy for patients with an acute coronary syndrome (ACS) and a history of coronary artery bypass grafting (CABG) remains incompletely defined. We examined the outcomes of patients with an ACS and prior CABG who were treated with tirofiban versus placebo among subjects with prior CABG in the Platelet Receptor Inhibition in Ischemic Syndrome Management in Patients Limited by Unstable Signs and Symptoms (PRISM-PLUS) trial. Of 1,570 patients treated with tirofiban plus heparin (n = 773) or heparin alone (n = 797), 231 had prior CABG. Compared with patients without prior CABG, those with prior CABG were more likely to have risk factors for a complicated ACS course, including severe coronary artery disease and heart failure (all p <0.0001), typically had clinical predictors of benefit from tirofiban, such as ST-segment depression (p = 0.01) or a TIMI risk score >or=4 (p <0.001), and were more likely to die or have a myocardial infarction or refractory ischemia at all time points examined (p <0.0001). Among patients with prior CABG, decreases in the incidence of death, myocardial infarction, or refractory ischemia with tirofiban and heparin versus heparin alone were noted at 7 and 30 days (7 days: 16.9% vs 29.0%, p = 0.035; 30 days: 25.0% vs 40.2%, p = 0.015). Trends toward a decrease in death, myocardial infarction, and refractory ischemia with tirofiban and heparin versus heparin alone in the prior CABG subgroup were noted at 48 hours and 180 days (48 hours: 6.5% vs 14.0%, p = 0.09; 180 days: 37.1% vs 48.6%, p = 0.057). Bleeding rates were similar in patients with and without prior CABG. Tirofiban was well tolerated and tended to decrease the considerable risk for ischemic ACS complications in patients with prior CABG.

Acute Disease↗

PubMed2004

Alternatives for discounting in the analysis of noninferiority trials.

Determining the efficacy of an experimental therapy relative to placebo on the basis of an active-control noninferiority trial requires reference to historical placebo-controlled trials. The validity of the resulting comparison depends on two key assumptions: assay sensitivity and constancy. Since the truth of these assumptions cannot be verified, it seems logical to raise the standard of evidence required to declare efficacy; this concept is referred to as discounting. It is not often recognized that two common design and analysis approaches, setting a noninferiority margin and requiring preservation of a fraction of the standard therapy's effect, are forms of discounting. The noninferiority margin is a particularly poor approach, since its degree of discounting depends on an irrelevant factor. Preservation of effect is more reasonable, but it addresses only the constancy assumption, not the issue of assay sensitivity. Gaining consensus on the most appropriate approach to the design and analysis of noninferiority trials will require a common understanding of the concept of discounting.

Clinical Trials as Topic↗

PubMed2004

Separate modeling approaches for survival analysis with inaccurate covariate measurements.

To fit the Cox regression model with time-varying covariate, ideally we need values of the covariate available for all patients in the risk set at each event time. But in reality, the covariate measurements are collected at limited patient-specific time points, and the data used for analysis are typically inaccurate with imputation errors. Four separate modeling-based methods for survival analysis with inaccurate covariate measurements are evaluated through extensive simulation studies. It is found that our proposed new method, which is based on the maximum likelihood principle, performs the best and is superior to a well-known method proposed by Prentice. These findings aid practitioners in the decision of which method to choose in practice and shed light on the direction of further research work.

Proportional Hazards Models↗

PubMed2003

Albuminuria and cardiovascular risk in hypertensive patients with left ventricular hypertrophy: the LIFE study.

BACKGROUND: Several studies have shown that albuminuria is associated with increased risk for fatal and nonfatal cardiovascular events, independent of conventional risk factors. The partition values for urine albumin-creatinine ratio (UACR) used to identify microalbuminuria have been based on studies that predicted risk in diabetic patients. OBJECTIVE: To determine whether the relation between albuminuria and cardiovascular risk can be used to predict cardiovascular morbidity and mortality in hypertensive patients. DESIGN: Multicenter cohort study derived from a randomized, controlled trial. PATIENTS: 8206 patients with stage II or III hypertension randomly assigned to double-blind therapy with losartan or atenolol. Follow-up was 39 122 patient-years. MEASUREMENTS: Renal glomerular permeability evaluated by UACR. RESULTS: In nondiabetic hypertensive patients with left ventricular hypertrophy, the risk for the composite cardiovascular end point increased continuously as albuminuria increased (P < 0.001 for trend). There was no specific threshold for increased risk. For every 10-fold increase in UACR, hazard ratios in nondiabetic patients increased as follows: composite end point, by 57% (95% CI, 40.6% to 75.0%); cardiovascular mortality, by 97.7% (CI, 66.5% to 235%); all-cause mortality, by 75.2% (CI, 54.0% to 99.4%); stroke, by 51.0% (CI, 28.8% to 76.9%); and myocardial infarction, by 45% (CI, 19.9% to 75.4%) (P < 0.001 for all comparisons). Values were similar in diabetic patients, although for myocardial infarction the trend was weaker and not significant. CONCLUSION: Increased UACR resulted in increasing risk for cardiovascular morbidity and mortality among hypertensive patients with left ventricular hypertrophy. We found no thresholds or plateaus. Risk increases at much lower UACR values than has been reported among diabetic patients.

Aged↗

PubMed2003

Proportion of treatment effect (PTE) explained by a surrogate marker.

In time-varying covariate analysis of clinical survival data, it is often of interest to estimate the proportion of treatment effect (PTE), along with its confidence intervals, explained by a surrogate marker. The conventional procedure for such an analysis fits data into two working models separately to estimate the treatment effects before and after adjustment of the covariate. The construction of confidence intervals for the PTE under the conventional procedure lacks support by standard statistical software such as SAS, and could be very computationally demanding even after the support is available in the future. To overcome this problem, we propose a new procedure to simplify the computation. Under the new procedure, the treatment effects before and after adjustment of the covariate are simultaneously estimated from a single model. More important than saving computational effort, the new procedure can also be effectively applied to multiple-covariate models for the decomposition of overall treatment effect and for the comparison of PTE among several surrogate markers. The new procedure is applied to the motivating data example from the LIFE study, and demonstrates flexibility that the conventional procedure currently lacks.

Antihypertensive Agents↗