Catherine M. Viscoli

Pioglitazone after Ischemic Stroke or Transient Ischemic Attack

BACKGROUND Patients with ischemic stroke or transient ischemic attack (TIA) are at increased risk for future cardiovascular events despite current preventive therapies. The identification of insulin resistance as a risk factor for stroke and myocardial infarction raised the possibility that pioglitazone, which improves insulin sensitivity, might benefit patients with cerebrovascular disease. METHODS In this multicenter, double-blind trial, we randomly assigned 3876 patients who had had a recent ischemic stroke or TIA to receive either pioglitazone (target dose, 45 mg daily) or placebo. Eligible patients did not have diabetes but were found to have insulin resistance on the basis of a score of more than 3.0 on the homeostasis model assessment of insulin resistance (HOMA-IR) index. The primary outcome was fatal or nonfatal stroke or myocardial infarction. RESULTS By 4.8 years, a primary outcome had occurred in 175 of 1939 patients (9.0%) in the pioglitazone group and in 228 of 1937 (11.8%) in the placebo group (hazard ratio in the pioglitazone group, 0.76; 95% confidence interval [CI], 0.62 to 0.93; P=0.007). Diabetes developed in 73 patients (3.8%) and 149 patients (7.7%), respectively (hazard ratio, 0.48; 95% CI, 0.33 to 0.69; P<0.001). There was no significant between-group difference in all-cause mortality (hazard ratio, 0.93; 95% CI, 0.73 to 1.17; P=0.52). Pioglitazone was associated with a greater frequency of weight gain exceeding 4.5 kg than was placebo (52.2% vs. 33.7%, P<0.001), edema (35.6% vs. 24.9%, P<0.001), and bone fracture requiring surgery or hospitalization (5.1% vs. 3.2%, P=0.003). CONCLUSIONS In this trial involving patients without diabetes who had insulin resistance along with a recent history of ischemic stroke or TIA, the risk of stroke or myocardial infarction was lower among patients who received pioglitazone than among those who received placebo. Pioglitazone was also associated with a lower risk of diabetes but with higher risks of weight gain, edema, and fracture. (Funded by the National Institute of Neurological Disorders and Stroke; ClinicalTrials.gov number, NCT00091949.).

Phenylpropanolamine and the Risk of Hemorrhagic Stroke

BACKGROUND Phenylpropanolamine is commonly found in appetite suppressants and cough or cold remedies. Case reports have linked the use of products containing phenylpropanolamine to hemorrhagic stroke, often after the first use of these products. To study the association, we designed a case-control study. METHODS Men and women 18 to 49 years of age were recruited from 43 U.S. hospitals. Eligibility criteria included the occurrence of a subarachnoid or intracerebral hemorrhage within 30 days before enrollment and the absence of a previously diagnosed brain lesion. Random-digit dialing identified two matched control subjects per patient. RESULTS There were 702 patients and 1376 control subjects. For women, the adjusted odds ratio was 16.58 (95 percent confidence interval, 1.51 to 182.21; P=0.02) for the association between the use of appetite suppressants containing phenylpropanolamine and the risk of a hemorrhagic stroke and 3.13 (95 percent confidence interval, 0.86 to 11.46; P=0.08) for the association with the first use of a product containing phenylpropanolamine. All first uses of phenylpropanolamine involved cough or cold remedies. For men and women combined, the adjusted odds ratio was 1.49 (95 percent confidence interval, 0.84 to 2.64; P=0.17) for the association between the use of a product containing phenylpropanolamine and the risk of a hemorrhagic stroke, 1.23 (95 percent confidence interval, 0.68 to 2.24; P=0.49) for the association with the use of cough or cold remedies that contained phenylpropanolamine, and 15.92 (95 percent confidence interval, 1.38 to 184.13; P=0.03) for the association with the use of appetite suppressants that contained phenylpropanolamine. An analysis in men showed no increased risk of a hemorrhagic stroke in association with the use of cough or cold remedies containing phenylpropanolamine. No men reported the use of appetite suppressants. CONCLUSIONS The results suggest that phenylpropanolamine in appetite suppressants, and possibly in cough and cold remedies, is an independent risk factor for hemorrhagic stroke in women.

Stratified randomization for clinical trials.

Trialists argue about the usefulness of stratified randomization. For investigators designing trials and readers who use them, the argument has created uncertainty regarding the importance of stratification. In this paper, we review stratified randomization to summarize its purpose, indications, accomplishments, and alternatives. In order to identify research papers, we performed a Medline search for 1966-1997. The search yielded 33 articles that included original research on stratification or included stratification as the major focus. Additional resources included textbooks. Stratified randomization prevents imbalance between treatment groups for known factors that influence prognosis or treatment responsiveness. As a result, stratification may prevent type I error and improve power for small trials (<400 patients), but only when the stratification factors have a large effect on prognosis. Stratification has an important effect on sample size for active control equivalence trials, but not for superiority trials. Theoretical benefits include facilitation of subgroup analysis and interim analysis. The maximum desirable number of strata is unknown, but experts argue for keeping it small. Stratified randomization is important only for small trials in which treatment outcome may be affected by known clinical factors that have a large effect on prognosis, large trials when interim analyses are planned with small numbers of patients, and trials designed to show the equivalence of two therapies. Once the decision to stratify is made, investigators need to chose factors carefully and account for them in the analysis.

Lower Baseline Glycemia Reduces Apparent Oral Agent Glucose-Lowering Efficacy: A meta-regression analysis

Perusal of advertisements for oral hypoglycemic agents in this and many other medical journals shows an emphasis on the absolute reduction in HbA1c (A1C). Evidence linking reduction in A1C in diabetic patients to prevention of macrovascular events is weak. However, epidemiological evidence suggests that the risk for cardiovascular disease in this group may actually begin at A1C concentrations well within the normal range (1). This association has led a number of professional organizations to recommend that A1C levels be brought to levels <6.5% (2). An important question to be asked is whether the reduction in A1C differs at lower versus higher baseline levels of A1C. Expectations for the degree of reduction to be attained with a given agent may be excessively optimistic when a person’s initial A1C is already <7.5–8.0%. Some of the deliberations of policy advisory groups are available. The European Agency for the Evaluation of Medicinal Products has published guidelines for diabetes product evaluation suggesting that the change in A1C be utilized as “primary analysis” of drug efficacy, although allowing the baseline A1C to be included as a covariate (3). A meeting of the Center for Drug Evaluation and Research Endocrinologic and Metabolic Drugs Advisory Committee of the U.S. Food and Drug Administration concluded that A1C should be the primary outcome variable for diabetes drugs and suggested an absolute decrease of 0.7% as the minimal acceptable level for approval (4). This may prevent acceptance of agents that are as effective as existing treatments at A1C levels …

Developing improved observational methods for evaluating therapeutic effectiveness

Therapeutic efficacy is often studied with observational surveys of patients whose treatments were selected nonexperimentally. The results of these surveys are distrusted because of the fear that biased results occur in the absence of experimental principles, particularly randomization. The purpose of the current study was to develop and validate improved observational study designs by incorporating many of the design principles and patient assembly procedures of the randomized trial. The specific topic investigated was the prophylactic effectiveness of beta-blocker therapy after an acute myocardial infarction. To accomplish the research objective, three sets of data were compared. First, we developed a restricted cohort based on the eligibility criteria of the randomized clinical trial; second, we assembled an expanded cohort using the same design principles except for not restricting patient eligibility; and third, we used the data from the Beta Blocker Heart Attack Trial (BHAT), whose results served as the gold standard for comparison. In this research, the treatment difference in death rates for the restricted cohort and the BHAT trial was nearly identical. In contrast, the expanded cohort had a larger treatment difference than was observed in the BHAT trial. We also noted the important and largely neglected role that eligibility criteria may play in ensuring the validity of treatment comparisons and study outcomes. The new methodologic strategies we developed may improve the quality of observational studies and may be useful in assessing the efficacy of the many medical/surgical therapies that cannot be tested with randomized clinical trials.

Insulin resistance and risk for stroke.

Background and purpose Resistance to insulin-mediated glucose uptake by peripheral tissues is a cardinal defect in type 2 diabetes mellitus. Insulin resistance is also common among nondiabetic individuals, and may be an important risk factor for stroke in both populations. The authors review the definition, epidemiology, and treatment of insulin resistance. Methods The authors searched Medline (1977–2001) and reviewed bibliographies to identify pertinent English-language publications. Results Insulin resistance is present in most patients with type 2 diabetes. It is also common among elderly persons, certain ethnic groups, and persons with hypertension, obesity, physical deconditioning, and vascular disease. The principal pathophysiologic defect is impaired intracellular signaling in muscle tissue leading to defective glycogen synthesis. Insulin resistance is associated with numerous metabolic, hematologic, and cellular events that promote atherosclerosis and coagulation. The association between insulin resistance and risk for stroke has been examined in four case-control studies and five prospective observational cohort studies. Six of the nine studies are methodologically sound and provide evidence that insulin resistance is associated with risk for stroke. ConclusionInsulin resistance may be a prevalent risk factor for stroke. New drugs can safely reduce insulin resistance and may have a role in stroke prevention.

Major Risk Factors for Aneurysmal Subarachnoid Hemorrhage in the Young Are Modifiable

Background and Purpose— To identify risk factors for subarachnoid hemorrhage (SAH) and intracerebral hemorrhage, we designed a case-control study of men and women 18 to 49 years of age (the Hemorrhagic Stroke Project [HSP]). This report focuses on SAH. Methods— Patients were recruited from 44 hospitals in the United States. Cases with SAH must have had a ruptured aneurysm documented by angiography or surgery. Two controls, identified by random digit dialing and matched to each patient for age, sex, race, and telephone exchange, were sought for each case subject. Results— Between 1994 and 1999, 425 patients with SAH were enrolled in HSP, and 312 cases met the criteria for aneurysmal SAH. The present analyses also included 618 matched controls. Of the 312 cases, 66% were current cigarette smokers compared with 30% of controls (adjusted odds ratio [OR], 3.73; 95% CI, 2.67 to 5.21). Cocaine use within the previous 3-day period was reported by 3% of cases and no controls (bivariate exact OR, 24.97; 95% exact CI, 3.95 to ∞; adjusted estimate not calculable). Other independent risk factors in the multivariable model included hypertension (adjusted OR, 2.21; 95% CI, 1.48 to 3.29), low body mass index (OR, 1.59; 95% CI, 1.08 to 2.35), primary family history of hemorrhagic stroke (OR, 3.83; 95% CI, 1.73 to 8.46), caffeine in pharmaceutical products (OR, 2.48; 95% CI, 1.19 to 5.20), lower educational achievement (OR, 2.36; 95% CI, 1.44 to 3.87), and nicotine in pharmaceutical products (adjusted estimate not calculable). Conclusions— Aneurysmal SAH may be largely a preventable disease among the young and middle-aged because several prevalent risk factors can be modified by medication (eg, hypertension) or behavioral change (eg, cigarette smoking, cocaine use). The association of caffeine and nicotine in pharmaceutical products and aneurysmal SAH warrants further study.

The Stroke Prognosis Instrument II (SPI-II) A Clinical Prediction Instrument for Patients With Transient Ischemia and Nondisabling Ischemic Stroke

BACKGROUND AND PURPOSE In 1991 we developed the Stroke Prognosis Instrument (SPI-I) to stratify patients with transient ischemic attack or ischemic stroke by prognosis for stroke or death in 2 years. In this article we validate and improve SPI-I (creating SPI-II). METHODS To validate SPI-I, we applied it to 4 test cohorts and calculated pooled outcome rates. To create SPI-II, we incorporated new predictive variables identified in 1 of the test cohorts and validated it in the other 3 cohorts. RESULTS For SPI-I, pooled rates (all 4 test cohorts) of stroke or death within 2 years in risk groups I, II, and III were 9%, 17%, and 24%, respectively (P<0.01, log-rank test). SPI-II was created by adding congestive heart failure and prior stroke to SPI-I. Each patients risk group was determined by the total score for 7 factors: congestive heart failure (3 points); diabetes (3 points); prior stroke (3 points); age >70 years (2 points); stroke for the index event (not transient ischemic attack) (2 points); hypertension (1 point); and coronary artery disease (1 point). Risk groups I, II, and III comprised patients with 0 to 3, 4 to 7, and 8 to 15 points, respectively. For SPI-I, pooled rates (3 cohorts excluding the SPI-II development cohort) of stroke or death within 2 years in risk groups I, II, and III were 9%, 17%, and 23%, respectively. For SPI-II, pooled rates were 10%, 19%, and 31%, respectively. In receiver operator characteristic analysis, the area under the curve was 0.59 (95% CI, 0.57 to 0.60) for SPI-I and 0.63 (95% CI, 0.62 to 0.65) for SPI-II, confirming the better performance of the latter. CONCLUSIONS Compared with SPI-I, SPI-II achieves greater discrimination in outcome rates among risk groups. SPI-II is ready for use in research design and may have a role in patient counseling.

Major Risk Factors for Intracerebral Hemorrhage in the Young Are Modifiable

Background and Purpose— To identify risk factors for intracerebral hemorrhage (ICH), we examined data from the Hemorrhagic Stroke Project (HSP), a case-control study of hemorrhagic stroke among men and women aged 18 to 49 years. Methods— Case subjects for the HSP were recruited from 44 hospitals in the United States. Eligibility criteria included an ICH within 30 days preceding enrollment, no history of stroke or known brain lesion. For this report, we focused on patients with primary ICH, defined as not associated with an aneurysm, arteriovenous malformation or other structural lesion. Two control subjects were sought for each case subject. A multivariate regression analysis was performed to determine risk factors for primary ICH. Results— A total of 1714 patients with hemorrhagic stroke were identified for participation in the HSP. Of these, 217 cases met the criteria for primary ICH. Cases with primary ICH were matched to 419 controls. Independent risk factors for ICH included hypertension (adjusted odds ratio [OR], 5.71; 95% CI, 3.61 to 9.05), diabetes (adjusted OR, 2.40; 95% CI, 1.15 to 5.01), menopause (adjusted OR, 2.50; 95% CI, 1.06 to 5.88), current cigarette smoking (adjusted OR, 1.58; 95% CI, 1.02 to 2.44), alcoholic drinks≥2/day (adjusted OR, 2.23; 95% CI, 1.16 to 4.32), caffeinated drinks≥5/day (adjusted OR, 1.73; 95% CI, 1.08 to 2.79), and caffeine in drugs (adjusted OR, 3.55; 95% CI, 1.24 to 10.20). Conclusions— Among young men and women, the major risk factors for primary ICH can be modified, suggesting that this type of stroke may be preventable. Our findings for caffeine and menopause warrant further study.

Prevalence of Abnormal Glucose Tolerance Following a Transient Ischemic Attack or Ischemic Stroke

BACKGROUND Despite current preventive therapies, patients with transient ischemic attack (TIA) and ischemic stroke remain at high risk for recurrent brain disease and cardiovascular events. In an effort to develop new therapies, abnormal glucose tolerance has recently been proposed as an interventional target. Among persons not otherwise known to be diabetic, impaired glucose tolerance (IGT) and diabetic glucose tolerance (DGT) are each associated with an increased risk for incident vascular disease, vascular disease mortality, and all-cause mortality. We conducted this study to determine if IGT and DGT are sufficiently common among patients with TIA and ischemic stroke to warrant therapeutic trials of antihyperglycemic agents. METHODS Men and women older than 45 years were recruited from 3 hospitals in south central Connecticut. Eligibility criteria included a recent TIA or nondisabling ischemic stroke, no history of physician-diagnosed diabetes mellitus, and a fasting plasma glucose level less than 126 mg/dL (<7.0 mmol / L). After an overnight fast, subjects were admitted to a clinical research center for a standard 75-g oral glucose tolerance test. Impaired glucose tolerance was defined by a 2-hour plasma glucose value of 140 to 199 mg/dL (7.8-11.0 mmol / L) and DGT by a value of 200 mg/dL or greater (> or =11.1 mmol/L). RESULTS Between June 2000 and August 2003, we enrolled 98 eligible patients. The average time from TIA or stroke to measurement of glucose tolerance was 105 days (range, 24-180 days) and the median age was 71 years. Twenty-seven subjects (28%) had IGT and 24 (24%) had diabetes. In a forward stepwise logistic regression model, only a fasting plasma glucose level of 110 mg/dL or greater (> or =6.1 mmol / L) and lower waist circumference were associated with an increased risk for IGT or DGT. CONCLUSIONS Impaired glucose tolerance and DGT are present in most persons with a recent TIA or ischemic stroke who have no history of diabetes and a fasting plasma glucose level less than 126 mg/dL (<7.0 mmol / L). Our findings bring new urgency to the initiation of research to examine the effectiveness of antihyperglycemic therapies among patients with cerebrovascular disease and abnormal glucose tolerance.