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C M Viscoli

Publications and source records attributed to C M Viscoli.

13 recordsLinked to original sources
PubMed1992

Preventive health strategies and the policy makers' paradox.

The likelihood of developing many diseases is predicted by levels of risk factors. Many public health strategies have been created to apply interventions (for example, drugs, diets, exercise) intended to lower levels of these factors and thereby prevent disease. Often, these strategies are based on the interpretation of incomplete evidence for the effectiveness of the interventions. The reason this evidence is and will likely remain incomplete is explained by the policy makers' paradox. The paradox occurs when evidence for an intervention's effectiveness is obtained in persons with the highest levels of a risk factor, but the application of the intervention may have the greatest potential for reducing disease burden in persons with lower levels. Resolution of the paradox requires consideration of the type and quality of evidence, the society's time preference for risk, and the society's choice about allocation of scarce resources.

Canada↗
PubMed1992

Problems in the conduct and analysis of randomized clinical trials. Are we getting the right answers to the wrong questions?

To achieve the goal of validity, the randomized clinical trial has emerged as the scientific "gold standard" for evaluating therapies in clinical medicine. Regardless of how well randomized clinical trials are designed, however, problems often occur during the conduct of the trials that give rise to methodologic challenges in the analysis of results. Primarily two types of problems, changes in intended treatment and the failure to ascertain the study outcomes, occur during the conduct of randomized clinical trials. We studied the current analytic strategies that are used to deal with these problems and how the use of these analytic strategies can change the focus of the research so that the trial no longer answers the relevant question. To ensure that the right question is answered, new methods of design and analysis are required that balance the goals of validity and clinical pertinence.

Evaluation Studies as Topic↗
PubMed1991

A prognostic system for transient ischemia or minor stroke.

OBJECTIVE: To build a prognostic system for patients with carotid transient ischemic attack or minor stroke. DESIGN: Inception cohort study with 2-year follow-up. SETTING: Urban community teaching hospital. PATIENTS: Eligible patients (n = 142), identified on a carotid ultrasound roster, had been hospitalized between 1984 and 1987 within 30 days of a first carotid transient ischemic attack or minor stroke. MEASUREMENTS: Stroke or death within 2 years. MAIN RESULTS: Three factors were associated with stroke or death: age of more than 65 years, diabetes, and hypertension. Based on regression coefficients, age of more than 65 years was assigned 3 points; diabetes, 3 points; and hypertension, 2 points. An initial prognostic system comprised risk groups 1 (0 points), 2 (1 to 5 points), and 3 (6 to 8 points). Outcome rates in the three groups were 2%, 31%, and 54% (P less than 0.0001), respectively. In an independent test sample, the corresponding outcome rates for the initial system were 12%, 21%, and 31% (P = 0.04). A final prognostic system, including two additional predictors (coronary heart disease [1 point] and the distinction between stroke and transient ischemic attack for the baseline event [2 points]), comprised risk groups 1 (0 to 2 points), 2 (3 to 6 points), and 3 (7 to 11 points). Corresponding outcome rates were 3%, 27%, and 48% (P less than 0.001) in the original cohort and 10%, 21%, and 59% (P less than 0.001) in the test cohort. CONCLUSION: For selected patients with carotid transient ischemia or minor stroke, five clinical features can be combined to stratify effectively the risk for a subsequent stroke or death.

Aged↗
PubMed1991

Patient acceptance of influenza vaccination.

PURPOSE: To determine whether patients' demographic, medical, and personal characteristics, including attitudes and beliefs about vaccination, health, and medical providers, are associated with acceptance of influenza vaccine. PATIENTS AND METHODS: Nine hundred sixty-five patients attending a university hospital-based general medicine clinic during the fall influenza vaccination period, including 624 patients for whom influenza vaccine was indicated, were observed in a prospective cohort study. In addition, 58 patients who refused influenza vaccine and an equal number who accepted it were interviewed over the telephone to examine their beliefs and behaviors in greater detail. RESULTS: Seventy-five percent of patients for whom influenza vaccine was indicated received it. Prospectively assessed patient characteristics that were significantly associated with nonvaccination included not believing vaccine prevents "flu" (relative risk [RR] 5.3), never received pneumococcal vaccine (RR 3.5), not vaccinated against influenza the previous year (RR 3.5), never vaccinated against influenza (RR 2.3), and felt sick after previous influenza vaccination (RR 2.3). Demographic characteristics and medical diagnoses were not significantly related to vaccination. Almost one half of 58 interviewed subjects who refused influenza vaccine cited fear of a reaction. Among retrospectively determined attitudes and beliefs significantly associated with refusal of influenza vaccine were not believing the vaccine works well (odds ratio [OR] 11.6), concern about a reaction (OR 9.3), and perception that the medical provider had not recommended it (OR 5.8). CONCLUSION: Demographic characteristics of patients and their medical diagnoses were not associated with acceptance of influenza vaccination. Among patients who were not vaccinated, doubts about the efficacy of influenza vaccine and fear of its side effects were common, and their perceptions of the medical provider's recommendation of vaccine appeared to be an important factor in the decision whether to accept it.

Aged↗
PubMed1991

Zidovudine (AZT) for treatment of patients infected with human immunodeficiency virus type 1. An evaluation of effectiveness in clinical practice.

To learn about the patterns of use and the effectiveness of zidovudine therapy in clinical practice, we conducted an observational cohort study of 86 patients with human immunodeficiency virus type 1 infection. All patients were followed up for at least 6 months after starting zidovudine (AZT) therapy. Of the 86 patients, 78 (91%) initially received full-dosage zidovudine (1200 mg/d), and eight received a reduced dosage (600 mg/d). During follow-up, the number able to maintain full-dosage zidovudine therapy decreased to 54 (63%) at 3 months and 40 (47%) at 6 months. Thirty-five patients required dosage reductions that lasted at least 7 days and were not preceded by an adverse outcome (death or opportunistic infection). Overall, adverse outcomes occurred for nine (26%) of those with dosage reductions compared with 22 (43%) of 51 patients with no previous dosage change. Even after adjusting for baseline cytopenias and the time of the dosage reductions, adverse outcomes did not occur significantly more often in patients who received reductions in their zidovudine dosage. Our results indicate that full-dosage zidovudine therapy cannot be maintained for most patients infected with human immunodeficiency virus, but that clinicians need not be pessimistic about treatment outcomes when dosage reductions are needed.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Treatment adherence and risk of death after a myocardial infarction.

The relation of treatment adherence to mortality after a myocardial infarction was investigated among 2175 participants in the Beta Blocker Heart Attack Trial, which had data for measures of treatment adherence, clinical severity, and the psychological and social features that may influence post-infarction mortality. Overall, patients who did not adhere well to treatment regimen (ie, who took less than or equal to 75% of prescribed medication) were 2.6 times more likely than good adherers to die within a year of follow-up (95% confidence interval, 1.2, 5.6). Poor adherers had an increased risk of death whether they were on propranolol (OR = 3.1) or placebo (OR = 2.5). Furthermore, this increased risk of death for poor adherers was not accounted for by measures of the severity of myocardial infarction, sociodemographic features (eg, race, marital status, education), smoking, or psychological characteristics (high life-stress or social isolation).

Adult↗
PubMed1990

Differences between women and men in survival after myocardial infarction. Biology or methodology?

To examine the impact of gender on survival after myocardial infarction, we performed a retrospective cohort study of 332 women and 790 men. Women who had a myocardial infarction were older and more often had hypertension, diabetes, previous heart failure, and impaired left ventricular function on admission. Cumulative 3-year mortality and in-hospital mortality rates were significantly higher in women than men, but mortality among hospital survivors was similar. After multivariate adjustment for baseline differences, mortality rates were not significantly different between women and men for in-hospital deaths, and mortality at 3 years among hospital survivors tended to be lower among women. We conclude that higher observed mortality rates following a myocardial infarction in women are related to differences in known risk factors for subsequent mortality and that gender should not be considered an independent risk factor for mortality after myocardial infarction.

Adult↗
PubMed1990

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.

Adrenergic beta-Antagonists↗
PubMed1989

New epidemiologic evidence confirming that bias does not explain the aspirin/Reye's syndrome association.

To determine the validity of the aspirin/Reye's syndrome association, we developed an epidemiologic investigation to assess the effects of five potential sources of bias. A case-control study incorporated procedures to avoid temporal precedence and susceptibility bias. These included classifying cases as having monophasic or biphasic patterns of illness and matching for severity of symptoms at zero-time. To evaluate the effect of a potential recall bias, an "alternate-condition" control group was enrolled. A medical record review study was conducted to assess the potential for diagnostic bias, and a blanket surveillance of all hospitals in a region was conducted to evaluate reporting bias. Twenty-four case subjects and 48 matched controls were enrolled. Eight-eight percent of case subjects and only 17% of controls had received aspirin prior to the onset of Reye's syndrome (matched odds ratio, 35; 95% confidence interval, 4.2 to 288). Further analyses demonstrated that the association could not be attributed to the five potential sources of bias.

Adolescent↗
PubMed1988

Clear cell adenocarcinoma of the vagina and cervix: incidence, undetected disease, and diethylstilbestrol.

We conducted an incidence study to determine the occurrence rates of clear cell adenocarcinoma (CCAC) of the vagina and cervix in young women (born in 1940 and thereafter), and a case-series analysis, focusing on the maternal history of pregnancy and delivery and in-utero exposure to diethylstilbestrol (DES). Overall, 10 cases of CCAC had been listed in the files of the Connecticut State Tumor Registry prior to the study, and each of the 10 cases were confirmed as valid. In addition, another 10 cases, all previously undetected, were found after the tissue slides of young women listed as having other cancers of the vagina and cervix were reviewed by expert pathologists, suggesting that prior estimates of the incidence rate for CCAC must be misleading unless special efforts are taken to identify undetected cases. The incidence rates of vaginal CCAC (11 cases total) were highest in 1975-1979, and decreased slightly during 1980-1982. In the cervix (nine cases total), the rate increased consistently since 1970. History of in-utero exposure to diethylstilbestrol was obtained for five of eight vaginal cases and four of eight cervical cases of CCAC. In all nine cases, exposure to diethylstilbestrol was associated with a history of bleeding during the pregnancy or prior miscarriage. We conclude that the finding of stable (or rising) incidence rates for CCAC occurring nearly 30 years after the marked decrease in diethylstilbestrol sales emphasizes the need for continued clinical and epidemiologic studies of the etiology and clinical course of CCAC.

Abortion, Spontaneous↗
PubMed1988

An ecogenetic hypothesis for lung cancer in women.

Epidemiologic studies have established a strong association between cigarette smoking and lung cancer, but the risk estimates for women are less impressive than for men. We assessed the possible role of family history and its interrelationship with cigarette smoking as risk factors for lung cancer in women by conducting a case-control study. Among 112 cases, 7% had a primary family member with lung cancer compared with only 3% of 224 controls for an odds ratio of 2.8. Cigarette smoking was present for 87% of the cases and 41% of the controls for an odds ratio of 11.3. The ecogenetic interrelationship of cigarette smoking and family history was supported by the gradient in the odds ratio for lung cancer created by the two variables: patients who never smoked but had a positive family history had an odds ratio of 5.7; patients who smoked but had a negative family history had an odds ratio of 15.1; and patients who smoked and had a positive family history had an odds ratio of almost 30. We conclude that family history may be an important risk factor for lung cancer in women, and that the ecogenetic interrelationship of family history with cigarette smoking may help explain the occurrence of this disease in women.

Adenocarcinoma↗