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H A Feldman

Publications and source records attributed to H A Feldman.

At least 19 recordsLinked to original sources
PubMed1998

Statistical design of REACT (Rapid Early Action for Coronary Treatment), a multisite community trial with continual data collection.

Unusual problems in statistical design were faced by Rapid Early Action for Coronary Treatment (REACT), a multisite trial testing a community intervention to reduce the delay between onset of symptoms of acute myocardial infarction (MI) and patients' arrival at a hospital emergency department. In 20 pair-matched U.S. communities, hospital staff members recorded delay time throughout a 4-month baseline period and the subsequent 18-month intervention period, during which one randomly selected community of each pair received a campaign of public and professional education. To exploit the continual nature of its data-collection protocol, REACT estimated the trend of delay time separately in each community by linear regression, adjusting for age, sex, and history of MI, and compared the ten adjusted slopes from intervention communities with those from control communities by a paired t-test. Power calculations based on the analytical model showed that with K=600-800 cases per community, REACT would have 80% power to demonstrate a differential reduction of 30 min in mean delay time between intervention and control communities, as well as effects on a variety of secondary outcomes. Sensitivity analysis confirmed that the number of communities was optimal within constraints of funding and that the detectable effect depended weakly on the effectiveness of matching but strongly on K, helping the investigators set operational priorities. The methodologic strategy developed for REACT should prove useful in the design of similar trials in the future.

Emergencies↗
PubMed1998

HDL cholesterol: trends in two southeastern New England communities, 1981-1993.

PURPOSE: Although public health interventions have not specifically targeted high density lipoprotein (HDL) cholesterol, observed changes in the prevalence of other cardiovascular risk factors would be expected to have differential effects on HDL. This study examined secular trends in HDL in relation to changes in other cardiovascular risk factors for the years 1981 through 1993 in the Pawtucket Heart Health Program (PHHP) study communities. METHODS: Nonfasting HDL levels were assessed in 12,223 respondents to six biennial population random sample surveys. RESULTS: Between 1981 and 1993, mean HDL cholesterol declined by 0.08 mmol/L in both men and women after adjustment for age, city, education, hormone use, medications, recent alcohol use, smoking, regular exercise, body mass index (BMI), and total cholesterol, (p for trend < 0.001). There was no apparent laboratory explanation for the trend which occurred concurrent with decreased smoking prevalence, increasing BMI and decreased prevalence of recent alcohol use. Decreasing HDL cholesterol was observed consistently across subgroups defined by smoking, alcohol use and BMI. CONCLUSIONS: Although several favorable cardiovascular risk factor trends have been observed in recent decades, declining HDL cholesterol is also of interest, particularly in conjunction with population increases in BMI.

Adult↗
PubMed1998

Low dehydroepiandrosterone sulfate and heart disease in middle-aged men: cross-sectional results from the Massachusetts Male Aging Study.

PURPOSE: Serum concentrations of the adrenal androgen dehydroepiandrosterone (DHEA) and its sulfate ester (DHEAS), both of which decline with age more markedly than other sex hormone levels, have been alternately credited and discredited as "protective" correlates of heart disease. Baseline data from the Massachusetts Male Aging Study (MMAS), collected in 1987-89, provided a large population-based random sample (n = 1709) in which to examine cross-sectionally the relation of DHEA and DHEAS levels to heart disease, while controlling for a comprehensive set of potential confounders including serum lipid and hormone levels as well as smoking, alcohol intake, obesity, hypertension, diabetes, diet, medication, physical activity, and psychological measures. METHODS: The subjects were men aged 40-70 years, randomly sampled from the Massachusetts state census listing, measured and interviewed at home. Nonfasting blood samples were assayed for hormones and lipids. RESULTS: In all strata of age, smoking, and alcohol intake, the age-adjusted odds ratio for self-reported heart disease was between 0.55 and 0.85 per standard deviation (SD) of log DHEA and DHEAS concentration. Multiple logistic regression analysis indicated a strong independent role for DHEAS as a predictor of self-reported heart disease, controlling for age and the potential confounders listed above. The multiply-adjusted odds ratio for heart disease was 0.64 per SD log DHEAS concentration, with 95% confidence interval (CI) 0.50-0.83 (P = 0.0002). The DHEAS effect was not diminished by controlling for use of cardiac, vasodilator, antihypertensive, or lipid-lowering medication. CONCLUSIONS: These findings suggest that serum DHEAS levels bear an inverse relationship to heart disease, independently of a large set of established cardiovascular risk factors. The cross-sectional nature of this study requires that the findings be interpreted with caution.

Aged↗
PubMed1998

Physician variability and uncertainty in the management of breast cancer. Results from a factorial experiment.

OBJECTIVES: The purpose of this research was to determine the influence of patient and physician characteristics on physicians' level of variability and certainty in breast cancer care. METHODS: One hundred twenty-eight physicians viewed a videotape of a simulated physician-patient interaction in which the patient has an "atypical" breast lump. Six patient characteristics (age, race, socioeconomic status, physical mobility, comorbidity, presentation style) were manipulated experimentally, resulting in a balanced set of 32 different "patients." Physician subjects were recruited to fill four equal strata defined by specialty (surgeons versus nonsurgeons) and experience (< or = 15 or > 15 years since graduation from medical school). RESULTS: More than half of the physicians offered a diagnosis of benign breast disease, a third offered a diagnosis of breast cancer, and the rest believed that the patient had a normal breast or something "other." Results also indicated that physicians' level of certainty and test ordering behavior varied with the diagnosis that was offered. Of the six patient characteristics, only socioeconomic status influenced physician certainty; physicians were more certain of their diagnosis when the patient was of a higher socioeconomic status. Surgeons were found to be more certain of their diagnosis compared with nonsurgeons. However, surgeons were less likely to order radiologic tests or a tissue sample for metastatic evaluation than were nonsurgeons. CONCLUSIONS: Overall, physicians displayed considerable variability and uncertainty when diagnosing and managing possible breast cancer.

Adult↗
PubMed1998

Rapid early action for coronary treatment: rationale, design, and baseline characteristics. REACT Research Group.

OBJECTIVE: Early reperfusion for acute myocardial infarction (AMI) can reduce morbidity and mortality, yet there is often delay in accessing medical care after symptom onset. This report describes the design and baseline characteristics of the Rapid Early Action for Coronary Treatment (REACT) community trial, which is testing community intervention to reduce delay. METHODS: Twenty U.S. communities were pair-matched and randomly assigned within pairs to intervention or comparison. Four months of baseline data collection was followed by an 18-month intervention of community organization and public, patient, and health professional education. Primary cases were community residents seen in the ED with chest pain, admitted with suspected acute cardiac ischemia, and discharged with a diagnosis related to coronary heart disease. The primary outcome was delay time from symptom onset to ED arrival. Secondary outcomes included delay time in patients with MI/unstable angina, hospital case-fatality rate and length of stay, receipt of reperfusion, and ED/emergency medical services utilization. Impact on public and patient knowledge, attitudes, and intentions was measured by telephone interviews. Characteristics of communities and cases and comparability of paired communities at baseline were assessed. RESULTS: Baseline cases are 46% female, 14% minorities, and 73% aged > or =55 years, and paired communities have similar demographics characteristics. Median delay time (available for 72% of cases) is 2.3 hours and does not vary between treatment conditions (p > 0.86). CONCLUSIONS: REACT communities approximate the demographic distribution of the United States and there is baseline comparability between the intervention and comparison groups. The REACT trial will provide valuable information for community educational programs to reduce patient delay for AMI symptoms.

Adult↗
PubMed1997

Joint analysis of three U.S. community intervention trials for reduction of cardiovascular disease risk.

During the 1980s three comprehensive community-based heart disease prevention trials were conducted in the United States. The Stanford Five-City Project, Minnesota Heart Health Program, and Pawtucket Heart Health Program involved 12 cities; six received a 5-8 year multifactorial risk reduction program. This analysis pools data from the three studies to delineate the common intervention effects with greater sample size and power than could be attained by the single studies. Time trends were estimated for cigarette smoking, blood pressure, total cholesterol, body mass index, and coronary heart disease mortality risk in women and men aged 25-64 years. The joint estimates of intervention effect were in the expected direction in nine of 12 gender-specific comparisons; however, these were not statistically significant. The results illustrate the analytic challenges of evaluating community-based prevention trials and point to the smaller than expected net differences, rather than small sample size, as the reason for few statistically significant effects in the three U.S. prevention trials.

Blood Pressure↗
PubMed1997

Patient, physician and presentational influences on clinical decision making for breast cancer: results from a factorial experiment.

This study examines the influence of six patient characteristics (age, race, socioeconomic status, comorbidities, mobility and presentational style) and two physician characteristics (medical specialty and years of clinical experience) on physicians' clinical decision making behaviour in the evaluation treatment of an unknown and known breast cancer. Physicians' variability and certainty associated with diagnostic and treatment behaviour were also examined. Separate analyses explored the influence of these non-medical factors on physicians' cognitive processes. Using a fractional factorial design, 128 practising physicians were shown two videotaped scenarios and asked about possible diagnoses and medical recommendations. Results showed that physicians displayed considerable variability in response to several patient-based factors. Physician characteristics also emerged as important predictors of clinical behaviour, thus confirming the complexity of the medical decision-making process.

Age Factors↗
PubMed1997

Parent and physician response to children's cholesterol values of 200 mg/dL or greater: the Child and Adolescent Trial for Cardiovascular Health Experiment.

OBJECTIVE: To determine parental actions and concerns and physician responses to parental notification that a child's cholesterol value was 200 mg/dL or greater, a value recommended by the National Cholesterol Education Program to warrant physician follow-up and evaluation. METHODOLOGY: A telephone survey of parents (n = 784) and physicians (n = 117) was carried out after parental notification of a total blood cholesterol value obtained as part of measurement done while participating in the Child and Adolescent Trial for Cardiovascular Health in 96 schools located in California, Louisiana, Minnesota, and Texas. RESULTS: Only 20% of parents contacted physicians. Factors associated with this action included whether the parent was notified once or twice, the level of the cholesterol, previous cholesterol testing in the parent, and medical insurance that covered the visit. Family history of cardiovascular disease, when other factors were considered, did not increase the likelihood that a physician contact would be made. After contact with the physician, 59% of physicians reported evaluating children for cholesterol; about half reported repeating the cholesterol determination. CONCLUSION: Parental knowledge of a child's cholesterol value of 200 mg/dL or greater did not result in substantially further seeking of health care.

Adolescent↗
PubMed1997

Nonmedical influences on medical decision making: an experimental technique using videotapes, factorial design, and survey sampling.

OBJECTIVE: To study nonmedical influences on the doctor-patient interaction. A technique using simulated patients and "real" doctors is described. DATA SOURCES: A random sample of physicians, stratified on such characteristics as demographics, specialty, or experience, and selected from commercial and professional listings. STUDY DESIGN: A medical appointment is depicted on videotape by professional actors. The patient's presenting complaint (e.g., chest pain) allows a range of valid interpretation. Several alternative versions are taped, featuring the same script with patient-actors of different age, sex, race, or other characteristics. Fractional factorial design is used to select a balanced subset of patient characteristics, reducing costs without biasing the outcome. DATA COLLECTION: Each physician is shown one version of the videotape appointment and is asked to describe how he or she would diagnose or treat such a patient. PRINCIPAL FINDINGS: Two studies using this technique have been completed to date, one involving chest pain and dyspnea and the other involving breast cancer. The factorial design provided sufficient power, despite limited sample size, to demonstrate with statistical significance various influences of the experimental and stratification variables, including the patient's gender and age and the physician's experience. Persistent recruitment produced a high response rate, minimizing selection bias and enhancing validity. CONCLUSION: These techniques permit us to determine, with a degree of control unattainable in observational studies, whether medical decisions as described by actual physicians and drawn from a demographic or professional group of interest, are influenced by a prescribed set of nonmedical factors.

Age Factors↗
PubMed1996

Outcomes of a field trial to improve children's dietary patterns and physical activity. The Child and Adolescent Trial for Cardiovascular Health. CATCH collaborative group.

OBJECTIVE: To assess the outcomes of health behavior interventions, focusing on the elementary school environment, classroom curricula, and home programs, for the primary prevention of cardiovascular disease. DESIGN: A randomized, controlled field trial at four sites with 56 intervention and 40 control elementary schools. Outcomes were assessed using prerandomization measures (fall 1991) and follow-up measures (spring 1994). PARTICIPANTS: A total of 5106 initially third-grade students from ethnically diverse backgrounds in public schools located in California, Louisiana, Minnesota, and Texas. INTERVENTION: Twenty-eight schools participated in a third-grade through fifth-grade intervention including school food service modifications, enhanced physical education (PE), and classroom health curricula. Twenty-eight additional schools received these components plus family education. MAIN OUTCOME MEASURES: At the school level, two primary end points were changes in the fat content of food service lunch offerings and the amount of moderate-to-vigorous physical activity in the PE programs. At the level of the individual student, serum cholesterol change was the primary end point and was used for power calculations for the study. Individual level secondary end points included psychological factors, recall measures of eating and physical activity patterns, and other physiologic measures. RESULTS: In intervention school lunches, the percentage of energy intake from fat fell significantly more (from 38.7% to 31.9%) than in control lunches (from 38.9% to 36.2%)(P<.001). The intensity of physical activity in PE classes during the Child and Adolescent Trial for Cardiovascular Health (CATCH) intervention increased significantly in the intervention schools compared with the control schools (P<.02). Self-reported daily energy intake from fat among students in the intervention schools was significantly reduced (from 32.7% to 30.3%) compared with that among students in the control schools (from 32.6% to 32.2%)(P<.001). Intervention students reported significantly more daily vigorous activity than controls (58.6 minutes vs 46.5 minutes; P<.003). Blood pressure, body size, and cholesterol measures did not differ significantly between treatment groups. No evidence of deleterious effects of this intervention on growth or development was observed. CONCLUSION: The CATCH intervention was able to modify the fat content of school lunches, increase moderate-to-vigorous physical activity in PE, and improve eating and physical activity behaviors in children during 3 school years.

Analysis of Variance↗
PubMed1996

Non-medical influences on medical decision-making.

BACKGROUND: The influence of non-medical factors on physicians' decision-making has been documented in many observational studies, but rarely in an experimental setting capable of demonstrating cause and effect. We conducted a controlled factorial experiment to assess the influence of non-medical factors on the diagnostic and treatment decisions made by practitioners of internal medicine in two common medical situations. METHOD: One hundred and ninety-two white male internists individually viewed professionally produced video scenarios in which the actor-patient, presenting with either chest pain or dyspnea, possessed various balanced combinations of sex, race, age, socioeconomic status, and health insurance coverage. Physician subjects were randomly drawn from lists of internists in private practice, hospital-based practice, and HMO's, at two levels of experience. RESULTS: The most frequent diagnoses for both chest pain and dyspnea were psychogenic origin and cardiac problems. Smoking cessation was the most frequent treatment recommendation for both conditions. Younger patients (all other factors being the same) were significantly more likely to receive the psychogenic diagnosis. Older patients were more likely to receive the cardiac diagnosis for chest pain, particularly if they were insured. HMO-based physicians were more likely to recommend a follow-up visit for chest pain. Several interactions of patient and physician factors were significant in addition to the main effects. CONCLUSIONS: The variability in decision-making evidenced by physicians in this experiment was not entirely accounted for by strictly rational Bayesian inference (the common prescriptive model for medical decision-making), in-as-much as non-medical factors significantly affected the decisions that they made. There is a need to supplement idealized medical schemata with considerations of social behavior in any comprehensive theory of medical decision-making.

Adult↗
PubMed1996

Development of the multidimensional index of life quality. A quality of life measure for cardiovascular disease.

OBJECTIVES: The purpose of this study was to design a multidimensional measure of health-related quality of life appropriate for patients with cardiovascular disease that was psychometrically sound, brief, and easy to administer. METHODS: Qualitative interviews conducted with healthy subjects and patients with cardiovascular diseases identified nine major quality of life domains. Based on the responses of 129 cardiovascular disease patients recruited from hospitals and clinics, a criterion-based approach was used to select 35 questionnaire items that best tapped these domains. Psychometric properties of the Multidimensional Index of Life Quality (MILQ) were tested with a sample of 348 patients with various cardiovascular diseases. RESULTS: Cronbach's alpha was 0.76 or higher for eight of the nine MILQ domains. Test-retest reliability coefficients were 0.73 or greater in all but two domains. Individual domain scores as well as a weighted overall quality of life index were correlated highly with self-assessed health and the number of heart-related symptoms. CONCLUSIONS: The Multidimensional Index of Life Quality is a psychometrically reliable and valid instrument for measuring quality of life in patients with cardiovascular diseases. The MILQ also may be a suitable measure for other types of chronic diseases.

Adult↗
PubMed1996

Validation of interviewer- and self-administered physical activity checklists for fifth grade students.

The purpose of the study was to evaluate two physical activity recall instruments appropriate for use in epidemiologic studies of fifth grade children. The instruments were similar, except one (PACI) was administered in a personal interview, and the other (SAPAC) was self-completed in a group setting. Both forms required children to report the minutes during the previous day they spent in 21 common physical activities that represented a range of intensities, plus sedentary pursuits. To validate the recalls, children simultaneously wore an accelerometer (motion sensor) and a heart rate monitor for at least 8 h the day before the interview. Subjects were 55 boys and 70 girls from four regions of the United States. The Pearson correlation between the self- and interviewer-administered forms was 0.76 (P < 0.001). The interviewer-administered form correlated 0.51 (P < 0.001) with the heart rate index and 0.33 (P < 0.001) with the accelerometer score. The self-administered form correlated 0.57 (P < 0.001) with the heart rate index and 0.30 (P < 0.001) with the accelerometer score. It is concluded that both self-report forms received moderate support for their validity in all gender and ethnic subgroups. The self-administered format is more cost-effective.

Child↗
PubMed1995

Cardiovascular risk factors among third grade children in four regions of the United States. The CATCH Study. Child and Adolescent Trial for Cardiovascular Health.

Data on cardiovascular risk factors (body mass index, triceps and subscapular skinfolds, blood pressure, serum total cholesterol, high density lipoprotein (HDL) cholesterol, and apolipoprotein B) were collected as part of the baseline examination (fall 1991) of the Child and Adolescent Trial for Cardiovascular Health, a multicenter school-based intervention study for promoting healthful behaviors. A total of 5,106 third grade children (mean age, 8.76 years) in four states (California, Louisiana, Minnesota, and Texas) were examined. After excluding 194 children of other or unknown origin, the study population consisted of 3,530 Anglo-American children, 674 African-American children, and 708 Latino children. African-American children were the tallest by 1-3 cm (p < 0.0001), while Latino children had the largest body mass index (p < 0.05). Blood pressure levels were similar for boys and girls and among the three races, but systolic levels were 2 mmHg higher in Texas than at the other sites. Serum total cholesterol levels were 5 mg/dl higher in girls than in boys (p < 0.05), while HDL cholesterol levels were 2 mg/dl higher in boys (p < 0.05). HDL cholesterol levels were highest in African-Americans (55.5 mg/dl) compared with Anglo-Americans (50.7 mg/dl) and Latinos (51.3 mg/dl) (p < 0.0001).

Analysis of Variance↗
PubMed1995

On the allometric mass exponent, when it exists.

Allometric power laws of the form q varies; is directly proportional to Mb are commonly used to describe the dependence of a physiological variable q on body mass M in a class of animals that vary widely in size. The theoretical basis for such a law has been ignored or misstated in much of the biological literature. In this paper, an axiomatic basis for establishing the existence of a power law is proposed and a formula for calculating the theoretical mass exponent b is derived. It is shown that the value of b, when it exists, depends not only on the physical dimensions of q but also on biological assumptions about the class of animals under consideration. Two examples are worked through, one concerning the flying speed of birds and one concerning the controversial subject of metabolic scaling in mammals. The wide range of mass exponents reported in the literature, it is argued, express no simple physical principle, but a variety of biological mechanisms including evolution, maturation, and seasonal adaptation.

Animals↗
PubMed1995

Statistical design of the Child and Adolescent Trial for Cardiovascular Health (CATCH): implications of cluster randomization.

This paper describes some statistical considerations for the Child and Adolescent Trial for Cardiovascular Health (CATCH), a large-scale community health trial sponsored by the National Heart, Lung, and Blood Institute. The trial involves randomization of entire schools rather than individual students to the experimental arms. The paper discussed the implications of this form of randomization for the design and analysis of the trial. The power calculations and analysis plan for the trial are presented in detail. The handling of outmigrating and immigrating students is also discussed.

Adolescent↗
PubMed1995

Measurement of self-efficacy for diet-related behaviors among elementary school children.

Health promotion interventions intended to improve dietary behavior frequently incorporate self-efficacy as a construct to enhance behavior change. This paper presents results from a study to establish psychometric properties of a scale to measure children's self-efficacy for selecting healthful food. As part of a series of pilot studies to develop instrumentation for the Child and Adolescent Trial for Cardiovascular Health (CATCH), data were collected on third and fourth grade students (n = 1,127). Data analyses were conducted to estimate internal consistency, test-retest reliability, factorial validity, and criterion related validity. Results revealed acceptable estimates of internal consistency for the dietary self-efficacy scale (coefficient alpha = .84). Self-efficacy was strong associated with the children's usual food choices, accounting for about 34% of variance (Multiple R = .58). Findings support using such an instrument for evaluating intervention programs addressing nutrition behavior and for studies to determine the association of self-efficacy to dietary behavior or related constructs.

Child↗