Biomedical subjects

H A Feldman

Publications and source records attributed to H A Feldman.

At least 55 records · Page 3Linked to original sources

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↗

PubMed1996

Batch sampling to improve power in a community trial. Experience from the Pawtucket Heart Health Program.

Experiments involving large social units, such as schools, work sites, or whole cities, are commonly limited in statistical power because the number of randomized units is small, leaving few degrees of freedom for residual (between-unit) error. The authors describe a method for increasing residual degrees of freedom in a community experiment without substantially increasing cost or difficulty. In brief, they propose that the experimental units should be divided into random subsamples (batches). Batch sampling can improve statistical power if the community endpoint means are stable over time or if their temporal variation is comparable in period to the batch-sampling schedule. The authors demonstrate the theoretical advantages of the batch system and illustrate its use with data from the Pawtucket Heart Health Program, in which such a design was implemented.

Analysis of Variance↗

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↗

PubMed1995

The Pawtucket Heart Health Program: community changes in cardiovascular risk factors and projected disease risk.

OBJECTIVES: Whether community-wide education changed cardiovascular risk factors and disease risk in Pawtucket, RI, relative to a comparison community was assessed. METHODS: Random-sample, cross-sectional surveys were done of people aged 18 through 64 years at baseline, during, and after education. Baseline cohorts were reexamined. Pawtucket citizens of all ages participated in multilevel education, screening, and counseling programs. RESULTS: The downward trend in smoking was slightly greater in the comparison city. Small, insignificant differences favored Pawtucket in blood cholesterol and blood pressure. In the cross-sectional surveys, body mass index increased significantly in the comparison community; a similar change was not seen in cohort surveys. Projected cardiovascular disease rates were significantly (16%) less in Pawtucket during the education program. This difference lessened to 8% posteducation. CONCLUSIONS: The hypothesis that projected cardiovascular disease risk can be altered by community-based education gains limited support from these data. Achieving cardiovascular risk reduction at the community level was feasible, but maintaining statistically significant differences between cities was not. Accelerating risk factor changes will likely require a sustained community effort with reinforcement from state, regional, and national policies and programs.

Adolescent↗

PubMed1994

Cohort versus cross-sectional design in large field trials: precision, sample size, and a unifying model.

In planning large longitudinal field trials, one is often faced with a choice between a cohort design and a cross-sectional design, with attendant issues of precision, sample size, and bias. To provide a practical method for assessing these trade-offs quantitatively, we present a unifying statistical model that embraces both designs as special cases. The model takes account of continuous and discrete endpoints, site differences, and random cluster and subject effects of both a time-invariant and a time-varying nature. We provide a comprehensive design equation, relating sample size to precision for cohort and cross-sectional designs, and show that the follow-up cost and selection bias attending a cohort design may outweigh any theoretical advantage in precision. We provide formulae for the minimum number of clusters and subjects. We relate this model to the recently published prevalence model for COMMIT, a multi-site trial of smoking cessation programmes. Finally, we tabulate parameter estimates for some physiological endpoints from recent community-based heart-disease prevention trials, work an example, and discuss the need for compiling such estimates as a basis for informed design of future field trials.

Analysis of Variance↗

PubMed1994

Construction of a surrogate variable for impotence in the Massachusetts Male Aging Study.

Uncollected data must be filled in after the fact in many epidemiological studies. We compared several methods for constructing a surrogate variable for erectile potency, based on responses to related questions, in the Massachusetts Male Aging Study (MMAS). Quadratic discriminant analysis performed best among the procedures tested, achieving high rates of correct classification in cross-validation of training data and (according to posterior estimates) in classification of MMAS subjects. Two versions of the surrogate variable were constructed, one involving a discrete classification and the other involving a set of continuous probabilities. The two versions were used to investigate medical correlates of impotence in MMAS and produced similar results, although the continuous version appeared to provide higher statistical power. We conclude that construction of a surrogate variable is a viable and potentially beneficial option in epidemiological investigations.

Adult↗

PubMed1994

Impotence and its medical and psychosocial correlates: results of the Massachusetts Male Aging Study.

We provide current, normative data on the prevalence of impotence, and its physiological and psychosocial correlates in a general population using results from the Massachusetts Male Aging Study. The Massachusetts Male Aging Study was a community based, random sample observational survey of noninstitutionalized men 40 to 70 years old conducted from 1987 to 1989 in cities and towns near Boston, Massachusetts. Blood samples, physiological measures, socio-demographic variables, psychological indexes, and information on health status, medications, smoking and lifestyle were collected by trained interviewers in the subject's home. A self-administered sexual activity questionnaire was used to characterize erectile potency. The combined prevalence of minimal, moderate and complete impotence was 52%. The prevalence of complete impotence tripled from 5 to 15% between subject ages 40 and 70 years. Subject age was the variable most strongly associated with impotence. After adjustment for age, a higher probability of impotence was directly correlated with heart disease, hypertension, diabetes, associated medications, and indexes of anger and depression, and inversely correlated with serum dehydroepiandrosterone, high density lipoprotein cholesterol and an index of dominant personality. Cigarette smoking was associated with a greater probability of complete impotence in men with heart disease and hypertension. We conclude that impotence is a major health concern in light of the high prevalence, is strongly associated with age, has multiple determinants, including some risk factors for vascular disease, and may be due partly to modifiable para-aging phenomena.

Adult↗

PubMed1994

Periodontal disease among New England elders.

Much of the existing oral epidemiologic literature is limited by having inadequate numbers of the oldest-old in their sample, having used rudimentary periodontal measures, or not having examined probability samples of community-dwelling elders. The New England Elders Dental Study (NEEDS) is the first study that documents the periodontal disease status of a probability sample of 554 adults aged 70 to 96 living within an entire U.S. Public Health Service region. The NEEDS study revealed substantially higher estimates of periodontal destruction among older adults than previous national studies would suggest. These results are consistent with several papers in the literature that suggest that periodontal disease rates are on the increase in older adults. In the coming decades dentistry should be prepared to meet the increasing need and demand for periodontal services in the growing older population.

Aged↗

PubMed1994

Prevalence of hypertension, dyslipidemia, and dyslipidemic hypertension.

BACKGROUND: It has been proposed that dyslipidemic hypertension is part of a distinct metabolic syndrome related to insulin resistance. This paper describes the prevalence and cross-sectional relations of dyslipidemic hypertension in a population-based sample of men and women. METHODS: In two southeastern New England communities, 11,199 randomly selected participants were evaluated as part of a cross-sectional surveillance program of coronary heart disease risk factors between 1981 and 1990. RESULTS: The frequency of dyslipidemia was 38% and of hypertension was 26.5%; the conjoint frequency (dyslipidemic hypertension) was 15.0%, which is 1.49 times the expected value if the two diseases were independent P < .05). Using a discrete multivariate model, dyslipidemia and hypertension were associated with sex, obesity, and diabetes mellitus. The excess association of dyslipidemic hypertension, compared with individual effects of dyslipidemia and hypertension, was not related to these factors. CONCLUSIONS: This study suggests that dyslipidemic hypertension is common but may not be a unique entity associated with a distinct metabolic syndrome.

Adolescent↗