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Biomedical subjects

J B McKinlay

Publications and source records attributed to J B McKinlay.

At least 19 recordsLinked to original sources
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↗
PubMed1997

Interviewer effects in a cohort study. Results from the Massachusetts Women's Health Study.

Although interviewer error is widely recognized as an important source of variation in epidemiologic investigations, scant published information exists documenting the impact of interviewer variation on study findings. Using data from the Massachusetts Women's Health Study, a population-based cohort study of 2,569 middle-aged women (1982-1987), the authors evaluated interviewer variation in responses to different types of questions, and assessed the impact of interviewer variation on inferences derived from study data. Respondent sociodemographic and lifestyle characteristics were similar for the four study interviewers at the first follow-up. No interviewer variation was detected for questions concerning recall of specific events, but responses to questions regarding recall of subjective or personal information or those which required further probing did differ significantly by interviewer. Adjustment for interviewer effects had no impact on the conclusions obtained from one analysis of predictors of depression, despite significant interviewer variation in the outcome and predictor variables, but it did change conclusions from an analysis of the impact of support networks on psychological symptoms, wherein the interviewer variable was strongly related to the outcome after data were controlled for predictor variables. Given these findings, examination of data for interviewer effects is advisable despite incorporation of quality control measures in a study's design.

Depression↗
PubMed1997

Physician characteristics: do they influence the evaluation and treatment of breast cancer in older women?

BACKGROUND: To determine if physician specialty, length of time in practice, and fear of malpractice influence the diagnosis and management of breast cancer in older women. METHODS: We used a fractional factorial design that controlled for patient age (65 or 80 years), race, socioeconomic status, mobility, comorbidity, and assertive behavior through 2 videotaped scenarios (a potential breast cancer [no. 1] and a known stage IIA breast cancer [no. 2]). One hundred twenty-eight white male physicians equally divided by specialty (surgeon versus nonsurgeon) and time in practice (< or = 15 or >15 years) viewed the videotapes and made recommendations. RESULTS: The physician subjects saw 46 patients per week, 59% female, and 47% age > or = 65. Their concern over malpractice was 4.7 (on a 10-point Likert scale with a higher score indicating more concern) and did not differ by specialty or time in practice (P values > 0.7). After viewing scenario no. 1, surgeons were less likely than nonsurgeons to consider breast cancer as the principal diagnosis (odds ratio [OR] = 0.4, 95% confidence interval [CI] = 0.2 to 0.9) and to obtain a tissue diagnosis (OR = 0.3, 95% CI = 0.1 to 0.9). However, in scenario no. 2, surgeons were more likely to offer reconstruction (OR = 3.8, 95% CI = 1.4 to 10.4). Physicians in practice < or = 15 years were more likely than those in practice <15 years to obtain a tissue diagnosis in scenario no. 1 (OR = 6.1, 95% CI = 1.9 to 19.2) and to perform full primary therapy in scenario no. 2 (OR = 2.8, 95% CI = 1.2 to 6.9). Physicians who performed an extensive metastatic evaluation (bone or computer tomography [CT] scan) had greater concern over malpractice than those who did not, as did physicians who performed an axillary node dissection (OR = 2.1, 95% CI 1.3 to 3.4 and OR = 1.8, 95% CI = 1.1 to 3.0). CONCLUSIONS: With the uncertainty of how to diagnose and treat older women with breast cancer, physician specialty, length of time in practice, and concern over malpractice do influence clinical decisions.

Age Factors↗
PubMed1997

Understanding the variability in the effectiveness of community heart health programs: a meta-analysis.

Over the past 25 years, community interventions to reduce cardiovascular disease (CVD) have been conducted around the world with very mixed results. This study uses meta-analysis to assess whether the variation in the observed effectiveness of community heart health programs (CHHP) is related to characteristics of the intervention program, the population under study, or the evaluation methods. A CHHP is defined as any primary prevention program that attempted to reduce the population burden of CVD by shifting the distribution of risk factors in a general population. To be included in the meta-analysis, a study must have utilized a reference group in the evaluation, employed a repeated independent cross-sectional measurement design, and reported sufficient outcome information for at least one of four major risk factors: smoking, total cholesterol, blood pressure, and body weight. Results of these studies are summarized with the effect size measure (Yi1-Yi2)-(Yr1-Yr2)Sr1 where Y = outcome measure, S = standard deviation of the outcome measure, 1 = baseline, 2 = follow-up. i = intervention, and r = reference community. This measure, which reports the net change in the intervention group in terms of the variability in the reference population before the start of the intervention, permits comparison across different outcome measures and facilitates the aggregation of effects across studies. Generalized least squares regression, which permits the incorporation of multiple, dependent effect sizes from a single study, was used to assess the impact of characteristics of the intervention (prevention strategy, type of mass communication, community organization, and environmental change), the population (setting, gender, year of follow-up measurement), and the evaluation design and implementation (the number of communities, matching of communities, the follow-up time, the response rate, and covariate adjustment in the analysis) on the effect sizes. The results of this analysis suggest that the characteristics of the evaluation method account for much of the heterogeneity in the outcome of CHHPs, though some intervention characteristics also play a role.

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

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

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

Does collecting repeated blood samples from each subject improve the precision of estimated steroid hormone levels?

Measuring levels of steroid hormones in epidemiologic studies is difficult because pulsatile release can cause the levels of many hormones to vary markedly over short intervals, leading to a loss of precision in between-subject comparisons. Clinicians often control this variation by collecting several samples from each subject at defined intervals and pooling these samples for assay. The number of samples per subject that would adequately control such variation in an epidemiologic study has not been fully investigated. This study examines the effects of collecting 1, 2, or 3 samples per subject on the variances of 11 hormones and sex hormone binding globulin in men and 6 hormones in women. Three samples were collected at 30-minute intervals from each of 20 men and 59 women and were assayed separately. Variances that would be obtained in studies collecting one, two, or three samples per subject were then estimated. Collecting more than one sample substantially reduced the variances of several hormones in men but not in women.

Adult↗
PubMed1996

A self-efficacy scale for HIV risk behaviors: development and evaluation.

To measure self-efficacy with respect to risk behaviors for HIV infection, a set of questionnaire items was developed regarding condom use, drug use with friends, and negotiations with potential sex partners. These items were tested with a sample of Latinos aged 14 to 22 years in two New England cities. A nine-item self-efficacy scale was found to have a high level of internal consistency (Cronbach's alpha = .77). Reliability coefficients were similar for men, women, and both English- and Spanish-speaking respondents. Strong associations with recent performance accomplishments, as specified in Bandura's social cognitive theory, support the construct validity of the scale.

Adolescent↗
PubMed1996

Some contributions from the social system to gender inequalities in heart disease.

Epidemiological understanding is incomplete if social system influences on statistical rates are not appropriately recognized. To the traditional epidemiological triumvirate of agent, host, and environment, a fourth influence must now be added--contributions from the social system (like government reimbursement policies, organizational priorities, and the variable behavior of providers). This paper has two sections: the first builds a progressively more complex model (from simple reification, through environmental and personal attributes, to social system influences) to depict the relative contribution of diverse influences to the social production of "facts." The second section considers how social system influences affect health statistics--most emphasis is given to the contribution of health provider behavior (using the widely accepted gender inequality in heart disease as an example). Data from a wide range of studies (employing seven different research methods) are consistent with an underlying thesis--that the gender difference in heart disease is as much a function of how providers and the system respond as it is of the biophysiology of patients and how they react to events. The incorporation of system influences permits the development of an epidemiological imagination, or the ability to link intimate health experiences with more remote social-structural influences.

Adult↗
PubMed1995

A comparison of anlaytic methods for non-random missingness of outcome data.

Missing outcome values occur frequently in survey data and are rarely missing randomly. Depending on the pattern of missingness, the choice of analytic method has implications for accuracy of the estimated outcome distribution as well as multivariate models. Data from a study of patterns of care in disabled elders were used to evaluate several common methods when missingness of the outcome was nonrandom. Results from single and multiple model-based imputation were compared with results from complete-case analysis and mean imputation. By ignoring nonrespondents' covariate information, the latter two methods yielded biased estimates of population means. Mean imputation and single model-based imputation underestimated standard errors by treating imputed values as if they were observed. Mean imputation also distorted the relationship between the outcome and predictors. Multiple model-based imputation provided an easily implemented method of adjustment for non-random non-response in both univariate and multivariate analyses.

Activities of Daily Living↗
PubMed1995

How costly is it to care for disabled elders in a community setting?

This article describes the total cost of care, including both informal caregiving and formal services for a cohort of disabled elderly living in the community. The cost of informal caregiving hours was calculated using a market value approach. The total annual cost of caring was estimated to be $9,600. Increased disability was associated with increased costs. High-cost elders were more likely to be severely disabled, live with their caregiver, and become institutionalized. For most elders, even the cost of a complete substitution of informal care for formal services, plus living expenses, was less costly than nursing home care.

Aged↗
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

The relation of smoking, age, relative weight, and dietary intake to serum adrenal steroids, sex hormones, and sex hormone-binding globulin in middle-aged men.

The relationships of cigarette smoking, age, relative weight, and dietary intake to serum dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulfate (DHEAS), androstenedione, cortisol, 3-alpha-androstanediol, 3-alpha-androstanediol-glucuronide, testosterone, albumin-bound testosterone, free testosterone, dihydrotestosterone (DHT), and sex hormone-binding globulin (SHBG) were examined cross-sectionally in 1241 randomly sampled middle-aged U.S. men. Compared with nonsmokers and independent of relative weight (body mass index) and age, cigarette smokers had increased serum levels of DHEA (18% higher, P = 0.0002), DHEAS (13% higher, P = 0.0007), cortisol (5% higher, P = 0.01), androstenedione (33% higher, P = 0.0001), testosterone (9% higher, P = 0.009), DHT (14% higher, P = 0.004), and SHBG (8% higher, P = 0.004). Androstenedione, total plasma testosterone, albumin-bound testosterone, DHT, and SHBG decreased with increasing relative weight. Age was positively associated with serum SHBG and negatively associated with albumin-bound testosterone, DHEA, and DHEAS. An association was found between alcohol intake and DHEA (r = 0.15; P = 0.0001), cortisol (r = 0.10; P = 0.0007), and 3-alpha-androstanediol-glucuronide (r = 0.08; P = 0.0004). Cortisol was the only hormone that was associated with carbohydrate intake (r = -0.09; P = 0.002). The only hormones associated with dietary lipids were DHT (for vegetable fat, r = 0.07; P = 0.02), cortisol (for total fat, r = 0.08; P = 0.007), and SHBG (for animal fat, r = -0.06; P = 0.05). In addition, SHBG was positively associated with dietary (r = 0.07; P = 0.008) and crude (r = 0.08; P = 0.007) fiber. These data suggest that serum adrenal steroid and sex hormone concentrations in middle-aged men are more influenced by cigarette smoking, age, and obesity than by dietary intake; however, serum adrenal steroids were influenced by alcohol intake.

Adrenal Glands↗
PubMed1994

Does the promotion and distribution of condoms increase teen sexual activity? Evidence from an HIV prevention program for Latino youth.

OBJECTIVES: Opponents of condom availability programs argue that the promotion and distribution of condoms increases adolescent sexual activity. This assertion was tested empirically with data from the evaluation of a human immunodeficiency virus (HIV) prevention program for Latino adolescents. METHODS: The onset of sexual activity, changes in the frequency of sex, and changes in the proportion of respondents with multiple partners were compared for intervention and comparison groups. Multivariate regression analysis was used to assess the effect of the intervention on these outcomes after adjustment for baseline differences between the intervention and comparison groups. RESULTS: Male respondents in the intervention city were less likely than those in the comparison city to initiate first sexual activity (odds ratio [OR] = 0.08). Female respondents in the intervention city were less likely to have multiple partners (OR = 0.06). The program promoting and distributing condoms had no effect on the onset of sexual activity for females, the chances of multiple partners for males, or the frequency of sex for either males or females. CONCLUSIONS: An HIV prevention program that included the promotion and distribution of condoms did not increase sexual activity among the adolescents in this study.

Adolescent↗
PubMed1994

Do blacks and whites differ in their use of health care for symptoms of coronary heart disease?

OBJECTIVES: The purpose of this study was to identify the role of race in seeking and receipt of care for symptoms of coronary heart disease. METHODS: Data on medical care, sociodemographic characteristics, symptoms, risk factors, income, and insurance were collected in a telephone interview for a random sample of 2030 Black and White adults in inner-city Boston. Rates of care-seeking for symptoms, amounts of delay in seeking care, and rates of receipt of care were compared for Blacks and Whites after adjustment for other characteristics. RESULTS: Before and after adjustment for other factors, Blacks and Whites were equally likely to seek care. Average delay time was shorter for Blacks, particularly Black women. With the exception of a lower rate of referral to cardiologists among Blacks, receipt of care was similar for Blacks and Whites who sought medical attention for symptoms. CONCLUSIONS: In an urban population of Blacks and Whites who were similar in socioeconomic status and access to medical care, there were few racial differences in coronary heart disease-related care patterns.

Black or African American↗