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Biomedical subjects

B S Hulka

Publications and source records attributed to B S Hulka.

At least 19 recordsLinked to original sources
PubMed1992

Methodological issues in epidemiologic studies using biologic markers.

Biologic markers are becoming prominent features of many classical epidemiologic studies. Their existence has also modified the character of some epidemiologic research such that the term "transitional epidemiologic studies" may be warranted. In the latter type of study, collaboration between laboratory and epidemiologic investigators is integral to the research. In this paper, goals, characteristics, and examples of transitional epidemiologic research are presented. Pertinent features are highlighted, including sources of misclassification and confounding, and elements of study design useful in reducing these potential biases. Sample size issues, transformation of variables, and sources of variability acquire enhanced importance. The study examples presented are intended to illustrate the altered substrate for these methodological features in studies using biologic markers.

Analysis of Variance↗
PubMed1992

Biomarkers of pesticide exposure.

Incorporation of biomarkers in studies of occupational exposure hazards is now recognized as a highly useful adjunct to the surrogate measures employed in the past, for example, time worked, ambient air data, interview responses. Application to studies of workers potentially exposed to pesticides has barely begun and provides many challenges to chemist/epidemiologist teams. This review indicates several excellent studies employing multiple-exposure measures to document the validity of specific biomarkers for particular exposure situations. In general, exposure reflected by urinary assays of specific pesticides is a low percentage of that indicated by dermal or breathing zone measures. Markers for many of the pesticides in current usage have yet to be developed and validated, and information on population variability is generally lacking for existing markers. The challenge provided by the complexity of multiple, and often unknown, exposures to individuals in pesticide environments has begun to be addressed employing cytogenetic or urinary measures that attempt to integrate these complex exposures. The lack of data regarding sensitivity and specificity of biomarkers, especially in complex exposure situations, is a major problem that perhaps will best be addressed by studies combining nonspecific measures with specific ones, utilizing stored sample banks created for that purpose. Expanding the repertoire of available biomarkers of pesticide exposure and employing multiple ones in well-designed study protocols will provide critical tools in the evaluation of pesticide safety and design of appropriate measures to minimize adverse exposures. Ironically, one of the problems that biological markers of exposure can help overcome, reliance on poorly measured ambient exposure data, hampers the evaluation of the markers themselves. Therefore, the combination of in vitro, animal, and human data will give the best picture of a marker's performance. (Wilcosky 1990).

Biomarkers↗
PubMed1992

Barrier methods of contraception and cervical intraepithelial neoplasia.

This North Carolina-based case-control study examined risk factors for cervical intraepithelial neoplasia (CIN). Cases were 103 women with biopsy-confirmed CIN II or III who were recruited from a referral dysplasia clinic. Controls were 258 family practice patients with normal cervical cytology. All subjects were interviewed regarding their sexual and reproductive history, Pap smear screening, active and passive cigarette exposures, and contraceptive use patterns. When compared with controls, cases were half as likely to have ever used barrier methods of contraception; the adjusted odds ratio was 0.5 (95% CI 0.2-0.9). The risk of CIN II/III decreased further with increasing years of barrier method use. Recency, latency, and age at first barrier method use were all associated with a reduced risk of CIN. Men and women should carefully consider the range of benefits of barrier method use as a means to reduce their risk of unwanted pregnancies, sexually transmitted diseases, and cervical neoplasia.

Adult↗
PubMed1992

Oral contraceptive use and cervical intraepithelial neoplasia.

To explore the somewhat controversial relationship between oral contraceptives and pre-invasive cervical cancer, 103 cases of biopsy-confirmed cervical intraepithelial neoplasia (CIN) II or CIN III were compared with 258 controls who had normal cervical cytology. Cases were slightly less likely than controls to have ever used oral contraceptives; the odds ratio, controlling for age, socioeconomic status, barrier method use, smoking history, age at first sexual intercourse, number of sex partners, current marital status, and number of Pap smears, was 0.7 (95% CI 0.3-1.6). Recency, latency, duration, and age at first oral contraceptive use were evaluated and in no instance was oral contraceptive use positively associated with CIN. This study adds to the body of knowledge that oral contraceptives are not associated with pre-invasive cervical cancer. Further, if oral contraceptive users continue to be regularly screened, their risk of developing the more invasive lesions should be very low.

Adolescent↗
PubMed1990

Atypical metaplasia and incidence of bronchogenic carcinoma.

The prognostic implication of atypical squamous metaplasia of the respiratory tract has been uncertain, especially for mild atypia. The relation between degree of severity of atypical metaplasia as detected by sputum cytology and incidence of bronchogenic carcinoma was assessed among 14,414 men aged 45 years or older who smoked one or more packs of cigarettes per day. Trial participants underwent sputum cytologic evaluations every 4 months for an average of 7.4 years as part of the Cooperative Early Lung Cancer Detection Program of the National Cancer Institute and were followed for the development of lung cancer between 1971 and 1983 at three institutions: The Johns Hopkins University, the Memorial Sloan-Kettering Cancer Center, and the Mayo Clinic. Analysis with logistic regression controlling for age, race, occupational exposures to lung carcinogens, average number of cytology records per year, and smoking habits revealed that the estimate of the relative rate (RR) of developing bronchogenic carcinoma was greater among men who had mild atypia as compared with men who had negative cytology readings, but there were marked differences among institutions (RR = 1.1, 95% confidence interval (Cl) 0.8-1.5 at The Johns Hopkins University; RR = 1.6, 95% Cl 1.1-2.5 at the Memorial Sloan-Kettering Cancer Center; and RR = 2.5, 95% Cl 1.6-4.0 at the Mayo Clinic). Results suggest that mild atypia as detected by cytologic evaluation of sputum is an indicator of a modest elevation in risk of bronchogenic carcinoma.

Carcinoma, Bronchogenic↗
PubMed1990

Principles of bladder cancer screening in an intervention trial.

Screening for preclinical disease in asymptomatic people is an accepted activity in occupational health programs, public health programs, and physicians' offices. Yet, only diseases with high morbidity and mortality, a detectable, prolonged preclinical phase, and treatment that can improve survival if applied before the onset of clinical manifestations are suitable for screening. Furthermore, the screening test must be simple to perform, acceptable to providers and recipients, safe, reasonably pain-free, low-cost, and a valid estimator of the true disease state. Even so, screening will succeed only if the condition has a high prevalence in the population being screened, in order that enough persons with disease are identified and treated to justify the cost and the stress experienced by screen-positive, disease-negative subjects. The ultimate goal of screening is to reduce disease-specific mortality. The one recognized study design that can demonstrate a reduction in mortality from cancer of the urinary bladder is a randomized, controlled clinical trial of a screening modality, eg, urinary cytology, in a population previously exposed to occupational carcinogens.

Bias↗
PubMed1990

Oral contraceptives and breast cancer: a case-control study with hospital and community controls.

Several recent reports have noted an increase risk of breast cancer associated with the use of oral contraceptives (OCs) among various subgroups of young women. These reports spurred us to analyze data from a case-control study in North Carolina of 158 breast cancer patients, 326 hospital controls, and 1140 community controls less than 60 years of age. A logistic regression model was used to calculate odds ratios and 95% confidence intervals and to control for potential confounders. No association between ever-use of OCs and the risk of breast cancer was found for cases compared with either control group. No increased risk was observed for OC use before age 25 or before first full-term pregnancy, or in relation to duration of use, recency of use, or time since first use. Analysis of the subgroup of women less than 45 years of age also showed no relationship between OC use and breast cancer risk. However, an elevated risk of breast cancer was observed among nulliparous women with 5 or more years of OC use in comparisons with hospital controls (odds ratio 7.8) and community controls (odds ratio 2.3). This analysis was based on small numbers of subjects and the 95% confidence intervals touched or overlapped with 1. An unexpected association between duration of OC use and breast cancer risk was found among older premenopausal women in comparisons of cases with both control groups. For these women, a trend was evident in the odds ratio by duration of OC use, and the comparison between cases and community controls was statistically significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Dietary fat and breast cancer: case-control and cohort studies.

An increased risk of breast cancer in relation to a high-fat diet has been reported in several case-control studies and one cohort study conducted in different parts of the world. Most of these studies provide data on the consumption of food groups high in animal fats, e.g., meats and dairy products. Studies reporting on the amount of fat constituents consumed, adjusted or unadjusted for total caloric intake, more frequently have shown no positive association. The latter studies are not all limited to countries such as the United States with an overall high dietary fat intake; one was reported from Japan where the traditional low-fat diet is giving way to more Western-style foods, resulting in greater dietary heterogeneity for the population. The hypothesis that dietary fat causes breast cancer has been seriously weakened by the recent negative reports from two U.S. cohort studies, employing well-recognized dietary assessment strategies and multivariable analytic methods. Still, the possibility exists that specific fat constituents either naturally present or produced during the food preparation process, or fats in the presence (or absence) of other foodstuffs could alter breast cancer risk. Different kinds of studies providing information on the biochemistry and biology of fats consumed by humans would help to give focus to future epidemiological studies.

Breast Neoplasms↗
PubMed1988

Benefits and risks of menopausal estrogen and/or progestin hormone use.

Current evidence is reviewed here on risks and benefits of estrogen and progestin use by peri- and postmenopausal women in relation to the following conditions: endometrial cancer, breast cancer, osteoporosis, and coronary artery disease (CAD). On balance, estrogen therapy appears to be beneficial for menopausal women, as it probably reduces the risks of CAD and osteoporosis, two of the major causes of mortality and morbidity. Although unopposed estrogen therapy increases the risk of endometrial cancer, that cancer is relatively rare and is not fatal in the vast majority of cases associated with estrogen use. Definitive conclusions about the relation of menopausal estrogens to breast cancer cannot be drawn due to inconsistent evidence to date. Although evidence from randomized controlled trials is lacking, biochemical and clinical evidence suggest that progestin supplementation is associated with a reduction in endometrial cancer risk in women taking menopausal estrogens. Progestin supplementation also may augment the beneficial effects of estrogens in providing protection against osteoporosis, although this effect is not yet well established. There is little direct evidence bearing on the relation of menopausal progestins to breast cancer. Although studies of CAD per se are lacking at present, progestins probably unfavorably alter lipoprotein profiles, thereby increasing a user's risk of CAD. Given the relatively high incidence and mortality of CAD in postmenopausal women, any negative effects on CAD risk could potentially counterbalance beneficial effects on other causes. We conclude that estrogen replacement therapy is of potential benefit to postmenopausal women, but that the question of progestin supplementation requires further study, particularly for CAD risk.

Breast Neoplasms↗
PubMed1987

Medical, life-style, and occupational risk factors for prostate cancer.

Information on suspected risk factors for prostate cancer was obtained from in-person interviews as part of a case-control study of tissue sex hormone receptors and serum hormone levels. The risk factors examined were medical history (including venereal disease), sexual history, smoking, alcohol consumption, and occupational exposures. Study subjects were 40 prostate cancer patients and 64 benign prostatic hyperplasia controls who were newly diagnosed during 1984-1985 at North Carolina Memorial Hospital in Chapel Hill. Subjects were white and black men aged 50 years and older. Comparisons of cases' and controls' past medical histories did not support a venereal disease hypothesis of prostate cancer etiology. The most prominent finding is an association with farming employment: 75% of cases compared to 38% of controls reported farmwork occupations. Exposures to pesticides and herbicides, while more common among the patients, did not account for the association detected for farming. No relationship was observed with cadmium exposure, the most frequently cited occupational risk factor for prostate cancer.

Adenocarcinoma↗
PubMed1987

Androgen receptors detected by autoradiography in prostatic carcinoma and benign prostatic hyperplastic tissue.

Androgen receptor (AR) content in prostatic tissues from patients with either cancer or benign prostatic hyperplasia (BPH) is of interest from at least two standpoints: receptors may be a feature of the pathogenesis of these conditions, and they may be important to the management and prognosis of prostatic cancer patients. For these reasons, a quantitative autoradiographic assay for AR content in prostatic tissues has been developed. Application of autoradiography to rodent tissues yielded results that were highly correlated with those from biochemical assays. Thus, the autoradiographic analyses with human tissues reported in this paper were undertaken. Average AR content in 22 prostatic carcinomas was lower than that in tissues from 14 patients with BPH; the median values of the affinity index, the quantitative estimate of receptor content, were 7.0 and 12.0, respectively. For the cancer tissues, a trend of declining receptor content with advancing stage of disease appeared but was not statistically significant. No association between receptor content and degree of tumor aggressiveness as measured by Gleason score and MD Anderson score was evident. Patient age and race were not related to receptor content in either type of tissue.

Aged↗
PubMed1987

Serum hormone levels among patients with prostatic carcinoma or benign prostatic hyperplasia and clinic controls.

This study sought to identify differences in serum hormone levels between prostatic cancer (CaP) patients, benign prostatic hyperplasia (BPH) patients, and clinic controls (CC). Serum testosterone, estradiol, and prolactin values were obtained from 35 CaP, 42 BPH, and 161 CC patients attending a single medical center between January 1984 and April 1985. Relative risk estimates adjusted for age and race were calculated to compare hormone values between each case group and the CC. The distributions of hormone values and the testosterone to estradiol (T/E) ratios were grouped into thirds with the lowest third forming the reference category. The relative risk estimates for BPH in the middle and high thirds of testosterone were greater than unity (1.26 and 2.10, respectively), whereas the relative risk estimates in the middle and high thirds of estradiol were less than unity (0.63 and 0.35, respectively). For the middle and high thirds of the T/E ratio, the relative risk estimates for BPH showed statistically significant three- to fourfold increases. Modest depression of serum testosterone and estradiol was noted for CaP patients compared to CC, although the differences were not statistically significant. This depression was interpreted to be a likely result of the malignant process rather than a cause of it, whereas the development of clinically evident BPH was felt to be a biologically plausible response to an elevated T/E ratio.

Age Factors↗
PubMed1979

Care process and patient outcome in diabetes mellitus.

The relationship between the process of medical care and patient outcome is a central issue in health services research. We examined this relationship in 244 patients with adult-onset diabetes mellitus, who were under the care of private internists and family physicians. Process measures included physician awareness of patients' concerns, communication of information from physician to patient, medication-taking behavior, physician adherence to minimum care criteria, and extent of patient utilization of services. Outcomes measured during and after a 6-month follow-up period, included diabetic control status and patient satisfaction with medical care. Potentially confounding variables included practice and physician characteristics, patient demographic characteristics, and measures of disease severity. There was a small statistically significant correlation between physician awareness and control status, but the association was not maintained when controlling for other variables. Communication of information from physician to patient was significantly (p less than .005) associated with satisfaction in the multiple regression analysis but explained only 4 per cent of the variance in patient satisfaction. Thus, in patients under treatment for diabetes, there was little association between certain measures of care process and patient outcome. We suggest that process and outcome assessments are distinct but complementary aspects of quality of care.

Adult↗
PubMed1979

Developing criteria for quality of assessment: effect of the Delphi technique.

We examined the effect of the Delphi iteration procedure in developing explicit criteria for ambulatory care assessment. Practicing internists chose items they believed to be essential with regard to the care of certain specified conditions. The initial responses were tabulated and "fed-back" to the participants. The second round of criteria selection, with the first-round summary available, produced few and relatively minor changes in the items chosen by group consensus.

Ambulatory Care↗
PubMed1978

Epidemiological applications to health services research.

A model is presented to illustrate some areas in which epidemiological thinking may be applied to health services research. The model is neither exhaustive nor exclusive, for other areas not specifically described as within the model are also a part of the domain of epidemiology, and several aspects of the model are shared with researchers in other disciplines. Selected examples of epidemiological applications are reviewed; these include: (1) the need for health care services, (2) the use of health services, (3) the impact of health programs on utilization patterns and on health status, and (4) the impact of therapeutic services on outcomes for specific diseases. Additional health services issues that are relevant to epidemiology are suggested.

Adolescent↗