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S S Coughlin

Publications and source records attributed to S S Coughlin.

At least 19 recordsLinked to original sources
PubMed1992

The logistic modeling of interobserver agreement.

An approach to the logistic modeling of interobserver agreement is described that allows for the estimation of a commonly employed measure of agreement. The dependent variable is defined to be 1 if the two raters agree, and 0 otherwise. Covariates may be included in the regression equation in order to obtain adjusted or subgroup-specific estimates of percent agreement. As an empirical example, logistic models were fitted to data from a validation study of the agreement between interview information and physician records on the history of post-menopausal estrogen use, from a case-control study of breast cancer conducted on Oahu, Hawaii. Variables found to be related to agreement in previous univariate analyses were examined as covariates in the logistic model. The directly calculated estimates of percent agreement agreed well with the modeled estimates derived from the regression coefficients. Thus, the logistic model may provide a useful alternative to existing methods for the description of interobserver agreement.

Breast Neoplasms↗
PubMed1992

The logistic modeling of sensitivity, specificity, and predictive value of a diagnostic test.

A method is described for modeling the sensitivity, specificity, and positive and negative predictive values of a diagnostic test. To model sensitivity and specificity, the dependent variable (Y) is defined to be the dichotomous results of the screening test, and the presence or absence of disease, as defined by the "gold standard", is included as a binary explanatory variable (X1), along with variables used to define the subgroups of interest. The sensitivity of the screening test may then be estimated using logistic regression procedures. Modeled estimates of the specificity and predictive values of the screening test may be similarly derived. Using data from a population-based study of peripheral arterial disease, the authors demonstrated empirically that this method may be useful for obtaining smoothed estimates of sensitivity, specificity, and predictive values. As an extension of this method, an approach to the modeling of the relative sensitivity of two screening tests is described, using data from a study of screening procedures for colorectal disease as an example.

Arterial Occlusive Diseases↗
PubMed1992

Sensitivity and specificity-like measures of the validity of a diagnostic test that are corrected for chance agreement.

Chance agreement may account for a sizeable proportion of the specificity of a screening test when the disease prevalence is low. Conversely, the observed sensitivity may be largely accounted for by chance agreement when the prevalence of disease is high. We derive descriptive statistics that are analogous to sensitivity and specificity and corrected for the agreement expected by chance. These coefficients of validity are shown to be dependent on the true prevalence of disease, as well as sensitivity and specificity.

Humans↗
PubMed1992

Ethics, scientific validity, and the design of epidemiologic studies.

Ethical conflicts between moral principles and methodologic standards sometimes occur in epidemiologic research. When dilemmas are discerned, they may be analyzed using the ethical principles of beneficence, nonmaleficence, justice, and respect for the autonomy of persons. We argue that, in addition to scientific validity, the welfare and rights of research subjects should be taken into account in making decisions regarding all aspects of the design and conduct of epidemiologic studies, and that the commitment of epidemiologists to the advancement of scientific knowledge should not outweigh or override all other considerations.

Beneficence↗
PubMed1992

Brief ischemia-reperfusion induces stunning of endothelium in canine coronary artery.

BACKGROUND: Brief ischemic episodes that induce stunning of the myocardium may also induce stunning of the coronary endothelium. To test this hypothesis, we examined both in vivo and in vitro responses of canine coronary arteries exposed to brief ischemia. METHODS AND RESULTS: Functional recovery of the endothelium was examined in vivo during reperfusion after 15 minutes of ischemia. Vasodilatory responses to acetylcholine were severely impaired during the first hour of reperfusion but gradually improved over a 90-minute period after ischemia. The vasoconstrictive response to U46619 was enhanced for the first 30 minutes of reperfusion and returned to normal within 60 minutes. In vitro vasomotor responses to potassium chloride, acetylcholine, bradykinin, and sodium nitroprusside were examined in isolated segments of canine coronary arteries preexposed in vivo to brief ischemia (10-30 minutes) and 20 minutes of reperfusion. The results showed enhanced contractile responses and blunted endothelium-dependent but not endothelium-independent vasodilatory responses of arterial rings subjected to 10 minutes of ischemia. Twenty and 30 minutes of ischemia completely impaired endothelium-dependent vasodilation. When reperfusion was extended to 120 minutes after 15 minutes of ischemia, vasodilatory responses to acetylcholine had recovered by almost 90%. Examination of endothelial integrity by transmission electron microscopy after 10-15 minutes of ischemia revealed no evidence of structural damage. Twenty and 30 minutes of ischemia induced cytoplasmic vacuolation, partial detachment of endothelium, and swelling of cytoplasmic organelles. CONCLUSIONS: These data support the hypothesis that brief ischemia-reperfusion induces stunning of endothelium in which endothelium-dependent vasodilatory function is impaired temporarily without morphological damage.

Acetylcholine↗
PubMed1992

A novel asthma camp intervention for childhood asthma among urban blacks. The Pediatric Lung Committee of the American Lung Association of the District of Columbia (ALADC) Washington, DC.

Following a needs assessment, the American Lung Association of the District of Columbia (ALADC) began a 3-year pilot program (1986 to 1989) to improve the health status of 5- to 10-year-old urban black asthmatic children. The authors hypothesized that participation in a 1-day asthma camp curriculum, using a collaborative multidisciplinary team approach between university and community-based staff, would provide an effective educational intervention to teach children and their families daily management strategies for asthma. The 84 participants (mean age: 9.6 years) were predominantly black (93%), male (73%), and from single-parent or single-guardian homes (52.7%). Follow-up interviews suggested that a high percentage of the children were using new techniques such as aerosol/inhalers (78%) and breathing/warm-up exercises (55%). Overall, participation in this novel program was associated with a clinically significant, 36% to 69% reduction in school absences, emergency room visits, and hospitalizations.

Black or African American↗
PubMed1991

Regression methods for estimating attributable risk in population-based case-control studies: a comparison of additive and multiplicative models.

A regression method that utilizes an additive model is proposed for the estimation of attributable risk in case-control studies carried out in defined populations. In contrast to previous multivariate procedures for the estimation of attributable risk, which have utilized logistic regression techniques to adjust for confounding factors, the model assumes an additive relation between the covariates included in the regression equation. As an empirical example, additive and logistic models were fitted to matched case-control data from a population-based study of childhood astrocytoma brain tumors. Although both models fitted the data well, the additive model provided a more satisfactory estimate of the risk attributable to multiple exposures, in the absence of significant additive interaction. In contrast to the results from the logistic model, the adjusted estimates of the risk attributable to each factor included in the additive model summed to the overall estimate for all of the factors considered jointly. Thus, the additive approach provides a useful alternative to existing procedures for the multivariate estimation of attributable risk when the additive model is determined to be appropriate on the basis of goodness-of-fit.

Astrocytoma↗
PubMed1991

Standard and controlled-release levodopa/carbidopa in patients with fluctuating Parkinson's disease on a protein redistribution diet. A preliminary report.

Ten patients with Parkinson's disease (PD) with motor fluctuations that responded to a protein redistribution diet were studied. All 10 patients were receiving standard Sinemet (levodopa/carbidopa). Five randomly selected patients were changed from standard Sinemet to a controlled-release form of Sinemet. The other five patients continued to receive standard Sinemet. To maintain the same degree of control of PD in the five patients switched to the controlled-release form of Sinemet, the daily levodopa intake increased. While receiving optimal therapy (standard Sinemet or controlled-release Sinemet) and a protein redistribution diet, all 10 patients then underwent hourly videotaping and blood sampling (for plasma levodopa levels) during 2 consecutive days. Videotapes were blindly reviewed for PD disability, dyskinesia, and the time required to walk a measured distance. Comparing the two groups, standard Sinemet with controlled-release Sinemet, respectively, mean levodopa requirements were 505 and 1895 mg, plasma levodopa levels were 6.1 and 17.6 mumol/L, and abnormal involuntary movement scale scores were 14 and 26. Their mean PD disability scores did not differ statistically or clinically. Also no statistically significant differences were noted in either their mean walking times or their mean daily dose frequencies.

Antiparkinson Agents↗
PubMed1991

The living will: a national survey.

This national survey examined the knowledge and use of the living will among 494 family physicians of the American Academy of Family Physicians in 39 jurisdictions with living will statutes. The findings revealed a positive relationship between physician knowledge of the living will and its clinical use. Additionally, a positive relationship between physician knowledge and willingness to initiate discussions on the document with patients was found. The implications of these findings, as related to disclosure of the living will in the informed consent process, is discussed.

Adult↗
PubMed1990

Recall bias in epidemiologic studies.

The factors which contribute to bias due to differential recall between cases and controls in retrospective studies have been little studied. A review of the literature on recall accuracy suggests that the extent of inaccurate recall is related to characteristics of the exposure of interest and of the respondents, though a distinction must be drawn between recall which is biased and that which is simply inaccurate. Interviewing technique and the study protocol, including the design of questionnaires and the motivation of respondents, play a central role and are under the control of the investigator. The results of validation studies carried out to date suggest that the likelihood of recall bias may be greater when recall is poor in general.

Bias↗