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Biomedical subjects

L A Thibodeau

Publications and source records attributed to L A Thibodeau.

12 recordsLinked to original sources
PubMed1983

Variation in antenatal testing over time and between clinic settings.

Variation in the use of diagnostic procedures may be due to characteristics of patients, physicians, or their environment. Testing rates for 24-hour urinary estriol levels (EST), diagnostic ultrasound, and antepartum fetal heart rate testing (AFHRT) were examined in 8,527 deliveries from 1975 through 1978. Over the period, utilization of EST remained constant at about 7% of deliveries, while ultrasound increased from 20% to 35% and AFHRT, from 7% to 12%. This increase persisted after stratifying patients on a multivariate confounder score using 45 items of clinical information. Those receiving antenatal care in a hospital-based group practice or a resident-staffed community clinic were more likely to be tested than patients seen in private offices or a prepaid group practice.

Adolescent↗
PubMed1983

Receiver operating characteristic analysis of diagnostic skill.

In an effort to assess diagnostic skill, the authors collected estimates of the probability of positive results for 392 chest x-rays and 595 throat cultures from 56 pediatricians at different stages in training. Positivity rates were 28.6% for x-rays and 32.9% for throat cultures. The ability to predict the outcome of chest x-rays (pneumonia or not) improved with training on two measures: 1) "calibration," the accuracy of the guessed probability of positivity, and 2) "operating characteristic," the ability to sort patients with negative x-rays from patients with positive x-rays. Improvement was most marked in the ability to predict that a patient with a positive x-ray would have a positive x-ray. For throat culture results, no regular improvement was found with training either in calibration or in operating characteristic. Measurements of calibration and operating characteristic are useful for assessing the effect of training on diagnostic skill.

Clinical Competence↗
PubMed1982

Proliferative and morphological changes in the pulmonary epithelium of the Syrian golden hamster during carcinogenesis initiated by 210Po alpha alpha-radiation.

The role of cellular proliferation in a two-stage model of carcinogenesis in the hamster lung was investigated. Syrian golden hamsters were treated intratracheally with either one instillation of 0.2 microCi of 210Po (Po-0 group), seven weekly instillations of BP (0-BP group), or 0.2 microCi 210Po followed 15 weeks later by either seven instillations of 0.9% NaCl solution (Po-Sal group) or seven instillations of BP (Po-BP group). All BP instillations were 3 mg each of BP:ferric oxide (1:1, w/w) carrier particles). Serial sacrifices were performed for up to 85 weeks. Two hr before sacrifice, each animal was given i.p. injections of 200 microCi of [3H]thymidine. Glycol methacrylate section autoradiographs (1 micrometer) were prepared. Labeling indices in the alveolar region, labeling of terminal bronchiolar cells, and morphological changes were examined. Equal numbers of Po-Sal and Po-BP animals developed lung tumors. No tumors were found in Po-0 or 0-BP animals. Tumor development was preceded by the appearance of hyperplastic areas of bronchiolar-type cells in the alveolar region and by changes in morphology of bronchiolar cells. Labeling indices in the alveolar region of the treated groups were slightly increased relative to untreated controls. Labeling of terminal bronchiolar cells was highest in the Po-BP and 0-BP groups and was associated with much inflammation. A single 0.9% NaCl solution instillation also increased proliferation of bronchiolar cells. We conclude that 0.9% NaCl solution instillations may potentiate carcinogenesis in the hamster lung by acting as a nonspecific stimulus to proliferation; in addition, we conclude that not all hyperplasia progresses on to form lung tumors in the Po-BP and Po-Sal groups.

Animals↗
PubMed1981

Effect of methoxsalen photochemotherapy on cost of treatment for psoriasis. An example of technological assessment.

In 1974 a new therapy that employs methoxsalen and ultraviolet A irradiation (PUVA) was introduced as an outpatient treatment for severe psoriasis. To study the effect of this therapy on the cost of treatment, we documented for 1,320 patients two major components of cost--hospitalization and PUVA treatments. When the one-year period before initiation of PUVA therapy was compared with a one-year period after initiation of PUVA therapy, average hospital days per person per year declined 77% (5.1 vs 1.2). This decrease in hospitalization was most notable among patients who continued to use PUVA therapy. Largely offsetting the reduction in cost from reduced hospitalization was the cost of PUVA treatments. Our data confirm the previously known effectiveness of PUVA therapy, and they provide no support for the hypothesis that PUVA substantially increases the cost of treating patients with severe psoriasis.

Ambulatory Care↗
PubMed1981

Assessment of the health effects of atmospheric sulfur oxides and particulate matter: evidence from observational studies.

Steadily rising energy costs have increased the need for reliable information on the health effects of atmospheric sulfur oxides and particulate matter. Because ethical and practical considerations limit studies of this question under controlled conditions, observational studies provide an important part of the relevant information. This paper examines the currently available epidemiologic evidence from population studies of the health effects of these pollutants. Nonexperimental studies also have important limitations, including the inability to measure accurately the exposure burden of free living individuals, and the potential for serious confounding by other factors affecting health. We begin with a discussion of some of these methodologic issues. The evidence is then reviewed, first in association with fluctuations in 24 hr mean concentration of sulfur oxides and particulate matter, and then in association with differences in mean annual concentration. In the last section, this evidence is summarized and used to approximate the exposure-response relationship linking pollutant concentrations with mortality and morbidity levels.

Air Pollutants↗
PubMed1980

A trial of two strategies to modify the test-ordering behavior of medical residents.

We studied two methods to reduce the ordering of laboratory and radiologic tests by medical residents in their first postgraduate year. Dividing the residents into three groups, we compared the effect of concurrent chart review and discussion in one group with the effect of a moderate financial incentive for limited ordering of tests in a second group. The third group of residents served as a concurrent control, and data on the testing patterns of residents at the same hospital during the year before the study provided a retrospective control.

Boston↗
PubMed1980

Variation in rates of diagnosis of acute otitis media.

Over 13 weeks during two periods in 1978 the diagnostic rate for acute otitis media was monitored among febrile children (aged one to five years) in the emergency room of a large children's hospital. Of the total 228 eligible children, 53 (23 percent) were diagnosed as having otitis media. The observed variation in the weekly diagnostic rates was significantly (p < .005) greater than that expected if the diagnosis rate were a constant 23 percent. Temporal variation in diagnostic rates was largely attributable to differences among individual providers and independent of level of training. For junior residents short-term learning, within the seven-week emergency room rotation, contributed significantly to the week-to-week temporal variation in diagnostic rates for acute otitis media.

Acute Disease↗
PubMed1980

Air pollution and human health: a review and reanalysis.

Since 1970, Lave and Seskin have published a series of articles dealing with the question, "Does air pollution shorten lives?" Their recent book reports revised and extended analyses of their previous studies emphasizing policy implications. We have undertaken a review of Lave and Seskin's book to evaluate the methodology used and hence gain some insight into the strength of the conclusions reached. This review concentrates on methodology and its application to establishing and quantifying the association between air quality and health. Beyond simply reviewing the analyses reported in Lave and Seskin's book, we have duplicated and expanded two of the reported analyses. Our detailed reanalysis is presented both to verify reported results, and to illustrate the difficulties encountered in such an analysis. Our overall conclusion is that Lave and Seskin have done a thorouth job of reporting and interpreting the various analyses that they performed. Lave and Seskin have made a pioneering effort in showing an association between mortality rates and air pollution. We do not disagree with the conclusion of the existence of an association but have some reservations about their methods of estimating its magnitude. We were particularly concerned that Lave and Seskin did not fully investigate how well their models fit these data. Our reanalysis results in estimated effects which differ considerably from the values reported by Lave and Seskin. Thus, we conclude that the regression coefficients are quite unstable and so must be used with care. Assessing the relative costs and benefits of reducing air pollution without extensive sensitivity analysis could, therefore, be misleading.

Air Pollution↗
PubMed1979

Risk of cutaneous carcinoma in patients treated with oral methoxsalen photochemotherapy for psoriasis.

A 2.1-year prospective study of 1373 patients given oral 8-methoxypsoralen photochemotherapy for psoriasis revealed 30 patients with a total of 48 basal-cell and squamous-cell carcinomas. The observed incidence of cutaneous carcinoma was 2.63 (95 per cent confidence limits = 1.91 to 3.90) times that expected for an age, sex and geographically matched population. Relative risk to patients with history of ionizing radiation was 3.68 (99 per cent confidence limits, 2.42 to 8.69). Patients with a previous cutaneous carcinoma had a relative risk of 10.22 (99 per cent confidence limits, 4.78 to 37.08). A higher than expected proportion of squamous-cell carcinomas and an excess of squamous-cell carcinomas in areas not exposed to sun were seen. New patients with known histories of ionizing-radiation exposure or of skin tumors should be given 8-methyoxypsoralen photochemotherapy only if they understand the risks and have disabling psoriasis untreatable by other means.

Administration, Oral↗
PubMed1979

Antinuclear antibodies and oral methoxsalen photochemotherapy (PUVA) for psoriasis.

In view of theoretical concern that psoralen ultraviolet A radiation (PUVA) therapy might induce a systemic lupus erythematosus-like syndrome, we studied serum antinuclear antibodies (ANAs) in patients with psoriasis who received PUVA and are participating in a five-year prospective study. At 14 centers, 1,023 patients had two or more ANA determinations. When first and last tests were compared, the incidence of positive tests for ANAs was not significantly different (P greater than .2). In addition, there was no apparent relationship between the frequency of PUVA treatments and the probability of a positive test. Over a two-year period, there is no evidence to indicate that PUVA therapy for psoriasis has resulted in a significantly higher number of positive tests for ANAs within our population.

Adolescent↗