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Biomedical subjects

J C Bailar

Publications and source records attributed to J C Bailar.

At least 55 records · Page 3Linked to original sources
PubMed1984

A classification for biomedical research reports.

Biomedical research uses a wide range of designs applied to problems in laboratory, clinical, and population settings. Whatever the nature of the study, a few key features--such as the admission rule, the method of allocating subjects to treatments, and the use of controls--largely determine the strength of scientific inferences. We used these and other features to classify the 332 Original Articles published in the New England Journal of Medicine during 1978-1979. This classification directs attention to critical aspects of study design and performance and can help in the choice of suitable research approaches and protocols. It emphasizes the critical role of the investigators' intent in performing and analyzing a study, and it alerts readers to important aspects of interpretation. We recommend that authors always report enough detail about their work for readers to apply this or a similar classification. Omission of such detail may limit the interpretation of a research study because a study that cannot be classified has probably been incompletely reported.

Clinical Trials as Topic↗
PubMed1984

Studies without internal controls.

Sometimes questions of clinical interest can be addressed only by investigations without concurrent controls that are under the supervision of the investigator (internal controls). Such studies nearly always make use of other types of comparisons (external controls), such as historical controls. In this paper we examine studies of clinical treatments that have weak internal controls or lack internal controls, as illustrated by recent examples from the Journal. These studies have a small but important and unique role in clinical investigation. Five interrelated features can add to the strength of such studies: (1) an intent by the investigator, expressed before the study, that the treatment will affect the outcomes reported; (2) planning of the analysis before the data are generated; (3) articulation of a plausible hypothesis before the results are observed; (4) a likelihood that the results would still have been of interest if they had been "opposite" in some sense; and (5) reasonable grounds for generalizing the results from the study subjects to a substantially broader group of patients. In spite of potential pitfalls, carefully selected and reported studies without internal controls can play a substantial part in the acquisition of scientific knowledge.

Animals↗
PubMed1984

Crossover and self-controlled designs in clinical research.

Crossover studies (clinical trials in which each patient receives two or more treatments in sequence) and self-controlled studies (in which each patient serves as his or her own control) can produce results that are statistically and clinically valid with far fewer patients than would otherwise be required. We investigated the use of the crossover design in the 13 crossover studies that appeared in the Journal during 1978 and 1979. We considered the following important features of design and analysis as they applied to these studies: the method by which patients were assigned to initial treatment (only 7 of 13 studies used random assignment); the determination of when to switch treatments (10 of the 13 used a time-dependent rule, and 3 a less appropriate disease-state-dependent rule); blinding of the crossover point (in only 3 of the 13 studies was the crossover point concealed, but in 4 of the remaining 10 concealment was impossible); assessment of the effects of the order of treatments (included in only 1 of the 13 studies); and the use of at least minimally acceptable statistical analysis (11 of the 13 studies had such an analysis). We also report briefly on 28 additional studies of a single treatment each, in which each patient served as his or her own control before or after treatment or both. The scientific issues were much the same as in crossover studies except that self-controlled comparisons of treatments tended to be less precisely designed and conducted and to focus on clinical problems and patient groups that are especially difficult to study.

Chronic Disease↗
PubMed1984

The multihit model of carcinogenesis: etiologic implications for colon cancer.

A new multihit model of carcinogenesis is developed for use in evaluating age-specific cancer incidence rates in human populations. The model allows for some heterogeneity in both risk (perhaps genetic) and pathway (number of hits). Fitting the model yields estimates of (1) levels of effect of background exposure to environmental agents, (2) tumor growth times after initiation of a malignant cell, and (3) relative sizes of high-risk groups in a human population. Maximum likelihood procedures are used to fit the model to the polyposis coli data of Veale and the colon cancer incidence data from the Third National Cancer Survey. Model estimates may be verified in some cases by review of independent data in the literature and results have both theoretical and practical implications. Findings are generally consistent with the adenoma-carcinoma etiologic sequence postulated by Hill, Morson and Bussey with one exception. A large proportion of the population may be at risk of four-hit colon tumors following a non-adenoma etiologic sequence.

Adolescent↗
PubMed1983

Designs for experiments--parallel comparisons of treatment.

Clinical trials of medical treatments often compare two treated groups or a treated group with a separate but concurrent control group. We have examined a consecutive series of 47 such parallel studies reported in the Journal in 1978-1979, including 35 with random assignment to the treated or control group, to discover how this approach is actually used. A major strength of these studies as a group was the frequent use of randomized treatment assignment. Common problems included lack of sufficient detail about methods of randomization, failure to provide enough detail about patient sources, and insufficient use of multivariate statistical techniques and of statistical modeling. We emphasize the importance of avoiding bias by balancing prognostic factors when assigning patients to treatments, reducing bias by modeling the influence of prognostic factors on response, and increasing precision by modeling. We also advocate the careful consideration of the relevance of a treatment comparison within the study to the external world of clinical practice.

Adult↗
PubMed1981

Late effects of radiation therapy for cancer of the uterine cervix.

This report presents follow-up information on 497 women diagnosed with cancer of the uterine cervix in Connecticut and California between 1932 and 1951 who received only radiation as their initial course of therapy. Patients entered into the study were all treated before age 55 and all were five-year-survivors following treatment in order to eliminate early deaths due to the cervical cancer. Three radiologic dosage groups (high, medium, and low) were formed with 93, 244, and 160 patients, respectively. For all dosage groups combined 108 subsequent cancers were observed more than 5 yr after cancer treatment compared with 64 expected (P less than 0.01). Sites for which subsequent cancers were significantly (P less than 0.05) in excess of expectation were rectum, ovary, lung, vulva and vagina, small intestine, oropharynx, and central nervous system excluding brain. The ratio of observed to expected cases of subsequent cancers rose only slightly with increasing radiologic dose. No significant differences in overall survival patterns for the three dosage groups were found. For all dosage groups survival was poorer than in the corresponding segment of the general population.

Adult↗
PubMed1978

Phase II study of adriamycin and bleomycin in patients with multiple myeloma.

Twenty-seven patients with far-advanced multiple myeloma, resistant to standard agents, were treated with either adriamycin (eight patients) or bleomycin (19 patients). Adriamycin was given iv at a dose of 60 mg/m2 every 3 weeks and bleomycin was administered im at a dose of 15 mg/m2 weekly. Drug toxicity was modest. One partial response was seen with each agent, both occurring in "good-risk" patients.

Aged↗