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Biomedical subjects

J A Hanley

Publications and source records attributed to J A Hanley.

At least 91 records · Page 5Linked to original sources
PubMed1983

Diffusion of innovations in burn care: selected findings.

Large sums of money are spent to support biomedical research, but relatively little effort is directed toward getting results to the clinical setting. Understanding the process underlying the diffusion of innovations would promote more efficient conversion of new knowledge into practice. This study examines the diffusion of innovations in burn care that were discussed at the United States National Institutes of Health 1978 Consensus Development Conference on Supportive Therapy in Burn Care. The study traces the awareness and use of innovations in burn care, the source and timing of new information to physicians and the ways in which characteristics of both innovations and physicians are related to the diffusion process. The principal basis for the study is a survey in five New England States of physicians who treat burn patients. The data suggested that between 56 and 97 per cent of physicians were aware of eight major advances. Physicians were more aware of high than low consensus treatments and the adoption rate and adoption level were higher for high consensus treatments. The three most important sources of information about the advances were staff conferences, journals and medical school.

Awareness↗
PubMed1983

Split-course versus continuous pelvis irradiation in carcinoma of the uterine cervix: a prospective randomized clinical trial of the Radiation Therapy Oncology Group.

In August 1980, the Radiation Therapy Oncology Group (RTOG) completed a prospective randomized clinical trial for the comparison of a split-course versus a standard continuous course of pelvic irradiation for carcinoma of the uterine cervix Stages II-B, III-A, III-B, and IV-A. The split-course consisted of 10 fractions of 250 rad each, 5 times a week, up to 2500 rad followed by a rest period of approximately 2 weeks and then another 2500 rad was given (250 X 10). The continuous course consisted of 30 fractions of 170 rad each, 5 times per week, for a total of 5100 rad. In both groups the external pelvis irradiation was followed by intracavitary brachytherapy in the uterus and vagina, with tandem-colpostat or tandem only, for a dose of 3000 rad at point A for the former, or at 2 cm from the center of the linear source for the latter. In cases where brachytherapy was not possible, a boost of external irradiation with reduced field, with a dose of 1600 rad (200 X 8) was advised. Three hundred and one patients were registered, of which 287 are currently evaluable. No differences between the treatments were detected for the following study end-points: treatment tolerance in terms of acute normal tissue reactions and completion of therapy, tumor control in the pelvis, severe late normal tissue reactions, and survival. In the entire study population the estimated tumor control in the pelvis at two years after initiation of therapy was: 81% for Stage II-B, 67% for III-A, 53% for Stage III-B, and 32% for Stage IV-A. The estimated two-year survival was: 70% for Stage II-B, 58% for III-A, 46% for III-B, and 23% for IV-A.

Adult↗
PubMed1983

Split-course radiation therapy of carcinoma of the base of the tongue: results of a prospective national collaborative clinical trial conducted by the Radiation Therapy Oncology Group.

One hundred forty-one patients with carcinoma of the base of tongue were randomized to receive either continuous course radiotherapy (6600 rad in 30/33 fractions over 7-8 weeks) or split course therapy (3000 rad in 10 fractions over 2 weeks, a three-week rest, 3000 rad in 10 fractions over 2 weeks). Both treatment groups tolerated the treatment well, but the continuous course group required more treatment modifications. The results of therapy, as judged by control of primary tumor, control of metastatic lymph nodes, time to failure and overall survival were comparable in the two treatment groups.

Aged↗
PubMed1983

A method of comparing the areas under receiver operating characteristic curves derived from the same cases.

Receiver operating characteristic (ROC) curves are used to describe and compare the performance of diagnostic technology and diagnostic algorithms. This paper refines the statistical comparison of the areas under two ROC curves derived from the same set of patients by taking into account the correlation between the areas that is induced by the paired nature of the data. The correspondence between the area under an ROC curve and the Wilcoxon statistic is used and underlying Gaussian distributions (binormal) are assumed to provide a table that converts the observed correlations in paired ratings of images into a correlation between the two ROC areas. This between-area correlation can be used to reduce the standard error (uncertainty) about the observed difference in areas. This correction for pairing, analogous to that used in the paired t-test, can produce a considerable increase in the statistical sensitivity (power) of the comparison. For studies involving multiple readers, this method provides a measure of a component of the sampling variation that is otherwise difficult to obtain.

Models, Theoretical↗
PubMed1983

Paired receiver operating characteristic curves and the effect of history on radiographic interpretation. CT of the head as a case study.

The use of a statistical technique for paired comparisons using receiver operating characteristic (ROC) curves is illustrated by studying the extent to which clinical history altered the interpretation of computed tomographic (CT) examinations of the head. Eighty-nine CT examinations of the head were presented in random order to four readers, first with minimum history (age and sex) and then several weeks later with complete neurological history as of the time the CT examination had been obtained. Using a paired ROC analysis, a small but significant (p less than .05) improvement was detected for the interpretations in the presence of complete history; for readings without history the average area was 94.4% and for readings with history it was 97.7%.

Brain Diseases↗
PubMed1983

Nonparametric estimation of a multivariate distribution in the presence of censoring.

This paper presents examples of situations in which one wishes to estimate a multivariate distribution from data that may be right-censored. A distinction is made between what we term 'homogeneous' and 'heterogeneous' censoring. It is shown how a multivariate empirical survivor function must be constructed in order to be considered a (nonparametric) maximum likelihood estimate of the underlying survivor function. A closed-form solution, similar to the product-limit estimate of Kaplan and Meier, is possible with homogeneous censoring, but an iterative method, such as the EM algorithm, is required with heterogeneous censoring. An example is given in which an anomaly is produced if censored multivariate data are analyzed as a series of univariate variables; this anomaly is shown to disappear if the methods of this paper are used.

Analysis of Variance↗
PubMed1982

Maximum attainable discrimination and the utilization of radiologic examinations.

Discriminant Analysis and other related statistical techniques are frequently used to sort patients into those most likely and those least likely to benefit from a certain intervention. Considerable data analysis and computation are often required to arrive at the best-fitting mathematical model which translates discriminating variables or indicants into probability predictions regarding the presence or absence of disease or the likelihood of a favourable outcome. Attempts to judge how well discriminant analysis performs or to determine why it does not perform better are hampered by not knowing what is the greatest degree of discrimination theoretically possible in a data set. In this paper we describe a method of calculating the maximum discrimination attainable in a data set and show how it can be used (1) to decide whether further model building is worthwhile, and (2) if so, to judge the discriminatory performance of any such models. We apply this tool to two previously published studies of radiologic utilization; the results provide reassurance that, at least on the basis of the presenting indicants, the patients were being adequately selected for the studies in question.

Health Services Research↗
PubMed1982

The meaning and use of the area under a receiver operating characteristic (ROC) curve.

A representation and interpretation of the area under a receiver operating characteristic (ROC) curve obtained by the "rating" method, or by mathematical predictions based on patient characteristics, is presented. It is shown that in such a setting the area represents the probability that a randomly chosen diseased subject is (correctly) rated or ranked with greater suspicion than a randomly chosen non-diseased subject. Moreover, this probability of a correct ranking is the same quantity that is estimated by the already well-studied nonparametric Wilcoxon statistic. These two relationships are exploited to (a) provide rapid closed-form expressions for the approximate magnitude of the sampling variability, i.e., standard error that one uses to accompany the area under a smoothed ROC curve, (b) guide in determining the size of the sample required to provide a sufficiently reliable estimate of this area, and (c) determine how large sample sizes should be to ensure that one can statistically detect differences in the accuracy of diagnostic techniques.

Evaluation Studies as Topic↗
PubMed1982

Computed tomographic studies of the head in a teaching hospital and a community hospital: a comparison.

This investigation compared the use of computed tomography (CT) of the head at a large primary medical-school-affiliated hospital and at a large community hospital. There were two aims: first, to study the intrinsic characteristics of the patients in an attempt to determine the potential for developing accurate discrimination algorithms; and second, to study the patterns of neurodiagnostic tests used at these facilities. The results indicated that separability of patients into normal and abnormal categories at both institutions was extremely small. In addition, there was no significant difference in the numbers of types of ancillary tests used at both institutions. Overall, these data once more confirm the difficulty of altering CT usage patterns in primary or secondary hospitals without significantly affecting the number of abnormal patients identified.

Boston↗
PubMed1981

Analysis of recurrence patterns following curative resection for carcinoma of the colon and rectum.

The records of 525 patients with adenocarcinoma of the colon and rectum were reviewed. Two hundred and eighty-five patients were evaluable following complete curative resections. These patients were evaluated for patterns of recurrence. The over-all recurrence rate was 78 of 285, 27 per cent. The over-all recurrence rate by site was 24.0, 10.0, 11.5 and 35.0 per cent for the right, transverse and left colon, the sigmoid and the rectum, respectively. The over-all failure rate by stage was 13 per cent for Stage A, 11 per cent for Stage B1, 32 per cent for Stage C1, 37 per cent for Stage B2-3 and 56 per cent for Stage C2-3. The over-all failure rate as related to Stages A, B1, C1, B2-3 and C2-3 and to site of primary disease was: right--zero, 9, 33, 28 and 43 per cent, sigmoid--11, 15, 40, 52 and 62 per cent; rectal group--29, 14, 40, 46 and 60 per cent as related to respective stages. There was one failure among the five patients with Stage B2-3 disease in the transverse group and two failures among the nine patients with Stage B2-3 and one failure in the one patient with Stage C2-3 within the left colon group. Individual types of failure were compiled. Lesions involving the rectum and sigmoid colon had a significant local-regional component to relapse. Tumors of the right, transverse and the left colon had a significant distant recurrence rate. Factors of primary site, age at diagnosis, extent of disease and histology were reviewed as to the over-all recurrence and specific failure sites. From this analysis, a schema involving patterns of failure as related to primary site and stage within the colon, rectum and sigmoid were developed.

Adenocarcinoma↗
PubMed1980

Streptozocin alone compared with streptozocin plus fluorouracil in the treatment of advanced islet-cell carcinoma.

To evaluate the treatment of advanced islet-cell carcinoma, we randomly assigned 84 patients to streptozocin alone or streptozocin plus fluorouracil. Each regimen was given in five-day courses. The most frequent toxic effects were nausea and vomiting, mild and reversible renal toxicity, and bone-marrow depression with the combination regimen. The combination had advantages over streptozocin alone in overall rate of response (63 vs. 36 per cent) and in rates of complete response (33 vs. 12 per cent). There was no evidence of a preferential response among types of functional tumors. Objective responses were generally of long duration (median, 17 months) and of substantive clinical benefit. Treatment with the combination also yielded a survival advantage over treatment with streptozocin alone (medians, 26 and 16 1/2 months), but this difference is not statistically significant. In spite of gastrointestinal side effects, streptozocin combined with fluorouracil appears to be a valuable treatment for advanced islet-cell carcinoma.

Adenoma, Islet Cell↗
PubMed1980

Tolerance of surgery after radical radiotherapy of carcinoma of the oropharynx.

The complications of salvage surgery after radical irradiation were studied in a group of 52 patients with oropharyngeal carcinomas. These patients were selected for surgery from a group of patients who had failed protocol therapy and who were registered in the Split-Course Study of the Radiation Therapy Oncology Group. The operative mortality was 1.9% (1/52). The most frequent serious complication was pharyngocutaneous fistua in 12% (6/52) of patients who underwent operations. The overall incidence of serious complications was 21% (11/52). The actuarial estimated five-year survival for the group who had undergone operation was 27%. We conclude that salvage surgery for residual or recurrent disease in oropharyngeal cancer after radical radiotherapy is feasible with a low surgical mortality and acceptable complication rates.

Aged↗
PubMed1979

Combination chemotherapy trials in metastatic carcinoid tumor and the malignant carcinoid syndrome.

One hundred eighteen patients with metastatic carcinoid tumor were randomized to treatment with streptozotocin combined with cyclophosphamide or with 5-fluorouracil (5-FU). Commonly experienced side effects were nausea, vomiting, leukopenia, thrombocytopenia, and nephrotoxicity. Objective response rates among eligible and evaluable patients treated with the 5-FU combination was 14 of 42 (33%) and with the cyclophosphamide combination, 12 of 47 (26%). Among those patients with carcinoids primary to the small bowel the respective response rates were 44% and 37%. The overall response rates for patients with carcinoids of pulmonary or unknown origin were only 12% and 17%. There was no significant difference in patient survival between the two treatment arms. Among 11 patients who received crossover therapy with 5-FU alone there were two responders. There were no responders among eight patients treated with cyclophosphamide alone. Urinary 5HIAA excretion proved to be a useful biologic marker in these patients that correlated well with the observed measurements of tumor bulk. Median survival times from the diagnosis of unresectable malignant disease related to sites of origin of carcinoid tumor were the following: small bowel, 28.4 months; pancreas, 24.0 months; lung, 15.1 months; and unknown origin, 9.0 months. Metastatic carcinoid tumor is a malignant disease susceptible to chemotherapeutic approaches and continued investigation of the therapy of these neoplasms should be strongly encouraged.

Adolescent↗