PubMed Health⌕ Search

Biomedical subjects

L Polissar

Publications and source records attributed to L Polissar.

36 records · Page 2Linked to original sources
PubMed1984

A case-control study of asbestos in drinking water and cancer risk.

The authors conducted a case-control, interview-based study of the risk of developing cancer from asbestos in drinking water. The Everett, Washington area was selected for the study because of the unusually high concentration of chrysotile asbestos in the drinking water it draws from the Sultan River (200 X 10(6) fibers/liter). Through a population-based tumor registry, the authors identified 382 individuals with cancer of the buccal cavity, pharynx, respiratory system, digestive system, bladder, or kidney, diagnosed between 1977 and 1980, and then interviewed them or their next-of-kin. The authors conducted similar interviews of a control group of 462 individuals. Finally, interviews were validated in several ways, including comparing the collected data with that from secondary sources. Estimates of exposure to asbestos in drinking water were based on residence and workplace history, and on individual water consumption. Four different measures of exposure were used. Cancer risk was estimated by logistic regression and other methods. The authors found no convincing evidence for cancer risk from imbibed asbestos. Exposure was similar between cases and controls. Confidence intervals for relative odds for almost all sites included unity. Out of 84 dependent estimates of risk by sex, site, and exposure measure, 63 indicated a protective effect and 21 indicated an increased risk. In instances where relative odds differed appreciably from unity for both males and females, the effect was protective. The relative odds of cancer for 20 years of exposure to Sultan River drinking water varied from 0.92 to 0.99 for females and 0.82 to 1.01 for males for all study sites grouped. For cancer of the digestive system, the corresponding range was 1.03 and 1.08 for females and 0.85 to 1.00 for males. There were six statistically significant associations (p less than 0.05). All involved male stomach (eight cases) and male pharynx (four cases), and indicate elevated risk. This number of significant associations is close to that expected (for the number of comparisons made). The female risks for these two sites indicate a protective effect, and it is concluded that the male results are probably due to chance.

Adult↗
PubMed1984

Care of patients with colorectal cancer. A comparison of a health maintenance organization and fee-for-service practices.

The presence of a population-based cancer registry in a community with a health maintenance organization (HMO) enabled a detailed, longitudinal comparison to be made of care given for colorectal cancer in an HMO with traditional fee-for-services (FFS) care. An interview survey of 39 HMO and 150 FFS patients was supplemented with data from the cancer registry. Patients seen by the two provider groups were similar with respect to sociodemographic characteristics, severity of disease at diagnosis, and concurrent medical conditions. The HMO patients received more prediagnostic care but did not receive definitive surgical treatment as quickly as the FFS group. There were few differences in care, however, once diagnosis was made; there were no differences in access to care, rates of definitive surgery, chemotherapy, radiation therapy, length of hospitalization, number of follow-up physician visits, and most measures of satisfaction with care. No differences in outcome, including 4-year survival and 1-year health status, were found. HMO patients expressed significantly less concern about the cost of their care. These findings suggest an initial hesitancy to provide definitive care by the HMO but no significant differences in either the process or outcome of care once definitive care is begun.

Colonic Neoplasms↗
PubMed1984

Accuracy of basic cancer patient data: results from an extensive recoding survey.

The accuracy of data coded from the medical records of 985 patients from 22 major U.S. cancer centers was checked by recoding during 1978-81. The 29 items covered demographics, diagnosis, and therapy. Original codes were compared to recodes, and disagreements were classified as major or minor. The highest rate of major disagreements, 23%, was for stage of disease, followed by 10% for histology and 7% for site. Major disagreement rates for most other items were under 7%. Only 3% of a large sample of major disagreements involved justifiable differences in interpretation; the others were due to errors in the use of records. Major disagreement rates varied by a factor of 10 across sites, 4 across centers, and 2 across stage of disease. For several items the code "unknown" was overused and led to disagreements. A new procedure is presented for analysis of disagreement rates. The results from this procedure can guide training effort to improve coding accuracy.

Data Collection↗
PubMed1983

Use of quantitative analysis of urine to assess exposure to asbestos fibers in drinking water in the Puget Sound region.

An earlier epidemiologic and electron microscopy study of drinking water in the Everett area of Washington State indicated large numbers of naturally occurring chrysotile asbestos fibers in the water. The purpose of the present study was to determine whether significant numbers of asbestos fiber could be demonstrated in the urine of donors residing in that area for less than 3 yr and over 20 yr where the tapwater contained about 200 X 10(6) fibers/L. A control group was obtained from Seattle where the tapwater asbestos fiber content was 100 times less. Urine samples, filtered control water, tapwater samples, and additional controls were processed for transmission electron microscopy by the use of the Nuclepore membrane filter-Jaffe wick procedure. Interference by mucus in the urine was reduced by treatment with hydrogen peroxide. Samples were taken over a period of 21 months. At no time during this period did the asbestos content of the urine samples consistently exceed that of the control waters. There was a significant difference (p less than 0.05) in the asbestos content of urine samples from subjects with less than 3 yr residence times versus greater than 20 yr. Asbestos concentration in urine samples from Everett residents as a whole did not differ significantly from that in samples from Seattle residents. Variable degrees of chrysotile contamination of control water samples and of Nuclepore membrane filters presented a problem. At present, the data are inconclusive but would suggest no relationship between high concentrations of fibers in drinking water and the numbers estimated for voided urine.

Adult↗
PubMed1983

Cancer risk from asbestos in drinking water: summary of a case-control study in western Washington.

We conducted a case-control, interview-based study of the risk of developing cancer from asbestos in drinking water. An area that included Everett, Washington, was selected for the study because of the unusually high concentration of chrysotile asbestos in drinking water from the Sultan River. Through a population-based tumor registry, 382 individuals with cancer of the buccal cavity, pharynx, respiratory system, digestive system, bladder, or kidneys, diagnosed between 1977 and 1980, were identified, and they or their next of kin were interviewed. We conducted validation checks of our interviews, including a comparison with secondary sources. Data on asbestos exposure were collected based on residence and workplace history, and on individual water consumption. Logistic regression was used to estimate cancer risk. We found no convincing evidence for increased cancer risk from imbibed asbestos. Confidence intervals for relative risks for almost all sites included unity. There were significantly elevated risks only for male stomach and male pharyngeal cancer, but these sex-inconsistent results, based on small numbers of cases, are probably due to other factors.

Adult↗
PubMed1982

Cancer incidence in relation to asbestos in drinking water in the Puget Sound region.

Population-based and proportional odds ratios for various cancers, based on incidence data from 1974-1977 and mortality data from 1965-1975 for western Washington State, were calculated in relation to three measures of exposure to asbestos in community water supplies. Six odds ratios were calculated for each neoplasm that occurred in sufficient numbers in each sex. About half of the 332 odds ratios calculated were above unity and half were below unity, and no more of them differed significantly from unity at the 5% level than would be expected by chance. Odds ratios for tumors of the small intestine were consistently elevated in both sexes, as were those for neoplasms of the thyroid, eye, testis, and prostate in males; however, odds ratios for brain tumors and leukemia were consistently less than one in both sexes. Chance is the most likely explanation for these findings. Results of this study and prior studies of cancer in relation to waterborne asbestos are inconsistent, and provide little evidence that asbestos in community water supplies has altered the risk of any cancer. However, all investigations conducted to date are correlational studies which have an inherently higher probability of failing to detect actual increased risks associated with imbibed asbestos, and additional studies of individual exposures are warranted. Neoplasms of the pancreas and small intestine should be included in such studies.

Adult↗
PubMed1982

Breast cancer in relation to patterns of oral contraceptive use.

A total of 112 white females residents of King County, Washington, aged 35-54 years, who had received a first diagnosis of invasive breast cancer between July 1977 add August 1978, were investigated concerning prior use of oral contraceptives. Their responses were compared with those of a random sample of 469 demographically comparable women from the same population. Overall, oral contraceptive use in cases and controls was similar. However, use of oral contraceptives in preparous women was more common among cases than controls, with the estimated risk of breast cancer associated with such use being 2.2 times that of nonusers (90% confidence interval = 1.1-4.6). This relationship could be explained only in part by the effect of oral contraceptives in postponing or preventing childbirth. The association of breast cancer with use of oral contraceptives prior to ever giving birth has been observed in three studies, including this one, suggesting that the susceptibility of breast tissue to hormonal factors that influence the development of malignancy may be altered by having been exposed to the events of pregnancy.

Adult↗
PubMed1982

Regression analysis in health services research: the use of dummy variables.

Dummy variables frequently are used in regression analysis but often in an incorrect fashion. A brief review of examples in the medical care literature showed that the interpretation of dummy variable regression coefficients and their significance was often incorrect or unclear. This article shows how dummy variables can be used and assessed properly. The importance of testing for the joint effect of a group of dummy variables is stressed. It also gives a standard and useful extension of the dummy variable technique to testing for the effect of collections of variables.

Blue Cross Blue Shield Insurance Plans↗
PubMed1982

Quality of care in women with stage I cervical cancer.

A study was done to assess the quality of care received by women with stage I cervical cancer. Through a population-based registry serving 13 counties of western Washington, including Seattle, we identified all women residents in whom local-stage cervical cancer developed between January 1974 and December 1978 (N=369). The cases were subdivided into stage IA (microinvasive) and stage IB (frankly invasive). Quality of care was defined as optimal or suboptimal at the outset of the study; this definition applied to all cases. In patients with stage IB cervical cancer, striking relationships were found between the quality of care and initial and referral hospital characteristics and physician's specialty. No differences were found, however, in three-year survival between the optimally and suboptimally treated groups.

Adenocarcinoma↗
PubMed1981

Continuing education in cancer for the community physician: design and evaluation of a regional table of contents service.

The Arnold Library of the Fred Hutchinson Cancer Research Center offered two groups of practicing physicians in nonmetropolitan areas of the Pacific Northwest an opportunity to review regularly their choice of eighteen cancer journal tables of contents with the added provision (in compliance with federal copyright laws) of being able to receive any articles of interest at no charge from the library. Forty-nine (38.9%) of the 126 physicians selected chose to participate in the program. Of these, 20 (40.8%) actually requested articles from the service. After six months of the service, all of the original 126 physicians were queried by questionnaire. Those who used the service felt it helped in their practice of medicine and that it should be continued. Those who chose not to receive the service generally had access to the eighteen journals elsewhere or saw very few cancer patients. A majority of the articles which had been requested emphasized patient treatment. Approximately 25% of one library technician's time and $360 for photocopy and mailing costs were required to operate the service for forty-nine physicians for six months. The service seemed to identify a select audience of regular users who perceived a benefit from its use.

Community Medicine↗
PubMed1980

The effect of migration on comparison of disease rates in geographic studies in the United States.

Cancer rates are often compared between counties or other geographic units as a method of testing for risk from environmental exposures. Migration between geographic areas greatly reduces the sensitivity of this method. Under simplifying assumptions the quantitative effect of migration on risk estimates is shown using migration and cancer incidence data for the United States. For example, 40--50% of the relative excess risk, defined as the relative risk minus one, is not reflected in the estimated risk for most cancers, when rates are compared between exposed and unexposed counties and migration has taken place during a 30-year latent period. More extreme losses of sensitivity also occur. Under the simplifying assumptions, the quantitative effect of migration on risk estimates is shown as a function of cancer site, latent period, and the type of geographic units for which rates are calculated--states, counties, or places. Also discussed are some implications of these findings for geographically-based studies and additional data needs for assessing the effect of migration.

Adolescent↗
PubMed1979

Effects of bacterial contamination of reagent water on selected laboratory tests.

The effects of three widely spaced levels of bacterial contamination of reagent water on several chemistry, radioimmunoassay, and coagulation procedures were studied. These included determinations of lactate dehydrogenase, creatine kinase, aspartate transaminase, alkaline phosphatase, blood urea nitrogen, total protein, thyroid-stimulating hormone, digoxin, thrombin time, activated partial thromboplastin time, and prothrombin time. Statistical analyses included calculations of means and coefficients of variation, and analysis of variance, as well as correlation coefficients for test results versus logarithm of bacterial contamination. Statistically and clinically significant differences occurred together only for an elevated level of creatine kinase.

Bacteria↗
PubMedDate not supplied

Reliability of basic cancer patient data.

Pooling patient data from multi-institutional medical chart review occurs commonly in the study of cancer and other diseases. To determine the consistency of reporting among institutions, we presented a test set of 25 standardized medical charts to coders at 18 Comprehensive Cancer Centers and compared their resulting codes. This study measures the reproducibility of coding by different persons, but does not assess the accuracy of the underlying medical record. Among 34 data items, we found high disagreement rates in coding stage of disease (14 per cent) and date of diagnosis (8 per cent). Primary site, histologic type and other key items had good reproducibility (disagreement rates less than or equal to 5 per cent). A number of minor disagreements indicated that detailed distinctions could not be reliably coded from medical charts.

Forms and Records Control↗
PubMedDate not supplied

Survival of colorectal cancer patients in relation to duration of symptoms and other prognostic factors.

The effect of duration of symptoms and other prognostic factors on survival was studied by interview using a population-based sample of 154 colorectal cancer patients. The authors found that symptom durations of up to approximately one year before diagnosis had no effect on survival. In addition, it was found that the total number of symptoms was a statistically significant predictor of survival, although no single symptom had a significant effect. Stage, sex, and site also were found to be significant predictors of survival, whereas age, socioeconomic status, and other factors were not predictive.

Age Factors↗