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G M Marsh

Publications and source records attributed to G M Marsh.

At least 19 recordsLinked to original sources

OCMAP-PLUS: a program for the comprehensive analysis of occupational cohort data.

The Occupational Cohort Mortality Analysis Program (OCMAP) has been redesigned for optimal microcomputer use and extended to include new computing algorithms. The new program, OCMAP-PLUS, offers a comprehensive, flexible, and efficient analysis of incidence or mortality rates and standardized measures in relation to multiple and diverse work history and exposure measures. New features include executable code, minimization of memory requirements, disk file storage of person-day arrays, stratified analyses by geographic area, employment status and up to eight exposure variables, a data imputation algorithm for study members with unknown race, and enhanced algorithms for constructing several time-dependent exposure measures. New modules create grouped data files for Poisson and logistic regression and risk set files for use in relative risk regression analysis. The Mortality and Population Data System (MPDS) provides external comparison rates and proportional mortalities. Analysis from two recent cohort mortality studies illustrate several new features.

Cohort Studies

Identification and case management in an HMO of patients at risk of preterm labor.

We carried out a study of pregnant patients in a health maintenance organization to identify and provide case management of women at risk of preterm labor and to determine important risk factors for preterm labor in a managed care population. Data were collected on 794 women who completed an initial prenatal care visit at HealthAmerica of Pittsburgh between July 15, 1994, and March 31, 1995, and delivered at a local Pittsburgh hospital. The patients were assessed during an initial call to schedule their first prenatal visit and also at the 8- to 15-week and 24- to 28-week prenatal visits. Patients scoring 10 or higher on the risk assessment form were referred to a nurse case manager who provided education and support. Results of a logistic regression analysis suggest that the risk assessment tool was effective in identifying women at risk for preterm labor. "Physical/stressful work", as assessed by the patient, history of a prior preterm birth, and multiple gestation were all statistically significant predictors of preterm birth. Further research is needed to confirm the finding that physical or stressful work is a significant predictor of preterm births and to determine which aspects of the work may increase the patient's risk. This study was based on 8 months of data; however, additional program implementation is needed to evaluate fully the potential long-term benefits of the program.

Case Management

A case-control study of hematopoietic and lymphoid neoplasms: the role of work in the chemical industry.

The present case-control study was conducted in an effort to determine if work in the chemical industry is related to excesses of certain hematopoietic and lymphoid neoplasms. Cases who died from non-Hodgkin's lymphoma, multiple myeloma, and leukemia were matched by race, gender, age, year of death, and county of residence to controls who died from cardiovascular disease. A total of 618 (309 matched pairs) white male residents of Kanawha County, WV, aged 23-96, who had died between 1965 and 1990 were identified. Conditional logistic regression was conducted and yielded an association between chemical industry work and death due to non-Hodgkin's lymphoma, multiple myeloma, and lymphoid leukemia among subjects who died at age < 65. These results are consistent with the findings of previous studies linking work in chemical manufacturing to hematopoietic and lymphoid neoplasms, and indicate that the excesses may be related to the occupational exposures in men who died at younger ages.

Aged

A case-control study of lung cancer mortality in six Gila Basin, Arizona smelter towns.

To investigate factors related to lung cancer mortality in six Arizona copper smelter towns, we identified 185 lung cancer cases and two matched controls per case from decedent residents during 1979-1990. Detailed information on lifetime residential, occupational, and smoking history was obtained by structured telephone interviews with knowledgeable informants. Interviews were completed for 82% of 183 eligible cases and 88% of the targeted number (366) of controls. Estimated historical environmental exposures to smelter emissions, based on atmospheric diffusion modeling of measured SO2 concentrations, were linked with residential histories to derive individual profiles of residential exposure. Occupational histories were characterized by potential exposure to smelter emissions, asbestos, and ionizing radiation. Conditional logistic regression was used to compare study factors in cases and controls with adjustment for potential confounding factors: gender, Hispanic ethnicity, and smoking. In overall and gender-specific analyses, no statistically significant associations were observed between lung cancer risk and any of the measures of residential exposure to smelter emissions considered (town of residence at time of death, highest level of exposure, and duration or cumulative exposure above background levels), or any of the estimated occupational exposures (definite or potential asbestos, potential ionizing radiation, definite or potential smelter). Among male residents of some, but not all, towns, there was some evidence of a positive association between lung cancer risk and reported copper smelter-related employment (reported as definite), with the highest risk observed for Miami, Arizona. This study provided little evidence of a positive association between lung cancer mortality and residential exposure to smelter emissions. Specific factors associated with the apparent heterogeneity in lung cancer risk across study towns cannot be identified in this community-based study.

Arizona

A two-stage protocol for verifying vital status in large historical cohort studies.

When access to the Social Security Administration's Master Death Claim File was restricted in the mid-1980s, researchers were left with no time- and cost-effective protocol for verifying the vital status of large historical cohorts. A two-stage tracing protocol was designed to overcome this restriction. Stage I relies on national-scale sources to focus on the complete and accurate identification of deaths among persons unconfirmed as alive and assumes that persons not identified as deceased are alive. Stage II tests the "alive" assumption by extensively tracing a random sample of cohort members with unconfirmed vital status. Stage II provides unbiased estimates of the proportion of deaths among the assumed "alives" in the cohort (misclassification rate) and the proportion of persons untraceable in the total cohort. This paper describes our two-stage protocol and an application to a large, ongoing occupational cohort study.

Aged

Over- and underrepresentation of short DNA words in herpesvirus genomes.

The relative abundance and rarity of DNA words have been recognized in previous biological studies to have implications for the regulation, repair, and evolutionary mechanisms of a genome. In this paper, we review several different measures of abundance and rarity of DNA words, including z-scores, representation ratios, and cross-ratios, that have appeared in the recent literature, and examine the concordance among them using the human cytomegalovirus genome sequence. We then rank all words of length k = 2, ..., 5 of seven herpesvirus genomes according to their abundance, as measured by one of the z-scores based upon a stationary Markov model of order k-2. Using a simple metric on the ranks of 2-words of the seven herpesvirus sequences, we construct an evolutionary tree. Several 3-words are observed to be consistently over- or underrepresented in all seven herpesviruses. Furthermore, clusters of some of the most over- and underrepresented 4- and 5-words in the genomes are identified with functional sites such as the origins of replication and regulatory signals of individual viruses.

Algorithms

Mortality among chemical workers in a factory where formaldehyde was used.

OBJECTIVES: An independent and updated historical cohort mortality study was conducted among chemical plant workers to investigate further an association between exposures to formaldehyde and particulates and cancers of the nasopharynx and lung reported in an earlier National Cancer Institute study of the same plant. METHODS: Subjects were 7359 workers who were first employed between 1941 and 1984 in a factory in Wallingford, Connecticut where formaldehyde was used. Vital status was determined on 31 December 1984 for 96% of the cohort and death certificates were obtained for 93% of 1531 known deaths. Exposures of individual workers were estimated quantitatively for formaldehyde, product particulates, and non-product particulates, and qualitatively for pigment. Statistical analyses focused on 6039 white men in 1945-84. Cohort data that could not have been included in the National Cancer Institute study were also analysed separately. RESULTS: Mortality among long term workers (employed > or = 1 y) was generally similar to or more favourable than that of the general population, and there was little evidence of a relation between either rates of lung cancer or standardised mortality ratios (SMRs) and several measures of exposure to formaldehyde, particulates, and pigment. For several causes including lung cancer, death rates among short term workers (employed < 1 y) were significantly increased. Short term workers did not seem to differ from long term workers for the exposures considered. Among all white men, a significant SMR of 550 (local comparison) for nasopharyngeal cancer (NPC) was based on the same four index cases identified in the earlier study of this plant. Only one case of nasopharyngeal cancer had any appreciable exposure to formaldehyde. No new cases of nasopharyngeal cancers were found among the cohort data that could not have been included in the National Cancer Institute study--that is, extended observation time and additional study members. CONCLUSIONS: Among workers employed for at least one year, this study provides little evidence that the risk of lung cancer is associated with exposure to formaldehyde alone or in combination with particulates or pigment. The significant increases in both the rates and SMRs for lung cancer seem to be primarily a phenomenon of short term workers, but the possibility remains that unmeasured occupational or non-occupational factors may have played a part.

Chemical Industry

Costs of diabetes in Texas, 1992.

OBJECTIVE: To estimate direct and indirect costs of diabetes in Texas in 1992. RESEARCH DESIGN AND METHODS: For most direct medical costs, we relied on third party and provider billing databases, including Medicare, Medicaid, VA facilities, public hospitals, and others. The researchers identified people with diabetes in the respective databases, located all records of their care, and sorted records as clearly, probably, or probably not attributable to diabetes on the basis of principal diagnoses. In most cases, costs were valued as allowable or paid charges. Some medical costs, such as private insurance, were estimated from national data and state surveys. Indirect costs included current short- and long-term disability costs and the discounted present value of future costs of mortality. Disability estimates relied on National Health Interview Survey (NHIS) data and U.S. Department of Labor wage data applied to Texas. Mortality estimates were based on death certificates. RESULTS: Total costs clearly or probably attributable to diabetes among Texans in 1992 were estimated at $4.0 billion. Direct medical costs were approximately $1.6 billion. Indirect costs were estimated at $2.4 billion. the largest direct costs were paid by Medicare. Most indirect costs were from long-term disability. CONCLUSIONS: This study demonstrates methods for conducting cost of illness studies at the state level. In a state like Texas, with a large and growing Mexican-American population, estimation of current and future economic costs of diabetes is vital for development of strategies to minimize social and economic consequences of diabetes.

Costs and Cost Analysis

Cancers related to exposure to arsenic at a copper smelter.

OBJECTIVE: This is an update of an earlier study on the relation between exposure to arsenic in air and deaths from respiratory cancer. The purpose was to verify earlier findings of a supralinear dose response relation and to examine relations with other cancers, particularly those reported in studies on drinking water. METHODS: An earlier study of 2802 men who worked at a copper smelter for a year or more during the period 1940-64 and who were followed up for deaths during the period 1941-76 was updated until 1986. Estimates of exposure for the period 1977-1984 were added. RESULTS AND CONCLUSIONS: The additional follow up confirms the earlier finding that at low doses the increments in death rates for respiratory cancer for a given increment in dose are greater than at high doses. The additional follow up also shows significant increases in cancer of the large intestine and bone, and SMRs > 150 for cancer of the buccal cavity and pharynx, rectal cancer, and kidney cancer. There was a positive relation between exposure to arsenic in air and kidney and bone cancer, but none for the other cancers, except respiratory.

Air

Statistical power to detect occupationally related respiratory cancer risk in a cohort of female employees in the US man-made vitreous fiber industry.

The current update of the US man-made vitreous fiber production worker cohort includes women for the first time. Preliminary comparisons of 3,820 female and 27,767 male workers from 11 participating fibrous glass plants show different hiring patterns during World War II. The gender-specific person-year distributions are similar with respect to duration of employment and time since first employment. The current follow-up of 118,559 person-years for women provides an estimated 80% power to detect a threefold relative risk of respiratory cancer for women who worked more than 14 years in these plants, based on a Poisson regression analysis of the cohort rates. When women comprise a small fraction of the cohort, the statistical power may be inadequate to detect risks of the magnitude typically of interest in studies of men.

Aged

Evaluation issues in the Drake Chemical Workers Notification and Health Registry Study.

The Drake Chemical Workers' Health Registry combined notification of workers about bladder cancer risk with access to a free program for screening and diagnosis. Evaluation of the project has given rise to several findings and new research questions. Findings in this article illustrate the following evaluation issues: 1) studying the combination of strategies that are most effective and cost effective to notify workers of their disease risks, 2) determining the realistic yield from strategies to gain participation in health screening and other protective services for notified workers, 3) identifying the notification strategies that were most effective for different kinds of participants, 4) using process evaluation to identify key activities for ensuring continued participation of cohort members in screening, and 5) examining the extent to which participants are willing to quit smoking to protect their health.

2-Naphthylamine

Trends in cancer mortality in Kanawha County, West Virginia, 1950-1984.

There has been much concern recently about possible adverse health effects related to exposure to toxic chemicals among residents of Kanawha County in southern West Virginia. An epidemiological study of trends in cancer mortality from 1950-1984 among the general population of Kanawha County in southern West Virginia was mounted. Cabell County, West Virginia was chosen to be a comparison county for Kanawha in addition to West Virginia and the total United States. The cancer mortality rates for white males and females were calculated using NCHS mortality data and Census Bureau population data available on the Mortality and Population Data System (MPDS) at the University of Pittsburgh. Mortality rates for cancer in Kanawha and Cabell Counties were evaluated over the time period 1950-1984 with an age-period-cohort (APC) analysis. In this analysis, poisson regression models were fit using the statistical program GLIM (Generalized Linear Models) to determine the separate effects of age, period of death, and birth cohort on the specific cancers of interest (lung, liver, bladder, CNS, leukemia, lympho-reticulosarcoma, all cancers). There were no significant county differences for cancer death rates between Kanawha and Cabell Counties except for leukemia among white males [O.R. = 1.27, 95% (C.I. = 1.03-1.6)], and for lympho-reticulosarcoma [O.R. = 1.66(1.24-2.07)], suggesting a possible occupational exposure. For leukemia, aleukemia, the effect observed seems to have declined. In contrast, the elevation of lympho-reticulosarcoma rates has remained in recent years (1970-1984).

Adolescent

A comparative ecological study of selected cancers in Kanawha County, West Virginia.

This study compares mortality rates for selected causes of death in Kanawha County, West Virginia, to rates reported in a number of geographically defined populations for 1950-1984. Specific conditions selected for study included cancers of the biliary passages and liver, the bladder and other urinary organs, and the central nervous system (CNS), as well as leukemia and aleukemia, lymphosarcoma and reticulosarcoma, Hodgkin's disease, and cancer of all other lymphopoietic tissue. The analysis made use of several techniques for the investigation of ecological data, including the modeling of rates using Poission regression. The primary findings of this study concern two subgroups of cancers of the lymphatic and hematopoietic tissue: (1) leukemia and aleukemia, and (2) lymphosarcoma and reticulosarcoma. For both subgroups of cancers, white male residents of Kanawha County show evidence of significantly elevated mortality rates over the 35-year period of this study.

Adult

Lung cancer mortality among industrial workers exposed to formaldehyde: a Poisson regression analysis of the National Cancer Institute Study.

The Formaldehyde Institute (FI) sponsored additional Poisson regression analysis of lung cancer mortality data from the joint National Cancer Institute (NCI)/FI cohort study of workers exposed to formaldehyde to investigate the previously reported effects of plant and latency period and to assess the impact of short-term workers (under 1 yr employment) on the results. There were 242 lung cancer deaths in this cohort of 20,067 white male workers. With OCMAP software, lung cancer death rates for the white males in this cohort were computed by plant, age, calendar time, and job type for several time-dependent formaldehyde exposures, including formaldehyde exposure in the presence of 12 selected co-exposures: ammonia (AM), antioxidants (AN), asbestos (AS), carbon black (CB), dyes/inks/pigments (DY), hexamethylenetetramine (HX), melamine (ME), particulates (PT), phenol (PH), plasticizers (PL), urea/urea compounds (UR), wood dust (WD), and a composite co-exposure (X5) involving AN, HX, ME, PH, and UR.A 1.6-fold increase in lung cancer risk was found, beginning approximately 16-20 yr after first employment in the study plants with no evidence of a differential effect of latency between hourly and salaried workers or among the various categories of formaldehyde exposure as measured by cumulative average intensity or length of exposure. The statistically significant heterogeneity in lung cancer risk among the 10 plants could not be explained by interplant differences in cumulative or average intensity of exposure to formaldehyde, either without regard to co-exposures or in the presence of any of the 12 co-exposures considered individually. Plant was not a statistically significant predictor of lung cancer risk when cumulative exposure to the composite X5 was included in the model, suggesting that some component of X5, or a correlate, could at least partly account for the overall heterogeneity. No significant associations were found for cumulative, average, or length of exposure to formaldehyde without regard to co-exposure, but positive associations were found for cumulative exposure to formaldehyde in the presence of several co-exposures (AN, HX, ME, PH, and UR). For workers who were never exposed to any of 10 co-exposures associated with an increased lung cancer risk, there was a decreasing pattern of estimated lung cancer risk ratios relative to cumulative formaldehyde exposure. Similar patterns were seen when the analysis was restricted to the long-term workers. Analysis of the internal cohort rates corroborates previous analyses of NCI/FI cohort data in that significant positive associations were found between the risk of lung cancer and cumulative exposure to formaldehyde in the presence of several of the same co-exposures. No such associations were found in the absence of these co-exposures.

Adult

Mortality patterns among petroleum refinery and chemical plant workers.

A historical cohort study was conducted to evaluate the mortality experience of 6,831 employees of the Shell Oil Company, Deer Park, Texas, petroleum refinery and chemical plant with emphasis on cancer mortality. Subjects were all workers with potential plant exposure who were employed for at least 3 months during 1948-72. Vital status was determined as of 12/31/83 for 98% of the cohort and death certificates were obtained for 95.4% of 1,180 observed deaths. The statistical analyses excluded 159 female study members. For all causes of death combined, all cancers combined, and for most of the nonmalignant disease categories examined, there were deficits in mortality among refinery workers, chemical plant workers, and workers with experience in both areas. These deficits were generally most pronounced for chemical plant workers. An analysis of specific cancer sites revealed patterns of increased risk suggestive of a possible relationship between occupational exposures in the refinery and lympho-reticulosarcoma. Patterns of increased risk were also observed among chemical plant workers for a category of lymphopoietic tissue cancers, including multiple myeloma, myelofibrosis, polycythemia vera, and certain non-Hodgkin's lymphomas. Some very limited evidence of a possible workplace association was also found among refinery workers for leukemia and cancers of the central nervous system and biliary passages/liver. No evidence was found of an increased risk for cancer of the respiratory system or stomach or for malignant melanoma. A work history review of all suspect cancer excesses failed to identify any common work areas, job assignments, or exposure potentials, although the lack of detailed data on specific chemical exposures precluded accurate assessments of exposure-response.

Actuarial Analysis