Search

A variety of dimensions (lengths and widths) of elongate mineral particles (EMPs) have been proposed as being related to health effects. In this paper, we develop a mathematical approach for deriving numerical conversion factors (CFs) between these EMP exposure metrics and applied it to the Minnesota Taconite Health Worker study which contains 196 different job exposure groups (28 similar exposure groups times 7 taconite mines). This approach comprises four steps: for each group (i) obtain EMP dimension information using ISO-TEM 10312/13794 analysis; (ii) use bivariate lognormal distribution to characterize overall EMP size distribution; (iii) use a Bayesian approach to facilitate the formation of the bivariate lognormal distribution; (iv) derive conversion factors between any pair of EMP definitions. The final CFs allow the creation of job exposure matrices (JEMs) for alternative EMP metrics using existing EMP exposures already characterized according to the National Institute of Occupational Safety and Health (NIOSH)-defined EMP exposure metric (length >5 µm with an aspect ratio ≥3.0). The relationships between the NIOSH EMP and other EMP definitions provide the basis of classification of workers into JEMs based on alternate definitions of EMP for epidemiological studies of mesothelioma, lung cancer, and non-malignant respiratory disease., (© The Author(s) 2020. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.)

This paper presents an evaluation of the sustainability of health and safety improvements in small auto collision shops 1 year after the implementation of a year-long targeted intervention. During the first year (active phase), owners received quarterly phone calls, written reminders, safety newsletters, and access to online services and in-person assistance with creating safety programs and respirator fit testing. During the second year (passive phase), owners received up to three postcard reminders regarding the availability of free health and safety resources. Forty-five shops received an evaluation at baseline and at the end of the first year (Y1). Of these, 33 were evaluated at the end of the second year (Y2), using the same 92-item assessment tool. At Y1, investigators found that between 70 and 81% of the evaluated items were adequate in each business (mean = 73% items, SD = 11%). At Y2, between 63 and 89% of items were deemed adequate (mean = 73% items, SD = 9.5%). Three safety areas demonstrated statistically significant (P < 0.05) changes: compressed gasses (8% improvement), personal protective equipment (7% improvement), and respiratory protection (6% decline). The number of postcard reminders sent to each business did not affect the degree to which shops maintained safety improvements made during the first year of the intervention. However, businesses that received more postcards were more likely to request assistance services than those receiving fewer., (© The Author 2014. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.)

The Rochester Epidemiology Project (REP) medical records-linkage system was established in 1966 to capture health care information for the entire population of Olmsted County, MN, USA. The REP includes a dynamic cohort of 502 820 unique individuals who resided in Olmsted County at some point between 1966 and 2010, and received health care for any reason at a health care provider within the system. The data available electronically (electronic REP indexes) include demographic characteristics, medical diagnostic codes, surgical procedure codes and death information (including causes of death). In addition, for each resident, the system keeps a complete list of all paper records, electronic records and scanned documents that are available in full text for in-depth review and abstraction. The REP serves as the research infrastructure for studies of virtually all diseases that come to medical attention, and has supported over 2000 peer-reviewed publications since 1966. The system covers residents of all ages and both sexes, regardless of socio-economic status, ethnicity or insurance status. For further information regarding the use of the REP for a specific study, please visit our website at www.rochesterproject.org or contact us at info@rochesterproject.org. Our website also provides access to an introductory video in English and Spanish.

In shaded environments, minimizing dark respiration during growth could be an important aspect of maintaining a positive whole-plant net carbon balance. Changes with plant size in both biomass distribution to different tissue types and mass-specific respiration rates (R(d)) of those tissues would have an impact on whole-plant respiration. In this paper, we evaluated size-related variation in R(d), biomass distribution, and nitrogen (N) and total nonstructural carbohydrate (TNC) concentrations of leaves, stems and roots of three cold-temperate tree species (Abies balsamea (L.) Mill, Acer rubrum L. and Pinus strobus L.) in a forest understory. We sampled individuals varying in age (6 to 24 years old) and in size (from 2 to 500 g dry mass), and growing across a range of irradiances (from 1 to 13% of full sun) in northern Minnesota, USA. Within each species, we found small changes in R(d), N and TNC when comparing plants growing across this range of light availability. Consistent with our hypotheses, as plants grew larger, whole-plant N and TNC concentrations in all species declined as a result of a combination of changes in tissue N and shifts in biomass distribution patterns. However, contrary to our hypotheses, whole-plant and tissue R(d) increased with plant size in the three species.

This paper examines effect modification of heat- and cold-related mortality in seven US cities in 1986-1993. City-specific Poisson regression analyses of daily noninjury mortality were fit with predictors of mean daily apparent temperature (a construct reflecting physiologic effects of temperature and humidity), time, barometric pressure, day of the week, and particulate matter less than 10 micro m in aerodynamic diameter. Percentage change in mortality was calculated at 29 degrees C apparent temperature (lag 0) and at -5 degrees C (mean of lags 1, 2, and 3) relative to 15 degrees C. Separate models were fit to death counts stratified by age, race, gender, education, and place of death. Effect estimates were combined across cities, treating city as a random effect. Deaths among Blacks compared with Whites, deaths among the less educated, and deaths outside a hospital were more strongly associated with hot and cold temperatures, but gender made no difference. Stronger cold associations were found for those less than age 65 years, but heat effects did not vary by age. The strongest effect modifier was place of death for heat, with out-of-hospital effects more than five times greater than in-hospital deaths, supporting the biologic plausibility of the associations. Place of death, race, and educational attainment indicate vulnerability to temperature-related mortality, reflecting inequities in health impacts related to climate change.

While time-series studies have consistently provided evidence for an effect of particulate air pollution on mortality, uncertainty remains as to the extent of the life-shortening implied by those associations. In this paper, the authors estimate the association between air pollution and mortality using different timescales of variation in the air pollution time series to gain further insight into this question. The authors' method is based on a Fourier decomposition of air pollution time series into a set of independent exposure variables, each representing a different timescale. The authors then use this set of variables as predictors in a Poisson regression model to estimate a separate relative rate of mortality for each exposure timescale. The method is applied to a database containing information on daily mortality, particulate air pollution, and weather in four US cities (Pittsburgh, Pennsylvania; Minneapolis, Minnesota; Seattle, Washington; and Chicago, Illinois) from the period 1987-1994. The authors found larger relative rates of mortality associated with particulate air pollution at longer timescale variations (14 days-2 months) than at shorter timescales (1-4 days). These analyses provide additional evidence that associations between particle indexes and mortality do not imply only an advance in the timing of death by a few days for frail individuals.

This paper examines associations between overall school functioning and frequency of violent behaviors among young adolescents (ages 10-14). The sample included 16 middle schools participating in an unrelated intervention study (on nutrition) in Minneapolis, Minnesota. A School Functioning Index, developed to characterize schools' overall stability, performance and demographics, was constructed using data from public archives and school administrator surveys. Data on violent behaviors and other variables were collected in student surveys in fall 1998 and spring 1999. We used multilevel modeling to assess the effect of school functioning on violent behavior after adjusting for known individual-level covariates of violent behaviors. We found an interaction between school functioning (group-level variable) and expectations for future education (individual-level variable). Among students who reported expectations of completing a college degree (71% of the sample), positive school functioning was negatively associated with violent behaviors. Among students that reported expectations of completing less than a college degree, no association was found between school functioning and violent behaviors. These results support earlier work suggesting that objectively measured school characteristics are associated with students' violent behaviors even after accounting for individual-level factors and also identify a subgroup of students for whom school detachment may be an issue.

The use of survival models involving a random effect or 'frailty' term is becoming more common. Usually the random effects are assumed to represent different clusters, and clusters are assumed to be independent. In this paper, we consider random effects corresponding to clusters that are spatially arranged, such as clinical sites or geographical regions. That is, we might suspect that random effects corresponding to strata in closer proximity to each other might also be similar in magnitude. Such spatial arrangement of the strata can be modeled in several ways, but we group these ways into two general settings: geostatistical approaches, where we use the exact geographic locations (e.g. latitude and longitude) of the strata, and lattice approaches, where we use only the positions of the strata relative to each other (e.g. which counties neighbor which others). We compare our approaches in the context of a dataset on infant mortality in Minnesota counties between 1992 and 1996. Our main substantive goal here is to explain the pattern of infant mortality using important covariates (sex, race, birth weight, age of mother, etc.) while accounting for possible (spatially correlated) differences in hazard among the counties. We use the GIS ArcView to map resulting fitted hazard rates, to help search for possible lingering spatial correlation. The DIC criterion (Spiegelhalter et al., Journal of the Royal Statistical Society, Series B 2002, to appear) is used to choose among various competing models. We investigate the quality of fit of our chosen model, and compare its results when used to investigate neonatal versus post-neonatal mortality. We also compare use of our time-to-event outcome survival model with the simpler dichotomous outcome logistic model. Finally, we summarize our findings and suggest directions for future research.

Objective: The objective of this paper is to report trends in mortality due to coronary heart disease (CHD), rates of first and recurrent hospitalized myocardial infarction, and survival after myocardial infarction in the Atherosclerosis Risk in Communities (ARIC) Study from 1987 through 1996., Method: The ARIC study used retrospective community surveillance to monitor admissions to acute care hospitals and deaths due to CHD (both in- and out-of-hospital) among all residents 35-74 years of age. The surveillance areas included over 360 000 men and women in four communities: Forsyth County, North Carolina; the city of Jackson, Mississippi; eight northern suburbs of Minneapolis, Minnesota; and Washington County, Maryland., Results: The annual age-adjusted mortality rate of CHD fell 3.2% (95% CI: 2.0, 4.3) among men and 3.8% (95% CI: 1.9, 5.6) among women. The greater part of the decline took place between 1987 and 1991. Significant declines were observed for both in-hospital and out-of-hospital CHD death. Significant improvements in case-fatality were also observed. Recurrent hospitalized myocardial infarction event rate fell an average of 1.9% per year among men (95% CI: 0.7, 3.1) and 2.1% (95% CI: 0.3, 3.9) among women. Average annual per cent change in incident hospitalized myocardial infarction was not statistically significant, except in blacks where there was evidence of an increase over time., Conclusion: Factors associated with the occurrence of recurrent hospitalized myocardial infarction, as well as those creating a better chance of survival after an event (including reductions in sudden death), were likely the prominent components in the recent decline in CHD mortality in ARIC communities.

Project Northland is a randomized trial designed to create, implement and evaluate multilevel, community-wide strategies to prevent alcohol use among adolescents. This paper will focus on the mediating outcomes of the early adolescent phase of Project Northland when the students in the study cohort were in Grades 6-8. The project was conducted in 24 school districts and adjacent communities in northeastern Minnesota. The intervention consisted of social-behavioral curricula in schools, peer leadership activities, parental involvement and education, and community-wide activities. At the end of 3 years of intervention, significantly fewer students in the intervention school districts reported alcohol use than students in the reference districts. Mediation analyses were conducted to investigate if the intervention's effects on mediating variables could explain the reduction in alcohol use. Important mediators of Project Northland's effect on alcohol use were: (1) peer influence to use, including normative estimates, (2) functional meanings of alcohol use, (3) attitudes and behaviors associated with alcohol and drug problems like stimulus seeking, rule violations and bad judgement, and (4) parent-child alcohol-related communication around alcohol use. In addition, among those who did not use alcohol at baseline, self-efficacy to refuse offers of alcohol was a significant mediator.

The pattern of deterioration in patients with Alzheimer's disease is highly variable within a given population. With recent speculation that the apolipoprotein E allele may influence rate of decline and claims that certain drugs may slow the course of the disease, there is a compelling need for sound statistical methodology to address these questions. Current statistical methods for describing decline do not adequately take into account between-patient variability and possible floor and/or ceiling effects in the scale measuring decline, and they fail to allow for uncertainty in disease onset. In this paper, the authors analyze longitudinal Mini-Mental State Examination scores from two groups of Alzheimer's disease subjects from Palo Alto, California, and Minneapolis, Minnesota, in 1981-1993 and 1986-1988, respectively. A Bayesian hierarchical model is introduced as an elegant means of simultaneously overcoming all of the difficulties referred to above.

A population-based case-control study of renal cell cancer was conducted in Minnesota between 1988 and 1990. It included 690 histologically confirmed incident cases identified through the state cancer surveillance system, and 707 age and sex frequency-matched controls. In this paper, the authors present estimates of the proportion of renal cell cancer cases attributable (or population attributable risk (PAR)) to 1) well-established risk factors, namely smoking, excess weight, and hypertension, and 2) more speculative risk factors, namely elevated protein intake, history of renal disease (i.e., stone, injury, or infection) and high parity among women. These estimates were based on information obtained from directly interviewed subjects (65% of cases and 100% of controls). The PARs for the three main risk factors were 21% for hypertension (defined by a reported personal history of hypertension or of treatment with antihypertensive or diuretic drugs), 21% for excess weight (defined by an elevation of the usual body mass index above the first quartile), and 18% for smoking (past and current). Overall, these three factors accounted for 49% of cases. The proportion increased to 60% when the three more speculative risk factors were considered as well. Sex-specific analyses revealed a greater impact of smoking among men mainly due to a higher prevalence of past smoking. In contrast, the impact of hypertension and excess weight was greater among women due to higher relative risks. These results suggest that 1) intervention measures aimed at reducing smoking, excess weight, and hypertension could substantially lower the overall incidence of renal cell cancer, and 2) intervention measures may have to be sex-specific. Conversely, because at least 40% of cases remain unexplained by the risk factors under study, further etiologic research is needed into renal cell cancer, an increasingly common form of cancer.

While most previous studies of elderly migration have investigated permanent migration using Census data, this paper employs household (micro) data from statewide surveys conducted in Arizona and Minnesota to analyze seasonal migration as an economic decision. Estimation of logistic regression models for each state indicate income and age are important determinants, whereas these variables have not proven significant in previous studies based on aggregate data. The results lead to the conclusion that seasonal migration may be an integral part of a life cycle of elderly migration.

The authors present a method of estimating the duration of ongoing prevention trials, showing how the method was applied to the Colon Cancer Control Study, a University of Minnesota study of occult blood testing undertaken to screen for colorectal cancer in older Minnesotans. In that study, begun in 1975 and ongoing, as in several other recent large prevention trials, it was necessary, after the start of the study, to revise upward the initial estimates of study duration derived from general population experience. The underestimates arose because the planners had not adequately taken various population selection factors into account in estimating the expected number of events in the control group. In this paper, the authors outline a method for estimating control group event rates and study duration requirements (and, in some circumstances, also sample size requirements) of prevention studies, via models of disease-specific and all-cause standardized mortality ratios which adjust for various selection effects. The authors also validate the model for disease-specific standardized mortality ratios by means of independent estimates of disease incidence and case survival.

We used findings from the Minnesota Senior Study to examine the theoretical and methodological difficulties of defining, coding, and analyzing data on older volunteers. This study, the first statewide survey of the needs and resources of the elderly in Minnesota in almost 20 years, found that over half (52%) of older Minnesotans do volunteer work for organizations--considerably higher than has been found in national surveys. Problems in definition and methodology, however, have confounded analyses. This paper proposes a new conceptual model for classifying volunteer roles, based on three dimensions: whether the voluntary service is "formal" or "informal"; whether the activity entails a regular or an occasional time commitment; and the nature of the service activity (person-to-community, person-to-object, or person-to-person).

The management of pancreatic pain is a controversial subject and the treatment recommended varies from one extreme to the other. Some authorities advise simply waiting for chronic pancreatitis to 'burn out', while others practise removal of the entire gland. In this paper we present 141 patients who underwent surgery for chronic pancreatitis at the Mayo Clinic. The main indication for operation was pancreatic pain and the choice of operation was based on anatomical abnormalities in the gland. The long-term results of the policy are reviewed (mean follow-up 8.5 years). Length of history, aetiology of disease, pancreatic dysfunction and pathology, time after operation and continued alcohol abuse were computer analysed for a statistically significant influence on pain relief, ability to work, pancreatic function and survival. There was one operative death (mortality rate 0.7 per cent). Continued drinking was not shown to affect postoperative pain relief but 10-year survival was significantly less in alcoholics than in those with non-alcoholic pancreatitis (P less than 0.02). Dilated ducts and duct calculi were associated with good results for pain relief although this association did not achieve statistical significance. Parenchymal calcification and time after operation did not influence the results of surgery. When the operation failed to relieve pain, spontaneous remission occurred in a few cases only. Seventy-seven per cent of patients had lasting relief of pain and operations selected on the basis of gross pathology were equally effective in relieving pain. Longitudinal pancreaticojejunostomy in those with dilated ducts and a Whipple operation for disease of the pancreatic head gave good results.(ABSTRACT TRUNCATED AT 250 WORDS)

Prior to 1979, epidemiologic studies which included mortality follow-up on large cohorts relied on death certificates from last state of residence and expensive follow-up techniques to determine survival. Beginning with 1979, the National Death Index can be used to search death certificate files from all 50 states, the Virgin Islands, and Puerto Rico. This paper addresses the issue of whether mortality follow-up in epidemiologic studies based on a single state death certificate search using only data available in 1970-1975 can be compared with post-1979 mortality follow-up using the National Death Index. This question was addressed by following a cohort of 2,925 coronary heart disease and cerebrovascular disease 1980 hospital discharges from 1980 through 1983 with the use of both the National Death Index and the Minnesota Death Index (MINNDEX). Algorithms for evaluating potential death certificate matches were developed independently for both systems. The systems agreed on the survival status of 98% of the cohort, and both identified 31% as dead. This study supports the comparison of results of National Death Index follow-up to pre-National Death Index studies using algorithms such as the MINNDEX, and provides evidence that trend analyses relying on single state death searches pre-1979 and on the National Death Index from 1979 are valid, particularly in chronically ill persons.