Dose–Time–Response Models for Radiation Carcinogenesis

Curtis, Stanley B.; Thomas, Duncan C.

doi:10.1016/b978-0-12-035416-0.50007-0

Cited by 4 publications

(2 citation statements)

References 37 publications

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“…Exposure to radiation from the atomic bombs at Hiroshima and Nagasaki is an example of this type of exposure. As time passed, leukemia rates among those exposed went up for a time, relative to that expected given their age, then came back down to about ''normal'' (NAS/ NRC, 1990;Curtis and Thomas, 1992). As illustrated in the hypothetical example in Figure 1, the effect of exposure 7.5 years since exposure is about ten times that after 18 years had elapsed.…”

Section: Latency Models For Protracted Exposuresmentioning

confidence: 94%

Latency analysis in epidemiologic studies of occupational exposures: Application to the Colorado plateau uranium miners cohort

et al. 1999

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Background Latency effects are an important factor in assessing the public health implications of an occupational or environmental exposure. Usually, however, latency results as described in the literature are insufficient to answer public health related questions. Alternative approaches to the analysis of latency effects are warranted. Methods A general statistical framework for modeling latency effects is described. We then propose bilinear and exponential decay latency models for analyzing latency effects as they have parameters that address questions of public health interest. Methods are described for fitting these models to cohort or case‐control data; statistical inference is based on standard likelihood methods. Application A latency analysis of radon exposure and lung cancer in the Colorado Plateau uranium miners cohort was performed. We first analyzed the entire cohort and found that the relative risk associated with exposure increases for about 8.5 years and thereafter decreases until it reaches background levels after about 34 years. The hypothesis that the relative risk remains at its peak level is strongly rejected (P > 0.001). Next, we investigated the variation in the latency effects over subsets of the cohort based on attained age, level and rate of exposure, and smoking. Age was the only factor for which effect modification was demonstrated (P > 0.014). We found that the decline in effect is much steeper at older ages (60> years) than younger. Conclusion The proposed methods can provide much more information about the exposure–disease latency effects than those generally used. Am. J. Ind. Med. 35:246–256, 1999. © 1999 Wiley‐Liss, Inc.

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Section: Latency Models For Protracted Exposuresmentioning

confidence: 94%

Latency analysis in epidemiologic studies of occupational exposures: Application to the Colorado plateau uranium miners cohort

et al. 1999

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“…A simple sum of time-specific exposures may be appropriate if separate exposures act independently and their effect is cumulative. However, for many types of exposure, the physiological changes that accompany aging might be expected to lead to changes in exposure effects (on either an absolute or a relative scale) [Curtis and Thomas, 1992;Jarvhom, 1992;Kirkwood, 1996]. As adults age, they experience declines in lung function [Knudson et al, 1983;Sherrill, Lebowitz et al, 1992], as well as reduced efficiency of the immune system [Narayanan, 1996;Pahlavani and Richardson, 1996], decreased physical and cellular repair processes [National Research Council and Committee on the Biological Effects of Ionizing Radiation (BEIR III), 1980; Charlton, 1996], and changes in cognitive function and reaction time [Fraser et al, 1996;Kluger et al, 1997].…”

Section: Introductionmentioning

confidence: 99%

Methods for investigating age differences in the effects of prolonged exposures

Richardson

Wing

1998

Am. J. Ind. Med.

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People experience physiological changes with age which may lead to changes in sensitivity to many kinds of exposure. In situations of prolonged, low level exposure, differences in the effects of exposures received at different ages may be difficult to evaluate, since study members receive low level exposures over a range of ages. Such investigations require examination of the effects of different age‐patterns of exposure. Three approaches to investigating age‐related variability in the effects of prolonged exposures are described: subcohort analyses; the use of smooth weighting functions; and, the evaluation of separate effects of cumulative exposures received at different age ranges. Each method can contribute to the overall evaluation of age‐specific exposure effects. These methods are illustrated with occupational cohort data for employees of Oak Ridge National Laboratory. The methods presented in this paper should facilitate examination of the effects of aging on sensitivity to prolonged exposures. Am. J. Ind. Med. 33:123–130, 1998. © 1998 Wiley‐Liss, Inc.

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Time‐varying exposure and the impact of stressful life events on onset of affective disorder

Wainwright

Surtees

2002

Statistics in Medicine

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Stressful life events are now established as risk factors for the onset of affective disorder but few studies have investigated time-varying exposure effects. Discrete (grouped) time survival methods provide a flexible framework for evaluating multiple time-dependent covariates and time-varying covariate effects. Here, we use these methods to investigate the time-varying influence of life events on the onset of affective disorder. Various straightforward time-varying exposure models are compared, involving one or more (stepped) time-dependent covariates and time-dependent covariates constructed or estimated according to exponential decay. These models are applied to data from two quite different studies. The first, a small scale interviewer-based longitudinal study (n = 180) concerned with affective disorder onset following loss (or threat of loss) event experiences. The second, a questionnaire assessment as part of an ongoing population study (n = 3353), provides a history of marital loss events and of depressive disorder onset. From the first study the initial impact of loss events was found to decay with a half-life of 5 weeks. Psychological coping strategy was found to modify vulnerability to the adverse effects of these events. The second study revealed that while men had a lower immediate risk of disorder onset following loss event experience their risk period was greater than for women. Time-varying exposure effects were well described by the appropriate use of simple time-dependent covariates.

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Dose–Time–Response Models for Radiation Carcinogenesis

Cited by 4 publications

References 37 publications

Latency analysis in epidemiologic studies of occupational exposures: Application to the Colorado plateau uranium miners cohort

Latency analysis in epidemiologic studies of occupational exposures: Application to the Colorado plateau uranium miners cohort

Methods for investigating age differences in the effects of prolonged exposures

Time‐varying exposure and the impact of stressful life events on onset of affective disorder

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