Prevalent cohort studies and unobserved heterogeneity

2019 ◽  
Vol 25 (4) ◽  
pp. 712-738
Author(s):  
Niels Keiding ◽  
Katrine Lykke Albertsen ◽  
Helene Charlotte Rytgaard ◽  
Anne Lyngholm Sørensen
2011 ◽  
Vol 174 (8) ◽  
pp. 969-976 ◽  
Author(s):  
A. Torner ◽  
P. Dickman ◽  
A.-S. Duberg ◽  
S. Kristinsson ◽  
O. Landgren ◽  
...  

2014 ◽  
Vol 05 (11) ◽  
pp. 1672-1683 ◽  
Author(s):  
Yujie Zhong ◽  
Richard J. Cook

Author(s):  
Seyed Mostafa Parizadeh ◽  
Majid Rezayi ◽  
Reza Jafarzadeh-Esfehani ◽  
Amir Avan ◽  
Hamideh Ghazizadeh ◽  
...  

Abstract. Background: Vitamin D deficiency (VDD) is a major public health problem. There are few comprehensive systematic reviews about the relationship between Vitamin D status and liver and renal disease in Iran. Methods: We systemically searched the following databases: Web of Science; PubMed; Cochrane Library; Scopus; Science Direct; Google Scholar and two Iranian databases (Scientific Information Database (SID) and IranMedex) up until November 2017 to identify all randomized control trials (RCTs), case control, cross-sectional and cohort studies investigating the association between vitamin D and any form of liver or kidney disease. Results: Vitamin D insufficiency, or deficiency (VDD), is highly prevalent in Iran, reports varying between 44.4% in Isfahan to 98% in Gorgan. There is also a high prevalence of VDD among patients with liver or kidney disease, and the administration of vitamin D supplements may have beneficial effects on lipid profile, blood glucose, liver function and fatty liver disease, and bone health. Low serum vitamin D levels are related with abnormalities in these laboratory and clinical parameters. Conclusion: VDD is prevalent in patients with chronic liver or renal disease in Iran. There appear to be several beneficial effects of vitamin D supplementation in vitamin D deficient patients with liver or kidney disease.


Crisis ◽  
2011 ◽  
Vol 32 (4) ◽  
pp. 204-216 ◽  
Author(s):  
M. L. Rurup ◽  
H. R. W. Pasman ◽  
J. Goedhart ◽  
D. J. H. Deeg ◽  
A. J. F. M. Kerkhof ◽  
...  

Background: Quantitative studies in several European countries showed that 10–20% of older people have or have had a wish to die. Aims: To improve our understanding of why some older people develop a wish to die. Methods: In-depth interviews with people with a wish to die (n = 31) were carried out. Through open coding and inductive analysis, we developed a conceptual framework to describe the development of death wishes. Respondents were selected from two cohort studies. Results: The wish to die had either been triggered suddenly after traumatic life events or had developed gradually after a life full of adversity, as a consequence of aging or illness, or after recurring depression. The respondents were in a situation they considered unacceptable, yet they felt they had no control to change their situation and thus progressively “gave up” trying. Recurring themes included being widowed, feeling lonely, being a victim, being dependent, and wanting to be useful. Developing thoughts about death as a positive thing or a release from problems seemed to them like a way to reclaim control. Conclusions: People who wish to die originally develop thoughts about death as a positive solution to life events or to an adverse situation, and eventually reach a balance of the wish to live and to die.


2008 ◽  
Vol 29 (3) ◽  
pp. 134-147 ◽  
Author(s):  
Manuel C. Voelkle ◽  
Nicolas Sander

University dropout is a politically and economically important factor. While a number of studies address this issue cross-sectionally by analyzing different cohorts, or retrospectively via questionnaires, few of them are truly longitudinal and focus on the individual as the unit of interest. In contrast to these studies, an individual differences perspective is adopted in the present paper. For this purpose, a hands-on introduction to a recently proposed structural equation (SEM) approach to discrete-time survival analysis is provided ( Muthén & Masyn, 2005 ). In a next step, a prospective study with N = 1096 students, observed across four semesters, is introduced. As expected, average university grade proved to be an important predictor of future dropout, while high-school grade-point average (GPA) yielded no incremental predictive validity but was completely mediated by university grade. Accounting for unobserved heterogeneity, three latent classes could be identified with differential predictor-criterion relations, suggesting the need to pay closer attention to the composition of the student population.


2017 ◽  
Vol 14 (3) ◽  
pp. 331-342 ◽  
Author(s):  
Thomas John Cooke ◽  
Ian Shuttleworth

It is widely presumed that information and communication technologies, or ICTs, enable migration in several ways; primarily by reducing the costs of migration. However, a reconsideration of the relationship between ICTs and migration suggests that ICTs may just as well hinder migration; primarily by reducing the costs of not moving.  Using data from the US Panel Study of Income Dynamics, models that control for sources of observed and unobserved heterogeneity indicate a strong negative effect of ICT use on inter-state migration within the United States. These results help to explain the long-term decline in internal migration within the United States.


Human Ecology ◽  
2016 ◽  
pp. 56-64
Author(s):  
K. K. Kholmatova ◽  
О. A. Kharkova ◽  
A. M. Grjibovski
Keyword(s):  

Author(s):  
K. . Togawa

Agricultural workers can be exposed to a wide variety of agents (e.g. pesticides), some of which may have adverse health effects, such as cancer. To study the health effects of agricultural exposures, an international consortium of agricultural cohort studies, AGRICOH, was established. The present analysis compared cancer incidence between the AGRICOH cohorts and the general population and found lower overall cancer incidence in the AGRICOH cohorts, with some variation across cohorts for specific cancer types. The observed lower cancer incidence may be due to healthy worker bias or lower prevalence of risk factors in the agricultural populations. Further analysis is underway.


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