scholarly journals Understanding bias when estimating life expectancy from age at death: a simulation approach applied to Morquio syndrome A

2022 ◽  
Vol 15 (1) ◽  
Author(s):  
Xue Yin ◽  
Jaeil Ahn ◽  
Simina M. Boca
Keyword(s):  
Life Expectancy ◽  
Rare Diseases ◽  
Estimation Methods ◽  
Simulation Approach ◽  
Analysis Framework ◽  
Death Record ◽  
Morquio Syndrome ◽  
Morquio Syndrome A ◽  
Biased Estimates ◽  
Death Data

Abstract Objective Life expectancy can be estimated accurately from a cohort of individuals born in the same year and followed from birth to death. However, due to the resource-consuming nature of following a cohort prospectively, life expectancy is often assessed based upon retrospective death record reviews. This conventional approach may lead to potentially biased estimates, in particular when estimating life expectancy of rare diseases such as Morquio syndrome A. We investigated the accuracy of life expectancy estimation using death records by simulating the survival of individuals with Morquio syndrome A under four different scenarios. Results When life expectancy was constant during the entire period, using death data did not result in a biased estimate. However, when life expectancy increased over time, as is often expected to be the case in rare diseases, using only death data led to a substantial underestimation of life expectancy. We emphasize that it is therefore crucial to understand how estimates of life expectancy are obtained, to interpret them in an appropriate context, and to assess estimation methods within a sensitivity analysis framework, similar to the simulations performed herein.

scholarly journals Understanding bias when estimating life expectancy from age at death: A simulation approach applied to Morquio Syndrome A

2020 ◽  
Author(s):  
Xue Yin ◽  
Jaeil Ahn ◽  
Simina M. Boca
Keyword(s):  
Life Expectancy ◽  
Rare Diseases ◽  
Estimation Methods ◽  
Survival Times ◽  
Biomedical Innovation ◽  
Downward Bias ◽  
Morquio Syndrome ◽  
Morquio Syndrome A ◽  
Death Data

BackgroundLife expectancy can be estimated accurately from a cohort of individuals born in the same year and followed from birth to death. Due to the difficult and time-consuming nature of following a cohort prospectively, life expectancy is often assessed based on death data, which may lead to potentially biased estimates. This is more likely to be a problem in rare diseases such as Morquio syndrome A.MethodTo investigate how accurate the estimation of life expectancy is using death data, we simulate the survival of individuals with Morquio syndrome A under four different survival scenarios. In each scenario, we estimate the mean and median survival times within a defined period and compare them with the true life expectancy.ResultsWhen life expectancy is constant during the entire period, using death data does not result in a biased estimate of life expectancy. However, when life expectancy increases during the follow-up period, using only death data leads to a substantial underestimation of life expectancy.ConclusionLife expectancy can change over time, along with changes in the environment and/or biomedical innovation. When the life expectancy is increasing — as is often expected to be the case in rare diseases — estimating it based on contemporary death data will result in a downward bias. Therefore, it is crucial to understand how estimates of life expectancy are obtained and to interpret them in an appropriate context, and to assess estimation methods within a sensitivity analysis framework, similar to the simulations performed herein.

scholarly journals A 16-year-old Girl with Morquio Syndrome: A Case Report

2018 ◽  
Vol 8 (3) ◽  
pp. 266-269
Author(s):  
AKM Motiur Rahman Bhuiyan ◽  
Maftahul Jannat ◽  
Md Zilan Miah Sarker ◽  
Mohammad Tanvir Islam ◽  
Amit Roy Chowdhury
Keyword(s):  
Autosomal Recessive ◽  
Autosomal Recessive Disorder ◽  
Consanguineous Marriage ◽  
Mucopolysaccharidosis Type ◽  
Skeletal Deformity ◽  
Type Iv ◽  
Morquio Syndrome ◽  
Radiological Changes ◽  
Morquio Syndrome A ◽  
Medical University

Morquio syndrome is a rare autosomal recessive disorder of mucopolysaccharide metabolism, also called mucopolysaccharidosis type IV. We report a case of Morquio syndrome in a16-year- old girl of normal intelligence, who got herself admitted in Bangabandhu Sheikh Mujib Medical University, Dhaka, Bangladesh. The patient had short stature and skeletal deformity and she belonged to a non-consanguineous marriage of her parents. She was diagnosed on the basis of clinical features, typical radiological changes and positive urinary mucopolysaccharide screening test.Birdem Med J 2018; 8(3): 266-269

scholarly journals New evidence on the impact of sustained exposure to air pollution on life expectancy from China’s Huai River Policy

2017 ◽  
Vol 114 (39) ◽  
pp. 10384-10389 ◽  
Author(s):  
Avraham Ebenstein ◽  
Maoyong Fan ◽  
Michael Greenstone ◽  
Guojun He ◽  
Maigeng Zhou
Keyword(s):  
Particulate Matter ◽  
Life Expectancy ◽  
Airborne Particulate Matter ◽  
Estimation Methods ◽  
Regression Discontinuity Design ◽  
Airborne Particulate ◽  
Life Years ◽  
Huai River ◽  
The Impact ◽  
New Evidence

This paper finds that a 10-μg/m3 increase in airborne particulate matter [particulate matter smaller than 10 μm (PM10)] reduces life expectancy by 0.64 years (95% confidence interval = 0.21–1.07). This estimate is derived from quasiexperimental variation in PM10 generated by China’s Huai River Policy, which provides free or heavily subsidized coal for indoor heating during the winter to cities north of the Huai River but not to those to the south. The findings are derived from a regression discontinuity design based on distance from the Huai River, and they are robust to using parametric and nonparametric estimation methods, different kernel types and bandwidth sizes, and adjustment for a rich set of demographic and behavioral covariates. Furthermore, the shorter lifespans are almost entirely caused by elevated rates of cardiorespiratory mortality, suggesting that PM10 is the causal factor. The estimates imply that bringing all of China into compliance with its Class I standards for PM10 would save 3.7 billion life-years.

Reply to the comment of Alkan Melikoglu ‘Joint manifestations can provide diagnostic clues in Morquio syndrome, a case report’

2019 ◽  
Vol 86 (1) ◽  
pp. 123-124
Author(s):  
Stéphane Mitrovic ◽  
Hélène Gouze ◽  
Thierry Schaeverbeke ◽  
Laure Gossec ◽  
Bruno Fautrel
Keyword(s):  
Case Report ◽  
Morquio Syndrome ◽  
Morquio Syndrome A

scholarly journals Testing for departure from uniformity and estimating mean direction for circular data

2017 ◽  
Vol 13 (1) ◽  
pp. 20160756 ◽  
Author(s):  
Graeme D. Ruxton
Keyword(s):  
Parameter Estimation ◽  
Confidence Interval ◽  
Current Practice ◽  
Circular Data ◽  
Estimation Methods ◽  
Population Parameters ◽  
Biological Studies ◽  
Selection For ◽  
Parameter Estimation Methods ◽  
Biased Estimates

Although circular data are common in biological studies, the analysis of such data is often more rudimentary than it need be. One of the most common hypotheses tested is whether the data suggest that samples are clustered around a certain specified direction, rather than being uniformly spread across all possible directions. Here, I use data from a recent publication on the compass directions of epiphytes and mistletoes on tree trunks. This is used to demonstrate how with relatively little extra work researchers can improve the rigour of testing such hypotheses, and this improved rigour can lead to biological insights missed by simpler analyses. Specifically, I highlight that a much broader range of null hypotheses can be tested than current practice, and that a range of methods are available for estimating a confidence interval for mean direction. I offer advice on appropriate selection for both tests and parameter estimation methods, and highlight the need to correct for the fact that sample estimates are biased estimates of population parameters for circular data.

Demographic Structure of Pecos Indians: A Model Based on Life Tables

1980 ◽  
Vol 45 (3) ◽  
pp. 518-530 ◽  
Author(s):  
Charles M. Mobley
Keyword(s):  
New Mexico ◽  
Life Expectancy ◽  
Data Base ◽  
Analytical Method ◽  
Life Tables ◽  
Demographic Analysis ◽  
Age At Death ◽  
Demographic Structure ◽  
Model Based ◽  
Death Data

Age-at-death data on over 2,000 burials from two pueblo sites in New Mexico are subjected to demographic analysis. Prior studies are reviewed to illustrate deficiencies and qualifications in the data base and the analytical method. The skeletal assemblage is subdivided into seven samples by chronological phase, and life tables are constructed. Aspects such as mortality and life expectancy are then examined for each phase and a diachronic model of demographic structure is developed for Pecos Indians between A.D. 1150 and 1700.

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