The Many Faces of Survivor Bias in Observational Studies on Trauma Resuscitation Requiring Massive Transfusion

Abstract Background Establishing causal effects in reproductive and perinatal epidemiology is challenging due to the many selection and attrition processes from preconception to the postnatal period. Further challenging, is the potential for the misclassification of exposures, outcomes and confounders, contributing to measurement error. The application of simulation enables the illustration and quantification of the magnitude of various types of bias commonly found in observational studies. Methods A systematic search was conducted in PubMed, Medline, Embase, CINAHL and Scopus in August 2020. A gray literature search of Google and Google Scholar, followed by a search of the reference lists of included studies, was undertaken. Results Thirty-nine studies, covering information (n = 14), selection (n = 14), confounding (n = 9), protection (n = 1), and attenuation bias (n = 1) were identified. The methods of simulating data and reporting of results varied, with more recent studies including causal diagrams. Few studies included code for replication. Although there has been an increasing application of simulation in reproductive and perinatal epidemiology since 2015, overall this remains an underexplored area. Conclusions The studies demonstrated effectiveness in the quantification of multiple types of bias using simulation. The limited use implies that further effort is required to increase knowledge of the application of simulation, which will thereby improve causal interpretation in reproductive and perinatal studies. Key messages Practical guidance for researchers is required in the development, analysis and reporting of simulation methods for the quantification of bias.

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O3B.3 Estimating the impact of changes to occupational standards for silica exposure on lung cancer mortality

Occupational and Environmental Medicine ◽

10.1136/oem-2019-epi.64 ◽

2019 ◽

Vol 76 (Suppl 1) ◽

pp. A24.2-A24

Author(s):

Alex Keil ◽

David Richardson ◽

Daniel Westreich ◽

Kyle Steenland

Keyword(s):

Lung Cancer ◽

Occupational Exposure ◽

Observational Studies ◽

Lung Cancer Mortality ◽

Occupational Exposure Limits ◽

Exposure Limits ◽

Silica Exposure ◽

Risk Of Death ◽

Survivor Bias ◽

The Impact

BackgroundRespiratory exposure to silica is associated with the risk of death due to malignant and non-malignant disease. 2.3 million U.S. workers are exposed to silica. Occupational exposure limits for silica are derived from a number of lines of evidence, including observational studies. Observational studies may be subject to healthy worker survivor bias, which could result in underestimates of silica’s impact on worker mortality and, in turn, bias risk estimates for occupational exposure limits.MethodsUsing data on 65 999 workers pooled across multiple industries, we estimate the impacts of several hypothetical occupational exposure limits on silica exposure on lung cancer and all-cause mortality. We use the parametric g-formula, which can account for healthy worker survivor bias.ResultsAssuming we could eliminate occupational exposure, we estimate that there would be 20.7 fewer deaths per 1000 workers in our pooled study by age 80 (95% confidence interval: 14.5, 26.8), including 3.91 fewer deaths due to lung cancer (95% CI: 1.53, 6.30). Less restrictive interventions demonstrated smaller, but still substantial risk reductions.ConclusionsOur results suggest that occupational exposure limits for silica can be further strengthened to reduce silica-associated mortality and illustrate how current risk analysis for occupational limits can be improved.

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Fluid therapy in trauma resuscitation : A review of changing practices.

Bangladesh Critical Care Journal ◽

10.3329/bccj.v6i1.36610 ◽

2018 ◽

Vol 6 (1) ◽

pp. 31-39

Author(s):

Kaja Mohammad Rasheed

Keyword(s):

Fluid Resuscitation ◽

Massive Transfusion ◽

Single Case ◽

Damage Control ◽

Fluid Management ◽

Laboratory Model ◽

Trauma Resuscitation ◽

High Quality ◽

Acute Trauma ◽

Medline Search

Background: Haemorrhage is the leading preventable cause of post trauma death. Acute trauma resuscitation has evolved over the last decade. The ATLS guidance used since 2012 is being updated in 2018.Objectives : To search relevant representative literature over 6 years between 2012 and 2018 to gain an insight into changing concepts, practices and recent advances in acute trauma fluid resuscitation and provide a structured review of the topic.Search methods: A relevant MEDLINE search was undertaken to obtain a list of 1512 articles from which 107 were utilised to prepare this review.Selection criteria:1. Inclusion: Articles from human medicine relevant to fluid resuscitation in trauma published in English between January 2012 and January 2018. 2.Exclusion: Articles restricted to Brain, spinal trauma or cardiovascular trauma, post traumatic arrest patients, animal or human laboratory model studies and articles on septic, postoperative, obstetric patients and single case studies were excluded.Results: This review categorises the topic into various parts to explain the evolving understanding of fluid resuscitation, trauma induced coagulopathy and endotheliopathy of trauma. The strategies for acute fluid management like damage-controlled resuscitation, balanced and haemostatic resuscitation and massive transfusion protocol are explained. A detailed discussion is carried out regarding crystalloid, colloid and blood transfusion. Special consideration is given to specific age groups, combat casualties and prehospital trauma care.Conclusions: Fluid resuscitation in trauma is a complex and rapidly evolving subject. Massive transfusion protocols and principles of damage control are significant for patient outcome. Standard guidance like ATLS is relevant and important for training professionals to deliver systematic, high quality of trauma care. There is scope for local improvisation based on resources and need for more high-quality trials and frequent systematic reviews.Bangladesh Crit Care J March 2018; 6(1): 31-39

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Simulation of survivorship bias in observational studies on plasma to red blood cell ratios in massive transfusion for trauma

British Journal of Surgery ◽

10.1002/bjs.7732 ◽

2011 ◽

Vol 99 (S1) ◽

pp. 132-139 ◽

Cited By ~ 25

Author(s):

A. M.-H. Ho ◽

P. W. Dion ◽

J. H. H. Yeung ◽

G. M. Joynt ◽

A. Lee ◽

...

Keyword(s):

Blood Cell ◽

Red Blood Cell ◽

Observational Studies ◽

Massive Transfusion ◽

Survivorship Bias

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Trauma resuscitation requiring massive transfusion: a descriptive analysis of the role of ratio and time

World Journal of Emergency Surgery ◽

10.1186/s13017-015-0028-3 ◽

2015 ◽

Vol 10 (1) ◽

Cited By ~ 11

Author(s):

Ruben Peralta ◽

Adarsh Vijay ◽

Ayman El-Menyar ◽

Rafael Consunji ◽

Husham Abdelrahman ◽

...

Keyword(s):

Massive Transfusion ◽

Descriptive Analysis ◽

Trauma Resuscitation

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Optimizing Transfusion Ratios in Massive Transfusion Protocols: An Argument Against the 1:1:1 Dogma and Approach to Trauma Resuscitation

Laboratory Medicine ◽

10.1309/lmjqnoqcfg4gkqrj ◽

2015 ◽

Vol 46 (2) ◽

pp. e46-e52 ◽

Cited By ~ 7

Author(s):

Jason A. Gregory ◽

Sonny S. Huitron ◽

Alan A. George ◽

Clayton D. Simon

Keyword(s):

Massive Transfusion ◽

Trauma Resuscitation

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Reverse survivor bias in observational studies involving cohorts: a lesson from '1:1' trauma studies

Hong Kong Medical Journal ◽

10.12809/hkmj134077 ◽

2013 ◽

Vol 19 (5) ◽

pp. 461-463 ◽

Cited By ~ 4

Author(s):

Anthony MH Ho ◽

◽

Peter W Dion ◽

John B Holcomb ◽

Randolph HL Wong ◽

...

Keyword(s):

Observational Studies ◽

Trauma Studies ◽

Survivor Bias

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Efficacy of a massive transfusion protocol for hemorrhagic trauma resuscitation

The American Journal of Emergency Medicine ◽

10.1016/j.ajem.2017.11.060 ◽

2018 ◽

Vol 36 (7) ◽

pp. 1178-1181 ◽

Cited By ~ 7

Author(s):

George Lim ◽

Katrina Harper-Kirksey ◽

Ram Parekh ◽

Alex F. Manini

Keyword(s):

Massive Transfusion ◽

Trauma Resuscitation ◽

Massive Transfusion Protocol ◽

Transfusion Protocol

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Prevalence of Survivor Bias in Observational Studies on Fresh Frozen Plasma

Anesthesiology ◽

10.1097/aln.0b013e318245c47b ◽

2012 ◽

Vol 116 (3) ◽

pp. 716-728 ◽

Cited By ~ 96

Author(s):

Anthony M.-H. Ho ◽

Peter W. Dion ◽

Janice H. H. Yeung ◽

John B. Holcomb ◽

Lester A. H. Critchley ◽

...

Keyword(s):

Randomized Controlled Trials ◽

Observational Studies ◽

Fresh Frozen Plasma ◽

Time Dependent ◽

Controlled Trials ◽

Randomized Controlled ◽

Before And After ◽

Fresh Frozen ◽

Survivor Bias ◽

Frozen Plasma

Observational studies on transfusion in trauma comparing high versus low plasma:erythrocyte ratio were prone to survivor bias because plasma administration typically started later than erythrocytes. Therefore, early deaths were categorized in the low plasma:erythrocyte group, whereas early survivors had a higher chance of receiving a higher ratio. When early deaths were excluded, however, a bias against higher ratio can be created. Survivor bias could be reduced by performing before-and-after studies or treating the plasma:erythrocyte ratio as a time-dependent covariate.We reviewed 26 studies on blood ratios in trauma. Fifteen of the studies were survivor bias-unlikely or biased against higher ratio; among them, 10 showed an association between higher ratio and improved survival, and five did not. Eleven studies that were judged survivor bias-prone favoring higher ratio suggested that a higher ratio was superior.Without randomized controlled trials controlling for survivor bias, the current available evidence supporting higher plasma:erythrocyte resuscitation is inconclusive.

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