Lecture 24 Epidemiologists in Policymaking

Lecture 24 Epidemiologists in Policymaking - Introduction...

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Introduction The parachute is used in recreational, voluntary sector, and military settings to reduce the risk of orthopaedic, head, and soft tissue injury after gravitational challenge, typically in the context of jumping from an aircraft. The perception that parachutes are a successful intervention is based largely on anecdotal evidence. Observational data have shown that their use is associ-ated with morbidity and mortality, due to both failure of the intervention1 ,2 and iatrogenic complications.3 In addition, “natural history” studies of free fall indicate that failure to take or deploy a parachute does not inevitably result in an adverse outcome.4 We therefore undertook a systematic review of randomised controlled trials of parachutes. http ://www.youtube.com/watch?v=
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Abstract Objectives: To determine whether parachutes are effective in preventing major trauma related to gravitational challenge. Design: Systematic review of randomised controlled trials. Data sources: Medline,Web of Science, Embase, and the Cochrane Library databases; appropriate internet sites and citation lists. Study selection: Studies showing the effects of using a parachute during free fall. Main outcome measure: Death or major trauma, defined as an injury severity score > 15. Results: We were unable to identify any randomised controlled trials of parachute intervention. Conclusions: As with many interventions intended to prevent ill health, the effectiveness of parachutes has not been subjected to rigorous evaluation by using randomised controlled trials. Advocates of evidence based medicine have criticised the adoption of interventions evaluated by using only observational data. We think that everyone might benefit if the most radical protagonists of evidence based medicine organised and participated in a double blind, randomised, placebo controlled, crossover trial of the parachute.
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Extra Credit Assignment in Bb>Course Documents Wed: Review session for final exam Course Evaluation online – PLEASE COMPLETE IT! No Discussion Sections this week Regular TA Office Hours this week Final Exam: Monday May 16 2:00 pm, in MVR G73 Announcements
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The many “contexts” for “Epidemiology in Context” The ability to detect the causes of a disease or condition may depend on the context in which in the study was done What kinds of people or patients? How much exposure was there (viz the dose-response curve)? Does the effect size (e.g., slope, OR) vary by other variables (eg. gender, SES)? The external validity of a finding depends on the similarity between the study’s context and the broader context to which it is to be generalized Causal inferences are made in the context of the total body of knowledge from epi and other disciplines The PPV of a screening indicator depends on the prevalence of the disease in the population (which depends in its context) The “acceptable” levels of Se, Sp, FN and FP depend on the implications of these for
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This note was uploaded on 11/20/2011 for the course NS 3500 taught by Professor Peletier during the Spring '11 term at Cornell University (Engineering School).

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Lecture 24 Epidemiologists in Policymaking - Introduction...

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