Case definition of pneumococcal pneumonia : a latent class analysis approach

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http://hdl.handle.net/10138/10695
Title: Case definition of pneumococcal pneumonia : a latent class analysis approach
Author: Snellman, Marja
Contributor: University of Helsinki, Faculty of Social Sciences, Department of Mathematics and Statistics
Date: 2007-08-24
URI: http://hdl.handle.net/10138/10695
Thesis level: master's thesis
Abstract: Community-acquired pneumonia (CAP) is a severe disease and a major cause of death worldwide especially among the elderly. The most common causative pathogen is Streptococcus pneumoniae, pneumococcus. The diagnosis of pneumococcal pneumonia is difficult because there is no gold standard, a diagnostic test that would identify all cases and yet be definite. National Public Health Institute has launched a Finnish Community-Acquired Pneumonia study investigating the frequency and causes of CAP among the elderly aged 65 years and above. Sputum, urine, blood and nasopharyngeal swab samples are the collected from the subjects enrolled in the study and a large number of microbiological assays are performed on samples. One of the main objectives is to find a case definition for pneumococcal pneumonia in the elderly. For this purpose, the accuracy of diagnostic tests performed in the study need to be evaluated. In the absence of gold standard, the true disease status of the subjects is latent and the sensitivities and the specificities of the tests cannot be estimated using conventional methods. The aim of this thesis is to to estimate the sensitivities and the specificities of diagnostic tests and estimate the prevalence of pneumococcal pneumonia among the elderly population in Finland using latent class analysis. The method is applied to data collected in the Finnish Community-Acquired Pneumonia study. Methodological issues in latent class analysis are discussed. In addition, a function for estimating the model parameters using statistical program R is presented. The main sources are: Agresti, Alan 2002: Categorical Data Analysis. Wiley. New York. Hagenaars, Jacques A. 1990: Categorical Longitudinal Data. Sage Publication. London Formann, A. - Kohlmann, T. 1996: Latent class analysis in medical research. Statistical Methods in Medical Research, 5, 179-211.
Description: Endast sammandrag. Inbundna avhandlingar kan sökas i Helka-databasen (http://www.helsinki.fi/helka). Elektroniska kopior av avhandlingar finns antingen öppet på nätet eller endast tillgängliga i bibliotekets avhandlingsterminaler.Only abstract. Paper copies of master’s theses are listed in the Helka database (http://www.helsinki.fi/helka). Electronic copies of master’s theses are either available as open access or only on thesis terminals in the Helsinki University Library.Vain tiivistelmä. Sidottujen gradujen saatavuuden voit tarkistaa Helka-tietokannasta (http://www.helsinki.fi/helka). Digitaaliset gradut voivat olla luettavissa avoimesti verkossa tai rajoitetusti kirjaston opinnäytekioskeilla.
Subject: pneumococcus
pneumonia
elderly
bacteria
diagnostics
sensitivity
specificity
latent class analysis


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