Individual trajectories in asthma and COPD : a longitudinal perspective to obstructive lung disease

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Managing chronic respiratory conditions such as asthma and Chronic Obstructive Pulmonary Disease (COPD) forms a notable burden on the healthcare system while the burden on an individual is equally notable as patients might suffer from a symptomatic disease for decades. However, not all asthma and COPD patients develop a disabling disease with frequent disease exacerbations and highest cost (in Quality Adjusted Life Years lost or healthcare spending). This variation in disease trajectories enables the analytical identification of distinct phenotypes over time. Retrospective data collected from a large number of patients could be used efficiently as the electronic health records are increasingly made available to researchers around the world. The aim of this project is to develop disease models based on longitudinal data to better capture the essential characteristics of obstructive lung disease, mainly focusing on COPD. Projects I III in this thesis are based on 2398 asthma and COPD patients retrospectively followed through electronic health records from year 2000 onwards. We aimed to analyse this real-world hospital based data using Hierarchical Models to assess the variation of development between individual patients over time. Unpublished Project IV is based on Health 2000 to 2011 follow-up study consisting of 1113 subjects from random Finnish population. The aim was to estimate Single Nucleotide Polymorphism (SNP) based heritability of Forced Expiratory Volume in 1 s (FEV1) level and development and to perform a Genome-Wide Association Study (GWAS) to identify possible genetic markers associated with FEV1 development over time. Our results suggest that the major determinants of Health Related Quality of Life (HRQoL) in mild or moderate COPD are the common comorbidities associated with COPD while in severe diseases the accentuated lung function has a major role. Over time, observable individual trajectories of HRQoL are presented in Asthma and COPD. Significant decline of HRQoL in Asthma was found to associate with obesity related diseases and states while the main determinants in COPD were poor lung function and increasing age. Psychiatric conditions were found associated in both Asthma and COPD. Using an unbalanced data (varying number of measurements and length of follow-up time) of lung function measurements, we were able to observe significant individual trajectories of FEV1 based on the past development. Significant and rapid decline was seen in 30% of the COPD cohort in the study while significant improvement was extremely rare. Rapid decline was associated with numerous exacerbation related markers. Our unpublished results suggest that development of FEV1 is significantly affected by common variants in DNA as genetic effects were estimated to explain 1/3 of the phenotypic variance in random Finnish population. One locus previously associated with the level of FEV1 was found associated with the development of FEV1. Suggestive evidence for two novel loci associated with FEV1 development was also identified. The findings underline the varying trajectories of HRQoL and lung function seen in a homogenous cohort of Asthma and COPD patients. This thesis aims to provide approaches and aspects to better understand the trajectories of a chosen parameter in asthma and COPD. The variation of e.g. lung function development is abundant, and we should not consider this variation as an obstacle but as a useful source of information as there might be genetic or environmental determinants causing this variation.Krooniset ahtauttavat keuhkosairaudet, kuten keuhkoahtaumatauti (COPD) ja astma ovat merkittäviä kansansairauksia Suomessa. Jopa lähes kymmenys maan aikuisväestöstä kärsii astmasta, COPD:n esiintyvyys ikääntyneillä miehillä saattaa olla vielä tätäkin suurempi. Kroonisina tiloina ahtauttavat keuhkosairaudet aiheuttavat huomattavan taakan niitä sairastaville potilaille sekä suuria kustannuksia yhteiskunnalle.
Tryckta ISBN978-951-51-1707-6
Elektroniska ISBN978-951-51-1708-3
StatusPublicerad - 2015
MoE-publikationstypG5 Doktorsavhandling (artikel)

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  • 3142 Folkhälsovetenskap, miljö och arbetshälsa
  • 3121 Allmänmedicin, inre medicin och annan klinisk medicin

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