title: A conceptual disease model for adult Pompe disease.
abstract: BACKGROUND
  Studies in orphan diseases are, by nature, confronted with small patient populations, meaning that randomized controlled trials will have limited statistical power. In order to estimate the effectiveness of treatments in orphan diseases and extrapolate effects into the future, alternative models might be needed. The purpose of this study is to develop a conceptual disease model for Pompe disease in adults (an orphan disease). This conceptual model describes the associations between the most important levels of health concepts for Pompe disease in adults, from biological parameters via physiological parameters, symptoms and functional indicators to health perceptions and final health outcomes as measured in terms of health-related quality of life.
  
  
  METHODS
  The structure of the Wilson-Cleary health outcomes model was used as a blueprint, and filled with clinically relevant aspects for Pompe disease based on literature and expert opinion. Multiple observations per patient from a Dutch cohort study in untreated patients were used to quantify the relationships between the different levels of health concepts in the model by means of regression analyses.
  
  
  RESULTS
  Enzyme activity, muscle strength, respiratory function, fatigue, level of handicap, general health perceptions, mental and physical component scales and utility described the different levels of health concepts in the Wilson-Cleary model for Pompe disease. Regression analyses showed that functional status was affected by fatigue, muscle strength and respiratory function. Health perceptions were affected by handicap. In turn, self-reported quality of life was affected by health perceptions.
  
  
  CONCLUSIONS
  We conceptualized a disease model that incorporated the mechanisms believed to be responsible for impaired quality of life in Pompe disease. The model provides a comprehensive overview of various aspects of Pompe disease in adults, which can be useful for both clinicians and policymakers to support their multi-faceted decision making.
authors.affiliation: Institute for Medical Technology Assessment, Department of Health Policy & Management, Erasmus University Rotterdam, BOX 1738, 3000DR, Rotterdam, The Netherlands. kanters@bmg.eur.nl.|Center for Lysosomal and Metabolic Diseases, Erasmus MC University Medical Center, Rotterdam, The Netherlands. kanters@bmg.eur.nl.
authors.forename: Tim A
authors.initials: TA
authors.lastname: Kanters
authors.affiliation: Institute for Medical Technology Assessment, Department of Health Policy & Management, Erasmus University Rotterdam, BOX 1738, 3000DR, Rotterdam, The Netherlands. redekop@bmg.eur.nl.
authors.forename: W Ken
authors.initials: WK
authors.lastname: Redekop
authors.affiliation: Institute for Medical Technology Assessment, Department of Health Policy & Management, Erasmus University Rotterdam, BOX 1738, 3000DR, Rotterdam, The Netherlands. m.rutten@bmg.eur.nl.
authors.forename: Maureen P M H
authors.initials: MP
authors.lastname: Rutten-Van Mölken
authors.affiliation: Center for Lysosomal and Metabolic Diseases, Erasmus MC University Medical Center, Rotterdam, The Netherlands. m.kruijshaar@erasmusmc.nl.
authors.forename: Michelle E
authors.initials: ME
authors.lastname: Kruijshaar
authors.affiliation: Center for Lysosomal and Metabolic Diseases, Erasmus MC University Medical Center, Rotterdam, The Netherlands. d.gungor@erasmusmc.nl.
authors.forename: Deniz
authors.initials: D
authors.lastname: Güngör
authors.affiliation: Center for Lysosomal and Metabolic Diseases, Erasmus MC University Medical Center, Rotterdam, The Netherlands. a.vanderploeg@erasmusmc.nl.
authors.forename: Ans T
authors.initials: AT
authors.lastname: van der Ploeg
authors.affiliation: Institute for Medical Technology Assessment, Department of Health Policy & Management, Erasmus University Rotterdam, BOX 1738, 3000DR, Rotterdam, The Netherlands. hakkaart@bmg.eur.nl.
authors.forename: Leona
authors.initials: L
authors.lastname: Hakkaart
mesh_terms: D003657:Decision Making; D005260:Female; D006009:Glycogen Storage Disease Type II / Q000523:psychology*; D006291:Health Policy; D006304:Health Status; D006305:Health Status Indicators; D006801:Humans; D008297:Male; D008875:Middle Aged; D008962:Models, Theoretical; D011788:Quality of Life / Q000523:psychology*; D035583:Rare Diseases / Q000523:psychology; D012044:Regression Analysis