title: Adherence to antidepressants among women and men described with trajectory models: a Swedish longitudinal study.
abstract: OBJECTIVE
  The purpose of this study are to analyse adherence to antidepressant treatment over 2 years in Sweden among women and men who initiated treatment with citalopram and to identify groups at risk of non-adherence using trajectory models.
  
  
  METHODS
  The study population, including individuals 18-85 years who initiated citalopram use between 1 July 2006 and 30 June 2007, was identified in the Swedish Prescribed Drug Register and followed for 2 years. Adherence was estimated with continuous measure of medication acquisition (CMA) and group-based trajectory modelling, a method which describes adherence patterns over time by estimating trajectories of adherence and the individual's probability of belonging to a specific trajectory.
  
  
  RESULTS
  The study population included 54,248 individuals, 64 % women. Mean CMA was 52 % among women and 50 % among men (p < 0.001). Five different adherence patterns (Trajectories) were identified. Similar proportion of women and men belonged to each Trajectory. Around 29 % of the women and 27 % of the men belonged to the Trajectory which showed full adherence throughout the 2-year study period. The other four Trajectories showed adherence that declined to different degrees and at different stages in time. Having low socioeconomic status was more common among individuals in Trajectories showing declining adherence than in the adherent Trajectory.
  
  
  CONCLUSIONS
  Using trajectory modelling, five Trajectories describing different patterns of adherence to citalopram treatment over time were identified. A large proportion discontinued treatment early and having low socioeconomic status increased the risk of being non-adherent.
authors.affiliation: Research and Development, Sahlgrenska University Hospital, Röda Stråket 8, 413 45, Gothenburg, Sweden. lotta.mardby@gmail.com.|Section of Epidemiology and Social Medicine, Department of Public Health and Community Medicine at Institute of Medicine, University of Gothenburg, Box 453, 405 30, Gothenburg, Sweden. lotta.mardby@gmail.com.|Novo Nordisk A/S, Box 50587, SE-202 15, Malmö, Sweden. lotta.mardby@gmail.com.
authors.forename: Ann-Charlotte
authors.initials: AC
authors.lastname: Mårdby
authors.affiliation: Section of Occupational and Environmental Medicine, Department of Public Health and Community Medicine at Institute of Medicine, University of Gothenburg, Box 100, 405 30, Gothenburg, Sweden.
authors.forename: Linus
authors.initials: L
authors.lastname: Schiöler
authors.affiliation: Section of Epidemiology and Social Medicine, Department of Public Health and Community Medicine at Institute of Medicine, University of Gothenburg, Box 453, 405 30, Gothenburg, Sweden.|Medical Evidence and Observational Research, AstraZeneca, Pepparedsleden 1, 431 83, Mölndal, Sweden.
authors.forename: Karolina Andersson
authors.initials: KA
authors.lastname: Sundell
authors.affiliation: Nordic School of Public Health, PO Box 421, 42140, Gothenburg, Sweden.|Department for Biomedicine and Public Health Research, University of Skövde, PO Box 408, SE 541 28, Skövde, Sweden.
authors.forename: Pernilla
authors.initials: P
authors.lastname: Bjerkeli
authors.affiliation: Nordic Health Economics AB, Medicinaregatan 8B, 413 90, Gothenburg, Sweden.
authors.forename: Eva
authors.initials: E
authors.lastname: Lesén
authors.affiliation: Department of Forensic Genetics and Forensic Toxicology, National Board of Forensic Medicine, 581 85, Linköping, Sweden.
authors.forename: Anna K
authors.initials: AK
authors.lastname: Jönsson
mesh_terms: D000328:Adult; D000368:Aged; D000928:Antidepressive Agents / Q000627:therapeutic use*; D015283:Citalopram / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D012923:Social Class; D013548:Sweden / Q000453:epidemiology; D016903:Drug Monitoring
chemical_list: D000928:Antidepressive Agents; D015283:Citalopram
keywords: Antidepressants; Gender; Medication adherence; Swedish prescribed drug register; Trajectory models