title: Decay of impact after self-management education for people with chronic illnesses: changes in anxiety and depression over one year.
abstract: BACKGROUND
  In people with chronic illnesses, self-management education can reduce anxiety and depression. Those benefits, however, decay over time. Efforts have been made to prevent or minimize that "decay of impact", but they have not been based on information about the decay's characteristics, and they have failed. Here we show how the decay's basic characteristics (prevalence, timing, and magnitude) can be quantified. Regarding anxiety and depression, we also report the prevalence, timing, and magnitude of the decay.
  
  
  METHODS
  Adults with various chronic conditions participated in a self-management educational program (n = 369). Data were collected with the Hospital Anxiety and Depression Scale four times over one year. Using within-person effect sizes, we defined decay of impact as a decline of ≥0.5 standard deviations after improvement by at least the same amount. We also interpret the results using previously-set criteria for non-cases, possible cases, and probable cases.
  
  
  RESULTS
  Prevalence: On anxiety, decay occurred in 19% of the participants (70/369), and on depression it occurred in 24% (90/369). Timing: In about one third of those with decay, it began 3 months after the baseline measurement (6 weeks after the educational program ended). Magnitude: The median magnitudes of decay on anxiety and on depression were both 4 points, which was about 1 standard deviation. Early in the follow-up year, many participants with decay moved into less severe clinical categories (e.g., becoming non-cases). Later, many of them moved into more severe categories (e.g., becoming probable cases).
  
  
  CONCLUSIONS
  Decay of impact can be identified and quantified from within-person effect sizes. This decay occurs in about one fifth or more of this program's participants. It can start soon after the program ends, and it is large enough to be clinically important. These findings can be used to plan interventions aimed at preventing or minimizing the decay of impact.
authors.affiliation: Department of Health Communication, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan. mjpark417@gmail.com
authors.forename: M J
authors.initials: MJ
authors.lastname: Park
authors.forename: Joseph
authors.initials: J
authors.lastname: Green
authors.forename: Hirono
authors.initials: H
authors.lastname: Ishikawa
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Yamazaki
authors.forename: Akira
authors.initials: A
authors.lastname: Kitagawa
authors.forename: Miho
authors.initials: M
authors.lastname: Ono
authors.forename: Fumiko
authors.initials: F
authors.lastname: Yasukata
authors.forename: Takahiro
authors.initials: T
authors.lastname: Kiuchi
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001007:Anxiety / Q000517:prevention & control*; D002908:Chronic Disease / Q000523:psychology*; D015331:Cohort Studies; D003863:Depression / Q000517:prevention & control*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010353:Patient Education as Topic; D012648:Self Care; D011795:Surveys and Questionnaires; D013997:Time Factors; D055815:Young Adult