title: Depression and diabetes treatment nonadherence: a meta-analysis.
abstract: OBJECTIVE
  Depression is common in patients with diabetes and is associated with worse treatment outcomes. Its relationship to treatment adherence, however, has not been systematically reviewed. We used meta-analysis to examine the relationship between depression and treatment nonadherence in patients with type 1 and type 2 diabetes.
  
  
  METHODS
  We searched MEDLINE and PsycINFO databases for all studies published by June 2007 and reviewed references of published articles. Meta-analytic procedures were used to estimate the effect size r in a random effects model. Significance values, weighted effect sizes, 95% CIs, and tests of homogeneity of variance were calculated.
  
  
  RESULTS
  Results from 47 independent samples showed that depression was significantly associated with nonadherence to the diabetes treatment regimen (z = 9.97, P < 0.0001). The weighted effect size was near the medium range (r = 0.21, 95% CI 0.17-0.25). Moderator analyses showed that the effect was significantly larger in studies that measured self-care as a continuous versus categorical variable (P = 0.001). Effect sizes were largest for missed medical appointments and composite measures of self-care (r values = 0.31, 0.29). Moderation analyses suggest that effects for most other types of self-care are also near the medium range, especially in studies with stronger methodologies.
  
  
  CONCLUSIONS
  These findings demonstrate a significant association between depression and treatment nonadherence in patients with diabetes. Studies that used stronger methodologies had larger effects. Treatment nonadherence may represent an important pathway between depression and worse diabetes clinical outcomes.
authors.affiliation: Behavioral Medicine, Department of Psychiatry, Massachusetts General Hospital Boston, Boston, Massachusetts, USA. jsgonzalez@partners.org
authors.forename: Jeffrey S
authors.initials: JS
authors.lastname: Gonzalez
authors.forename: Mark
authors.initials: M
authors.lastname: Peyrot
authors.forename: Lauren A
authors.initials: LA
authors.lastname: McCarl
authors.forename: Erin Marie
authors.initials: EM
authors.lastname: Collins
authors.forename: Luis
authors.initials: L
authors.lastname: Serpa
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Mimiaga
authors.forename: Steven A
authors.initials: SA
authors.lastname: Safren
mesh_terms: D003863:Depression / Q000150:complications* / Q000453:epidemiology; D003920:Diabetes Mellitus / Q000523:psychology*; D006801:Humans; D010349:Patient Compliance / Q000523:psychology*; D016312:Treatment Refusal / Q000523:psychology*