title: [Study Quality and its Influence on Treatment Outcome in Studies on the Effectiveness of Inpatient Psychotherapy - A Meta-Analysis].
abstract: BACKGROUND
  It is widely accepted that the quality of a study may affect its results. A possible influence of the studies' quality on the heterogeneity of the treatment effects will therefore be examined on the basis of studies being included in a recent meta-analysis on inpatient psychotherapy in German speaking countries.
  
  
  METHODS
  The quality of the 103 included studies was assessed by means of 19 criteria addressing general study quality as well as internal and external validity. We examined the relation between study quality and treatment outcome (quantified by effect size Hedges' g either for the Global Severity Index of the Symptom Checklist (SCL GSI) or for an overall outcome calculated across various measures) with univariate correlation analyses as well as metaregression.
  
  
  RESULTS
  Study quality varies considerably between the included studies but also between the different quality criteria. On average, the included studies show a medium quality. Most quality criteria do not correlate significantly with the treatment effects. Studies of higher quality tend to show higher treatment effects.
  
  
  CONCLUSIONS
  The operationalization of single quality items is still worthy of discussion since some criteria are hardly ever while others are always fulfilled. The study quality does not appear to be a homogenous concept, but there are positive as well as negative correlations between single criteria and treatment outcome. Accordingly, the calculation of a total quality score does not seem feasible.
  
  
  CONCLUSIONS
  Regarding the present meta-analysis on the effectiveness of psychotherapeutic hospital treatment, a systematic overestimation due to the inclusion of some studies with lower quality is not to be assumed.
authors.affiliation: Institut und Poliklinik für Medizinische Psychologie, Universitätsklinikum Hamburg-Eppendorf.
authors.forename: Sarah
authors.initials: S
authors.lastname: Liebherz
authors.affiliation: Institut und Poliklinik für Medizinische Psychologie, Universitätsklinikum Hamburg-Eppendorf.
authors.forename: Nele
authors.initials: N
authors.lastname: Schmidt
authors.affiliation: Institut und Poliklinik für Medizinische Psychologie, Universitätsklinikum Hamburg-Eppendorf.
authors.forename: Sven
authors.initials: S
authors.lastname: Rabung
mesh_terms: D006778:Hospitals, Psychiatric; D006801:Humans; D007297:Inpatients; D011613:Psychotherapy / Q000706:statistics & numerical data*; D036301:Qualitative Research; D012106:Research / Q000592:standards* / Q000706:statistics & numerical data; D012107:Research Design; D016896:Treatment Outcome