Conclusion Various methods have been used at all stages of CSPBM development .
The choice between developing a classification system de novo or from an existing instrument may depend on the availability of a suitable existing measure , while the choice between a decomposed or composite approach appears to be determined primarily by the purpose for which the instrument is design ed .
Background Health state utility values ( HSUVs ) are required to calculate quality -adjusted life-years ( QALYs ) .
They are frequently derived from generic preference-based measures of health .
However , such generic measures may not capture health attributes of relevance to specific conditions .
In such cases , a condition-specific preference-based measure ( CSPBM ) may be more appropriate .
Objective This systematic review aim ed to identify all published accounts of developing CSPBMs to describe and appraise the methods used .
Evaluation of a vision-related utility instrument: the German vision and quality of life index.
PURPOSE Multi-attribute utility instruments ( MAUIs ) , which contain a descriptive system , including several health dimensions with associated levels of increasing severity , are used commonly to measure utilities . However , the validity of the descriptive systems rarely is examined using modern psychometric theory . Therefore , we evaluated the psychometric properties of the German version of the  Vision and Quality of Life Index ( VisQol ) , a six-item vision-related MAUI . METHODS The German VisQol was self-administered to 340 patients and 280 controls . All subjects underwent a full ophthalmologic examination , including best-corrected visual acuity ( VA ) testing . The psychometric properties of the VisQoL were assessed using Rasch analysis . RESULTS The VisQoL 's descriptive system did not function in controls . In patients , after collapsing response categories to resolve disordered thresholds and omitting misfitting persons , the measurement properties ( i.e. , precision , unidimensionality , and targeting ) of the German VisQoL were satisfactory . Most person misfit related to unexpected responses to item 4 ( " organizing assistance " ) . Rasch-generated person estimates were not different between age categories , sex , or underlying ocular condition , but decreased significantly with presence of visual impairment in the better eye ( LogMAR ≥ 0.5 , 1.20 ± 4.62 compared to 3.46 ± 3.52 , P < 0.001 ) . CONCLUSIONS The German VisQoL 's descriptive system displayed adequate fit to the Rasch model after removal of a large proportion of patients with poor fit statistics . However , the wording of item four should be revised to reduce respondent confusion and measurement " noise . " The scale 's descriptive system does not function in a sample of visually unimpaired persons , most likely due to a lack of variance in the measured trait
Conclusion Various methods have been used at all stages of CSPBM development .
The choice between developing a classification system de novo or from an existing instrument may depend on the availability of a suitable existing measure , while the choice between a decomposed or composite approach appears to be determined primarily by the purpose for which the instrument is design ed .
Background Health state utility values ( HSUVs ) are required to calculate quality -adjusted life-years ( QALYs ) .
They are frequently derived from generic preference-based measures of health .
However , such generic measures may not capture health attributes of relevance to specific conditions .
In such cases , a condition-specific preference-based measure ( CSPBM ) may be more appropriate .
Objective This systematic review aim ed to identify all published accounts of developing CSPBMs to describe and appraise the methods used .