RESULTS We found that none of the 19 instruments have sufficiently comprehensive reporting of measurement or feasibility performance as would be required by regulatory authorities .
INTRODUCTION In an accompanying study we reported on the content of several activity rating scales that have been used for muscle disease .
To further aid in achieving consensus we conducted a systematic review to assess the quality of the 19 activity rating scales  design ed specifically for muscle disease .
Development and validation of a muscular dystrophy-specific functional rating scale
Objective : To develop a reliable and valid new rating scale for measuring the functional impact of muscular dystrophy . Design : Prospect i ve and longitudinal investigation . Setting : Three academic medical centres in Taiwan and the Muscular Dystrophy Association of Taiwan . Measures : The Brooke Scale , the Vignos Scale , the Barthel Index , muscular strength , contracture severity , and predicted forced vital capacity ( FVC% ) . Methods : Scale development was in three stages . In stage I , a preliminary pool of 53 items was generated from patient interviews ( n-/25 ) , literature review , existing functional rating scales and expert opinion . In stage II , these items were administered to 85 patients with muscular dystrophy . The result ing data were analysed to construct a rating scale ( the Muscular Dystrophy Functional Rating Scale , MDFRS ) that encompassed four unidimensional constructs : mobility , basic activities of daily living , arm function and impairment . In stage III , the measurement properties of this rating scale were assessed in 121 muscular dystrophy patients different from those examined with the preliminary instrument . Results : Internal consistency reliability was excellent for all domains of the final 33-item scale , with values of Cronbach ’s alpha ranging from 0.84 to 0.97 . Intraclass correlation coefficients for test-retest and inter-rater reliability were 0.99 for all domains of the MDFRS . The MDFRS showed moderate to high correlations with a range of functional rating scales measuring similar aspects and impairment parameters ( Spearman ’s rho=0.65 - 0.91 ; P<0.001 , each ) . Confirmatory factor analysis supported a unitary construct of the four-dimensional MDFRS . The MDFRS had small floor and ceiling effects in the study sample s. Sensitivity to change was confirmed by large st and ardized response means for the MDFRS total score . Conclusions : The MDFRS is a reliable and valid disease-specific measure of functional status for patients with muscular dystrophy
RESULTS We found that none of the 19 instruments have sufficiently comprehensive reporting of measurement or feasibility performance as would be required by regulatory authorities .
INTRODUCTION In an accompanying study we reported on the content of several activity rating scales that have been used for muscle disease .
To further aid in achieving consensus we conducted a systematic review to assess the quality of the 19 activity rating scales  design ed specifically for muscle disease .