Development of the gait assessment scale and gait quality and independence classification scale in patients with duchenne muscular dystrophy and investigation of the validity and reliability

The aim of the study was to develop and investigate the validity and reliability of the Gait Assessment Scale in Duchenne Muscular Dystrophy (DMD) (DMD-GAS) and the Gait Quality and Independence Classification Scale in DMD (DMD-GQICS). The scales were developed with the 2-round Delphi method. DMD-GAS and DMD-GQICS were statistically significant with a Content Validity Index of 0.90 and 0.96, respectively. Intra and inter-rater reliability and criterion validity of the final version of DMD-GAS were determined out of 56 patients (age=103.83±27.51 months, BMI=18.49±2.59 kg/m2). Internal consistency of the items of DMD-GAS was higher with Cronbach's Alpha coefficient of 0.94. The scale had excellent intra and inter-rater reliability with the Intraclass Correlation Coefficient of ≥ 0.90. The correlations between the total score of DMD-GAS and MFM (D1, D2, D3 and total), 6-Minute Walk Test (6MWT) and GAITRite data were analyzed. There was a positive excellent correlation between DMD-GAS and MFM-D1 (r=0.80) and MFM -total scores (r=0.78) while very strong, positive correlation with 6MWT (r=0.71; p<0.01). DMD-GAS was moderately correlated with MFM-D2 (r=0.44) and MFM-D3 (r=0.53) (p<0.01). There were positive, moderate correlations between DMD-GAS and walking speed (r=0.50) and stride length (r=0.56), and negative, very strong correlation with the support surface (r=-0.70; p<0.01). The intra and inter-rater reliability, and criterion validity of DMD-GQICS were also determined out of 69 patients (age=108±31.58 months; BMI= 18.88±2.64 kg/m2). According to Weighted Kappa analysis, a perfect agreement was determined between the assessments which indicate higher intra-rater reliability of the scale (K:0.92; p<0.01). According to the Fleiss Kappa analysis, an excellent agreement was determined between the raters which also indicate higher inter-rater reliability (K:0.81; p<0.01). The positive, excellent correlation was determined between DMD-GQICS and BLEFC (r=0.82), negative, excellent correlation with MFM-D1 and MFM total scores (r=-0.85; r=-0.62; respectively), and negative, strong correlations with MFM-D2 and MFM-D3 (r=-0.62; r=-0.69; respectively) which indicate the DMD-GQICS is a valid instrument (p<0.01). The results showed that DMD-GAS and DMD-GQICS, which are developed specific to DMD patients within the scope of this study, have the ability to evaluate gait compensations in terms of scope, and to classify the gait of patients in terms of quality and independence, and are consistent for repeated measurements. In addition, it is thought that these scales are easy and low-cost to apply and can be applied without revealing the fatigue symptom that is frequently seen in patients.