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Examining the validity of the SALSA scale as a generic measure of activity
Abstract
Background The SALSA scale is a questionnaire measuring activity limitation and safety awareness among people with peripheral nerve injuries. However, it is not yet validated as an instrument for people with other conditions. The objective was to examine the validity of the SALSA scale as a generic instrument to measure activity limitation in health conditions other than leprosy and diabetes.
Methods For the examination of the validity of the SALSA scale as a generic instrument a quantitative and qualitative approach have been used. For the quantitative part, activity limitation was measured by conducting the SALSA scale and the WHO-DAS II scale with two diagnostic groups. The first group consisted of people affected by leprosy or diabetes. The second group consisted of people with a locomotor disability related to conditions other than leprosy and diabetes. The correlation coefficient, the intraclass correlation coefficient (ICC), Cohen’s Kappa (k) and a Bland-Altman analysis were used to assess the level of agreement between the scores. For the latter two methods the scores were standardized to a 0 – 100 scale. In the qualitative part, semi-structured interviews with people with a locomotor disability and a focus group discussion with experts were conducted to assess the content validity of the scale for people with a locomotor disability.
Results 138 respondents participated in the quantitative part of the study. The SALSA scale and the WHO-DAS II scale were strongly correlated (r=0.79). The ICC for all paired measurements was 0.87. Cohen’s Kappa showed substantial agreement (k=0.67). The Bland-Altman method showed limits of agreement of -30.0 to 19.1. Six people with a locomotor disability and four experts participated in the qualitative part of the study. In this part of the study the content of the SALSA scale was considered as focusing too much on the sensory loss aspects of leprosy and diabetes and too little on the lower limb aspects which are the most common in locomotor disability.
Conclusion The quantitative study shows that the SALSA scale is a valid instrument for measuring activity limitation in persons affected by a locomotor disability. According to the qualitative method some adaptations would need to be made to improve this validity. However, adjustment may cause loss of sensitivity with regard to the special problems caused by sensory impairment. Overall we can conclude that the SALSA scale has shown to be a valid instrument for measuring activity limitation in persons affected by a locomotor disability.
Methods For the examination of the validity of the SALSA scale as a generic instrument a quantitative and qualitative approach have been used. For the quantitative part, activity limitation was measured by conducting the SALSA scale and the WHO-DAS II scale with two diagnostic groups. The first group consisted of people affected by leprosy or diabetes. The second group consisted of people with a locomotor disability related to conditions other than leprosy and diabetes. The correlation coefficient, the intraclass correlation coefficient (ICC), Cohen’s Kappa (k) and a Bland-Altman analysis were used to assess the level of agreement between the scores. For the latter two methods the scores were standardized to a 0 – 100 scale. In the qualitative part, semi-structured interviews with people with a locomotor disability and a focus group discussion with experts were conducted to assess the content validity of the scale for people with a locomotor disability.
Results 138 respondents participated in the quantitative part of the study. The SALSA scale and the WHO-DAS II scale were strongly correlated (r=0.79). The ICC for all paired measurements was 0.87. Cohen’s Kappa showed substantial agreement (k=0.67). The Bland-Altman method showed limits of agreement of -30.0 to 19.1. Six people with a locomotor disability and four experts participated in the qualitative part of the study. In this part of the study the content of the SALSA scale was considered as focusing too much on the sensory loss aspects of leprosy and diabetes and too little on the lower limb aspects which are the most common in locomotor disability.
Conclusion The quantitative study shows that the SALSA scale is a valid instrument for measuring activity limitation in persons affected by a locomotor disability. According to the qualitative method some adaptations would need to be made to improve this validity. However, adjustment may cause loss of sensitivity with regard to the special problems caused by sensory impairment. Overall we can conclude that the SALSA scale has shown to be a valid instrument for measuring activity limitation in persons affected by a locomotor disability.
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Thesis