4.3 Correlation values of both scales
The highest correlation was found between similar subdimensions of the scales namely between SF-36 Physical Functioning and SSQOL Physical Activities. This result shows that both subdimensions physically evaluate HRQOL in stroke patients using the same criteria. The weakest correlation between SF-36 Mental Health and SSQOL-Mood subdimensions may be related to the expressions of happiness-unhappiness included in the Mental Health dimension. In contrast to the findings in our study, in a study where WHOQOL-BREF and SSQOL were compared, a significant relationship was reported between Psychological Health (PSH) domain of WHOQOL-BREF and the Thinking subdimension of SSQOL31. Similarly, in a study comparing SF-36 with another stroke-specific scale (Stroke Impact Scale: SIS), in contrast to our study, it was reported that SIS assessed physical, and social functioning better than SF-36, and use of the items that measures these parameters in SF-36 was not appropriate for stroke patients17.
A moderate positive correlation found between the total score of the SSQOL scale and all subdimensions of SF-36, indicates that both scales could be used to assess quality of life in stroke. However, in general, the average scores of the SSQOL scale were higher relative to SF-36 scale, which could be interpreted as SSQOL being more appropriate for these patients. In addition, since the items of the disease-specific scales better describe the disease in question, use of disease-specific scales has been recommended in these studies17.