Validation of Kidney Disease Quality of Life Short Form 36 (KDQOL-SF™) in Malayalam among Patients Undergoing Haemodialysis in South Kerala

Introduction

In literature, the term “quality of life” is also often referred to as “well-being”. World Health Organization defines Quality of Life as individuals' perception of their position in life in the context of the culture and value systems in which they live and in relation to their goals, expectations, standards, and concerns.[1] Chronic kidney disease (CKD) is a worldwide health problem. One potential outcome of CKD is end-stage renal disease (ESRD), requiring costly renal replacement therapy in the form of dialysis or transplantation. The main cause of CKD is diabetes and hypertension. Since the prevalence of these chronic diseases are increasing in India, and about 25–40% of these subjects may develop CKD, the ESRD burden will rise and the health care system would need to take care of them.[2] A study conducted by Singh et al. reported the prevalence of CKD in India of 17.2%.[3] Hemodialysis is the most common mode of therapy worldwide, at least 80% of patients are on this mode of therapy.[4] It is used as a life-sustaining therapy for most of the patients. Studies proved that dialysis affect the Quality of life (QOL) of patients. Health related quality of life has been increasingly recognized as an important medical outcome in patients with CKD.[5] There are various tools available to measure the QOL, disease specific tools are also available. Kidney disease quality of life short form is developed by RAND to assess the QOL in CKD patients.[67] It was translated in many languages, but not in Malayalam. The objective of the study was to translate and validate the KDQOL-SF™ questionnaire into Malayalam.

Methods

Results

Table 1 shows the demographic characteristics of the people. Of the 112 patients undergoing dialysis, 74 (66.1%) were males. About 38.4% of the patients were in the age group 55–65 years. The mean age was 60.55 years with standard deviation of 11.77. Age ranged from 22 to 84. About 44.6% of patients had only high school education. Fifty percent of patients were getting some kind of insurance coverage. Table 2 describes the item internal consistency, item-discriminant validity and success rate of the KDQOL-SF™ scale. Item internal consistency was more than 0.4 for all scales except burden of kidney disease, sleep, and cognitive function after corrected for item-scale overlap. Success rate of item discriminant validity was 100% in all scales except of kidney disease, cognitive function, and sleep. Table 3 shows the mean, standard deviation (SD), floor and ceiling effects of the KDQOL-SF™ scales. The floor effect was found to be less than 15% except for social support, Role-physical and Role emotional. Ceiling effect was found to be above 15% for most of the scales. Highest mean score of 90.51 ± 18.78 was obtained for dialysis staff encouragement and lowest mean score of 26.87 ± 12.16 was for work status. The overall health score was 53.43 ± 11.48. Table 4 shows the scale level reliability and inter scale correlations. Reliability coefficient can be considered as the correlation between a scale and itself. The overall reliability of the tool was 0.81. Scale level reliability varies from 0.71 to 0.92, which support item homogeneity and internal consistency across scales. Since the reliability coefficients of each scale were greater than the inter-scale correlations, each scale can be considered to measure a distinct concept.

Discussion

Many western studies are there in the literature regarding the validation of KDQOL-SF™ tool.[141516171819202122] Among Indian language, KDQOL-SF™had been translated into Hindi,[23] Kannada,[24] Marathi[25] and Tamil.[26] But KDQOL-SF™ has not been translated and validated in Malayalam. This first Malayalam translated version was found to have good internal consistency of 0.81. The reliability coefficient Cronbach's alpha ranges from 0.71 to 0.92 in the 18 subscales. This is similar to the previous Indian studies, but the Marathi translated tool showed an internal consistency of more than 0.70 for all scales except the seven subscales. A study conducted in Bangalore using the English version of the tool also reported an internal consistency ranges from 0.61 to 0.94.[27] Results of the present study also agrees with the Western studies.[14151622] A study conducted in Egypt reported the value of Cronbach's alpha more then 0.7 for all scales except three subscales.[17] Translated version in Urdu, the national language of Pakistan also reported an internal consistency of more than 0.70 for 12 sub scales.[28] Thai version of the KDQOL-36 questionnaire had reliability coefficient from 0.799-0.827.[29] Sinhala, which is the most common language spoken in Sri Lanka had Cronbach's alpha more than 0.70 for all sub scales except cognitive function.[30]

Floor effects is highest for work status scale and ceiling effects higher for dialysis staff encouragement which is concurrent with Kuriakose et al.[27] and Park et al.[15] This is not agreeing with Mateti et al.,[24] however that study didn't report all the domains in ESRD-targeted areas. Item internal consistency of more than 0.4 is attained in most of the scales and item discriminant validity success rate varied from 88% to 100%. This is reported as 0.5 to 1.0 in Joshi et al.[22] Overall health rating score was obtained as 53.22 ± 11.48. Scale wise mean score in ESRD-targeted areas are in congruence with the findings of other south Indian studies,[242526] but not agreeing with the Role-Physical and Role-emotional mean scores of Mateti et al.[24] Among all the scales highest score was for Dialysis staff encouragement which is consistent with previous studies.[15222830] Least score is obtained for Work status which is agreeing with previous studies.[1528]

Conclusion

In summary, Malayalam version of KDQOL-SF™ is found to have good internal consistency, convergent validity and discriminant validity. So, this tool is a sound tool to access the QOL of Malayalam speaking patients with CKD.