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Saudi Journal of Kidney Diseases and Transplantation
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ORIGINAL ARTICLE Table of Contents   
Year : 2003  |  Volume : 14  |  Issue : 1  |  Page : 15-17
Development of SF-36 Questionnaire in the Measurement of Quality of Life in Patients on Renal Replacement Therapy in Iran


1 Department of Urology, Shariati Hospital, Tehran University of Medical Science, Tehran, Iran
2 Department of Biostatistics, School of Medicine, Tarbiat Modares University, Tehran, Iran

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   Abstract 

The measurement of quality of life in patients with chronic diseases such as renal insufficiency has come under increased attention recently. Many questionnaires have been developed and tested in terms of applicability, validity and reliability in different centers according to different cultural and geographical circumstances. The current study is contemplated to determine the reliability of the short form 36-item (SF-36) questionnaire related to quality of life that was translated into Farsi and modified by adding 25 specific items related to renal replacement therapy. The modified questionnaire was tested on 10 transplant patients within 6-12 months after operation. The test to retest time interval was three weeks. The answers to the questionnaire were obtained during a direct interview. The total reliability coefficient (RC) was 0.70. Deletion of items 20, 49 and 52 increased the RC to 0.75. Conclusion: this study shows that there is a considerable change of opinion in relation to the contents of the items between test-retest. Therefore, to refine this situation, there is a need to reconsider the contents of the items in the future studies.

Keywords: Quality of life, Renal replacement therapy, SF-36.

How to cite this article:
Mehraban D, Naderi G, Salehi M. Development of SF-36 Questionnaire in the Measurement of Quality of Life in Patients on Renal Replacement Therapy in Iran. Saudi J Kidney Dis Transpl 2003;14:15-7

How to cite this URL:
Mehraban D, Naderi G, Salehi M. Development of SF-36 Questionnaire in the Measurement of Quality of Life in Patients on Renal Replacement Therapy in Iran. Saudi J Kidney Dis Transpl [serial online] 2003 [cited 2020 Feb 19];14:15-7. Available from: http://www.sjkdt.org/text.asp?2003/14/1/15/33082

   Introduction Top


The measurement of quality of life in chronic diseases such as renal insufficiency has come under increased attention recently. Many questionnaires have been developed and tested in terms of applicability, validity, and reliability in different centers according to different cultural and geographical circum­stances. [1],[2],[3],[4],[5],[6],[7],[8],[9] Short form 36-item (SF-36) is a generic health related quality of life ques­tionnaire. It was extensively developed in 1980's. Later, this was translated into many languages and found its place as a valid and reliable tool in different cultural and geo­graphical situations.


   Material and Methods Top


The short form 36-item (SF-36) question­naire was translated into Farsi. [10],[11] Twenty­-five specific renal replacement therapy items were added to the end of the translated questionnaire.

To prepare the specific items, a list of related questions was generated. All the generic and the prepared list of specific items were presented to selected specialty groups that included urologists, nephrologists, nurses, psychologists, internists, biostatisticians, and patients. There were initially 75 proposed specific questions related to renal replacement that were validated by the face and content techniques. Accordingly, most questions were scratched out due to subject and/or concept overlap. Finally, the validated Farsi questionnaire included 36 common and 25 specific items.

The field part of the study was done at Dr. Shariati Hospital, University of Medical Sciences, of Tehran. Due to the time­dependency of the quality of life issue, we studied only renal replacement patients who had been on treatment for 6 to 12 months. After interviewing 19 renal transplant and two hemodialysis patients, only 10 transplant patients volunteered to participate in this study. The test to retest time interval was three weeks. The questionnaires were read face to face and in some cases, an expla­nation had to be given to further elucidate the subject. To obviate bias one interviewer was employed.


   Results Top


The study included ten patients (three women and seven men). The mean age was 31.6 years (21 to 44 years). Mean serum creatinine level was 181 µmol/L (109-545 µmol/L). Co-morbidity of hypertension and cardiac disease was found in one patient. Mean interval from transplantation was nine months (6-12 months).

The mean score in the test group was 25.8 (14.5-33), and in the retest group was 25.4 (18.6-35.7). The mean score of test and retest in women patients was 23.7 and 22.4, respectively. The mean score of test and retest in men was 26.7 and 26.7. There was a significant statistical difference between men and women mean scores of test and retest, respectively (p<0.008) and (p<0.007).

The correlation between scores of the test and serum creatinine level was 0.65 (p<0.05). The absolute number of the difference of the test and retest scores as correlated to serum creatinine level was 0.68 (p<0.03).

There was no correlation between the interval from transplantation and test and retest scores (p>0.05). The total reliability coefficient [12] as calculated according to the absolute number of the difference between the test and retest scores was 0.70. This figure increased to 0.72 after deletion of item number 20, to 0.74 after deletion of item number 52 and to 0.75 after deletion of item number 49. The reliability coefficients as calculated for different factors are shown in [Table - 1].


   Discussion Top


In our study, the females had lower score in the test and retest questionnaires. There was no correlation between serum creatinine level and test-retest scores. Moreover, there was a lack of correlation between the duration of transplantation and test-retest scores.

Deletion of items 20, 49 and 52 increased the RC, which shows that there is a considerable change of opinion in relation to the contents of the items between test and retest. To make the variability, there is a need to reconsider the contents of the items in the future studies. The reliability co­efficient of general health factor (questions 51 to 54), pain factor (questions 39 & 40), energy and emotions 'factor (questions 41 to 49) and social activities' factor (questions 38 to 50) was lower than the acceptable level. Perhaps, rewriting the relevant Farsi questions will improve these shortcomings in the future questionnaires.

The current total reliability co-efficient level of 0.70 seems acceptable, but we consider improving it to develop a more standard Iranian quality of life instrument for the evaluation of the patients on renal replacement therapy.

 
   References Top

1.Bowling A. Health-related quality of life: a discussion of the concept, its use and measurement. In: Bowling A. Measuring disease: a review of disease specific quality of life scales. Open University Press 1995;1-19.  Back to cited text no. 1    
2.Testa MA, Simonson DG. Assessment of quality of life outcomes. N Engl J Med 1996;334(28):835-40.  Back to cited text no. 2    
3.Guyatt GH, Feeney DH, Patrick DL. Measuring health-related quality of life. Ann Intern Med 1993;118:622-9.  Back to cited text no. 3    
4.Mingardi G, Cornalba L, Cortinovis E, Ruggiata R, Mosconi P, Apolone G. Health­related quality of life in dialysis patients. A report from an Italian study using the SF-36 health survey. DIA-QOL Group. Nephrol Dial Transplant 1999;14(6):1503-10.  Back to cited text no. 4    
5.Barry MJ. Quality of life and prostate cancer treatment. J Urol 1999;162:407.  Back to cited text no. 5  [PUBMED]  
6.Merkus MP, Jager KJ, Dekker FW, De Haan RJ, Boeschoten EW, Krediet RT. Quality of life over time in dialysis: The Netherlands co-operative study on the adequacy of dialysis. NECOSAD study group. Kidney Int 1999;56:720-8.  Back to cited text no. 6    
7.Merkus MP, Jager KJ, Dekker FW, Boeschoten EW, De Stevens P, Krediet RT. Quality of life in patients in chronic dialysis: Self assessment 3 months after the start of treatment. Am J Kidney Dis 1997; 29(4):584-92.  Back to cited text no. 7    
8.Mingardi G. From the development to the clinical application of a questionnaire on the quality of life in dialysis. The expe-rience of the Italian collaborative DIA-QOL (Dialysis Quality of Life) Group. Nephrol Dial Transplant 1998;(13)1:70-5.  Back to cited text no. 8    
9.Olschewski M, Schumacher M. Statistical analysis of quality of life data in cancer clinical trials. Stat Med 1990;9:749-63.  Back to cited text no. 9  [PUBMED]  
10.Guyatt GH. The philosophy of health­related quality of life translation. Qual Life Res 1993;2:461-5.  Back to cited text no. 10  [PUBMED]  
11.Guillemin F, Bombardier C, Beaton D. Cross-cultural adoptation of health-related quality of life measures: Literature review and proposed guidelines. J Clin Epidemiol 1993;46:1417-32.  Back to cited text no. 11  [PUBMED]  
12.Cronbach LJ. Co-efficient alpha and the internal structure of tests. Sychometrika 1951;16:297-334.  Back to cited text no. 12    

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Correspondence Address:
Massoud Salehi
Department of Biostatistics, School of Medicine, Tarbiat Modares University, P.O. Box 14155-111, Tehran
Iran
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PMID: 17657084

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    Abstract
    Introduction
    Material and Methods
    Results
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    References
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