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Journal of Postgraduate Medicine, Vol. 54, No. 4, October-December, 2008, pp. 273-275 Original Article Quality of life in thalassemia major: Reliability and validity of the Persian version of the SF-36 questionnaire Jafari H, Lahsaeizadeh S, Jafari P, Karimi M Hematology Research Center, Shiraz University of Medical Sciences, Shiraz Date of Submission: 17-Aug-2007 Code Number: jp08098 Abstract Aims: The objective of this study was to determine the reliability and validity of the eight-item Short Form Health Survey (SF-36) questionnaire translated into Persian for use in Iranian patients with thalassemia major. Keywords: Iran, quality of life, SF-36, thalassemia Inadequately treated thalassemia major is a potentially fatal disorder . [1] It is a serious public health issue throughout the Mediterranean region, the Middle East, the Indian subcontinent and Southeast Asia [2],[3] and in several other countries due to migration. [4] In the last 30 years, introduction of regular blood transfusion therapy and effective iron chelating therapy with desferrioxamine have markedly improved the life expectancy of these patients. [5],[6],[7] However, these patients now face newer challenges in obtaining higher education, securing employment and raising their own families. They are also confronted with other problems like bone disease, infertility and increased prevalence of psychiatric distress. [8] The Quality of Life (QOL) of individuals with thalassemia major is influenced by the following factors: impact of the diagnosis and treatment, having a chronic condition, appearance, treatment components like frequent hospital visits for transfusion, nightly subcutaneous infusions, delayed or absent sexual development, complications of the disease and therapeutic interventions and uncertainties about the future. [9] Various studies have shown that culture and education play a vital role as Khurana et al. , showed that adverse impact of thalassemia was perceived in the domains of education and sports. Most thalassemics were not satisfied with their body image. The adolescents were anxious about their future health and education. They mainly depend on their parents for monetary and emotional support. [10] A study in India showed that thalassemia is extremely stressful, and patients face a variety of physical, psychological, and social problems. The findings also showed that culture and education play a major role in illness experiences. [11] Hence, as Iran has a high prevalence of thalassemic patients, a survey was conducted to determine the reliability and validity of the Short Form Health Survey (SF-36) Questionnaire in patients with thalassemia major in Iran. Materials and Methods The standard "Forward-Backward" procedure was applied to translate the SF-36 questionnaire from English to Persian by a bilingual individual. The relevant cultural adaptation was also carried out (e.g. substituting golf and billiards into mild sports and changing mile to kilometer). The final form was administered by simple randomization to 200 patients amongst 810 individual thalassemic patients (from both rural and urban areas of Shiraz) aged over 15 years who came for blood transfusion to Dastgheib Hospital, Shiraz, south of Iran. The survey was carried out during 2004-05 in accordance with the ethical principles of the university hospital of Dastgheib (Shiraz, Iran) after the hospital′s ethics committee′s approval. The patients were requested to fill up the SF-36 questionnaire after obtaining written informed consent. Although the SF-36 is basically designed to be a self-administered questionnaire it can be completed through an interview in person, computerized administration or by telephone. [12] Hence, for illiterate individuals a trained person interviewed the patients face to face. There was no missing data. Age and sex of the patients were also recorded. Responses on the SF-36 form were scored according to the guidelines of the Clinical Outcome Evaluation System (COES) software. Statistical analysis : All statistical analyses were carried out using the SPSS 13 for Windows. Reliability and the internal consistency of the questionnaire were assessed by Cronbach′s alpha. Convergent and discriminant validity was checked using Spearman correlation. Construct Validity was checked by factor analysis. The correlation between sex and increase in age with the concepts of the QOL was also considered in our study. Results The mean age of 200 patients (105 males, 52.5%) enrolled in the survey was 19.81+/- 4.07 years (range: 15-32 years). All the patients were on regular blood transfusion therapy (every two to four weeks) with poor chelation therapy due to painful injections. The reliability of the questionnaire was obtained by Cronbach′s alpha coefficient (a= 0.915). In addition the Cronbach′s alpha coefficient to indicate items internal consistency reliability for each measure is present and all measures but role emotional showed satisfactory results. All scales met or exceeded the 0.70 level recommendation for group comparison with the exception of the role emotional scale (Cronbach′s α = 0.65) [Table - 1]. The reliability obtained for both males and females was 0.90 and 0.93, respectively. As shown in [Table - 1], the convergent validity for each item ranged from 0.57-0.69 for physical functioning (PF) scales, 0.61-0.70 for role physical (RP) scale, 0.85-0.90 for bodily pain (BP) scales, 0.64-0.74 for general health (GH) scales, 0.62-0.75 for vitality (VT) scales, 0.77-0.88 for social functioning (SF) scales, 0.56-0.73 for role emotional (RE) scales and 0.69-0.77 for mental health (MH) scales. [Table - 1] shows the results of item convergent, discriminant validity tests and internal consistency. The scaling success rates were 100% for convergent validity of each scale. Factor analysis was performed to determine that the Persian version measures two dimensions: physical and mental parameters. As showed in [Table - 2], all the items that should be in physical summary status (physical functioning, role physical, bodily pain) are in this group except general health that has been substituted with role emotional and the rest are in the mental summary status with the exception of role emotional. From the collected data it was seen that, overall, most of the patients in both sexes and all ages were in the lower range for mental and physical summary dimensions and their scaling parameters [Table - 3]. The analysis showed that there was no significant association between the gender and age with the questionnaire′s eight scaling items and the physical and mental summary (all P values> 0.05) Discussion The SF-36 questionnaire is a well-known instrument for measuring QOL of normal population as well as of individuals with various disease states. The scale translated into Persian was used for obtaining the validity and reliability of the questionnaire in general population in Iran in two studies. [13],[14] However, there has been no research on patients with thalassemia major using this instrument in Iran or elsewhere. This study reports data from a validation study of the eight-item questionnaire in thalassemic patients in Iran. In general, all psychometric tests of the SF-36 Iranian version showed satisfactory results. Reliability of the questionnaire as measured by the Cronbach′s a coefficient for all eight scales except the RE scale exceeded the recommended level. The fact that the RE scale performed differently from other scales might reflect the difficulty encountered in translating its items from English to Persian. However, in translating the RE items it was decided to use very similar vocabularies to indicate what are exactly asked for. The multi-item analysis of the SF-36 Iranian version of this study showed that the items related to each scale had a high correlation with its scale and low correlation with other scales. This reveals that the questionnaire has a high convergent validity and low discriminant validity for each scale and its items for thalassemic patients. The factor analysis clearly indicated that the questionnaire includes two underlying factors, namely physical and mental components, although the findings were not exactly similar to the original hypothesized associations and the translated form done by Montazer et al . [13],[15] This might be due to the difference in the studied populations, as Tehran is a representative sample of urban population but the patients in this study came from both rural and urban areas of Shiraz. [13] The general health was strongly associated with the mental component and the RE scale with the physical component while one expects a weak association with physical component. It is discussed that these might be due to the strong impact of mental health on Iranians′ QOL and the differences between the Asian culture and Western culture and it is not a structural defect since the validity of items and scales were satisfactory. [14],[16] In conclusion, the first survey on thalassemia major patients with the Iranian version of the SF-36 questionnaire proved to be acceptable and has a good structured characteristic. Thus, it is a reliable and valid instrument that can be used to measure the effects of thalassemia on these patients′ QOL and hence it is so important to promote a clear understanding of the disease and initiating intervention programs. References
Copyright 2008 - Journal of Postgraduate Medicine The following images related to this document are available:Photo images[jp08098t3.jpg] [jp08098t1.jpg] [jp08098t2.jpg] |
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