Psychometric Properties of the Persian Version of the Quality of Life in Epilepsy Inventory in the Later Life
Article information
Abstract
Background and Purpose
The reports indicate on the incidence of seizure disorder about 1.5 per cent of the normal elderly population. The Quality of Life in Epilepsy Inventory (QOLIE-31) has been pervasive simple tool to screen seizure in the busy neurophysiological settings and monitoring. It was constructed as self-administered tool in two formats, 89 and 31-items. To the reliability and validity of the QOLIE-31 across older adults in the southwest Iran and discuss its role in the detection of health-related quality of elderly patients with epilepsy.
Methods
About 73 older adults (mean age = 66.3 ± 1.71) were sampled from the eight hospitals and caring centres. They replied to the QOLIE-31. External and criterion validity was calculated by correlation to the SF-36 questionnaire, to check and validate the epilepsy specific dimensions. The QOLIE-31 includes seven subscales: overall quality of life, seizure worry, emotional well-being, energy/fatigue, cognitive, medication effects, and social function.
Results
There was significant difference within sample groups regarding main variables (p < 0.05). The coefficients of Cronbach’s alpha (α= 0.76), convergent validity (0.81), divergent validity (−0.21), external validity with overall score of SF-36 (0.87), and criterion validity (0.78) were estimated, which were significant at p < 0.01. The exploratory factor analysis demonstrated that the QOLIE-31 is organized into six factors, which clarifies 92 per cent of the scale’s variance. Second-order confirmatory factor analysis pointed out that the factor is well matched up onto a principal factor. Consequently, the 6-factors model was well appropriate for the data by the fit index techniques for adjusting the scale (AGFI = 0.94, GFI = 0.96, RMSEA = 0.003, IFI = 0.90, NFI = 0.95, CFI = 0.95).
Conclusions
The results pointed to the well-adjusted reliability and psychometric properties of the QOLIE-31 and its usefulness for the relevant studies as well.
Introduction
Epilepsy is a condition of decreasing neuronal system that usually begins to occur at any years of age. It is the most common neurological disorder-affecting people of all ages and is important to understand that epilepsy is a physical rather than mental disorder. There may be a problem by refusing to even talk about the symptoms. There are many different types of seizure, which are divided into two main groups i.e. generalized seizures, which occur when the disturbance is spread across all of the brain, and the second is partial seizures when only part of the brain is affected.1,2 Epilepsy can affect anyone at any time of life. It is more usually diagnosed in people under the age of 20 or those aged over 60. Most seizures are short-lived and need no medical attention.3–7 Over ten thousand articles on seizure (or epilepsy) for juveniles and youths can be found, but relatively less has been conducted on the older adults’ equivalent.8–10 The ratio of published studies of seizure within young adults to older adults is approximately 1:100.4,11–13 Attaining knowledge regarding epilepsy among elderly people will help the care-givers and gerontologists to achieve the ultimate goal of a dignified healthy ageing,14–17 and maintain the highest quality of life.8,18–21 Thus, it is adding life to years and not simply years to life.22,23 While ignorance about elderly seizure, having an instrument turns out to be a necessity.9,24–27 It is helpful even in the clinical treatment as well.28 The study was investigated to the standards of quality of life in epilepsy inventory in the later life, the shortened version (QOLIE-31) (1993, 2005) within older adults to introduce a relevant criterion. The measurement of external validity had contained correlating relation of the SF-36 and QOLIE-31 Inventories, to check the properties of the epilepsy specific dimensions.
Methods
About 73 men and women with age range of 57 to 91 and with the mean age of 66.3 ± 1.71 were sampled with the cluster-ratio sampling method from the eight medical centres and hospitals of Khuzistan province in the southwest Iran. The aged samples replied to the 31 items of QOLIE-31. The QOLIE-31 questionnaire mainly consists of a 31-item disability/symptom scale regarding epilepsy that was investigated by authors and literature reviews.2,4,7,12,13,20,22,24,27,29 It was developed in three version i.e. 89, 31, and 10 items. The 31 items is most common used version of QOLIE-31. Each item in the scale has several responses i.e. six response options from 1 = all of the time to 6 = none of the time severe (Item No: 2–12), four response options from 1 = very fearful to 4 = not fearful at all (Item No: 15–24). In addition, other formats have five response options from 1=not at all bothersome to 5=extremely bothersome (Item No: 25–30), and three closed-form and shaped items. If the 31 items are completed, a scale score ranging from 25 (no symptoms) to 125 (most severe symptoms), can be calculated. The QOLIE-31 contains 31 items on the following domains: overall quality of life (OQ), emotional wellbeing (EW), energy-fatigue (EF), cognitive functioning (CF), medication effects (ME), seizure worry (SW), and Social functioning (SF).
External and Criterion Validity
It was estimated by the correlations of overall scores of QOLIE-31 and its domains to other similar instrument like SF-36. The Pearson’s correlation coefficients was used to measure the relationship between scales of QOLIE-31 and SF-36. Strong correlations were expected between domains and scales with the same content. The SF-36 range from 0 to 100, with 100 representing the highest level of functioning possible in the QoL.
Translating the Instrument
Psychometric properties of the QOLIE-31 was evaluated in several divergent backgrounds and cultural groups i.e. Spanish, German, Thai, Norwegian, French, Italian, Portuguese, Serbian, Bulgarian, and Czech context.2,19,30–35 The study translated it into Persian from its English version4,12 by three instructors and an English language expert. The four translated versions were compared by the authors, and the researchers developed a common Persian text from them. Afterwards, the Persian version of the QOLIE-31 was translated back into English by an English language expert who had not seen the original English text and by a linguist. The English statements of the questionnaire that had been translated from Persian into English were compared with the original version, and any necessary revisions were made as well.
Setting and Participants
From the eight medical centres and hospitals of Khuzistan province in the southwest Iran, about 80 aged men who had been constant patients at the centers responded to the Iranian version of the QOLIE-31. Of the 80 responders, 73 had responded to all of the 31 items used in the inventory and included in the analysis. The mean age of the samples was 66.3 ± 1.71 (range 57–91) years.
Results
About 73 elderly patients were the samples of the study, 45 men (79.5%) and 28 women (20.4%) with a mean age of 68.9 years of old (standard deviation [SD] = 7.77). All of patients were replied to both inventories of study, QOLIE-31 and SF-36. The demographic characteristics are shown in Table 1 and clinical characteristics in Table 2. The comparing QOLIE-31 overall score made between elderly males and females regarding their health status, education, occupation, marital status, and other demographic characteristics, type of epilepsy, etiology, seizure type, seizure severity, and antiepileptic drugs, revealed statistically significant difference within samples.
Frequency distribution and comparison of seniors’ demographic and background profiles by gender (n = 73, p ≤ 0.05)
Frequency distribution and comparison of seniors’ clinical characteristics profiles by gender (n = 73, p ≤ 0.05)
Internal Consistency
The coefficients of Cronbach’s alpha (α = 0.89), convergent validity (0.81), divergent validity (−0.21), and criterion validity (0.78) were estimated, which were significant at ρ < 0.01. The discriminative power in the QOLIE-31 of sub-scales with overall score using Kolmogorov-Smirnov and Shapiro-Wilk tests of normality demonstrated an almost normal distribution (Table 3). Mean overall score was 52.5 (CI = 38–67) and SD = 19.42. Discriminative power testing showed that domains showed an almost normal distribution (Table 3).
Descriptive statistics and discriminative power in the QOLIE-31 of sub-scales with overall score
Regarding criterion validity, Pearson’s correlation coefficients were significant and appropriate for all sub-domains of QOLIE-31 and SF-36. This finding could suggest some specificity of these domains. Table 4 summarizes the appropriate correlation of the two questionnaires’ subscales.
Pearson correlations between QOLIE-31 and SF-36 sub-domains (p < 0.05)
Contrast Validity
The exploratory factor analysis demonstrated that the 31-items of QOLIE-31 for aged samples are organized into seven factors (factor 1: seizure worry, factor 2: overall QoL, factor 3: emotional wellbeing, & factor 4: energy/fatigue, factor 5: cognitive, factor 6: social functioning, and factor 7: medication effects) which clarify 94 percent of the scale’s variance. Second-order confirmatory factor analysis pointed out that the factors were well matched up onto a principal factor. According to the Table 5, the rotated factor matrix pattern of Varimax for the QOLIE-31’s subscale questions was considered. Those questions with factor loadings above 0.80 were selected.
Varimax rotated factors matrix of the QOLIE-31 (only factor loadings ≥5)
There are covariate between some items i.e. item No. 14 between factors No. 2 and 3, item No. 9 between factors No. 3 and 5, item No. 26 between factors No. 5 and 7 in Persian version of QOLIE-31. It may acclaim that covariate item of the factors like overall QoL, emotional wellbeing, cognitive, and medication effects could be reconstructed as well.
Consequently, the 7-factor model was appropriate for the data and the fit index techniques for adjusting the scale. The indexes of the model’s goodness of fit refer to the integrity of the 7-factor model with data. The χ2 to degrees of freedom is less than 2 in efficient models. It is closer to zero and will be closer. The root mean square error of approximation (RMSEA) and standardized root mean residual (SRMR) must be less than 0.05 that indicate to good models. The model pointed out the goodness of fit of the model in the study (AGFI = 0.94, GFI = 0.96, RMSEA = 0.003, IFI = 0.90, NFI = 0.95, CFI = 0.95).
As closer measure to 1 in the normed fit index (NFI), the comparative fit index (CFI), goodness-of-fit statistic (GFI), the incremental fit index (IFI), and the adjusted goodness of fit index (AGFI), they refer to the goodness and fit of model. They were more than 0.90 (Table 6).
The goodness of fit indexes model
Discussion
The aim of the study is to look for the relevant instrument regarding common symptoms of an nervous-related issue called Epilepsy within aged people in the Iranian social context, even the issue still is challengeable.3,4,9,13,20,21,26 So, the quality of life in epilepsy questionnaire (QOLIE-31, 1993 & 2005) was used and evaluated. The results stated to the well-adjusted psychometric properties, discriminative statistic, reliability, and validity of QOLIE-31 and usefulness of it in the relevant studies too. Regarding the external validity, correlation coefficients were significant and appropriate all sub-domains of QOLIE-31 with SF-36 as well. Therefore, future researchers should not limit themselves to the western scales,7,21 but should also consider specific cultural factors.
Persian-language version of QOLIE-31 illustrated appropriate satisfactory psychometric statistics, good reliability, high internal consistency, valuable discriminative characteristics. It has applicable level in the conceptual similarity to the original English-language version. Comparing the results of the study to other similar research indicated to adapting the measures to English, Italian, Bulgarian, Serbian, and French version of QOLIE-31.2,19,30–35
Regarding the findings of the study, the QOLIE-31 is appropriate for validity and reliability in the aged community of the Iranian society and it can be employed to measure quality of life of aged patient with seizure symptoms. Additionally, it is applicable by gerontologists, neuropsychologists, neurophysiologists, geronto-psychiatrics, and neurologists for the future studies as well as to the geriatrics in their diagnostics. Regarding the divergent background, it is first time suggested that in the future studies, the gender-related symptoms of epilepsy and moderating the seizure experience within minorities groups, which are compatible with communities like Iran’s native culture, be conducted and evaluated as well.
Acknowledgements
We wish to thank colleagues and the anonymous referees for their valuable comments.
Notes
Authors’ Contributions: AH contributed to the design, performed the interviews, AHH interpreted data from the interviews. LFS has contributed to the design, interpretation, and discussion. AN analysed the data and AA wrote the draft and has revised the content, scientific writing. All authors have approved the final manuscript as well.