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Table of Contents
ORIGINAL ARTICLE
Year : 2021  |  Volume : 25  |  Issue : 2  |  Page : 102-113

Factor structure of the Bengali version of atopic dermatitis burden scale for adults: A cross-sectional study


1 Department of Repertory, National Institute of Homoeopathy, Kolkata, West Bengal, India
2 Department of Practice of Medicine, D. N. De Homoeopathic Medical College and Hospital, Kolkata, West Bengal, India
3 Department of Organon of Medicine and Homoeopathic Philosophy, D. N. De Homoeopathic Medical College and Hospital, Kolkata, West Bengal, India
4 Department of Repertory, D. N. De Homoeopathic Medical College and Hospital, Kolkata, West Bengal, India
5 Department of Community Medicine, D. N. De Homoeopathic Medical College and Hospital, Kolkata, West Bengal, India
6 Department of Organon of Medicine and Homoeopathic Philosophy, The Calcutta Homoeopathic Medical College and Hospital, Kolkata, West Bengal, India
7 Department of Materia Medica, Mahesh Bhattacharyya Homoeopathic Medical College and Hospital, Howrah, West Bengal, India
8 Department of Pathology and Microbiology, D. N. De Homoeopathic Medical College and Hospital, Kolkata, West Bengal, India
9 Department of Organon of Medicine and Homoeopathic Philosophy, State National Homoeopathic Medical College and Hospital, Lucknow, Uttar Pradesh, India

Date of Submission30-Dec-2020
Date of Acceptance13-Jul-2021
Date of Web Publication29-Mar-2022

Correspondence Address:
Dr. Ekta Agrawal
Department of Repertory, National Institute of Homoeopathy, Under Ministry of AYUSH, Government of India, Block GE, Sector III, Salt Lake, Kolkata - 700 106, West Bengal
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jdds.jdds_145_20

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  Abstract 


Background: Atopic dermatitis (AD) is associated with increased burden and reduced health-related quality of life (HRQoL); however, there is no available Bengali questionnaire assessing the same. Purpose: We aimed to develop the Bengali version of the questionnaire and examine its cross-cultural adaptability considering linguistic equivalence. Methods: A multicentric, mixed methods, cross-sectional study was conducted through the consecutive sampling at the outpatients of three homeopathy hospitals in West Bengal. The Bengali version of the questionnaire was produced by standardized forward-backward translations. Psychometric analysis was run to examine its factor structure, validity, and reliability. Reliability was examined using internal consistency (n = 230). Construct validity was examined by the exploratory factor analysis (EFA; n = 115) using the principal component analysis (PCA; varimax rotation). Subsequently, confirmatory factor analysis (CFA; n = 115) was performed to verify the model fit. Results: The internal consistency (Cronbach's α =0.876 (95% confidence interval 0.851–0.898)), test-retest reliability and concurrent validity – all were within the acceptable limits. The Kaiser-Meyer-Olkin (KMO = 0.793) and Bartlett's test of sphericity (Chi-square: 1038.981 at 153° of freedom, P < 0.001) both suggested adequacy of the sample. In factor analysis using varimax, all the items loaded above the prespecified value of 0.4 and identified five components, explaining 68.3% of the variation. The goodness-of-fit of the 5-components model in CFA was also acceptable (comparative fit index = 0.858, Tucker Lewis index = 0.823, root mean square error of approximation = 0.102, and standardized root mean square residual = 0.188). Conclusion: The Bengali version of the questionnaire consisting of 18 items and framed within five components appeared to be a valid and reliable instrument measuring disease burden and HRQoL in adults suffering from AD.

Keywords: Atopic dermatitis, Bengali language, quality of life, reliability, validity


How to cite this article:
Agrawal E, Gautam AK, Shaikh AR, Dutta S, Dey S, Mukherjee SK, Saha S, Mandal S, Ghosh S, Koley M, Saha S. Factor structure of the Bengali version of atopic dermatitis burden scale for adults: A cross-sectional study. J Dermatol Dermatol Surg 2021;25:102-13

How to cite this URL:
Agrawal E, Gautam AK, Shaikh AR, Dutta S, Dey S, Mukherjee SK, Saha S, Mandal S, Ghosh S, Koley M, Saha S. Factor structure of the Bengali version of atopic dermatitis burden scale for adults: A cross-sectional study. J Dermatol Dermatol Surg [serial online] 2021 [cited 2022 Jul 2];25:102-13. Available from: https://www.jddsjournal.org/text.asp?2021/25/2/102/341199




  Introduction Top


Atopic dermatitis (AD) or atopic eczema is the most common chronic pruritic inflammatory condition of the skin, affecting mainly pediatric and adolescent populations. The symptomatology includes dry skin, papules, pruritus, serous exudates, excoriation, and lichenification. AD affects face, extensor surfaces of the body, fold of arms, legs, and neck. The prevalence of AD is 20% (5%–30% in the pediatric and 1%–10% in the adult population) worldwide; 12%–14% in Africa; 6%–10% in Latin America; 3%–6% in Asian-Pacific countries, Eastern Mediterranean region, and India.[1],[2] The prevalence is higher in developing countries due to increase urbanization, high socioeconomic status, higher family education, family history, female, small family size,[3] darker skin,[4] western diet consumption, and obesity.[5] Although it is not life-threatening, 60% of AD patients develop comorbidities such as asthma, allergic rhinitis, and food allergies.[3] AD also causes self-consciousness, anxiety, depression, loss of school days, work and daily activities, increase sick days in bed, sleeplessness due to pruritus, impact on personal relationship, participation limitation, and financial burden. High temperature, humidity, weather changes, harsh soaps and detergent, stress dust mites, inhalant allergens, etc., are exacerbating factors. Conventional treatment is dependent on severity and extent of disease, which includes avoidance of irritants, use of moisturizers, and treatment with topical and oral corticosteroids, phosphodiesterase inhibitors, immunosuppressant, antihistamines, phototherapy, and biologic therapy. These treatments are often ineffective.[6]

AD burden scale for adults (ADBSAs) is a patient administered 18-item tool for assessing the burden of AD in adults and also the impact of treatment. Each question has a six-point Likert scale. There are four dimensions – “Daily life,” “work and stress,” “care and management of disease,” and “economic constraints.” A global score is transformed onto a 0–100 scale by the sum of all individual item scores. A higher score indicates a higher AD burden[7] [Annexure I].

The Bengali version of the ADBSA [Annexure II] was developed earlier and was used in a pilot randomized trial of individualized homeopathy in AD to capture the impact of AD on health-related quality of life (HRQoL);[8] in this study, we assessed its psychometric validity and reliability.


  Methods Top


Study design

This multi-centric, noninterventional, cross-sectional, validation study was a mixed method study. It consisted of initial conceptualization of the questionnaire items, standardized translation procedures, face validation by pilot testing, field testing and psychometric assessment of the questionnaire.

Study setting

This multicentric study was conducted at the outpatient departments of National Institute of Homoeopathy (NIH), D. N. De Homoeopathic Medical College and Hospital (DNDHMCH), and Mahesh Bhattacharyya Homoeopathic Medical College and Hospital (MBHMCH). Institutional Ethical Committees (IECs) of respective institutions approved the protocol prior to initiation (NIH Ref. No. 5–23/NIH/PG/Ethical Comm. 2009/Vol. 5/2957, dated September 27, 2018; DNDHMCH Ref. No. DHC/Estt-175/15/863/18, dated September 13, 2018; and MBHMCH Ref. No. 1268/MBHMCH/CH/PRIN/ADM/19, dated September 6, 2019). The conduct of the study was supervised by the IECs and was in compliance with the declaration of Helsinki.

Questionnaire translation stages

The translation method followed standardized forward-backward processes that comprised of forward translation, synthesis, back translation, committee review, face validation, committee appraisal, field testing, and validation [Figure 1].
Figure 1: Study flow diagram

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Inclusion criteria

The inclusion criteria were newly diagnosed cases of AD (ICD-10-CM code L20.9) as per the UK diagnostic criteria[9] and patient-oriented scoring of AD (PO-SCORAD) more than 10, age 18–65 years, both sexes, literate patients, and providing written informed consent to participate in the trial. Patients already undergoing treatment for AD were planned to be interviewed on completely stopping the medicines and after wash-out phase of 1 month.

Exclusion criteria

The exclusion criteria were the patients who were too sick for consultation, diagnosed cases of unstable psychiatric illness affecting quality of life (QoL), uncontrolled or life-threatening illness affecting QoL or any organ failure, substance abuse and/or dependence, pregnant, puerperial and lactating women, and patients undergoing any kind treatment for AD or any other chronic disease within the last 6 months.

Sample size

Although recommendations for adequate sample size to conduct factor analysis lack clear scientifically sound recommendations and remain controversial,[10] still a sample size between 50 and 250 is usually preferred with most authors recommending at least 100 subjects.[11] Gorsuch's formula of subject to item ratio (5:1 or 10:1) is also used for the estimation of sample size for validation studies; thus, indicating a requirement of 90–180 samples for our study.[12] However, out of 253 participants approached, we were able to capture 230 responses in total with a response rate of 91%, of which first 115 were subjected to principal component analysis (PCA) and the next 115 to confirmatory factor analysis (CFA); thus, the sample size for our study might be considered as adequate.[13]

Sampling

Patients suffering from AD who attended the dermatology outpatients of the hospitals on the days of data collection were approached by the consecutive sampling and were invited to participate in the study subject to fulfilment of the prespecified eligibility criteria.

Data collection

Prior to obtaining responses on the patients' self-administered questionnaire, all the participants were provided with patient information sheets in local vernacular Bengali and written informed consents were obtained. Patients' privacy was maintained by concealing all the identifiable information. Another section in the questionnaire sought information regarding patients' sociodemographic features. The filled-in questionnaires were put inside envelops and sealed at the study site. The same self-administered questionnaire was filled in again by 30 participants selected randomly after 2 weeks, most likely in patients whose clinical state had not changed (confirmed over phone). A Microsoft Excel spreadsheet was used for the extraction of data and finally that was subjected to the statistical analysis.

Statistical analysis

It was conducted by using IBM® Statistical Package for the Social Sciences (SPSS)® software, version 20.0 and SPSS Amos® version 20.0 (IBM Corp., Armonk, NY, USA). First, adequacy of sample was checked using Kaiser-Meyer-Olkin (KMO) value and data appropriateness for PCA using Bartlett's test of sphericity. The KMO = 0.50 and above[14] with significant Bartlett's test of sphericity (P < 0.05) was considered appropriate for factor analysis. Then, exploratory factor analysis (EFA) using PCA with varimax rotation (eigenvalue above 1) was conducted to examine the uni-dimensionality of the construct. Only factors with loadings of 0.40 and above were retained. Next, questionnaire reliability was evaluated by the analyses of internal inconsistency and test-retest reliability. High internal consistencies were denoted by Cronbach's alpha of 0.5–0.7 and average item-total correlation in a moderate range of 0.3–0.9.[15] Alpha value of 0.9 and above was considered as excellent, while no meaningful construct was indicated by a correlation near 0.[16] Intra-class correlation coefficient values above 0.7 indicated that the questionnaire was stable over time, 0.4–0.7 indicated fair reliability, while poor reliability was demonstrated by the values <0.4.[17] Paired t-tests were used on randomly chosen 30 patients' responses to evaluate whether change in scores between the test-retest evaluations were statistically significant. Test-retest reliability was checked at 15-day intervals in patients whose clinical state had not changed (confirmed over phone).[18] Correlation statistics were used to assess the inter-item correlations between domains (item discriminant validity) and the overall score (internal item convergence). The instrument was considered to be internally consistent if the correlation value was found to be 0.4 or higher. Subsequently, concurrently validity was evaluated by Pearson's r statistics comparing the total questionnaire scores with simultaneously obtained PO-SCORAD values. Finally, a CFA model was developed to verify the goodness-of-fit of the a priori detected scales as suggested by EFA. In CFA, specific hypotheses are framed about the structure of factor loadings, and then, the inter-correlations are tested. The goodness of fit of the CFA models was evaluated utilizing the following multiple fit indices: Comparative fit index (CFI), normed fit index (NFI), Tucker Lewis index (TLI), root mean square error of approximation (RMSEA), standardized root mean square residual (SRMR), Bayesian information criterion (BIC), and Hoelter index. The recommendations for cutoff values indicating a good model fit are CFI or TLI ≥0.95, RMSEA ≤0.6 and SRMR ≤0.8.[19],[20] Statistical tests were two-tailed and were conducted with alpha fixed at 0.05.


  Results Top


Descriptive statistics

Descriptive statistics on sociodemographic features and obtained response statistics on individual items on the questionnaire were presented in terms of means, standard deviations, medians, inter-quartile ranges, skewness, and kurtosis [Table 1] and [Table 2].
Table 1: Baseline sociodemographic features (n=230)

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Table 2: Descriptive statistics of the questionnaire items, domains, and overall score (n=230)

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Exploratory factor analysis

Sample size was adequate as evidenced by the KMO = 0.793, much greater than the minimum Kaiser criterion of 0.5. A significant Bartlett's test of sphericity (Chi-square: 1038.981 at df = 153, P < 0.001) also signified that the R-matrix was not an identity matrix. Extraction was performed using the principal component method to verify the number of factors those bet explained the covariation matrix within the experimental sets of data. The first five components disclosed high eigenvalues, and subsequently, the curve dropped gradually before the final plateau was reached [Figure 2]. The correlation matrix was searched for values more than 0.9 to identify multi-co-linearity and singularity. Determinant of the correlation matrix was 0.616. Thus, multi-colinearity was not a problem for the dataset. The correlation matrix of the five components and total scores also revealed similar findings [Table 3]. Sample size of 115 was adequate for running PCA as the average communalities after extraction was 0.648, above the preferred cutoff of 0.5. The factor component matrix also supported the screenplot by representing information from initial unrotated solution and extracting five components explaining 68.3% of the total variance [Table 3] and [Table 4]. The rotated (varimax) component matrix was a matrix of factor loadings for each variable onto each factor. The absolute values <0.4 were suppressed, ensuring that factor loadings within ± 0.4 were not displayed in the output. After conducting factor rotation, those items were eliminated that loaded onto the same factor. Five subcomponents of the main construct were identified and named as below [Table 5]:
Figure 2: Scree plot

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Table 3: Inter-component correlation matrix (n=230)

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Table 4: Total variance (n=115)

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Table 5: Rotated component matrix - Factor loadings revealing five component structures (n=115)

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  1. Items 2, 3, 4, and 5: “Participation restriction”
  2. Items 8, 9, 10, 11, and 13: “Anxiety and financial burden”
  3. Items 1, 6, and 7: “Overall impact and sleep disturbance”
  4. Items 17 and 18: “Depression”
  5. Items 14, 15, and 16: “Economic burden.”


Internal consistency

The Cronbach's alpha value for the overall questionnaire was 0.876 (95% confidence interval 0.851–0.898) and alpha for the five subscales ranged between 0.738 and 0.857, indicating acceptable to good reliability. Estimated Spearman-Brown coefficient and Guttman's lambda split-half coefficient were also in acceptable limits [Table 6].
Table 6: Internal consistency of the questionnaire (n=230)

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Test-retest reliability

Individual subscale scores and total scores were largely stable with insignificant mean differences (all P > 0.05), thus indicating acceptable test-retest reliability [Table 7].
Table 7: Test-retest reliability of the questionnaire domains and overall score (n=30)

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Concurrent validity

The questionnaire had acceptable concurrently validity (Pearson's r = 0.588, P = 0.036).

Confirmatory factor analysis

The indices of CFA that confirmed model fit (χ2 = 237.507, degrees of freedom = 109, P < 0.001) were: CFI = 0.858, NFI = 0.772, TLI = 0.823, RMSEA = 0.102, SRMR = 0.188, BIC = 446.284, and Hoelter index (at α =0.05) =65, indicating an acceptable model fit and five distinct components [Figure 3].
Figure 3: The confirmatory factor analysis model. The CFA model; PR: Participation restriction, AFB: Anxiety and financial burden, OISD: Overall impact and sleep disturbance, EB: Economic burden

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  Discussion Top


Our findings support the validity and reliability of the developed questionnaire to assess impact of AD on HRQoL. EFA using PCA of the questionnaire identified a five components model. The overall goodness of fit of the 5-component model was confirmed by CFA. The internal consistency, test-retest reliability, and concurrent validity of the questionnaire – All were acceptable.

One of the major strengths of this study was to apply EFA and CFA on two different samples, each of size of 115. Our study yielded five individual subscales of the questionnaire as in earlier studies – But measured somewhat different dimensions from the English version. The original English version of ADBSA has four subscales – Daily life, work and stress, care and management of disease, and economic constraints. Both English and Bengali versions are provided with six-point Likert scales. Validation of English ADBSA involved a sample size of 128 adults; our sample size was 230. None of the questionnaires apply any recall period. Concurrent validity of English ADBSA was evaluated using short form-12 and dermatological life quality index questionnaire, but we used PO-SCORAD instead. Scores of both the questionnaires are interpreted in similar ways – Higher scores represent higher disease burden. English ADBSA components were identified by factor analysis; however, CFA was not run subsequently. We verified model fit of the 5-component model by CFA. Cronbach's alpha of the English version was 0.89, similar to our findings of 0.876. In the rotated component matrix of 18 items, 89% (16/18) had strong factor loadings of 0.60 and above. Thus, overall questionnaire psychometrics appeared promising and further translation and validation of the questionnaire is warranted into other Indian languages and on larger sample for better and large-scale utilization in a multi-ethnic Indian population.

Unlike other validation studies, there was no control (normal/healthy) group; hence, assessment of item discriminant validity was not possible. Besides, responsiveness of the questionnaire was not assessed because the treatment offered by the study sites was homeopathy exclusively and that was not an accepted standard treatment for AD until now. The internal consistency was reasonable and comparable to the existing original English version. Alpha has strict assumptions including unidimensionality, uncorrelated errors, and identical covariances between the items (tau equivalence). In most of the cases, these assumptions are violated and thus over-or underestimate the true reliability. Thus, alpha may not be the best choice for measuring reliability. The probable alternative may be Guttman's lambda or McDonald's omega which are not based on tau-equivalence. One important caveat was that consecutive sampling was used and which had introduced sampling bias into the study.

Thus, the validated Bengali questionnaire may serve as an important patient-administered outcome questionnaire to measure disease burden and impact of AD on HRQoL. The responsiveness and sensitivity to change of the questionnaire to measure symptoms and treatment effects was not assessed. Finally, to support the use for measuring the impact of clinical treatment, the final step in this development will be to define a minimally important difference of change reflecting a clinically meaningful difference.


  Conclusion Top


The developed Bengali version of ADBSA contains 18 items which are constructed within a 5-component model but which measured different dimensions from the English version. It is a reasonably valid and reliable tool to measure symptom severity and impact of AD on HRQoL in Bengali patients.

Acknowledgment

The authors appreciate the kind help received from Prof. (Dr.) Malay Mundle, Research Methodologist, Dr. Pankaj Kanti Jha and Dr. Chanchal Bhar, Consultant Dermatologists, Dr. Atanu Dogra and Dr. Kaustabh Manna, Psychologists, Mr. Kohinoor Chakraborty and Mr. Indrajit Mitra, Linguistic Experts for their services as expert panelist in the review committee. We are also grateful to the patients for their sincere participation.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.


  Annexure Top


Annexure I: Atopic dermatitis burden scale for adult – English version

Measuring time: Baseline / Month … / Month …

Patient's name: Age: Reg. No. Date:

Instructions: The following questions are related to and will ask you about the severity of symptoms of your atopic dermatitis or eczema. Kindly put a tick mark against appropriate boxes to give your answer.

1. My eczema disrupts my daily life

Never  Rarely  Sometimes  Often  Very often Constantly

2. My eczema affects how I organize my life

Never  Rarely  Sometimes  Often  Very often Constantly

3. I have given up certain hobbies because of my eczema

Never  Rarely  Sometimes  Often  Very often Constantly

4. I choose where I will spend my vacations based on my eczema

Never  Rarely  Sometimes  Often  Very often Constantly

5. My eczema prevents me from participating in certain sports

Never  Rarely  Sometimes  Often  Very often Constantly

6. My eczema disrupts my family life

Never  Rarely  Sometimes  Often  Very often Constantly

7. My eczema affects my sleep

Never  Rarely  Sometimes  Often  Very often Constantly

8. My eczema is the cause of tension with my significant other

Never  Rarely  Sometimes  Often  Very often Constantly

9. My family life is structured around my eczema

Never  Rarely  Sometimes  Often  Very often Constantly

10. Part of my budget is dedicated to treating my eczema

Never  Rarely  Sometimes  Often  Very often Constantly

11. I have the impression that my eczema is costing me more and more

Never  Rarely  Sometimes  Often  Very often Constantly

12. The foods I eat are chosen based on my eczema

Never  Rarely  Sometimes  Often  Very often Constantly

13. I dedicate a lot of time to the treatment of my eczema

Never  Rarely  Sometimes  Often  Very often Constantly

14. I hesitate to buy certain medications [for my eczema] that are not reimbursed

Never  Rarely  Sometimes  Often  Very often Constantly

15. I regularly skip work to see my doctor [about my eczema]

Never  Rarely  Sometimes  Often  Very often Constantly

16. I have had to take time off from work because of my eczema

Never  Rarely  Sometimes  Often  Very often Constantly

17. I am beginning to really get tired of my daily care

Never  Rarely  Sometimes  Often  Very often Constantly

18. My daily care is wearing me out tremendously

Never  Rarely  Sometimes  Often  Very often Constantly

Kindly check whether you have answered all the questions or not. Thanks for your participation.

……………………………………………………… ……………………………………………………

Patient's signature Doctor's signature

Annexure II: Atopic dermatitis burden scale for adult – Bengali version





 
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    Figures

  [Figure 1], [Figure 2], [Figure 3]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7]



 

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