Burden of adult neurofibromatosis 1: Translation, cultural adaption, and psychometric properties of the Iranian version

Abstract

Background: The notion of "burden" has taken a key place in the evaluation of care, and particular in the case of rare diseases. The aim of study was to evaluate the psychometric properties of the burden of neurofibromatosis 1 (BoN) questionnaire and the perceived disease burden.

Results: BoN with 15 items was translated into Persian and no items were removed from it based on content validity. The adequacy of sample was acceptable (KMO = 0.902), and Bartlett's test of sphericity revealed statistically significant results (P<0.001). Three factors were explored for the questionnaire based on exploratory factor analysis. Reliability of the scale was good (Cronbach’s alpha: 0.90) and Intra-class reliability was 0.85. The severity of burden of neurofibromatosis was moderate and the total mean score of burden was 33.12 ±16.12.

Conclusions: The Persian version of BoN is an acceptable tool in terms of structure and content that specifically addresses the practical aspects of daily activities for patients with neurofibromatosis.

Introduction

Neurofibromatosis Type 1 (NF1) or Von Recklinghausen's disease, is the most common autosomal dominant neuroectodermal disease, primarily described by the presence of six or more café-au-lait macules, intertriginous freckles, two or more neurofibromas as the most noticeable disease manifestation (1–3). NF1 is the most common type of this disease with estimated prevalence of about 1:2000–1:3500 individuals around the world (4, 5). Sign and symptoms vary from life-limiting to life-threatening conditions and significantly decrease the quality of life (6).

NF1 diagnosis is usually established clinically by dermatologists or pediatrician since it affects the skin in early age and the nervous system in later age. Genetic tests are not routinely required in low income countries. Chief complaint of NF1 patients is mostly cosmetic deformities and chronic pain and difficulty learning which subsequently lead to social complications, low self-esteem, depression experiences and mental disorders. Findings of previous studies have shown that the experience of depression and other psychiatric complications were higher in patients with NF1 compared to healthy adults (7, 8).

There is not ye a definitive treatment for NF1, and surgical treatments, chemotherapy and radiotherapy in cases of malignancies are treatment options. For the proper palliative management of NF1 patients with numerous psychiatric and psychological disorders, a systematic multidisciplinary approach must be considered including the coordination of dermatologists, neurologists, surgeons, psychologists and other health care workers involved with such patients. Health care professionals should also be familiar with health-related concept regarding this manner such as "individual disease burden" that was created to assess disease “disability” in the broadest sense, including social, psychological, physical features, and economic. The term "individual burden" came from the general concept entitled “Global Disease Burden” which was introduced in 2010 by the World Health Organization (WHO), for quantifying population health and determining action priorities (9). Individual burden is increasingly investigated and different studies created and validated specific assessment tools for burden of each skin diseases such as psoriasis, vitiligo, atopic dermatitis, hereditary ichthyosis, and infantile hemangioma (10–14).

Individual disease burden of neurofibromatosis was investigated first by Armand et al. (15). They developed and validated a questionnaire in French language entitled "Burden of Neurofibromatosis" (BoN) and investigated it among 60 adult patients. As the second step, they translated the tool from French to English language. To the best of our knowledge, There was no Iranian tool to measure the concept of burden; so we aimed to translate, cultural adapt and validate the BoN tool and investigate the psychometric properties of Iranian version of BoN.

Method

The methodological study was conducted as follows: a) Translation and adaptation of Burden of adult neurofibromatosis 1 (BoN) to Persian in 7 steps (16). b) Psychometric properties of the questionnaire.

Measures

Personal information checklist includes age, gender, education level, marital and employment status

Participant demographic information was collected from a self-administered questionnaire that included age, gender, level of education, marital status, and employment status.

The Burden of adult neurofibromatosis 1 (BoN) was developed by Armand et al in 2019 (15). It consists of 15 items and is rated on a 6-point scale, ranging from 0 (never) to 5 (constantly). By summing the scores of all items, the total score is calculated and the total score range is from 0 to 75. Higher scores indicate higher levels of burden of neurofibromatosis. The scale exhibited strong psychometric properties, including high internal consistency (α = .91).

Participants

Four hundred patients with neurofibromatosis were invited to participate in this study. Eligibility criteria for participants: a) Over 18 year’s old b) Neurofibromatosis disease approved by the Iranian Neurofibromatosis Association c) No history of psychiatric illness. The questionnaire was prepared electronically on the Google Form platform and the hyperlink sent to the participants and finally 356 people completed the questionnaire. Data collection took place between January 2020 and February 2020.

Translation Process

Initially, two bilingual translators independently translated the questionnaire from English to Persian. Subsequently, by a third bilingual translator, the two translations were compared and transformed to a single text. The text of the current questionnaire was then translated back into the original language by another bilingual translator and compared to the original version of the questionnaire. The opinions of 10 people were applied in the questionnaire and after applying the final corrections, the final version for psychometrics was prepared.

Psychometric Procedure

Content validity includes Content Validity Ratio (CVR) and Content Validity Index (CVI). Twenty experts reviewed the questionnaire items and chose one of the essential, useful but not necessary or unnecessary options (17). According to the Lawshe table, the accepted rate is 0.42 (18). None of the phrases have been deleted in this section. After applying expert opinions and enriching the phrases, 15 other experts reviewed the questionnaire to evaluate CVI (19). The validity of the construct was assessed by exploratory and confirmatory factor analysis (EFA and CFA). Also, 178 participants were used for each method.

Results

Three hundred and fifty-six patients participated in the present study. Details of participants' demographics are shown in Table 2. Most of these participants were female and single. The average age of the participants was 34.22 ± 8.6 years.

Table 2. The Demographic profile and Burden of adult neurofibromatosis 1

In the process of evaluating the content validity, no items were removed from the research, but changes were made in the form and richness of the words for better understanding. The CVR value was 0.5–0.9 for the items and 0.74 for the whole scale. The adequacy of the samples shown by the results of the EFA (KMO = 0.902). BTS results were statistically significant (P < 0.001) and led to the development of a three-factor solution as a domain. The CFA approved three factors as follows:

Factor 1, with six items on concentration and life with the disease;

Factor 2, with six items on the social burden of illness and future worries;

Factor 3, with three items on Perspectives.

The factor loadings of the 3-factor solution are shown in Table 3. The resulting domains accounted for 61.012% of the observed variance of BoN with 15 items.

Table 3. Factor loadings of BoN on rotated factor Pattern matrix

The BoN questionnaire’s fitness indicators are shown in Table 4.

Table 4. Model Fit Index Summary

The Cronbach's coefficients of the total scale was equal to 0.90 and 3 factors were 0.85, 0.85, and 0.53, respectively. The intraclass correlation of total scale was 0.85. The test-retest reliability was obtained on 30 evaluable subjects, demonstrating good reproducibility.

Burden Of Adult Neurofibromatosis 1

The participants' Burden of neurofibromatosis 1 is reported in Table 5. The total mean score of burden was 33.12 ± 16.12 with a variety between 0 and 75. The mean scores for the three questionnaire factors: “concentration and life with the disease”, “the social burden of illness and future worries”, and “Perspectives” were 10.36 ± 6.97, 17.23 ± 7.98 and 5.52 ± 3.71, respectively. Table 2 reports the relationship between Burden of neurofibromatosis 1 and demographic variables.

Discussion

The assessment of the burden of patient diseases with valid questionnaires has become an important task in community management (24) and one of the challenges mentioned in a review study is the heterogeneity of measurement tools used to assess disease burden (25). This study provides the Persian version of burden of neurofibromatosis type 1, validity, reliability of the questionnaire and the assessment of perceived pressures in patients with NF 1. The Persian version of the BoN questionnaire has good validity and reliability and can be used as a reliable tool for adult patients with NF 1.

The present study was performed with 356 participants. Based on KMO test, the sample size is excellent and adequate. The KMO value varies from zero to one, 0.5 to 0.6 sample size is not enough and 0.9 to 1 is reported as excellent. (20). The biggest limitation mentioned by Armand et al. as the developer of this questionnaire was its relatively small sample size of 65 patients (15). The KMO test in their study was 0.6. We were able to overcome this limitation.

In this study, we used CFA to examine the validity of the internal structure of scales (26). All fit indicators were within an acceptable threshold, indicating confidence in the validity of the internal structure. Armand et al. also mentioned the acceptability of fit indices in their study (15).

The reliability of BoN was 0.9 and the three determined factors also had acceptable values. Its acceptable value is estimated based on studies > 0.70 (22). The original version reported that the instrument reliability for the whole scale was 0.91 (15).

In this study, the severity of burden of neurofibromatosis was moderate. Age, marital status, occupation and education affected the patient's perceived burden. Armand et al. reported moderate severity of disease burden and reported a relationship between BoN and gender (15). Foji et al. identified 4 main categories for burden of neurofibromatosis type 1 in a qualitative study in Iran, including "deprivation and restriction", "social isolation", "ineffective adaptation to the disease", and "failing and falling behind in life", which indicates the perception of patients with NF (8). Kenborg et al. showed in their study that people with NF1 have recurrent clinical problems that persist and accumulate throughout life. Quantification improves our understanding of the conceptual complexities of disease burden (27).

One of the strengths of the present study is its sample size, despite the rarity of this disease and the small sample sizes in most studies, and the collection of samples from across the country. On the other hand, as we are translating and BoN psychometrics for the first time and no questionnaire in Iran specifically addressed this issue, it was very difficult to compare the situation. We suggest that researchers identify future factors affecting perceived disease burden. Limitations of the study we can mention the sampling method, which was not random and was convenience sampling. In addition, only those who could read, write, and access the Internet were able to participate in the study. Therefore, the burden of participants cannot be generalized to the whole community.

Conclusion

The Persian version of BoN is an acceptable tool in terms of structure and content that specifically addresses the practical aspects of daily activities for patients with neurofibromatosis, beyond the concept of quality of life. NF1 is a disease with wide dimensions, this tool can be used to better understand the individual burden of patients and play a role in decision making.

Declarations

Ethical consideration

This study was conducted following receipt of the ethics approval (IR.GOUMS.REC.1398.365) from the Golestan University of Medical Sciences. All patients gave informed consent for the use of data for research purposes.

Consent for publication

Not applicable.

Availability of data and materials

All data generated or analysed during this study are included in this published article

Conflict of interest

The authors declare that there are no conflict of interests.

Funded

None

Acknowledgements

Patients and the Iranian Neurofibromatosis Association are sincerely appreciated for participating in this study. Finally, thanks to the Student Research Committee of Golestan University of Medical Science.

Availability of data and materials 

All data generated and analyzed during this study are available in the published manuscript.

Authors’ contributions

RJ was responsible for analyzing the data, drafting the manuscript, reviewing the manuscript, and approving the final version. FM was responsible for collecting data, analyzing the data, drafting the manuscript, and approving the final version. ZY was responsible for collecting data and approving the final version. SF was responsible for collecting data. SG was responsible for reviewing the manuscript and approving the final version. AS was responsible for designing the study, reviewing the manuscript, and approving the final version. LJ was responsible for designing the study, reviewing the manuscript, and approving the final version. All authors read and approved the final article.

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