INTRODUCTION

Huntington’s disease (HD) is a debilitating neurodegenerative condition characterized by a spectrum of symptoms encompassing motor dysfunction, cognitive decline, and psychiatric manifestations [1]. As the disease relentlessly advances, the impact on patients and their caregivers intensifies, leading to challenges in multiple aspects of daily life. These challenges range from difficulties in speech (dysarthria), swallowing (dysphagia), and movement impairments to a progressive limitation in activities of daily living accelerated by dementia [2]. Additionally, emotional burdens, including depression and mood swings, contribute to the overall complexity of care and its effect on the well-being of both patients and their caregivers [2].

In recent years, a growing body of research has focused on evaluating and addressing the caregiver burden in HD. Recognizing the caregivers’ role is vital, as it directly impacts patients’ quality of life (QoL) and the overall well-being of the family. To facilitate this assessment, the Huntington’s Disease Quality of Life Battery for Carers (HDQoL-C) questionnaire was developed [3]. This questionnaire, consisting of 63 questions, comprises both demographic and objective queries and subjective inquiries tailored to the unique challenges faced by caregivers of individuals with HD.

To ensure that the HDQoL-C is a valuable resource for caregivers of HD patients in Korea, it is essential to validate its applicability in this specific cultural context. This study aimed to develop and validate the Korean version of the HDQoL-C (K-HDQoL-C) to assess the disease-related burden experienced by Korean caregivers of HD patients. By doing so, we seek to enhance the understanding of the unique challenges these caregivers face and provide a valuable tool for assessing and addressing their specific needs.

MATERIALS & METHODS

Questionnaire

The HDQoL-C is organized into four distinct parts: part 1 solicits demographic and objective information, part 2 delves into practical aspects of caregiving (7 items), part 3 assesses caregivers’ satisfaction with life (8 items), and part 4 explores caregivers’ feelings about living with and caring for someone with HD (17 items) [3]. All the questions are answered on a scale from 0 to 10. In the K-HDQoL-C, part 2 includes 7 items instead of the original 9, as two items related to access to and support from healthcare professionals are excluded. This decision is based on the distinct differences between the Korean and UK healthcare environments, as well as the recruitment of participants solely from specialist clinics in this study. Part 4 comprises 17 items, with 10 items addressing negative feelings and 7 items focusing on positive feelings, with reverse coding applied to the positive feelings. In parts 2 and 3, higher scores indicate more positive responses, whereas in part 4, higher scores reflect more negative feelings. This tool is instrumental in providing insights into the nuanced and multifaceted nature of the burdens of caregiving.

Study participants

We recruited caregivers of HD patients from the prospective multicenter Korean HD cohort [2]. The exclusion criterion was cognitive impairment in the caregivers (Mini-Mental Status Exam [MMSE] [4] score ≤20). The institutional review board at each participating center (Chungnam National University Hospital, IRB No. 2020-07-106) approved this study, and written informed consent was obtained from all participants.

Translation

The K-HDQoL-C was developed from the original English HDQoL-C questionnaire [3] through the following processes: forward translation and backward translation, expert committee review, pretest of the prefinal version, and development of the final Korean version (Supplementary Material in the online-only Data Supplement). All of these steps were performed with the original author’s consent.

Assessments

We collected demographic information from the caregivers, such as their age, sex, education years, marital status, HD duration in the family, duration of caregiving for HD family members, and relationship with HD patients. Clinical assessments for HD patients included the Unified Huntington’s Disease Rating Scale (UHDRS) [5] for motor assessment, functional assessment, independence scale, and functional capacity. For the cognitive evaluation of HD patients, we used the MMSE and Montreal Cognitive Assessment (MoCA) [6]. A popular caregiver self-reported measure used in common neurodegenerative diseases (e.g., dementia) in Korea, the Zarit Burden Interview-12 (ZBI-12) [7], was administered to test for correlations. For the test-retest reliability, scales and/or questionnaires were completed twice, in separate situations, with a sufficient time interval of 10–14 days to minimize learning effects.

Statistical analysis

Internal consistency was analyzed using the Cronbach’s α coefficients (criterion value for α ≥0.70). Test-retest reliability was assessed via the intraclass correlation coefficient in the two-way random effects model. Spearman’s rank correlation coefficients were used for associations with the ZBI-12 and other variables. All the statistical analyses were performed using version 26.0 (IBM Corp.).

RESULTS

This study enrolled 19 caregivers of HD patients (12 males, 7 females), and the mean age was 55.4±14.6 years. The demographic and clinical characteristics of the participants are summarized in Supplementary Table 1 (in the online-only Data Supplement). The mean duration of HD illness per family was 5.8±5.1 years, and the mean duration of caregiving for HD patients was 6.1±6.9 years. A total of 84.2% of the participants were primary caregivers. Additionally, 42.1% were partners of the patients, 21.1% were parents of the patients, and 21.2% were offspring of the patients. Seven participants (36.8%) had children that were at risk.

The scores for each part of the K-HDQoL-C are shown in Table 1. Among the 19 participants who completed the baseline evaluation, 19 participated in the retest study. Table 1 also includes data on the internal consistency of the K-HDQoL-C. The Cronbach’s α coefficients at baseline were 0.771 for part 2, 0.938 for part 3, and 0.891 for part 4, whereas the retest coefficients were 0.728 for part 2, 0.958 for part 3, and 0.896 for part 4. All the parts met the standard for good internal consistency (Cronbach’s α >0.70). The test-retest reliabilities of the K-HDQoL-C were excellent for all parts: 0.920 for part 2, 0.908 for part 3, and 0.936 for part 4 (Table 1).

There was no correlation between the K-HDQoL-C and the disease duration or cognitive function (MMSE and MoCA) (Supplementary Table 2 in the online-only Data Supplement). Among the subparts of the UHDRS, only the functional assessment showed a negative correlation with part 2 of the K-HDQoL-C (r=-0.545) (Figure 1A). Additionally, the average ZBI-12 score was 23.8±11.7, and significant correlations were observed between the ZBI-12 and part 3 (r=-0.780), part 4 (r=0.923), and the total score (0.796) of the K-HDQoL-C (Figure 1B-D).

DISCUSSION

We developed the K-HDQoL-C and evaluated its reliability and validity. With Cronbach’s α coefficients above 0.7 indicating acceptable internal consistency and reliability, all parts of the K-HDQoL-C showed satisfactory internal consistency. The test-retest reliability was good for all parts of the K-HDQoL-C.

In Western countries, numerous studies have examined the burden on caregivers of HD patients. These studies revealed that both UHDRS functional and cognitive assessments have detrimental effects on the QoL of patients and caregivers, with lower functional capacity associated with greater caregiver burden [8,9]. Compared with motor severity, cognitive function and behavioral problems are more closely linked to caregiver burden [10]. Likewise, research in Korea indicates that the caregiver burden for patients with HD is related to their functional capacity [2]. In our study, we found a negative correlation between the UHDRS functional assessment score and part 2 score, indicating that worse function was associated with greater caregiving burden. While the UHDRS motor symptom and global cognitive status scores did not significantly impact the caregiver burden score among our participants, caregivers’ burden was associated with the functional capacity score in this study. This result is understandable because the individual’s outcome is influenced by both motor and cognitive impairments related to HD.

As the HDQoL-C has been validated in multiple languages, studies have been conducted on the QoL of caregivers of HD patients using this tool. A study involving caregivers in Canada reported the following average score for each part: part 2 scored 46.5, part 3 scored 62.1, and part 4 scored 45.1 [11]. When compared with those in Canada, Korean caregivers seemed to suffer from relatively poor QoL in terms of caring and satisfaction with life and have much more negative feelings about life. Additionally, the mean ZBI-12 score for our caregivers was 23.8, which is much greater than the cutoff value of 12 points [7], indicating a greater level of burden than other advanced conditions, such as cancer, dementia, and acquired brain injury [7]. On the basis of the correlation between the ZBI-12 and part 3 of the K-HDQoL-C, greater caregiver burden was associated with lower life satisfaction. Similarly, the correlation between the ZBI-12 and part 4 of the K-HDQoL-C revealed that a greater caregiver burden was linked to more negative emotions about life. Interestingly, life satisfaction and negative feelings about life in Korean participants did not correlate with the duration of HD illness, functional capacity, motor severity, or cognitive dysfunction of the patients. Part 4 addresses feelings about life and reflects the caregiver’s personal and subjective state of mind. These findings suggest that unmet needs within the Korean healthcare system may influence the emotional well-being of HD patients’ families. A recently published practical guide for managing HD in Korea emphasizes the importance of providing comprehensive support to both HD patients and their families [12]. On the basis of these findings, there is a clear need to strengthen policies to support caregivers in their challenging roles.

Overall, the K-HDQoL-C appears to be a reliable tool for assessing the challenges faced by HD caregivers in Korea, particularly in terms of caregiving and life satisfaction. The present study underscores the need for culturally sensitive interventions and resources to better support Korean caregivers, addressing both the emotional and psychological burdens unique to their caregiving experiences.

Notes

Conflicts of Interest

The authors have no financial conflicts of interest.

Funding Statement

None

Acknowledgments

Permission to use the HDQoL-C was kindly provided by Dr. Aimee Aubeeluck at the University of Nottingham.

Author Contributions

Conceptualization: Eungseok Oh, Jee-Young Lee. Data curation: Eungseok Oh, Jee-Young Lee. Formal analysis: Hee Jin Chang, Eungseok Oh, Jee-Young Lee. Investigation: all authors. Methodology: Eungseok Oh, Jee-Young Lee. Project administration: Eungseok Oh, Jee-Young Lee. Resources: all authors. Supervision: Eungseok Oh, Jee-Young Lee. Validation: all authors. Visualization: Hee Jin Chang, Eungseok Oh, Jee-Young Lee. Writing—original draft: Hee Jin Chang, Eungseok Oh, Jee-Young Lee. Writing—review & editing: all authors.

Supplementary Materials

Figure 1.

Correlations between the K-HDQoL-C and clinical variables. Scatter plots showing the relationships between the K-HDQoL-C part 2 of caregivers and the UHDRS functional assessment of the patients they are caring for (A) and between the ZBI-12 and the K-HDQoL-C part 3 (B), part 4 (C), and total score (D). The correlation coefficients (r) and p values are presented by Spearman’s rank test. UHDRS, Unified Huntington’s Disease Rating Scale; K-HDQoL-C, Korean version of the Huntington’s Disease Quality of Life Battery for Carers; ZBI-12, Zarit Burden Interview-12.

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