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Psychometric of the Persian version of Quality of Life in Late-Stage Dementia (QUALID) in the elderly with Alzheimer’s disease
  1. Zahra Amrollah Majdabadi Kohne1,2,
  2. Abbas Ebadi3,
  3. Mansoureh Ashghali-Farahani4,
  4. Saleheh Tajali5,
  5. Sahar Keyvanloo Shahrestanaki6
  1. 1Nursing and Midwifery Care Research Center, Health Management Research Institute, Iran University of Medical Sciences, Tehran, Iran
  2. 2Department of Community Health and Geriatric Nursing, School of Nursing and Midwifery, Tehran University of Medical Sciences, Tehran, Iran
  3. 3Behavioral Sciences Research Center, Life style institute, Nursing Faculty, Baqiyatallah University of Medical Sciences, Tehran, Iran
  4. 4Nursing and Midwifery Care Research Center, Health Management Research Institute, School of Nursing and Midwifery, Iran University of Medical Sciences, Tehran, Iran
  5. 5Department of Pediatric Nursing, School of nursing and midwifery, Tehran University of Medical Sciences, Tehran, Iran
  6. 6Department of Community Health Nursing and Geriatric Nursing, Nursing and Midwifery Care Research Center, School of Nursing and Midwifery, Tehran University of Medical Sciences, Tehran, Iran
  1. Correspondence to Dr Mansoureh Ashghali-Farahani; m_negar110{at}yahoo.com

Abstract

Background Improving the quality of life (QoL) is a significant healthcare priority, and it is an important health outcome for elderly individuals with Alzheimer’s disease. Quality of Life in Late-Stage Dementia (QUALID) is a specific scale used to measure the QoL in elderly individuals with Alzheimer’s. So far, limited quantitative research has been conducted on the psychometric properties of this scale.

Aims This study was conducted to translate the QUALID Scale into Persian and evaluate its psychometric properties among family and professional caregivers of elderly individuals with Alzheimer’s disease in Tehran.

Methods A cross-sectional methodological study was conducted among family and professional caregivers of elderly individuals with Alzheimer’s in Tehran, Iran in 2022. The questionnaire was translated into Persian using the forward–backward method. Face and content validity were assessed. Additionally, construct validity was examined using exploratory factor analysis (EFA) with Equamax rotation (n=210) and confirmatory factor analysis (CFA) (n=155). Cronbach’s alpha and interclass correlation coefficient (ICC) were estimated to determine reliability.

Results A total of 365 caregivers with a mean age of 14.18±42.60 years participated in this study. In the face and content validity phase, all 11 items were retained. To determine the construct validity, two factors were extracted in the EFA phase, including behavioural signs of discomfort and behavioural signs of social interaction. The findings of the CFA also indicated that all goodness of fit indices supported the final model. The Cronbach’s alpha was excellent for both factors (0.814), and the ICC was calculated as 0.98.

Conclusion Based on the findings of this study, it can be concluded that the Persian version of the QUALID Scale has sufficient validity and reliability for measuring the QoL in elderly Iranian individuals with Alzheimer’s.

  • ELDERLY
  • QUALITY OF LIFE
  • Dementia

Data availability statement

Data are available on reasonable request.

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WHAT IS ALREADY KNOWN ON THIS TOPIC

  • A few tools are for measuring the quality of life (QoL) in older adult’s individuals with Alzheimer’s.

  • In Iran, there is not a report about assessment of the validity and reliability of Quality of Life in Late-Stage Dementia (QUALID) Scale.

WHAT THIS STUDY ADDS

  • Persian version of QUALID Scale has high reliability and validity.

HOW THIS STUDY MIGHT AFFECT RESEARCH, PRACTICE OR POLICY

  • QUALID Scale can be incorporated into health provider and family caregivers, especially at Alzheimer care centres.

  • QUALID Scale will provide an efficient method to identify measuring the QoL in elderly Iranian individuals with Alzheimer’s.

Background

The population ageing is a global phenomenon, and one of the most significant consequences of this phenomenon is the increase in neurodegenerative diseases or dementia.1 Dementia is a chronic syndrome and a broad term for the irreversible decline in cognitive, behavioural, social and physical functions. It is one of the leading causes of functional dependency and mortality in older adults. Currently, more than 55 million people are living with dementia worldwide, and nearly 10 million new cases are added each year. Therefore, dementia is considered a major health problem in the field of geriatric health.2

Alzheimer’s disease is the most common form of dementia. It imposes a wide range of physical, emotional, psychological, social and economic needs on the affected individuals, their families and their caregivers, ultimately leading to a decline in functioning, loss of independence and a significant reduction in their quality of life (QoL).3 Some studies have shown that the elderly individuals suffering from Alzheimer’s experience the lowest levels of QoL.4 For this reason, it is necessary for these patients to receive specialised treatment and support, addressing their needs in various physical, psychological and social dimensions.5 Overall, improving the QoL is a crucial healthcare priority and a significant health outcome in elderly individuals with Alzheimer’s.6 Furthermore, considering the increasing incidence and prevalence of Alzheimer’s disease in the elderly and its direct impact on their QoL, this issue should be well addressed, and appropriate measures should be taken to enhance the QoL of this population.7

In the first step, there is a need for a suitable tool to assess the level of QoL in elderly individuals. The Quality of Life in Late-Stage Dementia (QUALID) is one of the most important tools specifically used to measure the QoL of elderly individuals with Alzheimer’s, which was developed by Weiner in 2000. This scale consists of 11 items. The tool measures observable behaviours and emotional states of the individual using a five-point Likert scale. The score range is from 11 to 55, with lower scores indicating higher QoL and a score of 55 representing the highest level of QoL.8 This scale is completed by caregivers who have had significant contact with the patient for at least 3 days during the past week. The strengths of this measure include its specific focus on dementia and its evaluation as one of the tools with the best evidence of validity and reliability.8 The validity and reliability of this scale have been assessed in several countries, including Sweden, Norway and Spain, in multiple languages such as English, Spanish, Norwegian, Japanese, Italian and Czech.9 10

According to a literature search, several generic tools are available for measuring the QoL in dementia. However, there is no specific tool for assessing the QoL of patients with dementia in Iran, and the QUALID is currently not available in Persian. Therefore, the increasing number of elderly people and Alzheimer’s disease highlights the need for nurses to pay attention to their QoL as a vulnerable population. Having a reliable tool available to measure the QoL of elderly people with Alzheimer’s is crucial. Since the adaptation and validation of tools in other languages are important for cross-cultural comparisons and providing scientific evidence, this study was conducted to translate the QUALID into Persian and evaluate the psychometric properties of the translated scale. Considering that tool psychometrics requires a quantitative analysis process, the present study was conducted based on the philosophy of positivism.

Methods

A cross-sectional methodological study was conducted to validate a scale. The study was carried out among family caregivers of elderly individuals with Alzheimer’s disease and professional caregivers of elderly individuals with Alzheimer’s disease residing in elderly care centres in Tehran, Iran, from March to December 2022.

Scale: Quality of Life in Late-Stage Dementia (QUALID)

This scale, designed by Weiner in 2000, is used to measure the QoL of elderly individuals with Alzheimer’s disease. This scale measures 11 observable behaviours related to activities and emotional states. The scale is completed by an informed individual who is familiar with the elderly person with Alzheimer’s, such as a family member or a professional caregiver who has had significant interaction with the patient at least 3 out of the past 7 days to ensure accuracy in scoring the items. It takes approximately 5–10 min to complete the scale. The items assess the emotional states and observable behaviours of the patient, including: (1) smiling, (2) being sad, (3) crying, (4) displaying facial expression of discomfort or pain, (5) engaging in repetitive position changes, (6) making verbalizations suggesting discomfort, (7) being irritable or aggressive, (8) enjoying eating, (9) enjoying touching/being touched, (10) enjoying interacting with others and (11) appearing calm and comfortable.

The response options include rarely or never (1), less than once a day (2), at least once a day (3), nearly half of the day (4) and most of each day (5). The scoring method for this instrument involves summing up the responses. The scores range from 11 to 55, with 11 indicating the highest level of QoL. The reliability of the instrument, assessed using the interclass correlation coefficient (ICC), was found to be 0.82.8 The validity and reliability of this instrument have been examined in several countries, including Sweden (2007), Norway (2015) and Spain (2010).

The demographic characteristics collected from participants includes age, gender, marital status, education level, relationship to the person with Alzheimer’s and the number of years they have been caring for them.

Participants and study setting

The participants were selected using convenience sampling. The required sample size was determined based on the recommendations of Kline (2014), considering the number of questionnaire items. A sample size of 3–10 participants per item was collected for exploratory factor analysis (EFA), and a sample size of 30 participants per factor was selected for confirmatory factor analysis (CFA). Since the questionnaire consists of 11 items and taking into account that the acceptable sample size should not be less than 200, as well as considering a minimum 10% dropout rate, a sample size of 215 participants was considered for EFA and 150 participants for CFA. In total, 365 caregivers of elderly individuals with Alzheimer’s disease, including both family caregivers and professional caregivers in elderly care centres, were selected based on the inclusion criteria using convenience sampling method. SPSS V.26 and Lisrel V.8.8 were used for statistical analysis.

The caregivers who provided care for elderly individuals with Alzheimer’s, either as family members or professional caregivers, and had the ability to understand and communicate in Persian were included in the study. The exclusion criterion was a lack of willingness to continue participation in the study.

Data collection

Translate back translation

Initially, permission was obtained from the developer of the QUALID to carry out the translation and validation process. The translation was then performed using the forward and backward translation method recommended by the WHO. For this purpose, the English version of the scale was independently translated into Persian by two individuals proficient in both English and Persian languages, familiar with research and knowledgeable about the subject matter. One of the translators had expertise in research and its terminology, while the other had no familiarity with research terminology. The translators were instructed to maintain fidelity to the English text while avoiding literal translation and to record all appropriate equivalents for English words and phrases, which would be referred to and substituted if necessary in subsequent stages. Finally, two independent Persian translations of the QUALID were obtained at the end of this stage.

The second phase involved the analysis and merging of the two obtained Persian translations. In this phase, the two Persian translations of the scale and their recorded equivalents were reviewed and revised by the project executives, collaborators and translators. After examining both translations and discussing the existing differences, efforts were made to resolve any discrepancies between the two translations. Ultimately, by considering all options, a Persian version of the scale was prepared. Then, in the third phase, two individuals proficient in both English and Persian languages (different from the initial translators) who had no knowledge of the English version of the scale or the research process translated the Persian version into English.

In the fourth stage, after reviewing and making necessary corrections, the two English translations were combined by the research team, and the resultant English version was compared with the original English version of the questionnaire. Finally, the resultant English version was sent to the original developer of the tool for validation to examine the validity and accuracy of the items. Their feedback was then used to make corrections and psychometric adjustments. It should be noted that the aim of all the aforementioned stages was to ensure the compatibility and harmonisation of the translated version with the original scale.

Validity

Face validity

In the next stage, face validity was measured qualitatively using cognitive interviews. To assess the qualitative face validity, the scale was given to 10 caregivers who were caring for elderly individuals with Alzheimer’s disease. Their feedback on the appropriateness, difficulty, relevancy and ambiguity of the items was then examined through interviews.11

Content validity

Then, content validity was assessed both quantitatively and qualitatively. To perform qualitative content validity, interviews were conducted with 10 experts, including one clinical psychologist, one psychiatrist, six assistant professors in gerontology and two experienced associate professors in questionnaire design. They qualitatively examined the questionnaire and provided their opinions regarding adherence to grammar rules, appropriate word usage, proper placement of items and scoring. The experts did not introduce any changes to the questionnaire. Quantitative content validity was also assessed by calculating the Content Validity Index (CVI) for the items. The same 10 experts were used for assessing content validity.12

The CVI indicates the relevance of the items in the scale. Therefore, we requested the same 10 experts to assess the items based on the options ‘not cultural relevant’, ‘somewhat relevant’, ‘cultural relevant but needs revision’ and ‘completely cultural relevant’ and assigned scores of 1, 2, 3 and 4, respectively. The CVI for each item was calculated by dividing the number of participants who gave it a score of 3 or 4 by the total number of participants. Item acceptance was determined based on the CVI Score, where a score above 79% indicated an appropriate item, a score between 70% and 79% indicated the need for revision and reconsideration and a score below 70% indicated that the item was unacceptable leading to its removal.11

Construct validity

In the next stage, the construct validity was examined. In this study, EFA was conducted using two tests, the Kaiser-Meyer-Olkin (KMO) and Bartlett’s test of sphericity, to assess data suitability, sampling adequacy and the normality of the data for factor extraction using the maximum likelihood method with Equamax rotation. A total of 215 samples were evaluated.11

Furthermore, CFA was employed to evaluate the most common goodness of fit indices for the proposed model. This analysis was conducted with 150 samples, considering acceptable thresholds, using maximum likelihood estimation (Coolican, 2017). Root mean square error of approximation (RMSEA)<0.08, Comparative Fit Index (CFI)>0.9, Parsimonious CFI>0.5, Parsimonious Normed Fit Index>0.5, Incremental Fit Index>0.9 and Minimum Discrepancy Function divided by df (CMIN/DF)<3 were considered acceptable.13 14

Consistency

Internal consistency

The Cronbach’s alpha method was used to examine internal consistency reliability.

External consistency

To measure external consistency reliability, the test–retest or stability method was applied using the ICC. For this purpose, a separate subsample consisting of 30 caregivers completed the questionnaire two times, 2 weeks apart. To evaluate the measurement accuracy, the SEM (SEM=SD×√ (1−ICC)) was calculated.

Results

In general, a total of 365 caregivers (mean age: 14.18±42.60 years, range: 18–85 years) participated in this study. The majority of participants (66.2%) were women and the rest were men (33.8%). Furthermore, most participants had a bachelor’s degree (50.8%). The demographic characteristics of the participants are presented in table 1.

Table 1

Demographic characteristics of participants (n=394)

Face and content validity

In the face validity and content validity phase, all items were reviewed and revised based on the feedback from caregivers and experts regarding comprehension, clarity, ambiguity and semantic convergence. The CVI was 1 for all items and the Scale Content Validity Index (S-CVI) was also 1. Therefore, in the face and content validity phase, all 11 items were retained.

Construct validity

Exploratory factor analysis

The KMO test (0.833) and Bartlett’s test of sphericity (p<0.001) indicated that the sampling adequacy was sufficient and appropriate for factor analysis. The two factors were extracted from the total of 11 items. The first factor extracted was the behavioural signs of discomfort (eight items), and the second factor was the behavioural signs of social interaction (three items). These factors explained 31.63% and 18.31% of the total variance (49.95%) of the QoL, respectively. The detailed results of the EFA are presented in table 2.

Table 2

The result of exploratory factor analysis on the five factors of ……. (N=211)

Confirmatory factor analysis

In the next stage of construct validity, the model underwent testing using CFA. The findings of the CFA confirmed all the goodness of fit indices for the final model. The results indicated that all the model fit indices were within an acceptable range, thereby demonstrating sufficient fit for the two-dimensional model of the QUALID (figure 1). For instance, the RMSEA was 0.092 (CI: 0.073 to 0.11) and the CFI (CMIN/DF) was 2.7 (p<0.001). The results of the other model fit indices are presented in table 3.

Figure 1

Confirmatory factor analysis. RMSEA, root mean square error of approximation.

Table 3

Acceptable goodness of fit threshold for confirmatory factor analysis

Reliability

The findings showed excellent Cronbach’s alpha for both factors. Additionally, based on the results of relative stability reliability, ICC was 0.98 indicating that the instrument has excellent relative measurement stability over time. Absolute stability reliability was 1.00 based on the SEM results, suggesting that the instrument may have an error of±1.00 in measuring this concept (table 4).

Table 4

Results of internal consistency and stability of QUALID

Discussion

The results of this study showed that the QUALID is a reliable and valid scale for caregivers to assess the QoL of individuals with Alzheimer’s disease. This scale consists of 11 items and two factors that explain 49.95% of the total variance of the intended concept. Based on the results of this study, the items of the QUALID had high face validity. Additionally, the scale had a high Content Validity Ratio (CVR) value and demonstrated acceptable clarity. Hence, the items of the QUALID were validated according to the results and based on the kappa value. Furthermore, in terms of construct validity, the EFA following the KMO test and Bartlett’s test indicated that the samples were adequate and appropriate. Based on the results of the EFA using maximum likelihood estimation with Equamax rotation, two factors, namely ‘behavioural signs of discomfort’ and ‘behavioural signs of social interaction factor’, demonstrated an acceptable level of QoL. The final model of the QUALID was validated based on CFA. The results of this study indicated that the QUALID had a very acceptable Cronbach’s alpha coefficient. Moreover, ICC revealed that this instrument had excellent measurement stability over time. Resnick et al15 conducted to assess the validity and reliability of the QUALID. The results showed that QoL had a significant relationship with age (r=0.11, p=0.19) and race (r=0.11, p=−0.01, p=0.96). Additionally, a significant relationship was observed between gender and QoL, with women reporting lower QoL compared with men (r=0.04, p=0.17). Similar to our study, the items of the scale were found to be appropriately mapped to the targeted concept. Furthermore, the results indicated the internal consistency and validity based on item fit and correlation between the QUALID items. In this study, the validity of the QUALID was acceptable, and its reliability was reported to be 0.89, as assessed by the Cronbach’s alpha coefficient, which is consistent with the findings of our study.15 Garre-Olmo et al16 conducted a study to assess cross-cultural adaptation and psychometric validation of the Spanish version of the QUALID Scale. The findings indicated satisfactory criterion validity and construct validity of all items of the scale. The internal consistency of the QUALID Scale as a multidimensional instrument was also acceptable (Cronbach’s alpha coefficient: 0.74). In this study, three factors were identified: behavioural signs of discomfort, behavioural signs of social interaction and signs of negative affective mood. According to the results of this study, the inter-respondent reliability (ICC=0.74) and the inter-rater reliability (ICC=0.95) were acceptable,16 which are consistent with the results of the present study. The results of the present study demonstrated that the QUALID Scale effectively portrayed the QoL in patients with advanced dementia. Falk et al17 (2007) reported the satisfactory internal consistency (Cronbach’s alpha coefficients: 0.74) and inter-rater reliability (0.69) and the high test–retest reliability (0.86) of the QUALID Scale. Similarly, in a study by Novella et al18, the inter-respondent reliability was reported to be 0.82. Weiner et al8 studied the initial version of the QUALID and found high internal consistency among the scale items as well as high test–retest reliability. Jeong et al19 conducted a study to validate the Korean version of the QUALID and reported that the dimensionality of the QUALID Scale differed from the original one-factor structure and a three-factor model fit the data better. Validity analysis showed significant association between QUALID and cognitive function, activities of daily living, depressive symptoms and pain. Additionally, test–retest and inter-rater tests confirmed the measurement stability. The results of the Bartlett’s test of sphericity (p<0.001) and KMO (0.801) confirmed the appropriateness of the data for performing a principal component analysis.19 Three factors were extracted from the Korean version of the QUALID, which accounted for a total of 64.9% of the variance. The three factors were ‘discomfort’ (items 4, 5, 6, 7 and 11), ‘social interaction’ (items 1, 9 and 10) and ‘depression’ (items 2, 3 and 8). The Cronbach’s alpha coefficients for factors 1 and 2 were above 0.70, indicating acceptable internal consistency. The reliability of the tool was also reported as 0.81.19

It should be noted that QoL itself has a separate questionnaire and is a complex concept.20 However, the QUALID can be used to assess the QoL in individuals with advanced dementia.21 QoL is an important outcome for individuals with dementia.22 Based on the findings of this study and comparing them with previous studies, the QUALID Scale can be useful and applicable for assessing the QoL in elderly individuals with advanced stages of dementia.

Limitations

The data collection was conducted in Iran and was limited to a single city. Therefore, generalisability of the study may be a limitation that was addressed by the researcher through selecting homogeneous samples. For this reason, it is suggested to implement psychometric tools in more cities in future studies. Additionally, besides Iran, there are other countries where Persian is spoken, but they have different cultural backgrounds compared with Iran. The researcher considered the cultural context of Iran when examining the applicability of the scale.

Conclusion

Based on the results of the present study, the QUALID Scale is a reliable and valid measure for assessing the QoL in individuals with advanced stages of dementia. Considering the findings of this study, the QUALID Scale can be used for a comprehensive examination of the QoL in elderly individuals with dementia to aid in necessary planning for care services and improving their QoL. This tool can be suitable for all healthcare providers, patients and their families in helping to enhance the QoL for elderly individuals with dementia. It is recommended to conduct further research to investigate the applicability of this tool in different cultural settings and contexts.

Data availability statement

Data are available on reasonable request.

Ethics statements

Patient consent for publication

Ethics approval

The authors would confirm that informed consent was obtained from all participants. Written ethical approval was obtained from the Iran University of Medical Sciences, Tehran, Iran (IR.IUMS.REC.1400.652). Permission to translate the QUALID Scale into Persian was obtained from the developer of the original scale. Meanwhile, all methods were performed in accordance with the relevant guidelines and regulations.

Acknowledgments

The authors would like to appreciate all participants who volunteered for this project.

References

Footnotes

  • Contributors ZAMK: investigation, data curation, writing — original draft preparation, writing — reviewing and editing; AE: project administration, supervision, methodology, analysis, writing — reviewing and editing; MA-F: project administration, supervision, full responsibility for the work and/or the conduct of the study, access to the data, and controlled the decision to publish, methodology, writing — reviewing and editing; ST: methodology, writing — reviewing and editing, SKS: investigation, data curation, writing — original draft preparation, software, writing — reviewing and editing; The authors read and approved the final manuscript.

  • Funding This study was approved and financially supported by the Nursing Research Center of Iran University of Medical Sciences, Tehran, Iran (approval code: 1400-1-25-20850).

  • Competing interests None declared.

  • Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.

  • Provenance and peer review Not commissioned; externally peer reviewed.