This study received an ethics approval by the University of Dodoma Research Ethics Committee (Ref: UDOM/DRP/REC/63/). The study adopted a methodological approach to translate the MoCA-5-min and evaluate for its psychometric characteristics among the older adults in Chamwino district central Tanzania. The diagnostic accuracy against the psychiatrist’s rating of MCI and dementia was also compared with that of the IDEA cognitive screening. Multiple steps were followed to validate the translated instrument. Firstly, an exploratory factor analysis (EFA) was performed to identify the underlying factor structure of the scale. Cronbach’s alpha and item analysis were performed to determine the internal consistency of the MoCA-5-min. A test-retest reliability over a six-week period was computed. Concurrent validity was examined by identifying its correlation with the IDEA cognitive screening. Construct validity was evaluated by examining whether the MoCA-5-min was related to the comparing constructs including age, education, depressed mood, mental health and functional status on instrumental activities of daily living in the relationships as suggested by literature [19, 20]. The diagnostic accuracy of the MoCA-5-min against the psychiatrist’s neurocognitive diagnosis rated by using DSM-V criteria was also examined.
Translation and cultural modifications of the instrument
A two-phase translation process was followed. First, the original Chinese version of the MoCA-5-min was translated to English by two independent translators, both fluent in English and Chinese. The two versions were harmonised through face to face discussion between the two translators to ensure agreement in the concepts and meanings of each item. The original developer of the instrument who is also fluent in both English and Chinese validated the conceptual and semantic equivalency of the English translated version in accordance with the original Chinese version [21].
Second, a forward and backward translation approach as recommended by Brislin [22, 23] was followed to translate the English version of the MoCA-5-min to Kiswahili version. Two independent bilingual individuals who are experienced in dementia research translated the instrument to Kiswahili language. One version of the translated tool was created upon discussion between the two translators to resolve the discrepancies and agree on the conceptual and semantic equivalency with the English version. There was no cultural modification of the items because all items were deemed relevant to the Tanzania older population except for four words in the multiple-choice list, including ‘demin’, ‘velvet’, ‘daisy’ and ’tulip’. The lack of cultural relevance is mainly because these textile materials and flowers were uncommon or not available in Tanzania. Upon discussion among the translators and the research team, the textile materials including “linen”, “wool”, “sunflower” and “lily” were used instead. All these items have similar popularity as the items in the original version for the Tanzania population.
Two registered psychiatrists who had been involved in dementia research validated the Swahili version of the instrument for cultural relevancy of the items. The final version of the instrument was translated back to English by the blinded bilingual translator. The back-translated version was compared with the original version and the identified discrepancies were used to make revision to the forward Kiswahili translated version to cross check if the conceptual meanings retained between the original English version and the Kiswahili version [23].
Settings and Participants.
The participants were recruited from six villages of the Chamwino district from January to February 2019 with convenience sampling. More than 80% of the older adults in Chamwino district live in the rural setting. The district comprise of about 24,154 older adults making 7.3% of the total population [24]. Eligible participants included those who were aged 60 or older, dwelling in the study villages, speaking Kiswahili, and consented to participate in the study. Those with severe physical illness or diagnosed with mental illnesses were excluded because of ethical reasons and/or possible bias of cognitive evaluation.
Sample size estimation.
Power analysis was used to determine the minimum sample size required for the multivariate analysis to examine the construct validity of the MoCA-5-min. As recommended by Anthoine et al, the computed number of subjects for bivariate correlation (r > 0.2, α = 0.05 and β = 0.2) of the new and the reference scale to examine the concurrent validity was 200 [25]. As recommended by McNeil [26], the criterion validity using area under the receiver operating characteristics curves (AUC) analysis to predict the diagnostic accuracy, a minimum sample of 73 was needed with assumption that the level of significance was 5% and power as 80%, at least 25% of the sample had MCI and the diagnostic accuracy of the MoCA-5-min to detect MCI would be moderate (i.e. AUC = 70%). This study recruited a total sample of 202 participants.
Data collection procedure
The research assistant approached the potential participants and conducted the screening against the eligibility criteria. After obtaining the written consent from the eligible participants, two cognitive tests including the MoCA-5-min and the IDEA cognitive screening were administered to each participant by two trained research assistants. This was followed by administering the questionnaires for measuring the comparing constructs including depression and IADL. Thereafter, the participants were assessed by a registered psychiatrist, who was blinded from the cognitive test results, using the DSM-V criteria for neurocognitive evaluation [27]. Cognitive reassessment using MoCA-5-min was done to a subgroup of participants (n = 40) at six weeks later for assessing the test-retest reliability.
Study instruments
Montreal Cognitive Assessment 5- minutes protocol (MoCA-5-min): A 4-item tool which examines five cognitive domains: auditory attention, executive functions/language, orientation, verbal learning/encoding and memory. The scores range from 0 to 30, with higher scores indicating better cognitive function. The original Hong Kong version of the MoCA-5-min demonstrated good agreement (r = 0.87, p < 0.001) with that of the full MoCA, and had an acceptable power to discriminate individuals with cognitive impairment from those without (AUC = 0.78) [18].
IDEA cognitive screening: A six-item cognitive assessment tool which measures orientation, verbal fluency, abstract reasoning, delayed recall and praxis. The scores range from 0 to 15, and higher scores indicate better cognitive function [28]. The instrument was validated in Tanzania with good discriminatory power for dementia with AUC = 0.917, and a sensitivity and specificity of 84.6%, and 89.1% respectively at a cut-off score of ≤ 8 [16].
Geriatric Depression Scale-15 items (GDS-SF): It was used to measure depressive symptoms. The instrument has 15 self-reported dichotomous items of YES or NO, with higher scores indicating more depressive symptoms, scores > 5 suggest the presence of depression [29]. Our previous study in Tanzania (data will be published elsewhere) translated and validated the instrument and found the Cronbach’s alpha was 0.81 and an excellent construct validity by showing a strong negative correlation with the Mental Health Inventory (MHI-5) (r = - 0.790, p < 0.001).
Mental Health Inventory-5 items (MHI-5): Is a brief screening questionnaire which assesses emotional well‐being. It has 5 items to be rated on a scale ranging from 1 (all the time) to 6 (none of the time). As a subscale of the Short Form Health Survey (SF-36), MHI-5 was validated in Tanzania and demonstrated acceptable internal consistency(Cronbach’s α = 0.78) and the correlation between MHI-5 and the hypothesized scale was 0.55 with 95% scaling success rate [30].
Lawton Instrumental Activities of Daily Living (Lawton IADL): Is a questionnaire that measures functional ability in 8 domains of instrumental activities of daily living (IADL): telephone use, shopping, food preparation, housekeeping, laundry, mode of transportation, medication responsibility and handling finances. The scores range from 0 to 8, with higher scores indicating better functional ability [31]. Our previous study translated and validated the instrument, the internal consistency was good (Cronbach’s α = 0.81) with item total correlation ranging from 0.36 to 0.69. The instrument also demonstrated good concurrent validity with IDEA study Instrumental Activities of Daily Living (IDEA-IADL) questionnaire for measuring instrumental activities of daily living (r = - 0.593 p < 0.001). (Data will be published elsewhere).
Data analysis
Analyses were performed using Statistical Package for Social Sciences version 25 [32]. Descriptive statistics were used to summarize socio-demographic characteristics of the sample. Internal consistency of the MoCA-5-min was determined by computing the Cronbach’s alpha (α), item analysis and item-to total correlations [33, 34]. EFA was performed using the principal component method and oblique rotation [35] to determine the underlying factor structure of the scale. Further, the intraclass correlation coefficient (ICC) was computed to examine the six weeks test-retest reliability of the MoCA-5-min using 40 randomly selected participants.
As for the concurrent validity, the Pearson’s correlation coefficient was used to examine the correlation of the MoCA-5-min scores with that of IDEA cognitive tests. Construct validity was examined by using multivariate regression to identify the independent relationships between the tested MoCA-5-min score and the hypothesized relating constructs including age, educational level, depression, psychological well-being and IADL function, as suggested by literature [19, 20]. Variables which demonstrated bivariate relationship with MoCA-5-min at p ≤ 0.2 were entered to the multivariate regression model. Finally, the receiver operating characteristics (ROC) analysis was performed to examine the discriminatory power of the MoCA-5-min against the psychiatrist’s rating of the neurocognitive diagnosis, using the AUC ≤ 0.7 defined as acceptable discriminatory power [26]. Then, the sensitivities, specificities and the probable cut-off scores of MoCA-5-min for detecting MCI and dementia was determined [36]. Its diagnostic accuracy was also compared with that of the IDEA cognitive screening.