DESCRIPTION OF THE VARIABLES UNDER STUDY:
- DEPENDENT VARIABLES:
- Everyday Cognition: measured by the Everyday Cognition Battery (ECB).
- Cognitive performance: measured by the Rapid Assessment of Cognitive Functions (ERFC).
- INTERVENING VARIABLES: Age, gender and level of education.
MEASURES
Each participant performed a total of 8 assessments, 2 (initial and final) for each of the 4 stages of intervention. The first assessment of the study was conducted at the beginning of the Occupational Therapy Programme for the period 2014-2015, and the last assessment corresponds to the end assessment of the programme for the period 2017-2018.
DEPENDENT VARIABLES: For the dependent variables, in both groups, the participants were evaluated with two hetero-administered questionnaires:
Everyday Cognition Battery (ECB) [9, 17, 18]:
It should be noted that little use has been made in Spain of this type of measures. Among the existing assessment measures, we have selected the ECB (Everyday Cognition Battery) for our study.
The ECB is a test intended for the evaluation of everyday cognition in the elderly without cognitive impairment. This questionnaire assesses cognitive competence in three instrumental domains of daily life: medication use, financial management and planning, and nutrition and meal preparation. These instrumental tasks have been described as universal, basic, and mandatory, since it is assumed that most older adults have acquired knowledge and substantial experience in these domains. Daily cognitive tasks are drawn from the broader set of IADL (Lawton & Brody, 1969) [29], a set of tasks in which older adults frequently participate in their daily lives. These are tasks that older adults are expected to perform well in order to maintain independent functioning in the real world [30].
The ECB Battery includes the following traditional psychometric measures: inductive reasoning, knowledge, declarative memory, and working memory.
Within the ECB, there are 4 tests, each designed to assess a single cognitive ability: ECB Inductive Reasoning Test, ECB Knowledge Test, ECB Computation Span Test (Working Memory) and ECB Recognition Test (Declarative Memory).
For the study, we selected the last, since it evaluates memory, which led us to think about the importance of memory in older adults, both measured objectively and subjectively. Within the ECB Recognition Test, we focused on tests that assessed medication take and adherence to treatment.
The ECB Battery scales between 0 and 10, that is, it has a maximum score of 10. The lower the score, the lower the cognitive performance during the development of daily activities.
Rapid Assessment of Cognitive Functions (ERFC) [31]:
This test evaluates cognitive ability and allows a quick assessment and early diagnosis of a possible cognitive deficit. It consists of 13 subtests that measure the following cognitive functions: temporospatial orientation, attention and memory (explores the attention span, immediate memory and working memory and, furthermore, memory, which examines long-term learning capacity, without help or through induced memory, consisting of offering semantic clues to words not freely remembered.), mental calculation (explored through two subtractions), reasoning and judgment, similarities (evaluates the capacity for abstraction), comprehension (specifically assesses listening comprehension), naming (explored through the naming of two real objects and two images), repetition, written order (evaluate written comprehension), verbal fluency (examines semantic fluency and, furthermore, alternate phonetic fluency), praxis (studies the symbolic gesture or ideomotor praxia and constructive praxia), visual recognition (assesses visual gnosia) and writing (explored through the copying and dictation of two words).
The ERFC Questionnaire has a maximum score of 56, except for illiterate subjects, whose maximum score is 51, once the subtests of mental calculation, written order and writing have been eliminated, which require that the evaluated participants have numerical and literacy skills.
The cut-off point for the ERFC that indicates a possible cognitive impairment is located at 51 out of 56 (with a sensitivity of 0.92 and a specificity of 0.86) and at 46 points out of 51 for the group of illiterate subjects (with a sensitivity of 0.9 and specificity of 0.88).
As in the present study one of the exclusion criteria would be not having numerical and literacy skills, the group of illiterate participants would not be included, so the maximum score in our case is 56 points.
INTERVENING VARIABLES: A register sheet containing personal details, along with the level of studies and the day centre to which they were assigned, was designed.
SAMPLING SIZE
Participants of the study were recruited by convenience sample. The study sample was made up of all the users from the different day centres or associations for older people enrolled in the Occupational Therapy Programme who met the selection criteria and who authorised their participation in the study on a voluntary basis.
The sample size estimation was also based on the sample size reported by the author for the validation of the ECB Battery (with an initial sample of 174 participants and a final sample of 114 participants) [9].
RANDOMISATION
For the randomization procedure, since each participant had to enrol in his or her corresponding day centre for older people and all participants who enrolled received intervention under the Occupational Therapy Programme, it was not possible to randomise participants, so group randomisation was performed instead.
The process of randomising the groups of participants was conducted with respect to the order of the centres where the programme was carried out, by the method of simple random assignment. This was done using a table of random numbers, which was generated by a researcher external to the study. Using this table, the centres that obtained an even number were assigned to the experimental group and the centres that obtained an odd number were assigned to the control group.
MASKING
The assessments were conducted by five qualified occupational therapists, of whom only one subsequently performed the intervention. In this way, 80% of the evaluations were carried out by an external evaluator, to control, as far as possible, interference or bias in the results.
Furthermore, except for the professional who performed the interventions, the rest of the evaluators did not know whether the participants belonged to the control group or to the experimental group. As for the participants, they remained blinded for the entire duration of the study.
STATISTICAL ANALYSIS
The variables of the study were analysed by the statistics of Shapiro-Wilk and Kolmogorov-Smirnov to know the normality of the sample at the beginning of the study, therefore determining the path to follow. The verification of the assumption of normality, according to both tests, oriented the calculations by a non-parametric route (p<0.05).
Given the result of the study of normality of the sample (non-parametric analysis), for the descriptive analysis of the socio-demographic characteristics and the scores of each of the tests used, the variables were described with the corresponding statistics, using the median as a measure of centralisation and the interquartile range.
To understand the psychometric properties of the scales, Cronbach's alpha coefficient, a factor analysis and a Pearson correlation were used.
Given the complexity of the study, follow-up comparisons of participants over time (repeated measurements) and/or of different groups (independent groups) were scheduled.
Firstly, and before carrying out the comparison of ranks through change of score, we studied whether all the initial conditions were similar between the groups to study. For this, the Mann-Whitney U Test or the Kruskal-Wallis Test were used, with equality when p˃0,05.
Comparisons of two ranks were resolved with the Mann-Whitney U Test (independent groups) or with the Wilcoxon T-test (repeated measurements).
Comparisons of three or more averages were analysed with the Kruskal-Wallis H Test (independent groups) or with Friedman's Q Test (repeated measurements).
The correlation analysis was solved with the Spearman's rank correlation coefficient (Spearman's rho).
This study is presented following the guidelines of CONSORT.