Defining Cut-off Scores for MMSE in an Educated and Illiterate Arabic Speaking Egyptian Elderly Population

Background With aging of the population dementia became a public health problem increasing health care costs. It affects about 5-10% of elderly population above the age of 65 with doubling prevalence each 5 years till reaching about 50% at the age of 85 1, 2 . The Mini-Mental State Examination (MMSE) was published in 1975 as a practical method to assess cognitive functions. Although it has some advantages as it is affected by age and education and does not measure executive function, indeed it is the most commonly used screening method in the assessment of the severity of dementia in clinical and research fields and for longitudinal follow up of patients. Researchers stated that most of the healthcare professionals use the MMSE and its variants during their medical practice 3, 4.

education, and ethnicity 7 .There is no universally accepted cut-point based on age and education level.The most commonly reported cutpoints were 23/24 and 24/25 8 .Only one study in Egypt 9 determined the effect of education on MMSE score with no overall cutoff points for the test or for highly educated group of population.There are questions about the accuracy of scores of MMSE in illiterate and low educated people; as false positive results may lead to classifying normal illiterate people to have cognitive impairment 10 , implicating the need for modification in the test for illiterate and low educated geriatric population.The Diagnostic and statistical Manual IV (DSM IV) focuses on a categorical approach in spite of the difficulty in differentiating "normal" from "pathological" impairment at certain ages 11.The study aimed to define cutoff points of MMSE for diagnosing dementia in Egyptian elderly illiterate and educated people.Methods Cross sectional study where 159 of community dwelling elderly were recruited from: relatives of patients in the geriatric and ophthalmology wards, patients attending geriatrics outpatient clinic and geriatric clubs.

Inclusion criteria:
-Arabic speaking males and females aged 60 years or more.
-Oral consent was taken from all participants.

Exclusion criteria:
-Subjects who refused to participate in the study.Measures I) MMSE -The 30 points-scale was administered evaluating orientation, registration, attention and calculation, recall, language (repetition and complex command) and visuospatial functions 3 -Modifications were done in item of calculation using reversed days of the week (instead of serial 7s subtractions starting from 100) in illiterate people, people who can only read and write and those with primary school education.

II) DSM IV criteria for dementia -According to the American Psychiatric Association Diagnostic and Statistical Manual of Mental Disorders IV (DSM-IV)
participants were asked about the presence of 1) Memory impairment plus at least one of the followings: 2) Aphasia, apraxia, agnosia or disturbance in executive functioning.
-Participant were considered positive for dementia if the above domains were positive, affecting them socially or functionally and after the exclusion of having delirium at the present time.
It was used as the standard test for diagnosing dementia with results of MMSE correlated to DSM IV results.

Statistical Analysis
The statistical analysis was carried out with the Statistical Package for the Social Sciences for Windows version 16.0 (SPSS Inc., Chicago, IL, USA.).Sensitivity, specificity, positive and negative predictive values, and their 95% confidence interval levels for cutoff points were calculated for MMSE.ROC curve was conducted to determine MMSE cut off points.Figure 1 shows ROC curve for sensitivity and specificity of MMSE cutoff points.The cutoff of points in illiterate and low educated people as shown in Table 2 was ≤ 21 with 91% sensitivity and 33.3% specificity.Table 3 shows cutoff points in high educated people was ≤ 22 with 94% sensitivity and 70.2%specificity.

Discussion
MMSE is one of the most widely used tests for cognitive screening all over the world and though conflicts exist regarding its accuracy; the American Academy of Neurology in its guidance and the Alzheimer's Association in their guidance suggested MMSE as an important tool for cognitive screening 12. Though MMSE is widely used in Egypt, there are no cutoff points for diagnosing dementia in Egyptian population.It is difficult to use the same measures and cutoff points used worldwide because of the difference in educational and cultural background.Cut off points, sensitivity, specificity, positive predictive value, and negative predictive value were calculated for the MMSE according to DSMIV criteria for dementia.However, regarding level of education; the cut-off points of the current study were ≤ 22 for participant > 9 years of education (sensitivity=94%, specificity=70.2%)and ≤ 21 for participants ≤ 9 years of education (sensitivity= 91%, specificity=33.3%),nearly the same cut-off points in the study conducted by Kochhann and colleges in 2010 (13) which were 21 for the illiterate group (sensitivity=93%, specificity=82%), 22 for the low education group (sensitivity=87%, specificity=82%), 23 for the middle education group (sensitivity=86%, specificity=87%) and 24 for the high education group (sensitivity=81%, specificity=87%).The study carried out by Kochhann and colleges in 2010 was able to stratify their sample into 4 levels of education with 4 cut-off points, which could be contributed by their large study sample 968 participants in comparison with 159 participants in the current study.

Conclusion
This is the first study in Egypt to define cutoff points for diagnosis of dementia using MMSE in illiterate and educated geriatric people.The new cut-off scores are ≤ 22 for subjects > 9 years education and ≤ 21 for illiterate subjects and those <9.

Figure
Figure 1: ROC Curve demonstrating sensitivity and specificity of MMSE cut-off points