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Differences in use of abbreviated mental test score by geriatricians and psychiatrists

^a Department of Liaison Psychiatry, Leeds General Infirmary, Leeds LS1 3EX

Correspondence to: Dr Holmes.

Cognitive impairment is common in elderly people and is associated with increased morbidity and mortality,¹ but confusion is often poorly recognised and documented by medical staff.^{2 3} Thus, routine cognitive screening of elderly patients in hospital has been recommended.⁴

One validated and widely used screening instrument is the abbreviated mental test score, in which the maximum score is 10 and a score below 7 suggests cognitive impairment.⁵ It is widely used in clinical and research settings in Britain for detecting and monitoring cognitive impairment and is easily administered and well tolerated by raters and subjects. Inconsistencies in giving and scoring the test will affect its reliability, validity, and sensitivity in detecting change. We noticed differences between colleagues in the use and scoring of this test and investigated how it was applied in routine clinical practice.

Subjects, methods, and results

We contacted 105 doctors who regularly assessed elderly patients; one was not aware of the abbreviated mental test score and was excluded. Of the remaining 104 doctors, 58 were psychiatrists (six consultants, five staff grades, four senior registrars, 19 registrars, and 25 senior house officers) and 46 were geriatricians (11 consultants, three senior registrars, five registrars, and 27 senior house officers). We asked them to list the items they used when giving the test; doctors referred to preprinted questions if they usually used them in their clinical practice.

Only 23 doctors used the 10 items from the original validated version of the abbreviated mental test score. The median number of original questions asked was 8 (interquartile range 6-9). Table 1 shows the frequency with which items were used. There was no significant difference in the total number of original items used between psychiatrists (median 7, range 1-10) and geriatricians (median 8, range 3-10; Mann-Whitney U test P = 0.260) or between senior house officers (median 7.5, range 3-10) and higher grades (median 8, range 1-10; Mann-Whitney U test P = 0.077). One example of a common substitution was the patient's name, an item which had the lowest sensitivity of all items used in the original validation of the test.⁵

Table 1--Use of original 10 items in abbreviated mental test score by 104 doctors, with suggested scoring instructions5
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                                    No of doctors
Test item                            using item    Scoring instructions*
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Age                                      71        Score for exact age only
Date of birth                            84        Score for correct date and month (year not required)
Year                                     66        Score for current year only
Time of day                              78        Score if correct to the nearest hour
Place                                    91        Score if exact address or name of hospital given ("in hospital" is insufficient)
Monarch                                  85        Score for current monarch only
Year of first world war                  79        Score for year of start or finish (both not necessary)
Counting backwards from 20 to 1          85        Score if no mistakes or subject corrects himself or herself spontaneously
Recognition of two people                75        Score if roles of two people correctly recognised--for example, doctor and nurse
Recall of three point address such       61        Score if registered correctly near beginning of test and on recall at end of test
 as 42 West Street
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*Each correct response scores 1 mark; no half marks given. Score of less than 7 suggests subject may be confused..

We then asked each of the doctors to score a set of the same responses to the 10 original items; we said the responses to them with additional information such as the correct age and date of birth of the respondent and the time and place of testing. The correct score was 5, but scores ranged from 3.5 to 9 (mean 6.32 (95% confidence interval 6.08 to 6.57)). No significant difference was seen between psychiatrists (mean 6.17 (5.89 to 6.45)) and geriatricians (6.51 (6.08 to 6.94)) or between senior house officers (6.60 (6.24 to 6.95)) and higher grades (6.05 (5.72 to 6.37)). Seventeen doctors obtained the correct score, but only one of them scored each individual item correctly. Forty one doctors scored 7 or more, incorrectly classifying the respondent as being cognitively intact. Items scored incorrectly were counting backwards from 20 to 1 (85 doctors), place (81), recall of an address (79), and time of day (70). The use of half marks by 78 doctors contributed to incorrect scoring.

Comment

We studied doctors working in units where the abbreviated mental test score was commonly used and found inconsistencies in items and scoring that are likely to lead to inconsistencies in practice between doctors. Patients are often tested sequentially, but it cannot be assumed that the abbreviated mental test score as used in clinical practice will be sensitive in detecting changes in cognitive state.

Items testing short term memory and orientation in time were often omitted. These are the components of cognitive function most commonly impaired in dementia and delirium. The removal of these items further questions the validity of the abbreviated mental test score as used routinely.

Medical staff need to be trained in using and scoring the abbreviated mental test score. Preprinted lists of the correct items may be helpful and should be readily available when assessing patients.

We thank Allan House for comments on the manuscript.

Funding: None.

Conflict of interest: None.

1. Rabins PV, Folstein MF. Delirium and dementia: diagnostic criteria and fatality rates. Br J Psychiatry 1982;140:149-53. [Abstract/Free Full Text]
2. Ardern M, Mayou R, Feldman E, Hawton K. Cognitive impairment in the elderly medically ill: how often is it missed? International Journal of Geriatric Psychiatry 1993;8:929-37.
3. Gustavson Y, Brannstrom RNT, Norberg A, Bucht G, Winblad B. Under-diagnosis and poor documentation of acute confusional states in elderly hip fracture patients. J Am Geriatr Soc 1991;39:760-5. [Medline]
4. Royal College of Physicians. Organic mental impairment in the elderly: implications for research, education and provision of services. A report of the Royal College of Physicians by the College Committee on Geriatrics. J R Coll Physicians Lond 1981;15:141-67. [Medline]
5. Hodkinson HM. Evaluation of a mental test score for assessment of mental impairment in the elderly. Age Ageing 1972;1:233-8. [Abstract/Free Full Text]

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