Neurological Case Study

Short communication

Brief report: Use of the Mini-Cog as a screening tool for cognitive impairment in diabetes in primary care

A.J. Sinclair a,*, R. Gadsby a, R. Hillson b, A. Forbes c, A.J. Bayer d

a Institute of Diabetes for Older People, Beds & Herts Postgraduate Medical School, Putteridge Bury Campus, Hitchin Road, Luton LU2 8LE, UK b Diabetes and Endocrine Unit, The Hillingdon Hospital, Uxbridge, Middlesex, UK c Department of Primary Care and Child Health, King’s College, London, UK d Cochrane Institute of Primary Care and Public Health, School of Medicine, Cardiff University, UK

d i a b e t e s r e s e a r c h a n d c l i n i c a l p r a c t i c e 1 0 0 ( 2 0 1 3 ) e 2 3 – e 2 5

a r t i c l e i n f o

Article history:

Received 26 September 2012

Received in revised form

24 November 2012

Accepted 2 January 2013

Published on line 23 January 2013

Keywords:

Diabetes

Screening

Cognitive impairment

Dementia

Elderly

Primary care

a b s t r a c t

The Mini-Cog was shown to be a brief, acceptable and practical cognitive screen for older

people with diabetes when administered by a primary care nurse. It could be integrated

easily into the annual diabetes review and help to identify those who may benefit from extra

help with their management.

# 2013 Published by Elsevier Ireland Ltd.

Contents available at Sciverse ScienceDirect

Diabetes Research and Clinical Practice

j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / d i a b r e s

1. Introduction

There is increasing recognition of the increased prevalence of

dementia, that it may develop earlier in people with diabetes

[1–3] and that significant cognitive impairment can adversely

affect diabetes self care [4,5]. Early detection promotes timely

intervention, improves patient and carer quality of life,

reduces total care expenditure [6] and promotes more

appropriate diabetes care [7]. The Mini-Cog is a brief and well

validated screening test for cognitive decline [8,9], widely used

in clinical practice, recommended in guidelines and with

* Corresponding author. Tel.: +44 07801 136112; fax: +44 01582743286. E-mail address: [email protected] (A.J. Sinclair).

0168-8227/$ – see front matter # 2013 Published by Elsevier Ireland L http://dx.doi.org/10.1016/j.diabres.2013.01.001

possible advantages over other commonly used screening

tools [10–12]. It has not been studied specifically in people with

diabetes. This study investigated feasability and diagnostic

accuracy of the Mini-Cog as a cognitive screen of older people

with diabetes in primary care.

2. Patients and methods

Patients with diabetes being seen in general practice for

routine review of diabetes care, aged 55 years or older, without

prior diagnosis of cognitive impairment, with adequate

td.

Table 1 – Patient characteristics.

Age (years)

55–64 49 (24%)

65–74 67 (33%)

75–84 76 (38%)

85+ 9 (5%)

Median (range) 72 (55–91)

Gender

Male 122 (61%)

Female 79 (39%)

Ethnicity

White 184 (92%)

Minority 16 (8%)

Years since diabetes diagnosis

Median (range) 7 (1–43)

Most recent HbA1c (%)

Mean (sd) 7.03 (1.23)

Treatment

Diet only 34 (17%)

Oral hypoglycaemics 147 (73%)

Insulin 29 (14%) 12 also on

oral hypoglycaemics

d i a b e t e s r e s e a r c h a n d c l i n i c a l p r a c t i c e 1 0 0 ( 2 0 1 3 ) e 2 3 – e 2 5e24

hearing and vision, medically stable and able to communicate

in English were recruited (Table 1). Practice nurses adminis-

tered to consenting patients the Mini-Cog, consisting of 3-item

recall and clock drawing, followed by the MMSE, with different

3-item recall [13]. The standard algorithm was used to score

the Mini-Cog (number of words recalled plus up to two points

for the clock drawing) with a score <4 on the Mini-Cog and <24

on MMSE (or refusal) defining cognitive impairment. These

patients were referred to the GP for appropriate management.

The study was considered by East of England Research Ethics

Committee, who judged it good clinical practice.

3. Results

201 patients were suitable for analysis. None refused the

Mini-Cog, but three refused the MMSE (all <4 on Mini-Cog and

referred to GP). The mean time taken to complete the Mini-

Cog was 118 (sd 45) s. No patient took longer than 5 min. There

was 99% agreement (Cohen’s Kappa 0.949) between the nurse

scoring of the Mini-Cog and an expert’s later review. Table 2

shows distribution of scores by age group. 35 (17.4%) were

screen-positive (score <4), with the proportion rising with

age. 22 (10.9%) had MMSE <24 and the Mini-Cog and MMSE

agreed in 182/201 cases (90.5%). Comparing patients with

Mini-Cog scores 0–3 with MMSE score <24 showed Mini-Cog to

have a sensitivity of 86.4% (19/22; 95% confidence interval

Table 2 – The Mini-Cog scores of patients by age group.

Mini-Cog scores No. of patients

0 2 (1%) 35 (17.4%) screen-po

1 4 (2%)

2 9 (4%)

3 20 (10%)

4 30 (15%)

5 136 (68%)

64.0–96.4%), a specificity of 91.1% (163/179; 95%CI 85.6–94.6%),

a positive predictive value of 54.3% (19/35; 95%CI 36.9–70.8%)

and a negative predictive value of 98.2% (163/166; 95%CI 94.4–

99.5%). The positive and negative likelihood ratios (not

dependent on prevalence of cognitive impairment) were

9.66 (95%CI 5.88–16) and 0.15 (95%CI 0.05–0.43) respectively.

Increasing Mini-Cog cut-off from 4/5 or 5/5, to 5/5, increased

sensitivity to 95.4% (21/22), but lowered specificity to 75.4%

(135/179). Using the original cut-off of 3/5 to 5/5 yielded lower

sensitivity of 40.0% (9/22) with specificity of 90.5% (162/179).

4. Discussion

This study demonstrates that, in the primary care population

studied, the Mini-Cog was a useful screening measure to

identify older patients with diabetes who may have some

significant cognitive impairment. One in six patients assessed,

all not previously known to have problems, were screen

positive using cut off of <4 to identify possible impairment.

These patients could then be assessed further to confirm

significant cognitive problems likely to impact on ability of

patients to effectively self-manage their diabetes, and so

identify those who may require additional support [7].

The Mini-Cog takes less time than the MMSE that can

reliably detect patients in general practice with cognitive

impairment, especially those with dementia [14], but is

controlled by copyright. Thus the Mini-Cog is likely to be

more acceptable to patients and staff in primary care, with

high sensitivity (86%) and specificity (91%) for cognitive

impairment. Likelihood ratio for a screen positive on the

Mini-Cog was 9.66 and for a screen negative was 0.15. In the

study population, with a pre-test probability of 11% for

significant cognitive impairment, probability rose to 54%

when the Mini-Cog screen was positive, with negative post-

test probability of 2%. Performance in our population with

diabetes was at least as good as reported in the general older

population in primary care [11,12].

There are limitations of our study. Patients without

adequate vision or unable to speak English were not included.

The subjects were a convenience sample, which may intro-

duce potential bias, as evidenced by probable under-repre-

sentation of women and people aged more than 85 years. Bias

also may have arisen as the same person administered both

Mini-Cog and MMSE. Otherwise, the methodology met all the

QUADAS quality assessment criteria for studies of diagnostic

test accuracy [15]. The outcome of patients referred to their GP

for further assessment is not known and so further studies are

No. aged

55–64 65–74 75–84 85+

sitive 2(3%)

1(2%) 1(1%) 2(3%)

4(6%) 5(7%)

2(4%) 8(12%) 9(12%) 1(11%)

7(14%) 6(9%) 15(20%) 2(22%)

39 (80%) 48 (72%) 43(57%) 6(66%)

d i a b e t e s r e s e a r c h a n d c l i n i c a l p r a c t i c e 1 0 0 ( 2 0 1 3 ) e 2 3 – e 2 5 e25

need to identify impact of positive screening on subsequent

management and outcome.

In conclusion, the Mini-Cog is a potentially useful screen-

ing tool for significant cognitive impairment in people with

diabetes in primary care and can be integrated easily into the

annual review. Identifying patients with cognitive impairment

will allow for development of compensatory strategies and

adaption of the diabetes self-management support provided.

Screening patients will also promote earlier intervention to

support those at greater risk or in the early stages of dementia,

in keeping with latest guidelines [16].

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