Original Research Article Accepted: February 8, 2010 Published online: April 6, 2010
Dement Geriatr Cogn Disord 2010;29:259–264 DOI: 10.1159/000288772
Mild Cognitive Impairment in Medical Inpatients: The Mini-Mental State Examination Is a Promising Screening Tool G.M. De Marchis a, b G. Foderaro d J. Jemora a F. Zanchi c A. Altobianchi c E. Biglia c F.M. Conti c R. Monotti a G. Mombelli a
a
Department of Internal Medicine, Ospedale La Carità, Locarno, b Department of Neurology, Inselspital, Bern University Hospital, Bern, c Hildebrand Clinic, Brissago, and d Clinica al Parco, Lugano, Switzerland
Key Words Mild cognitive impairment ⴢ Medical inpatients ⴢ Medical/systemic disease ⴢ Mini-Mental State Examination ⴢ Neuropsychological assessment
out previously known cognitive deficits. In view of therapies preventing the progression of MCI to dementia, MCI screening will be crucial. The MMSE represents a promising screening tool for MCI in medical inpatients. Copyright © 2010 S. Karger AG, Basel
Abstract Aim: To assess the prevalence of mild cognitive impairment (MCI) in medical inpatients aged 55–85 years without known cognitive deficits, and how often ward physicians mentioned MCI in their discharge notes. Moreover, we aimed to identify variables associated with MCI and to assess the sensitivity and specificity of the Mini-Mental State Examination (MMSE) for MCI. Methods: Two neuropsychologists administered a 60-min battery of validated tests to evaluate different cognitive domains. The diagnosis of MCI was based on a prespecified algorithm. The sensitivity and specificity of the MMSE for MCI were calculated. Results: Fifteen patients showed a normal cognitive profile (21.4%), while 55 patients (78.6%) showed MCI. Ward physicians, blinded to the results of the neuropsychological evaluation, did not mention MCI in their discharge notes of any of the evaluated patients. The only variable independently associated with MCI was the MMSE. A MMSE score of ^28 showed a sensitivity of 85.5% and a specificity of 66.7% for MCI. Conclusion: MCI is frequent albeit overlooked in elderly medical inpatients with-
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Introduction
Mild cognitive impairment (MCI) is defined as a cognitive impairment that, while unusual for the respective age group, does not interfere with daily activities [1]. MCI represents a risk factor for the near-term development of dementia. While a return to normal is seen in some MCI patients (18% in 4 years) [2], progression to dementia is likely. The progression rates of MCI to dementia reported in the literature vary considerably and range between 5.4 and 11.7% per year [3–5]. MCI screening is thus gaining importance in view of future therapies preventing the progression of MCI to dementia. We propose elderly medical inpatients as an important target population for MCI screening. In this population, the recently reported prevalence of different forms of cognitive impairment ranges from 32.3 to 42.4% [6, 7]. Furthermore, ward physicians may play a crucial role in documenting MCI in the discharge notes and sugGian Marco De Marchis Department of Neurology, Inselspital, Bern University Hospital Freiburgstrasse CH–3010 Bern (Switzerland) Tel. +41 31 632 2111, Fax +41 31 632 0321, E-Mail gian-marco.demarchis @ insel.ch
gesting neuropsychological follow-up after hospital discharge. To be translated into every-day clinical practice, MCI screening has to rely on an accurate and quick screening tool rather than a complex neuropsychological evaluation. MCI screening in medical inpatients should be feasible by both trained paramedical personal and physicians, not only by neuropsychologists. In this context, the Mini-Mental State Examination (MMSE) represents a potential screening tool because it is widely used and proven to reliably detect cognitive impairment [8]. While the current literature strongly advocates further investigations of MCI in medical inpatients [1], data on the subject are sparse. Moreover, the role of the MMSE as a screening tool for MCI in medical inpatients remains uncertain. This study aimed to assess the prevalence of MCI in medical inpatients aged between 55 and 85 years without previously known cognitive deficits, and how often ward physicians mentioned MCI in their discharge notes. Moreover, the study aimed to identify variables associated with MCI and to assess the sensitivity and specificity of the MMSE for MCI screening.
Patients and Methods Patients and Setting The regional ethical committee approved the study, and all enrolled patients provided written informed consent prior to enrolment. We conducted this study between January 31, 2007, and July 1, 2008, in the medical ward of the community-based Hospital La Carità, Locarno, located in the Italian-speaking part of Switzerland. Eligible medical inpatients were 55–85 years old, had no documented cognitive impairment, participated in normal daily activities, and spoke Italian as their native language. Exclusion criteria were previous institutionalisation, a stroke having occurred within the month preceding the neuropsychological testing, encephalitis, a clinical condition that could compromise reliable neuropsychological testing (e.g. delirium, frank dyspnoea or acute pain), and treatment with hypnotics (benzodiazepines; zolpidem and related drugs) mainly prescribed for insomnia within 18 h prior to testing. The data collection was planned before the performance of the neuropsychological tests so that the study could be defined as a prospective study according to the Standards for Reporting of Diagnostic Accuracy criteria [9]. Eligibility criteria were determined on the basis of the admission notes, with the exception of activities of daily life (ADL). ADL were assessed on the first admission day by a reference nurse via a standardised interview in use at the Hospital La Carità. Informants were included in the interview whenever possible. Moreover, J.J. assessed the basic ADL according to the Katz ADL index [10] and instrumental ADL (IADL) according to the IADL index [11]. By patient interview, J.J. assessed education years and smoking history. The admission diagnosis was coded according to the International Statistical Classification of Diseases, 10th Revision.
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Medications with potential psychotropic effects (corticosteroids, opioids) were documented based on the in-hospital medication log of each patient. The following parameters were assessed on the basis of the discharge notes: comorbidities according to the Charlson index [12], vitamin B1/B12/E deficiency, borreliosis, syphilis, hypothyroidism, alcohol dependence, arterial hypertension and dyslipidaemia. In order to minimise the influence of the acute somatic illness, neuropsychological testing was conducted during the last 3 days of hospitalisation. Two trained neuropsychologists (F.Z. and A.A.) tested the selected inpatients on a weekly basis so that the study population was not a consecutive series. The present manuscript is based on the Standards for Reporting of Diagnostic Accuracy checklist, which consists of 25 items and recommends the use of a diagram to describe the study design and patient flow (fig. 1) [9]. Neuropsychological Tests The 60-min battery of neuropsychological tests consisted of the Rey-Osterrieth Complex Figure [13], Stroop test [14], verbal fluency test [15], auditory verbal learning test [16] and the modified card sorting test [17]. The results of each test were corrected for age and education by each patient’s score, based on previously published studies on the Italian-speaking population. Immediately after neuropsychological testing, the MMSE [18] and the Italian version of the Hospital Anxiety and Depression Scale (HADS) were administered [19, 20]. A cutoff subscore of 7 points for both HADS subscales, anxiety and depression, was used [19, 20]. The HADS and MMSE were used to characterise the cohort, not for the detection and classification of MCI. The ward physicians were not aware of the results of the battery of neuropsychological tests. Statistical Analysis Discrete variables are reported as counts (percentages), and continuous variables as medians with interquartile ranges (IQR). To identify variables associated with MCI, we grouped all patients with any form of MCI and compared them to patients without MCI. We used the 2 test to compare frequencies and the MannWhitney U test to compare continuous variables. Variables with p ! 0.10 in univariate analysis with MCI as the dependent variable were included in a logistic regression analysis. Odds ratios are reported with 95% CI. The sensitivity and specificity of the MMSE for any form of MCI were calculated using receiver operating characteristic (ROC) curves. To identify the cutoff points for the different MMSE scores, we preselected a sensitivity cutoff of 80% and then selected the MMSE score with the greater sum of specificity plus sensitivity. Only patients who completed the testing battery were included in the analysis. Two-tailed p ! 0.05 was considered significant. For statistical analysis, we used SPSS version 16.0.
Results
Between January 31, 2007, and July 1, 2008, we invited 104 eligible patients to participate in the study; 72 patients accepted, 32 patients refused (acceptance rate: 69.2%), and 70 patients completed the neuropsychological evaluation (completion rate: 97.2%) (fig. 1). De Marchis et al.
Eligible patients n = 104
Excluded patients n = 34 32 did not give consent 2 did not complete the tests
Patients completing the neuropsychological evaluation n = 70
MCI n = 55
Normal result n = 15
aMCI multidomain n = 24
Non-amnestic MCI multidomain n = 13
Non-amnestic MCI single domain n = 12
aMCI single domain n=6
Fig. 1. Study design and patient flow chart.
Patients The median age of the patients who completed testing was 74 years (IQR: 68–81 years); 38 patients (54.3%) were men, and the median duration of education completed was 8 years (IQR: 8–10.5 years). The median Charlson index score was 2 (IQR: 1–3). Arterial hypertension was present in 50 patients (71.4%), 39 patients (55.7%) had a history of smoking, dyslipidaemia was present in 32 patients (45.7%), and diabetes mellitus in 26 patients (37.1%). No patient had a documented vitamin B1 or vitamin E deficiency or suffered from HIV, borreliosis or syphilis. According to the HADS, 32 patients (45.7%) showed anxiety, and 13 patients showed depression (18.6%) (table 1). The most frequent reason for admission to the medical ward were diseases of the circulatory system (31.4%), diseases of the respiratory system (21.4%) and neoplasms (8.6%).
Results of Neuropsychological Evaluation In total, 55 patients (78.6%) showed evidence of MCI, while 15 patients (21.4%) did not (fig. 1). The ward physicians did not mention MCI in their discharge notes of any of the evaluated patients. In univariate analysis, the median MMSE score of the whole population was 26 (IQR: 23–29), with a median MMSE score of 29 (IQR: 28–29) in the cognitively normal patients and 26 (IQR: 23–28) in the patients showing MCI (p ! 0.0001). Besides the MMSE score, the only variables significantly associated with MCI in univariate analysis were age and education: patients with MCI were older [77 (IQR: 70–81) vs. 70 years (IQR: 60–74 years); p = 0.003] and less educated [8 (IQR: 7.75–10) vs. 10 years (IQR: 8–12 years); p = 0.001] than were patients without MCI (table 2). We detected no statistically significant difference in the frequency of anxiety and depression between cognitively normal patients
MCI in Medical Inpatients
Dement Geriatr Cogn Disord 2010;29:259–264
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Table 1. Baseline characteristics of patients evaluated for MCI
Table 2. Univariate and multivariate analyses comparing patients
with no cognitive impairment to patients with MCI Patients evaluated for MCI (n = 70) Age, years Sex (men), n Education, years Charlson index Comorbidities, n Congestive heart failure Diabetes mellitus without end-organ damage Chronic pulmonary disease Any malignancy Myocardial infarction Peripheral vascular disease Renal disease (moderate or severe) Metastatic solid malignancy Cerebrovascular disease Liver disease (mild) Gastrointestinal ulcer disease Connective tissue disease Liver disease (moderate or severe) Diabetes mellitus with end-organ disease Cardiovascular risk factors, n Arterial hypertension Smoking history Dyslipidaemia Diabetes mellitus Medications, n Glucocorticoids Opioids Others, n Alcohol abuse Vitamin B12 deficiency Hypothyroidism Vitamin B1 deficiency/vitamin E deficiency/ HIV infection/borreliosis/syphilis
Univariate analysis
74 (68–81) 38 (54.3) 8 (8–10.5) 2 (1–3) 31 (44.3) 25 (35.7) 14 (20.0) 11 (15.7) 10 (14.3) 7 (10.0) 7 (10.0) 5 (7.1) 4 (5.7) 3 (4.3) 2 (2.9) 1 (1.4) 1 (1.4) 1 (1.4) 50 (71.4) 39 (55.7) 32 (45.7) 26 (37.1) 17 (24.3) 8 (11.4) 9 (12.9) 8 (11.4) 6 (8.6)
Age, years Sex (men), n Education, years Charlson index MMSE score HADS positive for anxiety HADS positive for depression Arterial hypertension Smoking Dyslipidaemia Diabetes mellitus Previous stroke Alcoholism Vitamin B12 deficiency Hypothyroidism Current use of glucocorticoids Current use of opioids
normal (n = 15)
MCI (n = 55)
p
70 (60–74) 9 (60) 10 (8–12) 2 (0–4) 29 (28–29) 6 (40.0) 3 (20.0) 10 (66.7) 8 (53.3) 5 (33.3) 5 (33.3) 1 (6.7) 3 (20) 2 (13.3) 2 (13.3) 3 (20.0) 4 (26.7)
77 (70–81) 0.003 29 (52.7) 0.77 8 (7.75–10) 0.001 2 (1–3) 0.54 26 (23–28)
