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Cutaneous Adverse Drug Reactions in Older Adults Part I: Assessment and Diagnosis

Cutaneous Adverse Drug Reactions in Older Adults Part I: Assessment and Diagnosis

Teaser: 

G.A.E. Wong, MBChB, MRCP (UK); N.H. Shear, MD, FRCP(C), Divisions of Dermatology and Clinical Pharmacology, Sunnybrook & Women’s College Health Sciences Centre, University of Toronto, Toronto, ON.

Cutaneous adverse drug reactions (ADR) are a common problem affecting ambulatory and hospitalized patients. Older patients may be more predisposed to ADR due to inappropriate prescribing of medications, age-associated changes in pharmacokinetics and pharmacodynamics, altered homeostatic mechanisms, multiple medical pathology and use of drugs with a narrow therapeutic margin. In this first of two articles, a practical approach to the assessment and diagnosis of patients with suspected drug-induced rashes will be described. A subsequent article will discuss the management of patients with cutaneous ADR.
Key words: adverse drug reaction, skin, rash, cutaneous, diagnosis, assessment.

Neuropsychological Assessment in Dementia

Neuropsychological Assessment in Dementia

Teaser: 

Larry Leach, PhD, Cpsych
Psychologist, Department of Psychology,
Baycrest Centre for Geriatric Care,
Adjunct Professor, Department of Psychology,
University of Toronto,
Toronto, ON.

The accurate and reliable assessment of dementia is essential not only for the purpose of diagnosis, but also because recent advances offer promise for treatment. With the advent of new treatments, early diagnosis becomes even more important because those individuals in the early stages of a disease such as Alzheimer are likely to benefit the most from treatment. Dementia is not a disease but rather a constellation of symptoms that reflect brain dysfunction. The most common clinical criteria of dementia (the DSM-IV) requires the presence of dysfunction in memory and one or more other mental functions such as language, reasoning, perception, attention or spatial awareness. In addition, the mental dysfunction must interfere with the performance of daily activities. There are many neurological diseases that can lead to dementia, Alzheimer disease being the most common. Recent statistics published by the Canadian Consensus Conference on Dementia indicate that dementia is present in approximately 8% of Canadians. The prevalence of dementia changes dramatically with age, increasing from 2.4% of Canadians aged 65-74 to 34.5% over the age of 85.

In order to determine if an individual has some form of dementia they must undergo special tests of mental functions referred to as mental status exams or neuropsychological assessments. Such tests much meet three general criteria: they must be reliable; they must be sensitive to dementia; and they must be specific to the dementia. Reliability ensures that results can be repeated within acceptable limits of error. Sensitivity requires that the test must be able to identify individuals who are known to have dementia. Specificity requires that the test must be able to identify individuals who are known not to have dementia. Over the years, various mental status examinations have also been developed to help identify the presence of cognitive impairments that are sufficiently severe to represent a dementia. The reliability, sensitivity and specificity of tests are often documented but unfortunately, one characteristic--the predictive ability--has not always been thoroughly documented or appreciated. The predictive ability involves two complementary characteristics, positive and negative prediction. In contrast to sensitivity and specificity, which reflect how well a test identifies individuals who are known to have (or not to have) dementia, positive and negative predictions reflect the likelihood that a person has the disease given a certain test result. Positive prediction is the probability that a positive test result indicates the presence of dementia. Negative prediction is the probability that a negative test result represents the absence of dementia. Positive or negative prediction is what a clinician should be most concerned with. After all, if a clinician knew that the person has a dementia then there would be no problem. There is one aspect about predictive ability that is not fully appreciated: predictive ability varies with the prevalence of dementia. As disease prevalence increases, positive prediction increases but negative prediction decreases. Conversely, as disease prevalence decreases negative prediction increases while positive prediction decreases. This lack of appreciation of the change in predictive ability of a test with disease prevalence can lead unwary clinicians into a false sense of security with respect to the outcomes of test results.

One of the most commonly used tests of mental status is the Mini-Mental Status Examination (MMSE). This test is the most frequently used diagnostic tool to determine presence of cognitive impairment for the diagnosis of dementia. Although the sensitivity and specificity of the MMSE appear acceptable, evaluation of the positive and negative prediction across different levels of prevalence reveals that the MMSE is less than stellar. For example, a positive test result of an MMSE (based on a cut-off score of 24/30) obtained in a situation where the prevalence of dementia is expected to be 2.4% is only 12% accurate. In other words, 88% of the positive test results would likely come from normal individuals! Furthermore, the sensitivity and specificity of the MMSE has also been shown to vary with age and education of people, but age corrections are seldom applied in many clinical settings. The Mattis Dementia Rating Scale (DRS) has been shown to have excellent sensitivity and specificity; in addition, it has excellent positive and negative predictive ability across a wide range of prevalence of dementia. The MMSE has a large following due to the short amount of time it takes to administer (approximately 10 minutes), but the greater predictive ability of the DRS makes it well worth the 25 minutes it may take to administer.

Although a short test such as the DRS is sensitive to cognitive impairment, it has the shortcoming of failing to identify specific patterns of dysfunction relating to various types of dementia. For this purpose, neuropsychological tests are far superior. A detailed neuropsychological assessment can clearly and reliably define those cognitive domains that are deficient and intact. Furthermore, the neuropsychological tests have been shown to correlate with regional brain dysfunction. Although patterns of dysfunction relate to brain dysfunction they do not always identify cause. Numerous case studies have demonstrated that individuals, who have been diagnosed as having one form of dementia on the basis of patterns of impairment, have been shown to have another cause of dementia at autopsy. This represents a limitation to the present diagnostic techniques based primarily on clinical signs and symptoms. Nevertheless, an appreciation of the extent as well as type of cognitive impairment can prove to be valuable in the treatment of individuals with dementia. Despite this limitation, the pattern of deficits due to dementia are clearly distinguishable from those cognitive disruptions associated with depression.

CCCAD: More Effort to be Spent on Distribution

CCCAD: More Effort to be Spent on Distribution

Teaser: 

A. Mark Clarfield, MD

In 1989 the first Canadian Consensus Conference on the Assessment of Dementia (CCCAD) met in Montreal to try to come to grips with the vexed question of dementia assessment. In those days, there was still a lively debate going about the extent to which dementia should be worked up in an attempt to find the "reversible" cases.

Nearly ten years later in 1998, the group reconvened to look at assessment again but extended its mandate as well. What follows is a brief "compare and contrast" essay which examines what the two meetings had in common as well as how they differed.

To start off, they were both held in the beautiful city of Montreal, in 1989 under the joint chairmanship of myself and Dr. Serge Gauthier. In 1998, Dr. Gauthier was still in charge but this time Dr. Chris Patterson of McMaster University joined as the co-chair. (In 1992, I had moved to Israel, but was honoured to be invited back.)

In 1989 before (or perhaps at the beginning of) the extensive government cutbacks, we were able to fund the meeting with 50% government money, both federal and Quebec provincial. The rest of the support came from private sources, mainly drug companies. By 1998 it seems that government wanted no part of consensus meetings at least in the field of the dementias, and they did not participate in the funding this time.

A decade ago the 38 participants were mainly Canadian with four American visitors.