Diagnostic Test Accuracy Studies in Dementia: A Pragmatic Approach

160 Pages·2015·2.25 MB·English

by  A.J. Larner (auth.)

Diagnostic Test
Accuracy Studies
in Dementia
A Pragmatic Approach
A.J. Larner
123
Diagnostic Test Accuracy Studies in Dementia

A.J. Larner
Diagnostic Test Accuracy
Studies in Dementia
A Pragmatic Approach
A.J. Larner
Cognitive Function Clinic
Walton Centre for Neurology
and Neurosurgery
Liverpool
UK
ISBN 978-3-319-16696-4 ISBN 978-3-319-16697-1 (eBook)
DOI 10.1007/978-3-319-16697-1
Library of Congress Control Number: 2015937383
Springer Cham Heidelberg New York Dordrecht London
© Springer International Publishing Switzerland 2015
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To Martin
Loyal cousin; dedicated healthcare
professional

Pref ace
T his book has evolved from more than a decade of personal experience in conducting
diagnostic test accuracy studies of clinical signs and cognitive and non- cognitive
screening instruments in a dedicated cognitive disorders clinic. Many of these studies
have been published, and are summarised elsewhere (Larner 2014a, b).
T he ageing of the human population with the consequent increase in numbers of
individuals affl icted with cognitive impairment and dementia mandates diagnostic
test accuracy studies to identify and eventually treat these patients effectively. If, as
seems likely, population based testing for early identifi cation becomes the future
policy norm, the requirement for tests with established high diagnostic test accuracy
is self-evident. A rigorous methodology developed to generate meaningful data
from such studies is therefore an imperative need.
A s well as giving a general overview, the book gives particular emphasis to, and
argues in favour of, what I have previously termed “pragmatic diagnostic accuracy
studies” (Larner 2012a, 2014a: 33–5). This methodology seems to me to correspond
largely with Sackett and Haynes’ (2002) nomenclature of addressing a “Phase III
question”, i.e. among patients in whom it is clinically sensible to suspect the target
disorder, does the test result distinguish those with and without the target disorder?
Consecutive patients should be studied to answer such questions, and hence this
approach, with certain limitations, would seem to fi t very well with the idiom of
day-to-day clinical practice. Hence, such pragmatic diagnostic test accuracy stud-
ies, far from being the preserve of large, well-funded, often international, collabora-
tive groups comprised of an intellectual elite (as for most randomised controlled
trials), may fall relatively easily within the ambit or compass of jobbing work-a-day
clinicians (like myself), a phenomenon which I have elsewhere ventured to term
“micro-research” (Larner 2012b: xv). It is hoped that a brief exposition on some of
the practicalities of pragmatic diagnostic test accuracy studies will encourage read-
ers as to their feasibility without the necessity for a large research infrastructure or
funding, and hence to identify suitable research questions and undertake the appro-
priate empirical studies. No in-depth mathematical expertise is required for the
application of the few equations found in the text (moreover, statistical programmes
are also available), nor any familiarity with probability theory, for which reason
vii
viii Preface
probability notation is eschewed. Lest a discourse on method be deemed too arid,
the text is leavened with some examples taken from the literature on diagnostic
studies in dementia.
T he book is structured as for a research publication, i.e. Introduction, Methods,
Results, Discussion, with a few digressions where necessary. Since methodology is
paramount, this of necessity comprises the longest overall section of the book
(Chaps. 2 and 3 ). The chosen structure also follows the published guidelines for the
assessment of the quality of studies examining the diagnostic accuracy of clinical
tests, such as the Standards for Reporting Diagnostic Accuracy (STARD; Bossuyt
et al. 2003) and the Quality Assessment of Diagnostic Accuracy Studies (QUADAS
and QUADAS-2; Whiting et al. 2004, 2011). More recently, STARD guidelines for
reporting diagnostic test accuracy studies in dementia (STARDdem) have emerged
from the Cochrane Dementia and Cognitive Improvement Group (Noel-Storr et al.
2014), so this is an apposite moment to produce a book-length treatment of these
issues as related to dementia practice. However, the content here is rather more
discursive, and perhaps less prescriptive, than in the aforementioned guidelines,
refl ective of individual practice. Readers will (hopefully) therefore be helped to
negotiate the sometimes bumpy path between the aspirations of principles and the
messy realities of practice, and therefore be able to be “doing science” in some
sense without being superfi cialist. Studies examining cognitive screening instru-
ments are particularly emphasized, refl ecting the author’s area of particular interest
(greater detail on some of the instruments examined may be accessed elsewhere:
Larner 2013), but as the detection of disease biomarkers has become of increasing
importance to diagnosis, as refl ected in more recent sets of diagnostic criteria for
neurodegenerative disorders, these too will be considered.
A lthough the focus of this book is dementia and cognitive disorders, the approach
described may be applicable not only to other areas of neurological practice but also
of medicine and even surgery.
Liverpool, UK A. J. Larner
References
Bossuyt PM, Reitsma JB, Bruns DE, et al. The STARD statement for reporting studies of diagnos-
tic accuracy: explanation and elaboration. Clin Chem. 2003;49:7–18.
L arner AJ. Pragmatic diagnostic accuracy studies. h ttp://bmj.com/content/345/bmj.e3999?tab=responses .
28 August 2012a.
L arner AJ. Dementia in clinical practice: a neurological perspective. Studies in the dementia clinic.
London: Springer; 2012b.
Larner AJ (ed.). Cognitive screening instruments. A practical approach. London: Springer; 2013.
Larner AJ. Dementia in clinical practice: a neurological perspective. Pragmatic studies in the
cognitive function clinic. (2nd edition). London: Springer; 2014a.
Larner AJ. Neurological signs of possible diagnostic value in the cognitive disorders clinic. Pract
Neurol. 2014b;14:332–5.
Noel-Storr AH, McCleery JM, Richard E, et al. Reporting standards for studies of diagnostic test
accuracy in dementia: the STARDdem Initiative. Neurology. 2014;83:364–73.
Preface ix
Sackett DL, Haynes RB. The architecture of diagnostic research. In: Knottnerus JA, editor. The
evidence base of clinical diagnosis. London: BMJ Books; 2002. p. 19–38.
Whiting P, Rutjes AW, Dinnes J, Reitsma J, Bossuyt PM, Kleijnen J. Development and validation
of methods for assessing the quality of diagnostic accuracy studies. Health Technol Assess.
2004;8:iii, 1–234.
Whiting PF, Rutjes AW, Westwood ME, et al. QUADAS-2: a revised tool for the quality assess-
ment of diagnostic accuracy studies. Ann Intern Med. 2011;155:529–36.