Open AccessEvaluating cognitive screening instruments with the “likelihood to be diagnosed or misdiagnosed” measure
Author(s) -
Larner Andrew J.
Publication year - 2019
Publication title -
international journal of clinical practice
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.756
H-Index - 98
eISSN - 1742-1241
pISSN - 1368-5031
DOI - 10.1111/ijcp.13265
Subject(s) - medicine , dementia , metric (unit) , montreal cognitive assessment , cognitive impairment , false positive paradox , cognition , cognitive test , diagnostic accuracy , psychiatry , radiology , pathology , statistics , operations management , mathematics , disease , economics
Objectives To calculate “number needed to diagnose” ( NND ), “number needed to predict” ( NNP ), and “number needed to misdiagnose” ( NNM ) for cognitive screening instruments which are commonly used in suspected dementia and mild cognitive impairment, and from these to calculate a “likelihood to be diagnosed or misdiagnosed” ( LDM ) metric as the ratio of NNM to either NND or NNP . Methods Datasets from pragmatic diagnostic test accuracy studies examining four commonly used cognitive screening instruments (Mini‐Mental State Examination, MMSE ; Montreal Cognitive Assessment, Mo CA ; Mini‐Addenbrooke's Cognitive Examination, MACE ; Six‐item Cognitive Impairment Test, 6 CIT ) were analysed to calculate NND , NNP , and NNM , and from these derive values for LDM . Findings Although all the tests had low NND and NNP as desired, NNM was also low. Hence, only MMSE and 6 CIT achieved LDM > 1 for dementia diagnosis, and only MACE and 6 CIT had LDM > 1 for diagnosis of mild cognitive impairment. Conclusions The likelihood to be diagnosed or misdiagnosed ( LDM ) metric may indicate the utility or inutility of diagnostic tests for clinicians and patients. LDM values may clarify the inevitable trade‐off between sensitivity and specificity and hence clinician purpose in administering the diagnostic test (minimising false negatives or false positives).