'Attended alone' sign: validity and reliability for the exclusion of dementia

Research Letter 'Attended alone' sign: validity and reliability for the exclusion of dementia SIR—The diagnosis of dementia according to DSM-IV-TR criteria is based on clinical findings [1]. NINCDS–ADRDA criteria for Alzheimer's disease (AD) are clinically based and supported by investigation findings [2]. Proposed new diagnostic criteria for AD attempt to incorporate biomarkers, but not all of these may be easily available outside major research centres [3]. Hence, the need remains for simple, reliable, valid tests based on clinical assessment to confirm or exclude the diagnosis of dementia. The importance of collateral history from a knowledgeable informant when assessing individuals complaining of memory problems and in the diagnosis of dementia syndromes , particularly AD, has been emphasised in diagnostic guidelines [4, 5]. It has been previously reported that failure to attend memory clinic consultation with an informant, despite prior provision of written instruction to do so included with the clinic appointment information, was a robust sign of the absence of dementia [6]. A further study was undertaken to measure the reliability of the 'attended alone' sign in an independent patient cohort and to validate it against clinical diagnostic criteria. All consecutive patients seen by one consultant neurologist when attending the Cognitive Function Clinic based in a regional neuroscience centre over a 4-year period (Septem-ber 2004–August 2008 inclusive) were included in the study. On arrival, it was noted whether the patient attended alone or with informant(s) (relatives, friends or carers). This information was not used in the diagnosis of dementia to avoid incorporation bias [7] although clearly the clinician could not be blinded to the information. Dementia was diagnosed by DSM-IV-TR criteria [1] based on clinical interview, informant interview where possible , neuropsychological testing and structural brain imaging (CT ± MRI), as in previous cohorts reported from this clinic [6, 8, 9]. The 'attended alone' sign was considered as a test for dementia and compared with clinical criteria-based diagnosis. The STARD checklist for reporting diagnostic accuracy studies was observed [10] and basic principles of evidence-based diagnosis were applied [11] to calculate test sensitivity , specificity, positive and negative predictive values (PPV, NPV), diagnostic odds ratio (DOR) and positive and negative likelihood ratios (LR+, LR−) with 95% confidence intervals (CI). A total of 240 patients were diagnosed with dementia, and 312 were adjudged not demented, a dementia prevalence (43.5%, 95% CI = 39.3–47.6%) similar to that reported in previous cohorts from this clinic …