Single screening questions for cognitive impairment in older people: a systematic review

Single-item screening questions may be a practical first step in screening for cognitive problems in older people. A form of single-item cognitive assessment is proposed in the NHS England and Wales dementia strategy. We aimed to provide a review and synthesis of the evidence regarding the performance of single-item tests for detection of cognitive impairment.

This review used Cochrane diagnostic test accuracy procedures. Two independent researchers searched for relevant papers across multiple, cross-disciplinary electronic databases using previously validated search strings. Our index test was any single screening question for cognitive impairment, including factor analysis of multi-item tools. Our reference standards included clinical diagnosis and multi-domain cognitive assessments.

From 884 titles, 11 studies were identified as eligible for inclusion. Four studies were graded low risk of bias and recruited a representative patient sample. Five papers described a single screening question for cognitive impairment with each using a different question. Sensitivity ranged from 26 to 96% and specificity from 45 to 100%. Six papers described the component analysis of multiple item tools with broadly worded single questions ('decline in memory function', 'changes in ability to think and reason' or 'learning new things') performing best.

Informant-based, single-item screening questions show promise for detecting cognitive impairment. However, there was substantial heterogeneity in format and application of single-item screens, and several studies were of poor methodological quality. Currently, there is insufficient evidence to support routine screening using a single-item approach.