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Back in September 2024, Victoria Gabb told us she was starting a project that most researchers would have quietly got on with in the background: developing a core outcome set for mild cognitive impairment. Over the following year she walked us through how she was building it, what she learned interviewing 41 people living with MCI, and what patient and public involvement actually looked like week to week rather than what it looks like on a funding application.
That last post ended with a promise: the main study was done, and the next instalment would cover how the consensus process went. Victoria’s been busy since – this week, instead of a blog, the first output from that programme of work landed in Alzheimer’s & Dementia.
Outcomes reported in interventional studies for mild cognitive impairment: a scoping umbrella review to inform core outcome set development is a scoping umbrella review – pulling together evidence from multiple existing systematic and scoping reviews rather than searching primary trials from scratch. Victoria and colleagues from Bristol, Bath and Exeter searched six databases from inception to August 2023, screened 15,460 records, and worked through to 39 eligible reviews covering 154 primary studies and 14,064 participants across 31 countries. Cognitive interventions and multi-domain interventions were the most common types tested, with studies running from 2002 to 2022.
From that body of work, 552 verbatim outcomes were extracted and standardised down to 143 unique outcomes across 18 domains. Global cognition was the only outcome reported by more than half of all studies (69%); executive function, episodic memory, memory and attention followed some way behind, and depression was the most-reported outcome outside the cognitive domain (24% of studies). At the other end, two-thirds of the 143 outcomes were reported by three studies or fewer, and nearly a third appeared in just one. Functional, social and quality-of-life outcomes – the things that arguably matter most to someone living with MCI day to day – were measured far less often than cognitive test scores.
That spread is the paper’s central finding: with 143 outcomes in circulation and two-thirds of them barely used, there’s no shared standard for what “success” looks like in an MCI trial. The authors note this heterogeneity limits evidence synthesis and makes it hard to compare treatments or pool results across studies – exactly the gap a core outcome set is meant to close.
On what happens next, the authors are candid that this review only tells half the story. The outcomes here reflect what researchers, clinicians and funders have chosen to measure – not necessarily what matters most to someone living with MCI or the people who support them day to day. So the next stage is one-to-one interviews with people with MCI, their partners and relatives, and the professionals who work with them, to identify outcomes this literature search may have missed. Those findings will feed into a Delphi study and a consensus meeting to agree the final core outcome set. The authors also flag a second piece of unfinished business: alongside agreeing what to measure, the field still needs a matching core measurement set specifying how – since the review found the same instrument (the Stroop test, for instance) being used to measure five different things across different trials.
Read the full paper: Alzheimer’s & Dementia, DOI 10.1002/alz.71800
