Towards a core outcome set (COS) for intrinsic capacity (IC) intervention studies in adults in midlife and beyond: a scoping review to identify frequently used outcomes and measurement tools

Abstract

This scoping review was conducted to identify the outcomes and measurement tools used in IC intervention studies, as first step towards the development of a core outcome set (COS) for IC trials. PRISMA-ScR and COS-STAD were followed. The review considered randomized controlled trials targeting IC published in Medline, Scopus, Embase, Cochrane Central Register of Controlled Trials, and clinicaltrials.gov, until June 2023. Of 699 references, 534 studies were screened once duplicates were removed, 15 were assessed for eligibility, and 7 (4 articles and 3 protocols) met eligibility criteria. Twenty-eight outcomes were identified (19 related to IC and its domains and 9 unrelated). The most reported primary outcome was the change in IC levels postintervention (5 over 7 studies) and the most reported outcomes (either as primary and/or secondary) were the changes in physical performance and in depressive symptoms (6 over 7 studies). Fifty-five tools used to construct the domains' z-scores and/or assess the effect of interventions were identified (47 related to IC and its domains and 8 unrelated). The most reported tool was an IC Z-score, calculated by 4 domains' z-scores: locomotor, vitality, cognitive, and psychological (5 over 7 studies). The tools differed among studies (10 locomotor related, 6 vitality related, 16 cognitive related, 8 psychological related, 6 sensorial related, 8 unrelated tools). The vast heterogeneity (28 outcomes and 55 tools within 7 studies) highlighted the need of a COS. These outcomes and tools will be presented to experts in a future step, to select the ones that should be taken into consideration in IC trials.

Keywords: Core outcome set; ICOPE; Intrinsic capacity; Older people; Scoping review.

Fig. 1

Flow diagram of the scoping review according to PRISMA 2020 for systematic reviews which included searches of databases and registers

Fig. 2

Frequency of the 28 outcomes reported in Intrinsic capacity (IC) intervention studies: 19 outcomes related to IC and its domains and 9 unrelated outcomes (n = 7). The * indicates the 9 outcomes unrelated to IC and its domains, reported in IC intervention studies. The number of outcomes unrelated to IC and its domains and the number of measurement tools unrelated to IC and its domains are different (9 and 8, respectively), as the measurement tool for change in frailty status was not explicitly mentioned

Fig. 3

Frequency of the IC Z-score and the ten measurement tools related to the locomotor domain in IC intervention studies (n = 7). For scoping review purposes, the IC Z-score, the domains’ z-scores, and the tests have been considered as “measurement tools’’ (i.e., “measurement tools “ equals “assessment tools”, “tools”, or “tests”)

Fig. 4

Frequency of the IC Z-score and the six measurement tools related to the vitality domain in IC intervention studies (n = 7). For scoping review purposes, the IC Z-score, the domains’ z-scores, and the tests have been considered as “measurement tools’’ (i.e., “measurement tools” equals “assessment tools”, “tools”, or “tests”)

Fig. 5

Frequency of the Intrinsic capacity (IC) Z-score and the 16 measurement tools related to the cognitive domain in IC intervention studies (n = 7). For scoping review purposes, the IC Z-score, the domains’ z-scores, and the tests have been considered as “measurement tools’’ (i.e., “measurement tools” equals “assessment tools”, “tools”, or “tests”)

Fig. 6

Frequency of the Intrinsic capacity (IC) Z-score and the eight measurement tools related to the psychological domain in IC intervention studies (n = 7). For scoping review purposes, the IC Z-score, the domains’ z-scores, and the tests have been considered as “measurement tools” (i.e., “measurement tools” equals “assessment tools”, “tools”, or “tests”)

Fig. 7

Frequency of the Intrinsic capacity (IC) Z-score and the six measurement tools related with the sensorial domain in IC intervention studies (n = 7). For scoping review purposes, the IC Z-score, the domains’ z-scores, and the tests have been considered as “measurement tools” (i.e., “measurement tools” equals “assessment tools”, “tools”, or “tests”). The IC Z-score has been included in this figure for figure drafting purposes, due to the low frequencies of these tools in the RCTs

Fig. 8

Frequency of the 8 measurement tools, unrelated to Intrinsic capacity (IC) and its domains, reported in IC intervention studies (n = 7). For scoping review purposes, the IC Z-score, the domains’ z-scores, and the tests have been considered as “measurement tools” (i.e., “measurement tools” equals “assessment tools”, “tools”, or “tests”). The IC Z-score has been included in this figure for figure drafting purposes, due to the low frequencies of these tools in the RCTs. The number of outcomes unrelated to IC and its domains and the number of measurement tools unrelated to IC and its domains are different (9 and 8, respectively), as the measurement tool for change in frailty status was not explicitly mentioned