Intrinsic Capacity Index and Cross-sectional Associations with Geriatric Outcomes in Community- Dwelling Older Adults

Technical Summary: Intrinsic Capacity Index and Cross-sectional Associations with Geriatric Outcomes

Problem Statement
While Intrinsic Capacity (IC) is recognized by the World Health Organization (WHO) as a central determinant of healthy aging, its operationalization remains a significant challenge in clinical and community settings. Existing measurement approaches vary widely in domain selection, instruments, and statistical aggregation, lacking a universally accepted index for routine use. Furthermore, there is a scarcity of pragmatic, validated tools suitable for community-based screening, particularly in primary care environments where time is limited. This study addresses the need to develop a feasible, multidomain IC index based on the WHO ICOPE framework that can be administered in community settings to identify vulnerability before irreversible loss of autonomy occurs.

Methodology

• Study Design and Population: A cross-sectional study was conducted between January 2024 and December 2025 in Albacete, Spain. The sample consisted of 286 community-dwelling adults aged 60 and older (mean age 73.3 years; 64% female), recruited through community pharmacies. Participants were required to be native Spanish speakers and free of major neurological, psychiatric, or active oncological conditions.
• Instrumentation (The Intrinsic Capacity Index - ICI): The researchers constructed a novel ICI by summing five binary domains (0 = impaired, 1 = preserved) derived from validated instruments:
  1. Sensory: Self-reported visual or hearing impairment.
  2. Cognition: Montreal Cognitive Assessment (MoCA) score ≥ 26.
  3. Psychological: Geriatric Depression Scale-5 (GDS-5) score < 2.
  4. Vitality: Mini-Nutritional Assessment-Short Form (MNA-SF) score of 12–14.
  5. Locomotion: International Physical Activity Questionnaire (IPAQ) short form, classifying "Moderate" or "High" activity as preserved.
     The total ICI score ranges from 0 to 5.
• Outcome Measures: The study examined associations with frailty (FRAIL scale), functional dependence (Barthel Index for BADL; Lawton and Brody Scale for IADL), polypharmacy (≥5 medications), and lifestyle factors (cognitive reserve, Mediterranean diet adherence).
• Statistical Analysis: Psychometric properties were assessed using tetrachoric correlations, Cronbach's alpha, and Principal Component Analysis (PCA). Associations between the ICI and geriatric outcomes were analyzed using generalized linear models with Gaussian family, identity link, and robust standard errors, adjusting for age, sex, cognitive reserve, diet, and comorbidities.

Key Contributions

• Development of a Pragmatic Tool: The study proposes a simplified, binary-scored ICI specifically designed for community settings (e.g., pharmacies) where comprehensive geriatric assessments are often unfeasible.
• Psychometric Characterization: The paper provides an initial psychometric evaluation of this specific operationalization, noting that while the domains are conceptually distinct (low internal consistency), they form a unidimensional latent construct in this sample.
• Validation of Associations: It demonstrates that the ICI is significantly associated with established geriatric syndromes, including frailty, functional dependence, and polypharmacy, in a real-world Spanish community sample.

Results

• Descriptive Statistics: The mean ICI score was 3.66 (SD 0.95). Scores declined significantly with age, dropping from a mean of 3.83 in the 60–69 age group to 3.14 in those aged 80 and older. The lowest scores were observed in women aged 80+.
• Psychometric Properties: The index exhibited a right-skewed distribution. Intercorrelations among the five domains were generally weak, with the strongest association found between psychological and vitality domains (r = 0.458). Internal consistency was low (Cronbach's alpha = 0.275), consistent with the theoretical view of IC as a broad, multidomain construct rather than a reflective scale. PCA retained a single dominant factor explaining 27.8% of the variance, with psychological (0.75) and vitality (0.71) domains showing the highest factor loadings.
• Associations with Outcomes:
  • Frailty and Dependence: Lower ICI scores were strongly associated with frailty (frail individuals: 3.03 vs. robust: 3.94; p < 0.001) and functional dependence in BADL and IADL.
  • Medication and Comorbidities: Lower ICI scores correlated with higher medication counts, polypharmacy, and the use of antidepressants or anxiolytics.
  • Protective Factors: Higher cognitive reserve and adherence to the Mediterranean diet showed consistent positive associations with ICI scores across adjusted models.

Significance and Claims
The authors conclude that the proposed Intrinsic Capacity Index appears to be a feasible multidomain marker of vulnerability for community-dwelling older adults. They posit that the tool may be useful for screening in community settings to identify individuals at risk of unhealthy aging trajectories before overt disability establishes. However, the authors maintain a modest stance regarding the tool's current status, explicitly stating that longitudinal validation is still needed to confirm its predictive utility. The study emphasizes that while the ICI offers a practical approach to operationalizing the WHO ICOPE framework, it should be viewed as an operational index rather than a definitive reference measure, given the lack of a gold standard for IC measurement.