The dietary inflammatory index (DII®) and its association with cognition, frailty, and risk of disabilities in older adults: A systematic review.

BACKGROUND & AIMS: Systemic inflammation is considered an important issue in older adults and is associated with adverse health outcomes, such as frailty and cognitive impairment. Diet is a critical associated factor, and the dietary inflammatory index (DII®) is proposed as a promising tool to identify the association between diet and health outcomes. Our aims were: (i) to investigate the association between the DII® and frailty, cognition, and the consequent risk of disability in older adults; (ii) to discuss particularities of the use of DII® with older adults.

METHODS

The research question was based on the PICOS strategy: Population = older adults; Intervention or Exposure = DII; Comparison = any comparator; Outcomes = frailty, cognition, and risk of disability; Type of study = cohort, cross-sectional or case-control studies. We searched publications in two electronic databases (PUBMED and Web of Science) up to May 20th, 2020.

RESULTS

Seven studies met our criteria. Three investigated cognition (one cohort and two cross-sectional), and four investigated frailty or risk of disability (one cohort and three cross-sectional); none of the studies investigated both outcomes (frailty and cognition) simultaneously. The studies presented some issues, mainly concerning: (i) the collection of dietary data and calculation of the DII; (ii) the study design; (iii) calculation of the sample size; (iv) eligibility criteria; (v) time for follow-up; (vi) and choice of covariates.

CONCLUSION

despite the issues, the use of DII resulted in a significant association, or predictive value, with variables related to frailty and cognitive decline. Further studies, with sensitivity analysis of the different components of this index, are needed. DII showed to be a promising tool in the investigation of geriatric syndromes. This systematic review was registered in PROSPERO (CRD42020155672).