Functional capacity, renal function and vitamin D in community-dwelling oldest old

Area of Science:

• Gerontology and Geriatric Medicine
• Nephrology
• Nutritional Science

Background:

• Aging is associated with a decline in physical and mental functional capacity.
• Kidney function, measured by estimated glomerular filtration rate (eGFR), and vitamin D levels (25(OH)D) are crucial for maintaining health in older adults.

Purpose of the Study:

• To investigate the association between declining eGFR and serum 25(OH)D levels with physical and mental functional capacity in individuals aged 80 and older.

Main Methods:

• A cross-sectional study of 205 independent, community-dwelling elderly subjects (≥80 years).
• Functional capacity assessed via Geriatric Depression Scale (GDS), Instrumental Activities of Daily Living (IADL), Mini-Mental State Examination (MMSE), Verbal Fluency Test (VF), handgrip strength, and chair-rise time.
• Combined creatinine and cystatin C-based eGFR and serum 25(OH)D levels were measured.

Main Results:

• Each year of life reduced functional capacity by approximately 10%.
• A 1 ml/min/m² increase in eGFR was linked to a 2% higher likelihood of adequate Instrumental Activities of Daily Living (IADL) performance.
• Serum 25(OH)D levels between 15.00-22.29 ng/ml improved performance in Verbal Fluency Test (VF), IADL, handgrip strength, and chair-rise time compared to lower levels.

Conclusions:

• Age-related decline in renal function impacts the ability to perform activities for independent living, but not specific cognitive or physical domains.
• Low serum 25(OH)D levels appear to be a more significant marker of functional decline risk than eGFR in the oldest, community-dwelling elderly.
• Maintaining adequate vitamin D levels may be crucial for preserving functional independence in advanced age.