Olfaction and kidney function in community-dwelling older adults.

Area of Science:

• Gerontology
• Nephrology
• Sensory Science

Background:

• Kidney function naturally declines with age in older adults.
• Reduced olfaction is observed in individuals with advanced kidney diseases.
• The relationship between olfactory decline and kidney function decline or chronic kidney disease (CKD) risk remains unclear.

Purpose of the Study:

• To investigate the association between olfactory function and kidney function in older adults.
• To determine if poor olfaction serves as a marker for declining renal function or future CKD risk.

Main Methods:

• Secondary data analysis from the Health Aging and Body Composition Study (N=1427-2531).
• Olfaction assessed using the Brief Smell Identification Test (B-SIT) categorizing function as anosmia, hyposmia, moderate, or good.
• Estimated Glomerular Filtration Rate (eGFR) calculated using CKD-EPI equation; CKD defined as eGFR<60 ml/min/1.73m² or eGFR decline ≥1 ml/min/1.73m²/year.
• Weighted regression models and absolute risk regression used to analyze associations and account for competing risks.

Main Results:

• Poor olfaction (anosmia, hyposmia) at baseline was significantly associated with lower mean eGFR.
• Anosmia at baseline predicted significantly lower eGFR seven years later, though this association attenuated after adjusting for baseline eGFR.
• Olfactory function was not found to be associated with the risk of incident CKD or CKD hospitalization.

Conclusions:

• In adults over 70, diminished olfactory function is correlated with poorer kidney function.
• Poor olfaction is not a predictor of future chronic kidney disease (CKD) or related hospitalizations in this age group.
• Further investigation in younger populations is recommended to clarify these associations.