The Association of Odor Identification with Nutritional Status and Systemic Inflammation in Patients with Advanced Chronic Kidney Disease.

Abstract

Background: Anorexia is common in patients with chronic kidney disease (CKD) and could lead to protein energy wasting (PEW). An altered sense of smell, a reflection of olfactory dysfunction, is a potential mechanism that exacerbates the impact of anorexia on PEW. In this study, we examined the extent of the altered sense of smell and its association with PEW in patients with moderate to advanced CKD.

Methods: We studied 139 individuals (34 healthy subjects - controls, 50 patients with stage 3-4 CKD, 55 patients on maintenance hemodialysis - MHD) using the odor identification test (Sniffin' Sticks odor screening test containing 12 different smells). The odor identification test was scored as either correct or incorrect, and each participant's total odor score was calculated. Malnutrition Inflammation Score (MIS) was used to assess PEW.

Results: Patients with CKD had higher C-reactive protein (CRP) and lower serum albumin concentrations compared to healthy individuals. Total odor scores were different between groups, with controls having the highest scores and MHD patients having the lowest scores. A similar difference was observed in MIS, MHD patients displaying the worst nutritional score (p ≤ 0.001). The number of participants with severe olfactory dysfunction (≤ 6 correct answers) was significantly higher in the CKD and MHD groups compared to the controls (p ≤ 0.01). There was an inverse trend between the total odor score and the MIS score for the study population. However, this relationship was not statistically significant (r = -0.124, p = 0.21).

Conclusion: This cross-sectional study suggests that olfactory dysfunction, as assessed by the odor identification test, is altered in patients with advanced CKD, most notably in ones on MHD. Although the diminished sense of smell was observed alongside development of PEW, we explicitly noted that there is no statistically significant correlation.