Abstract
Background: Olfactory function of patients with chronic kidney disease (CKD) is often affected by the disease. This predisposes them to malnutrition, poor quality of life and worsens disease prognoses. It is therefore imperative that factors that predict olfactory dysfunction and its severity are identified for prompt treatment. Aim: To identify factors associated with olfactory dysfunction and its severity among adults with CKD. Materials and methods: This was a prospective, hospital-based case-control study of adult patients with CKD at the University College Hospital, Ibadan, Nigeria. The control groups were age and gender matched healthy volunteers without CKD. Interviewer-assisted questionnaires were administered to participants to obtain biodata, relevant clinical data, and renal disease information. Olfactory Threshold (OT), Odour Discrimination (OD) and Odour Identification (OI) tests were carried out on participants using the “Sniffin sticks test”. Factors that predict olfactory dysfunction were identified among the spectrum of the disease severity. Results: There were 100 patients with CKD and 100 healthy controls, age ranges between 19 and 86 years (mean±SD=46.3+13.9 years) for the cases and between 20 and 85 years (mean±SD=43.4+14.9 years) for the control, respectively. The mean Total Threshold Discrimination and Identification (TDI) scores were 26.0 ± 6.4 and 33.8 ± 3.3 in cases and controls, respectively, p - 0.01. The prevalence of olfactory dysfunction among patients with CKD was 77% (hyposmia 72%, anosmia 5%), while the control population had a prevalence of 16% and all were hyposmia. Increasing age was associated olfactory dysfunction [OR 2.71, 95% CI (1.5344 – 7.0611), p - 0.01] while the sub-analysis also showed that increasing age was also associated with the scores in all the three olfactory tasks; OI(p=0.014), OD(p=0.001), OT(p=0.040) and TDI(p=0.001), but only affected the OD (0.002) among the controls. Other factors independently associated with olfactory dysfunction were duration of CKD [OR 1.84 (1.3502 – 9.3692), p - 0.02] and dialysis status [OR 0.65, 95% CI (0.2405 – 0.8366), p - 0.01] while the stages of CKD had no association with olfactory dysfunction [OR 1.1, 95% CI (0.8514 – 1.3315), p - 0.58]. Conclusion: There was high prevalence of olfactory dysfunction among adults with CKD. Increasing age, duration of CKD and dialysis status were identified as predictors of olfactory dysfunction while there was no association between severity of CKD and olfactory dysfunction.