Olfactory Dysfunction in Primary Ciliary Dyskinesia: A Systematic Review and Meta-analysis

Background: Olfactory dysfunction is a recognised but poorly characterised comorbidity of Primary Ciliary Dyskinesia (PCD). No prior systematic review has synthesised its prevalence or clinical correlates. Methodology: A PRISMA compliant systematic review and meta-analysis was conducted. Five databases were searched to February 2026. Observational studies reporting olfactory function in confirmed PCD were included. Risk of Bias was assessed using the Newcastle-Ottawa Scale. A random-effects meta-analysis using the Freeman-Tukey double arcsine transformation was performed to calculate pooled prevalence with 95% confidence intervals (CI) and prediction intervals (PI). Results: Twelve studies (n=865) were included. Overall pooled prevalence of olfactory dysfunction was 43.4% (95% CI 25.2-62.5%; 95% PI 0.1-99.0%). Objective psychophysical testing yielded a significantly higher pooled prevalence of 66.1% (95% CI 55.5-76.0%; 95% PI 38.4-88.9%) compared to patient-reported outcome measures (30.5%; 95% CI 11.4-54.0%). Older age, greater sinonasal disease burden, and specific ciliary ultrastructural defects were associated with worse olfactory function. A striking discordance between objective dysfunction and subjective awareness was observed across multiple studies. Conclusions: Olfactory dysfunction is highly prevalent in PCD and substantially under-recognised by patients. Routine objective olfactory screening should be integrated into standard multidisciplinary PCD care.