Nocturia and obstructive sleep apnea in spinal cord injured patients - a cohort study

Purpose: To describe the prevalence of nocturia and obstructive sleep apnea (OSA) in a cohort of spinal cord injury (SCI) patients and to describe their association. Additionally, to assess clinical and urodynamic data explaining nocturia and to evaluate the effect of OSA management with continuous positive airway pressure (CPAP).

Method: Retrospective analysis of data from patients with SCI followed in a tertiary care rehabilitation center with a specialized sleep and neuro-urology units. All adult SCI patients who underwent urodynamic assessment before polysomnography (PSG) between 2015 and 2023 were eligible. Subjective (nocturia) and objective data (urodynamic data, polysomnography, CPAP built-in software) were collated from the Handisom database (database register no. 20200224113128) and the medical records of SCI patients. Statistical testing used Mann-Whitney test for non-parametric variables, Fisher's exact test for contingency analysis and the Spearman correlation test to assess correlations. A p-value < 0.05 was considered significant. Statistical analyses were performed using GraphPad Prism v9.

Results: 173 patients (131 males, 42 females) were included. The majority of patients were paraplegic (n = 111 (64,2%)) and had complete lesions (n = 75 (43,4%)). A total of 100 patients had nocturia (57,5%). The prevalence of OSA (Apnea Hypopnea Index (AHI) ≥ 15/h) in the studied population was 61,9%. No correlation was found between nocturia and OSA. A significant difference was observed between patients with and without nocturia in terms of the presence of neurogenic detrusor overactivity (p = 0,049), volume at the first detrusor contraction (p = 0,004) and the bladder functional capacity (p < 0,001).

Conclusion: Nocturia and OSA are highly prevalent in patients with SCI, but no statistical association was found between these two disorders. A prospective study focusing on nocturnal polyuria will be needed to assess the impact of OSA on lower urinary tract symptoms in SCI patients.