Predictors of Long-Term Relapse in Primary Monosymptomatic Nocturnal Enuresis: A Retrospective Cohort Study

Nocturnal enuresis is defined as involuntary urination during sleep in children, particularly those aged 5 years or older. Primary monosymptomatic nocturnal enuresis (PMNE) involves nighttime wetting without daytime symptoms, and although factors like reduced bladder capacity, nocturnal polyuria, and impaired arousal contribute, predictors of long-term relapse remain uncertain.

This retrospective cohort study included 227 children aged ≥5 years with strictly defined PMNE who achieved complete remission following a standardized 3-month treatment protocol (alarm therapy, desmopressin, or desmopressin plus oxybutynin). All children underwent ICCS-based assessment, including physical examination, urinalysis, ultrasonography, UFM, a 48 h frequency/volume (F/V) diary, and post-void residual measurement. One year after treatment discontinuation, patients were reassessed using a 14-day wet-night diary. Predictors of relapse were analyzed using comparative statistics.

At 1-year follow-up, 48.5% of children experienced relapse. Age, sex, treatment modality, family history, and baseline wet-night frequency were not associated with relapse (p > 0.05). Diary-based FBC was significantly higher than UFM-based capacity (p < 0.001). Reduced diary-based mean FBC/EBC ratios were significantly more common among relapsing children (p < 0.001), whereas UFM-derived ratios showed no significant difference (p = 0.052). ROC analysis demonstrated moderate discriminatory performance for diary-based FBC/EBC (AUC 0.671). A ratio > 79% predicted sustained remission with 83.6% specificity and a positive predictive value of 73.5%.

Diary-derived bladder capacity is the strongest predictor of long-term relapse in PMNE and outperforms UFM-based assessment. A mean FBC/EBC ratio > 79% provides a clinically useful threshold for identifying children at low risk of recurrence. Those with reduced diary-based capacity may benefit from closer follow-up or extended maintenance therapy.