Background: To improve compliance with voiding diaries in children with primary monosymptomatic nocturnal enuresis (PMNE), a new modified 3-day weekend frequency–volume chart (FVC) was designed, and the compliance and validity of this modified FVC was evaluated by comparing with the International Children's Continence Society (ICCS) recommended voiding diary.

Methods: A total of 1200 patients with PMNE were enrolled in the study from 13 centers in China and were randomly assigned to record this modified FVC or the ICCS-recommended voiding diary. The primary outcome measure was the compliance, assessed by comparing the completing index and the quality score of diaries between two groups. The secondary outcome measure was the validity, evaluated by comparing the constituent of subtypes, micturition parameters and response rate to desmopressin.

Results: Among the 1200 participants enrolled in the study, 447 patients completed the ICCS-recommended voiding diary and 469 completed the modified diary. The diurnal completing index and the quality score of the modified FVC group were better than those of the ICCS group. In addition, there was no significant difference between these two groups in the subtype classification, or in the response rate to desmopressin.