Predictive parameters of response to desmopressin in primary nocturnal enuresis

Introduction/Background Many recent treatment guidelines have advocated the importance of a full noninvasive medical evaluation. To individualize treatment, special emphasis must be put on recording of the maximum voided volume (MVV) and nocturnal diuresis in a diary or frequency/volume chart. Objective The aim of this study was to identify any possible predictive factors to desmopressin response. Study design This study is a re-analysis of a prospective, open-label, multinational, phase-IV study evaluating <= 6 months of treatment with desmopressin tablets for children with primary nocturnal enuresis. The children were enrolled between April 2002 and December 2004 from 86 centers in four countries: UK, Canada, Germany and France. A total of 936 children were screened; 744 children aged 5-15 years participated in the study. Of these, 471 children completed the study with 6 months follow-up and recording in a frequency/volume chart. All children experienced six or more wet nights during the 14-day screening period. Exclusion criteria were: organic pathology, treatment for enuresis within the past year, previous treatment for enuresis for >4 weeks, diurnal symptoms, renal or central diabetes insipidus and the use of systemic antibiotics or other drugs known to affect desmopressin activity. The predictive value of number of wet nights a week, fluid intake, daytime voiding frequency and diuresis was investigated by performing a multinomial logistic regression. Results Of the demographic variables, age was the only significant predictor for response to desmopressin. Controlling for age, the significant predictive variables were: number of wet nights a week, average voided volume daytime, maximum voided volume daytime, total daytime diuresis, nocturnal diuresis (see Figure), maximum voided volume 24 h and total 24 h diuresis. More than 80% of the children had no nocturnal polyuria and a low maximum voided volume. Discussion Performing a secondary analysis is a limitation because the original study was not designed for that. A new prospective study is ethically hardly defendable for children if data are available from previous literature [1]; therefore, a re-analysis was the appropriate choice. The study confirms the predictive value of age, number of wet nights a week and nocturnal diuresis [1,2]. Conclusions The study demonstrates that desmopressin response rates are higher in children with greater age, limited number of wet nights a week and nocturnal polyuria. Only a minority of a primary nocturnal enuresis population, based on history alone, had nocturnal polyuria. The majority had a low maximum voided volume. The results clearly stress the importance of a frequency/volume chart for individualizing therapy to the characteristics, thereby resulting in elevated success rates.