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The Prevalence of Nocturia and Nocturnal Polyuria: Can New Cutoff Values Be Suggested According to Age and Sex?

Zumrutbas A.E. et al.

International Neurourology Journal 2016 Dec;20(4):304-310

Commentary by Philip Van Kerrebroeck

The definition of nocturia and nocturnal polyuria index remains a controversial issue and reliable data to (re)consider the definitions are limited. The aims of this study were to assess the prevalence of nocturia and nocturnal polyuria (NP) and to define eventually new cutoff values according to age and sex for both conditions.

The researchers collected and analysed data from a population-based prevalence survey conducted among a random sample of 2,128 adults. Participants were requested to fill out a questionnaire including the International Continence Society (ICS) definitions of lower urinary tract symptoms and the International Consultation on Incontinence Questionnaire - Short Form. Additionally, a 1-day bladder diary was given to each individual. The participants were divided into 5 age groups. The prevalence of nocturia was calculated based on definitions of nocturia as 1 voiding episodes, 2 episodes, and  ≥3 episodes. NP was evaluated according to the ICS definition. The mean ± standard errors and 95th percentile values were calculated in each group as new cut-off values for NP.

The prevalence of nocturia was estimated as 28.4%, 17.6%, and 8.9% for 1, 2, and ≥3 voiding episodes each night, respectively. When nocturia was defined as 2 or more voiding episodes at night, the prevalence decreased significantly. The mean NP index was 29.4% ± 15.0% in men and 23.1% ± 11.8% in women. For the age groups of <50 years, 50-59 years, and ≥60 years, the new cutoff values for the diagnosis of NP were calculated as 48%, 69%, and 59% for men and 41%, 50%, and 42% for women, respectively.

The authors conclude based on their results that waking up once for voiding might be within the normal spectrum of behaviour. They propose that the definition of NP should be modified, and that new cut-off values should be defined using the data presented in their and additional future studies.