title: Determinants of nocturia: the Krimpen study.
abstract: OBJECTIVE
  Many conditions and characteristics are cross-sectionally associated with nocturia. However, to our knowledge longitudinal associations of frequency-volume chart based nocturia have not yet been studied. We identify (modifiable) determinants of nocturia in older men in a longitudinal setting.
  
  
  METHODS
  A longitudinal, community based study was conducted among 1,688 men age 50 to 78 years in Krimpen aan den IJssel, The Netherlands with planned followup rounds at 2, 4 and 6 years. Men without a history of radical prostatectomy, transurethral surgery, or bladder or prostate cancer were included in the study. Data were obtained using frequency-volume charts, from which the nocturnal voiding frequency, maximum voided volume and (nocturnal) urine production were determined. Nocturia was defined as a nocturnal voiding frequency of 2 or more episodes. Polyuria was defined as greater than 2,800 ml voided per 24 hours. For nocturnal polyuria we used the 2 definitions of 1) greater than 33% of 24-hour voided volume and 2) nocturnal urine production of greater than 90 ml per hour. Conditions and characteristics were determined via medical examinations and questionnaires. A generalized linear mixed effect model was used to determine factors longitudinally associated with nocturia.
  
  
  RESULTS
  Age (50 to 55 years vs greater than 60 years), maximum voided volume (greater than 300 ml vs less than 300 ml), 24-hour polyuria, nocturnal polyuria (both definitions) and lower urinary tract symptoms were all longitudinally associated with an increased prevalence of nocturia in older men.
  
  
  CONCLUSIONS
  A smaller maximum voided volume, lower urinary tract symptoms, 24-hour polyuria and nocturnal polyuria are significant and potentially modifiable determinants of nocturia. The finding that both definitions for nocturnal polyuria are independent significant determinants may indicate a 2-step etiologic process for nocturnal polyuria.
authors.affiliation: Department of Urology, University Medical Center Utrecht, Utrecht, The Netherlands. Electronic address: b.vandoorn@umcutrecht.nl.
authors.forename: Boris
authors.initials: B
authors.lastname: van Doorn
authors.affiliation: Department of Urology, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Esther T
authors.initials: ET
authors.lastname: Kok
authors.affiliation: Department of General Practice, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Marco H
authors.initials: MH
authors.lastname: Blanker
authors.affiliation: Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Paul
authors.initials: P
authors.lastname: Westers
authors.affiliation: Department of Urology, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: J L H Ruud
authors.initials: JL
authors.lastname: Bosch
mesh_terms: D000368:Aged; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D053158:Nocturia / Q000150:complications* / Q000209:etiology*
keywords: epidemiology; lower urinary tract symptoms; nocturia; polyuria; prostatic hyperplasia