Understanding the elements of overactive bladder: questions raised by the EPIC study
Authors: Irwin Debra E. , Abrams Paul , Milsom Ian , Kopp Zoe , Reilly Kate ,   EPIC Study Group
Published: March 2008

OBJECTIVESTo compare the prevalence of frequency and nocturia and the bother they impose in a population‐based sample of men and women using current International Continence Society (ICS) definitions of lower urinary tract symptoms (LUTS) and commonly used alternative definitions of these LUTS to emphasize the importance of standardizing the definitions when evaluating overactive bladder (OAB) syndrome; we also describe the spectrum of LUTS and bother they impose in this population with OAB.SUBJECTS AND METHODSSeveral validated disease‐specific measures were used in a population‐based, cross‐sectional telephone survey of adults aged ≥18 years in five countries. The population with OAB was defined as those participants who answered ‘yes’ to questions about urgency or urgency urinary incontinence according to ICS standards. The prevalence of daytime frequency and nocturia within the OAB population was examined using two different criteria for each symptom. Frequency was defined using the current ICS definition (i.e. subject’s perception of whether they urinated too often during the day) or more than eight daytime voids. Nocturia was defined according to the ICS definition of having to wake once or more per night to void and using the threshold of waking twice or more per night to urinate. Urinary symptom bother within the OAB population was compared using the different criteria for frequency and nocturia.RESULTSIn all, 1434 participants (502 men and 932 women) were classified as having OAB; 31% of men and 25% of women with OAB had daytime frequency consistent with the ICS definition. The ICS‐defined frequency identified a population with a varied distribution of reported daytime voiding frequencies; most respondents reported frequencies below the threshold of nine daytime voids. The ICS‐defined daytime frequency was reported as bothersome by more than half of the OAB population (46% of men, 66% of women). Of the OAB population, ≈75% reported one or more nocturia episodes per night, and ≈40% reported two or more per night. The proportion of the OAB population that was bothered by nocturia increased markedly as the number of nocturia episodes increased. Among those with OAB, the most prevalent combination of OAB symptoms was urgency and nocturia. More than half of those with OAB reported urgency combined with three or more other LUTS (including voiding and postmicturition symptoms), and the number of LUTS reported increased with age. The proportion of the population reporting symptom bother increased as the number of reported LUTS in that population increased.CONCLUSIONSThe ICS definitions for daytime frequency as ‘the subject’s perception of urinating too often’ and for nocturia as ‘one or more episodes per night’ adequately described bladder symptoms within the OAB population when assessed by the level of symptom bother. Urgency was uncommon in isolation and did not alone impose as high a level of bother as when combined with other LUTS. In this population, the most predominant manifestation of OAB was a combination of urgency with one or more other OAB symptoms. Symptom bother became more common as the number of symptoms reported increased. LUTS other than the defining symptoms of OAB were also highly prevalent within the OAB population.