title: Empirical evaluation of grouping of lower urinary tract symptoms: principal component analysis of Tampere Ageing Male Urological Study data.
abstract: WHAT'S KNOWN ON THE SUBJECT? AND WHAT DOES THE STUDY ADD?: The ICS has divided LUTS into three groups: storage, voiding and post-micturition symptoms. The classification is based on anatomical, physiological and urodynamic considerations of a theoretical nature. We used principal component analysis (PCA) to determine the inter-correlations of various LUTS, which is a novel approach to research and can strengthen existing knowledge of the phenomenology of LUTS. After we had completed our analyses, another study was published that used a similar approach and results were very similar to those of the present study. We evaluated the constellation of LUTS using PCA of the data from a population-based study that included >4000 men. In our analysis, three components emerged from the 12 LUTS: voiding, storage and incontinence components. Our results indicated that incontinence may be separate from the other storage symptoms and post-micturition symptoms should perhaps be regarded as voiding symptoms.
  
  
  OBJECTIVE
  To determine how lower urinary tract symptoms (LUTS) relate to each other and assess if the classification proposed by the International Continence Society (ICS) is consistent with empirical findings.
  
  
  METHODS
  The information on urinary symptoms for this population-based study was collected using a self-administered postal questionnaire in 2004. The questionnaire was sent to 7470 men, aged 30-80 years, from Pirkanmaa County (Finland), of whom 4384 (58.7%) returned the questionnaire. The Danish Prostatic Symptom Score-1 questionnaire was used to evaluate urinary symptoms. Principal component analysis (PCA) was used to evaluate the inter-correlations among various urinary symptoms.
  
  
  RESULTS
  The PCA produced a grouping of 12 LUTS into three categories consisting of voiding, storage and incontinence symptoms. Post-micturition symptoms were related to voiding symptoms, but incontinence symptoms were separate from storage symptoms. In the analyses by age group, similar categorization was found at ages 40, 50, 60 and 80 years, but only two groups of symptoms emerged among men aged 70 years. The prevalence among men aged 30 was too low for meaningful analysis.
  
  
  CONCLUSIONS
  This population-based study suggests that LUTS can be divided into three subgroups consisting of voiding, storage and incontinence symptoms based on their inter-correlations. Our empirical findings suggest an alternative grouping of LUTS. The potential utility of such an approach requires careful consideration.
authors.affiliation: Department of Urology, Tampere University Hospital and University of Tampere, Tampere, Finland. antti.j.poyhonen@gmail.com
authors.forename: Antti
authors.initials: A
authors.lastname: Pöyhönen
authors.forename: Jukka T
authors.initials: JT
authors.lastname: Häkkinen
authors.forename: Juha
authors.initials: J
authors.lastname: Koskimäki
authors.forename: Matti
authors.initials: M
authors.lastname: Hakama
authors.forename: Teuvo L J
authors.initials: TL
authors.lastname: Tammela
authors.forename: Anssi
authors.initials: A
authors.lastname: Auvinen
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D005387:Finland / Q000453:epidemiology; D006801:Humans; D059411:Lower Urinary Tract Symptoms / Q000145:classification* / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D025341:Principal Component Analysis; D011795:Surveys and Questionnaires