title: Frequency-volume chart: the minimum number of days required to obtain reliable results.
abstract: OBJECTIVE
  There is wide variation in the number of days necessary to maintain a diary and still furnish reliable data on which to base a sound clinical assessment. Estimates range from 1 day to 2 weeks, 7 days probably being the criterion standard. The goal of this retrospective study was to evaluate how much the 7-day period could be shortened without compromising the reliability of data.
  
  
  METHODS
  Various lengths of frequency-volume (FV) charts (from 1 day to 6 days) were compared with the standard 7-day charts on 14 FV parameters.
  
  
  RESULTS
  Overall results show that a 4-day dairy is nearly identical to the 7-day chart (most r > or = 0.95). Results of the 1-, 2-, and 3-day charts were frequently different statistically from the 7-day chart, whereas comparison of the 4-day chart with the 7-day chart showed no statistically significant differences. In addition, results of 4-day FV charts from a new control cohort showed no significant differences from the 7-day charts of the main cohort.
  
  
  CONCLUSIONS
  In conclusion, our study indicates that the 4-day chart is as reliable as the 7-day chart. This reduction in the length of time, although easier for the patients, does not compromise the diagnostic value of the FV charts.
authors.affiliation: Hôpital Maisonneuve-Rosemont, Division of Urology, Universitéde Montréal, Montreal, Quebec, Canada. eschick@videotron.ca
authors.forename: Erik
authors.initials: E
authors.lastname: Schick
authors.forename: Martine
authors.initials: M
authors.lastname: Jolivet-Tremblay
authors.forename: Charles
authors.initials: C
authors.lastname: Dupont
authors.forename: Pierre E
authors.initials: PE
authors.lastname: Bertrand
authors.forename: Jocelyne
authors.initials: J
authors.lastname: Tessier
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008499:Medical Records / Q000592:standards*; D008875:Middle Aged; D010349:Patient Compliance; D015203:Reproducibility of Results; D012189:Retrospective Studies; D014555:Urination Disorders / Q000175:diagnosis*