title: Seasonal variation in the acute presentation of urinary calculi over 8 years in Auckland, New Zealand.
abstract: METHODS
  Symptom prevalence (retrospective cohort) Level of Evidence 2b.
  
  
  OBJECTIVE
  To determine the incidence of acute presentation of urinary calculi (UC) in Auckland, New Zealand, during the period 1999-2007, and whether there was any significant seasonal variation.
  
  
  METHODS
  The details of all UC within the population presenting acutely to public hospitals in Auckland between 1999 and 2007 were collected using clinical coding searches International Classification of Disease 10th revision (Australian Modification) N132 and N20. Climatic variables for the Auckland region were obtained from the National Institute of Water and Atmospheric Research, New Zealand. The mean atmospheric temperature, hours of sunshine and humidity data were calculated monthly for this period.
  
  
  RESULTS
  During the study there were 7668 acute presentations of UC in the Auckland region. A Poisson regression model showed that the number of presentations was significantly related to temperature (P < 0.001) and hours of sunshine (P = 0.004) but not humidity (P = 0.14). For each degree increase in temperature the number of presentations increased by 2.8% (95% confidence interval 1.3-4.3%). For each 1-h increase in sunshine, the number of presentations increased by 0.2% (0.06-0.33)%.
  
  
  CONCLUSIONS
  The acute presentation of UC in Auckland, New Zealand, varies significantly with temperature and hours of sunshine. Humidity was not a significant factor.
authors.affiliation: Department of Urology, Auckland City Hospital, University of Auckland, Auckland, New Zealand. losumsum@gmail.com
authors.forename: Sum Sum
authors.initials: SS
authors.lastname: Lo
authors.forename: Richard
authors.initials: R
authors.lastname: Johnston
authors.forename: Ahmed
authors.initials: A
authors.lastname: Al Sameraaii
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Metcalf
authors.forename: Michael L
authors.initials: ML
authors.lastname: Rice
authors.forename: Jonathan G
authors.initials: JG
authors.lastname: Masters
mesh_terms: D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009520:New Zealand / Q000453:epidemiology; D016012:Poisson Distribution; D012621:Seasons; D014545:Urinary Calculi / Q000453:epidemiology*; D055815:Young Adult