title: Waiting time in relation to wait-list size at registration: statistical analysis of a waiting-list registry.
abstract: OBJECTIVE
  To examine the relationship between the length of a waiting list for elective vascular surgery and the delay before undergoing the operation.
  
  
  METHODS
  We undertook a prospective cohort study of patients registered on the waiting list for elective vascular surgery at an acute care hospital in Ontario. Regression analysis of wait times to express the admission rate in one group relative to another, with the ratio of rates being a measure of the difference between groups.
  
  
  RESULTS
  List length at registration was associated with length of wait (log-rank test 596.4, p < 0.0001). Patients who were registered when the list length exceeded the weekly service capacity had 70% lower conditional probability of undergoing surgery than those on a list with fewer patients (rate ratio 0.30, 95% confidence interval [CI] 0.26-0.36) after adjustment for sex, age, procedure and period. Registering more than 5 patients when the list was short had an independent effect (rate ratio 0.61, CI 0.45-0.82).
  
  
  CONCLUSIONS
  The number of registrants on a surgical wait list has an effect on the length of delay in providing necessary treatment. Our results suggest that a regulated list-length policy may contribute to reducing waiting times. Hospital managers may also use the findings to reduce uncertainty in reporting expected waits given the current list size, thereby improving resource planning.
authors.affiliation: Department of Health Care and Epidemiology, University of British Columbia, Vancouver, BC. sobolev@interchange.ubc.ca
authors.forename: Boris
authors.initials: B
authors.lastname: Sobolev
authors.forename: Peter
authors.initials: P
authors.lastname: Brown
authors.forename: David
authors.initials: D
authors.lastname: Zelt
authors.forename: Lisa
authors.initials: L
authors.lastname: Kuramoto
mesh_terms: D015331:Cohort Studies; D017558:Elective Surgical Procedures / Q000191:economics / Q000706:statistics & numerical data*; D006297:Health Services Accessibility / Q000706:statistics & numerical data*; D006801:Humans; D009864:Ontario; D010343:Patient Admission / Q000706:statistics & numerical data*; D012042:Registries; D014850:Waiting Lists