title: What can be gained from comprehensive disaggregate surveillance? The Avon Surveillance System for Sexually Transmitted Infections.
abstract: OBJECTIVE
  To describe a new disaggregate surveillance system covering key diagnosed sexually transmitted infections in a UK locality.
  
  
  METHODS
  The Avon System for Surveillance of Sexually Transmitted Infections (ASSIST) collects computerised person- and episode-based information about laboratory-diagnosed sexually transmitted infections from genitourinary medicine (GUM) clinics, the Avon Brook Clinic, and the Health Protection Agency and trust laboratories in primary care trusts in Avon. The features of the system are illustrated here, by describing chlamydia-testing patterns according to the source of test, age and sex, and by mapping the distribution of chlamydia across Bristol, UK.
  
  
  RESULTS
  Between 2000 and 2004, there were 821,685 records of tests for sexually transmitted infections, with 23,542 positive results. The proportion of tests and positive results for chlamydia and gonorrhoea sent from general practice increased over time. Most chlamydia tests in both GUM and non-specialist settings were performed on women aged >25 years, but positivity rates were highest in women aged <25 years. The positivity rate remained stable between 2000 and 2004. Including data from all diagnostic settings, chlamydia rates were about twice as high as those estimated only from genitourinary clinic cases.
  
  
  CONCLUSIONS
  The ASSIST model could be a promising new tool for planning and measuring sexual health services in England if it can become sustainable and provide more timely data using fewer resources. Collecting denominator data and including infections diagnosed in primary care are essential for meaningful surveillance.
authors.affiliation: Department of Social and Preventive Medicine, University of Bern, Bern, Switzerland.
authors.forename: Wendi
authors.initials: W
authors.lastname: Slater
authors.forename: Katharine
authors.initials: K
authors.lastname: Sadler
authors.forename: Jackie A
authors.initials: JA
authors.lastname: Cassell
authors.forename: Paddy
authors.initials: P
authors.lastname: Horner
authors.forename: Nicola
authors.initials: N
authors.lastname: Low
mesh_terms: D000328:Adult; D017677:Age Distribution; D000368:Aged; D000553:Ambulatory Care / Q000706:statistics & numerical data; D002690:Chlamydia Infections / Q000175:diagnosis / Q000453:epidemiology*; D003219:Confidentiality; D003625:Data Collection / Q000592:standards; D004739:England / Q000453:epidemiology; D005260:Female; D006801:Humans; D008875:Middle Aged; D011159:Population Surveillance; D012189:Retrospective Studies