title: Sevenfold rise in likelihood of pertussis test requests in a stable set of Australian general practice encounters, 2000-2011.
abstract: OBJECTIVE
  To better understand the role that diagnostic test-ordering behaviour of general practitioners has on current pertussis epidemiology in Australia.
  
  
  METHODS
  Analysis of Australian general practice encounter data (from the Bettering the Evaluation and Care of Health [BEACH] program) on 13 "pertussis-related problem" (PRP) codes that were most likely to result in a pertussis laboratory test request and Australian pertussis notifications data (from the National Notifiable Diseases Surveillance System [NNDSS]) for the period April 2000 to March 2011.
  
  
  METHODS
  The change in the proportion of PRP general practice encounters with a pertussis test request between 2000 and 2011, and the change in national pertussis notifications over the same period.
  
  
  RESULTS
  The proportion of PRP encounters resulting in a pertussis test request increased from 0.25% between April 2000 and March 2004 to 1.71% between April 2010 and March 2011 (odds ratio, 7.0; 95% CI, 5.5-8.8). The BEACH data on pertussis testing and NNDSS data on pertussis notifications were highly correlated (r = 0.99), and the notification data mirrored the likelihood of a pertussis test request in general practice. The proportion of NNDSS pertussis notifications with a polymerase chain reaction (PCR)-confirmed diagnosis increased from 16.3% between April 2000 and March 2004 to 65.3% between April 2010 and March 2011.
  
  
  CONCLUSIONS
  An increase in pertussis testing following recognition of early epidemic cases may have led to identification of previously undetected infections, resulting in a further increase in notified disease and awareness among GPs. The changing likelihood of being tested may also be due to expanding availability and use of PCR testing in Australia.
authors.affiliation: Queensland Children's Medical Research Institute, Brisbane, QLD, Australia. marlena.kaczmarek@mh.org.au
authors.forename: Marlena C
authors.initials: MC
authors.lastname: Kaczmarek
authors.forename: Lisa
authors.initials: L
authors.lastname: Valenti
authors.forename: Heath A
authors.initials: HA
authors.lastname: Kelly
authors.forename: Robert S
authors.initials: RS
authors.lastname: Ware
authors.forename: Helena C
authors.initials: HC
authors.lastname: Britt
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Lambert
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D001315:Australia / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D018563:Disease Notification / Q000706:statistics & numerical data; D058006:General Practice / Q000706:statistics & numerical data*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008875:Middle Aged; D010818:Practice Patterns, Physicians' / Q000706:statistics & numerical data*; D014917:Whooping Cough / Q000175:diagnosis* / Q000453:epidemiology; D055815:Young Adult