title: Evolving epidemiology of injecting drug use-associated infective endocarditis: A regional centre experience.
abstract: OBJECTIVE
  Injecting drug use (IDU) is a major risk factor for infective endocarditis (IE). An understanding of the epidemiology of IE and IDU is vital for delivery of health care for this disease. Our aim was to examine the rates of IDU-associated IE (IDU-IE) in a single centre over the last 12 years.
  
  
  METHODS
  Retrospective analysis of two cohorts of consecutive patients (n = 226) admitted with IE from 2002 to 2013. Numbers of cases and rates of IE were compared between two cohorts (2002-2006 and 2009-2013). Rate ratios were calculated using Poisson distributions. Poisson regression was used to examine relationship over time.
  
  
  RESULTS
  One hundred thirty cases of endocarditis were seen in the first observation period (6 IDU-IE) and 96 in the second observation period (15 IDU-IE). The estimated incidence rate of IE had fallen from 10.1 to 6.45 per 100, 000 person-years [rate ratio 0.64, 95% confidence interval (CI) 0.48, 0.85]. In contrast, the estimated incidence rate of IDU-E has risen from 0.48 to 0.79 per 100, 000 person-years (rate ratio 1.65, 95% CI 0.59, 4.57). Incidence rate regression suggests that the number of IDU-IE cases is expected to increase by a factor of 1.25 (95%CI 1.09-1.44) for each increase of 1 year.
  
  
  CONCLUSIONS
  Over the last decade, there has been a decrease in incidence rate and total number of cases of IE but a rise in rate and number of cases of IDU-IE. This may indicate increasing IDU or increased rates of endocarditis in intravenous drug users in this region. This finding may inform health-care planning in the area.
authors.affiliation: MonashHEART, Monash Health, Melbourne, Australia.
authors.forename: Matthew K Y
authors.identifier: http://orcid.org/0000-0002-7088-226X
authors.initials: MK
authors.lastname: Tung
authors.affiliation: MonashHEART, Monash Health, Melbourne, Australia.
authors.forename: Melanie
authors.initials: M
authors.lastname: Light
authors.affiliation: Department of Medicine, St Vincent's Hospital Melbourne, Melbourne, Australia.
authors.forename: Rinky
authors.initials: R
authors.lastname: Giri
authors.affiliation: Biostatistics Unit, Barwon Health, Geelong, Australia.|School of Medicine, Deakin University, Geelong, Australia.
authors.forename: Stephen
authors.initials: S
authors.lastname: Lane
authors.affiliation: The Geelong Hospital, Barwon Health, Geelong, Australia.
authors.forename: Alan
authors.initials: A
authors.lastname: Appelbe
authors.affiliation: The Geelong Hospital, Barwon Health, Geelong, Australia.
authors.forename: Craig
authors.initials: C
authors.lastname: Harvey
authors.affiliation: School of Medicine, Deakin University, Geelong, Australia.|The Geelong Hospital, Barwon Health, Geelong, Australia.
authors.forename: Eugene
authors.initials: E
authors.lastname: Athan
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D003695:Delivery of Health Care / Q000458:organization & administration*; D004696:Endocarditis / Q000453:epidemiology* / Q000209:etiology; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D016012:Poisson Distribution; D012189:Retrospective Studies; D012307:Risk Factors; D015819:Substance Abuse, Intravenous / Q000150:complications*; D013997:Time Factors
keywords: Staphylococcus aureus; endocarditis; heart valve; intravenous substance abuse; needle-exchange programs