Infective endocarditis: valvular surgery, valve abnormalities and previous endocarditis increased the risk

Clinical bottom line (level 3b)

  1. Patients with the following were at increased risk of developing infective endocarditis
    • severe valve disease (NNH = 160 at years)
    • cardiac valvular surgery (NNH = 270 at unknown)
    • previous endocarditis (NNH = 550 at unknown)
    • known mitral valve prolapse (NNH = 1100 at unknown)
    • any cardiac valvular abnormality (NNH = 1300 at unknown)
    • rheumatic fever (NNH = 1600 at unknown)
  2. Dental procedures did not clearly increase the risk of developing infective endocarditis.
Strom et al: Annals of Internal Medicine 1998; 129 (10): 761-769
Expires September 2003

The study

Case-control study with objective outcomes, adjusted for confounding factors, not validated in an independent set of patients.

Setting: 54 acute hospitals, USA

546 patients (aged 18 to 98; mean 59, ?% male) infective endocarditis

Excluded if
  • aged < 18
  • iv drug users
  • developed endocarditis in hospital


    • Cases: 273 patients (% male, mean age ): with definite, probable or possible community -acquired infective endocarditis (95% with multiple positive blood cultures)
    Controls: 273 patients (% male, mean age ): matched for age, sex and neighbourhood of residence

    Factors studied:
  • dental procedures in last 3 months, cardiac risk factors - known mitral valve prolapse, from a questionnaire: history of congenital heart disease, rheumatic fever, cardiac valvular surgery, previous endocarditis, other valvular heart disease, heart murmur without other known cardiac abnormalities.


    • Factors summarised:
  • other valvular heart disease usually complex mixed valvular heart disease, often with prosthetic valves
  • cardiac valvular surgery
  • previous episode of endocarditis
  • known mitral valve prolapse
  • any cardiac valvular abnormality
  • rheumatic fever
  • congenital heart disease
  • heart murmur and no other cardiac abnormality
  • any dental procedure


    • Conditional regression analysis performed on risk factors.

    Outcomes studied:
  • infective endocarditis

    • The evidence

    Patient expected event rate for infective endocarditis: 0.0050%
    risk factor for
    infective endocarditis     		adjusted OR
    (95% CI)    		 NNH
    (95% CI)
    other valvular heart disease 131
    (6.9 to 2489)     		160
    (9 to 3400)
    cardiac valvular surgery 74.6
    (12.5 to 447)     		270
    (46 to 1700)
    previous episode of endocarditis 37.2
    (4.4 to 317)     		550
    (64 to 5900)
    known mitral valve prolapse 19.4
    (6.4 to 58.4)     		1100
    (350 to 3700)
    any cardiac valvular abnormality 16.7
    (7.4 to 37.4)     		1300
    (550 to 3100)
    rheumatic fever 13.4
    (4.5 to 39.5)     		1600
    (520 to 5700)
    congenital heart disease 6.7
    (2.3 to 19.4)     		3500
    (1100 to 15000)
    heart murmur 4.2
    (2.0 to 8.9)     		6300
    (2500 to 20000)
    any dental procedure 1.4
    (0.7 to 2.7)     		50000
    (-67000 to 12000)

    Comments

    1. Patient expected event rate based on incidence in non-iv drug users in a US county.

    Citation

    1. Strom BL, Abrutyn E, Berlin JA, et al: dental and cardiac risk factors for infective endocarditis: a population-based, case-control study. Annals of Internal Medicine 1998; 129 (10): 761-769
    Contributor: Chris Ball and Clare Wotton, September 1999
    Reviewer:

    Clinical Question.
    Patient patients
    Intervention or Exposure cardiac and dental risk factors
    Outcome infective endocarditis