Q fever endocarditis caused by Coxiella burnetii is a potentially fatal disease characterised by a chronic evolution. To assess the long-term outcome and identify prognostic factors for mortality, surgical treatment, and serological changes in
Q fever endocarditis, we did a retrospective study in the French National Referral Centre.
METHODS: Patients included were diagnosed with
Q fever endocarditis at our centre from May, 1983, to June, 2006, and followed up for a minimum of 3 years for each patient, history and clinical characteristics were recorded with a standardised questionnaire. Prognostic factors associated with death, surgery, serological cure, and serological relapse were assessed by Cox regression analysis. Excised heart valve analysis was assessed according to
duration of treatment.
FINDINGS: 104 patients were identified for inclusion in the study, although one was lost to follow-up; median follow-up was 100 months (range 37-310 months). 18 months of treatment was sufficient to sterilise the valves of all the patients except three, and 2 years of treatment sterilised all valves except one. In a multivariate Cox regression analysis, the major determinants associated with mortality were age (hazard ratio 1.11, 95% CI 1.05-1.18, p=0.003),
stroke at diagnosis (7.09, 2.00-25.10, p=0.001),
endocarditis on a prosthetic valve (6.04, 1.47-24.80, p=0.044), an absence of a four-times decrease of phase I
IgG and
IgA at 1 year (5.69, 1.00-32.22, p=0.049), or the presence of phase II
IgM at 1 year (12.08, 3.11-46.85, p=0.005). Surgery was associated with
heart failure (2.68, 1.21-5.94, p=0.015) or a cardiac
abscess (4.71, 1.64-13.50, p=0.004). The determinants of poor serological outcome were male sex (0.47, 0.26-0.86, p=0.014), a high level of phase I
IgG (0.65, 0.45-0.95, p=0.027), and a delay in the start of treatment with
hydroxychloroquine (0.20, 0.04-0.91, p=0.037). Factors associated with relapse were
endocarditis on a prosthetic valve (21.3, 2.05-221.86, p=0.01) or
treatment duration less than 18 months (9.69, 1.08-86.72, p=0.042).
INTERPRETATION: