Analysis of mortality and risk factors associated with native valve endocarditis in drug users:: The importance of vegetation size

Background Native valve endocarditis in drug-user patients had a microbiology, a frequency of involvement of different cardiac valves, and a prognosis that differ from those in non-drug users. A retrospective study of native valve endocarditis cases in intravenous drug users diagnosed from 1985 to 1999 in our institution was performed to analyze the inhospital mortality of drug users with native valve endocarditis and to identify factors predictive of mortality. Methods All patients fulfilled the Duke's criteria for definite or probable endocarditis. Analysis of predictors of inhospital mortality was restricted to right-sided infective endocarditis (IE) with definite diagnosis and echocardiographic data. The following variables were analyzed: sex, HIV serostatus, CD4 cell count <200/mm(3), time of IE diagnosis (before 1993 or after 1993), previous valvulopathy, polymicrobial IE, fungal etiology (mixed or alone), neurological complication, arterial emboli, pulmonary emboli, congestive heart failure, vegetation size (VS) >2 cm, and inhospital cardiac surgery. Logistic regression was used in a multivariate model to identify factors independently associated with mortality. Adjusted odds ratios (OR) and 95% CIs were examined. Results Four hundred ninety-three cases of IE were diagnosed in this period. Two hundred twenty cases of native valve endocarditis in intravenous drug users were identified. Fourteen cases in this group died (6%). Mean time from diagnosis to death was 18.5 +/- 15 days (range, 3-52). Vegetation size was available in 111 cases. Univariate analysis identified the following variables associated with inhospital mortality in right-sided cases: VS >2 cm and fungal etiology, In multivariate analysis, the variables associated with mortality that achieved statistical significance were size of vegetation >2 cm (P = .014, OR 10.2, 95% CI 1.6-78.0) and fungal etiology (P = .009, OR 46.2, 95% CI 2.4-1100.9). Conclusions The main prognostic factors of inhospital mortality in right-sided IE in drug users in our series were VS >2 cm and fungal etiology. The role of early surgery in these patients should be reevaluated.