Patients with infective endocarditis and history of injection drug use in a Swedish referral hospital during 10 years

Background Patients with injection drug use (IDU) have increased risk of developing infective endocarditis (IE). Previous studies have reported recurrent IE, increased duration of hospital stay, poor adherence and compliance as well as higher mortality and worse outcomes after surgery in the IDU-IE patient group. Further studies are needed to provide a basis for optimized care and prevention of readmissions in this population. This study aims to describe the clinical characteristics and outcomes among patients with IDU-IE. Methods Data of adults with IDU-IE and non-IDU-IE, treated between 2008 and 2017 at the Karolinska University Hospital in Stockholm were obtained from the Swedish National Registry of Infective Endocarditis. Clinical characteristics, microbiological results, treatment durations, results from echocardiography and in-hospital mortality were compared between the groups. Results Of the total 522 patients, 165 (32%) had IDU-IE. Patients with IDU-IE were younger than the patients with non-IDU-IE (mean age IDU-IE: 41.6 years, SD 11.9 years; non-IDU-IE: 64.3 years, SD 16.4 years; P < 0.01). No difference in distribution of gender was observed, 33% were females in both the IDU-IE and the non-IDU-IE group. History of previous IE (IDU-IE: n = 49, 30%; non-IDU-IE: n = 34, 10%; P < 0.01) and vascular phenomena (IDU-IE: n = 101, 61%; non-IDU-IE: n = 120, 34%; P < 0.01) were more common among patients with IDU-IE while prosthetic heart valves (IDU-IE: n = 12, 7%; non-IDU-IE: n = 83, 23%; P < 0.01) and known valvular disease (IDU-IE: n = 3, 2%; non-IDU-IE: n = 78, 22%; P < 0.01) were more common among patients with non-IDU-IE. Aetiology of Staphylococcus aureus (IDU-IE: n = 123, 75%; non-IDU-IE: n = 118, 33%; P < 0.01) as well as tricuspid (IDU-IE: n = 91, 55%; non-IDU-IE: n = 23, 6%; P < 0.01) or pulmonary valve vegetations (IDU-IE: n = 7, 4%; non-IDU-IE: n = 2, 1%; P < 0.01) were more common in the IDU-IE group. The overall incidence of IDU-IE decreased during the study period, while the incidence of definite IE increased (P < 0.01). Conclusions This study presents that patients with IDU-IE were younger, less frequently treated with surgery and had higher prevalence of vascular phenomena and history of previous IE, aspects that are important for improved management of this population.