Long-term outcomes are poor in intravenous drug users following infective endocarditis, even after surgery

Background:

Previous studies of outcomes in people who inject drugs (PWID) with infective endocarditis (IE) have often been retrospective, had a small sample size, the duration of follow-up has been short and limited to patients who were operated on.

Methods:

PWID treated for IE between 01/01/2006 and 31/12/2016 were identified from a prospectively collected database. PWID hospitalised with other infections acted as a novel comparison group. Outcomes were all-cause mortality, cause of death, relapse, recurrence and re-operation.

Results:

There were 105 episodes of IE in 92 PWID and 112 episodes of other infections in 107 PWID in whom IE was suspected but rejected. Survival at 30 days for the IE group was 85% and 30-day survival following surgery was 96%. The most common pathogens were Staphylococcus spp. (60%) and Streptococcus spp. (30%). The surgical intervention rate was 47%. Survival for the IE group at 1, 3, 5 and 10 years was 74%, 63%, 58% and 44%, respectively. This was significantly lower compared with the comparator group of other infections in PWID (p=0.0002). Mortality was higher in patients who required surgery compared to those who did not (HR 1.8, 0.95-3.3). The commonest cause of death was infection (66%), usually a further episode of IE (55%).

Conclusions:

Whilst early survival was good, long-term life-expectancy was low. This was attributable to ongoing infection risk, rather than other factors known to affect prognosis in PWID. Surgery conferred no long-term survival advantage. More efforts are needed to reduce re-infection risk following an episode of IE in PWID.