Absence of Significant Interaction Between Serum Albumin Level and Carbapenem Type on 30-Day Mortality in ESBL-positive E. coli and K. pneumoniae Bacteremia: A Multicenter Cohort Study with Inverse Probability of Treatment Weighting Analysis.

Abstract

The Infectious Diseases Society of America guidelines recommend group 2 carbapenems over ertapenem (group 1 carbapenem) for treating extended-spectrum β-lactamase (ESBL)-producing Enterobacterales infections in patients with hypoalbuminemia, but clinical evidence supporting this restriction of ertapenem is limited. We assessed whether the effect of serum albumin level on treatment outcome differed by carbapenem group in ESBL-producing bacteremia. We conducted a multicenter retrospective cohort study at three hospitals, enrolling adults treated exclusively with either group 1 or group 2 carbapenems due to ESBL-positive E. coli or K. pneumoniae bacteremia (2013-2020). Baseline characteristics were balanced by inverse probability of treatment weighting (IPTW). Thirty-day mortality was analyzed using a multivariable weighted Cox proportional hazards model including an interaction term between serum albumin level and carbapenem group, and 14-day mortality was analyzed with the same interaction term in a multivariable weighted logistic regression model. From the 573 eligible patients, an IPTW pseudo-population of 565.1 weighted patients with good covariate balance (all standard mean differences <0.1) was analyzed (group 1 carbapenem, 374.9; group 2 carbapenem, 190.2) Overall 30-day and 14-day mortalities were 7.9% (44.9 weighted deaths) and 5.1% (29 weighted deaths), respectively. There was no significant interaction between serum albumin level and carbapenem group for either 30-day mortality (P = 0.92) or 14-day mortality (P = 0.36). The therapeutic efficacy of ertapenem appears to be comparable to that of group 2 carbapenems for the treatment of ESBL-producing Enterobacterales bacteremia across the observed range of serum albumin levels.