Attributable clinical and economic burden of carbapenem-non-susceptible Gram-negative infections in patients hospitalized with complicated urinary tract infections

Abstract

Gram-negative complicated urinary tract infections (cUTIs) can have serious consequences for patients and hospitals. To examine the clinical and economic burden attributable to Gram-negative carbapenem-non-susceptible (C-NS; resistant/intermediate) infections compared with carbapenem-susceptible (C-S) infections in 78 US hospitals. All non-duplicate C-NS and C-S urine source isolates were analysed. A subset had principal diagnosis ICD-9-CM codes denoting cUTI. Collection time (<3 vs≥3 days after admission) determined isolate classification as community or hospital onset. Mortality, 30-day re-admissions, length of stay (LOS), hospital cost and net gain/loss in US dollars were determined for C-NS and C-S cases, with the C-NS-attributable burden estimated through propensity score matching. Three subgroups with adequate patient numbers were analysed: cUTI principal diagnosis, community onset; other principal diagnosis, community onset; and other principal diagnosis, hospital onset. The C-NS-attributable mortality risk was significantly higher (58%) for the other principal diagnosis, hospital-onset subgroup alone (odds ratio 1.58, 95% confidence interval 1.14-2.20; P<0.01). The C-NS-attributable risk for 30-day re-admission ranged from 29% to 55% (all P<0.05). The average attributable economic impact of C-NS was 1.1-3.9 additional days LOS (all P<0.05), US$1512-10,403 additional total cost (all P<0.001) and US$1582-11,848 net loss (all P<0.01); overall burden and C-NS-attributable burden were greatest in the other principal diagnosis, hospital-onset subgroup. Greater clinical and economic burden was observed in propensity-score-matched patients with C-NS infections compared with C-S infections, regardless of whether cUTI was the principal diagnosis, and this burden was most severe in hospital-onset infections.