The association between comorbid illness, colonization status, and acute hospitalization in patients receiving...

Long-term acute care (LTAC) hospitals provide specialized care for survivors of critical illness who require prolonged mechanical ventilation. These chronically ill patients often have multiple comorbidities and are colonized with antibiotic-resistant organisms. We investigated the association of comorbidities and colonization status with outcomes in patients requiring prolonged mechanical ventilation in an LTAC facility. We hypothesized that comorbidity burden and colonization with multiple drug resistant organisms would be associated with worse clinical outcomes.

We performed a retrospective, cohort study of 157 mechanically ventilated subjects in an urban LTAC facility admitted from January 2007 to September 2009. Comorbidity burden was documented from pre-admission data using the Charlson Comorbidity Index. Colonization data were obtained from surveillance cultures. Outcomes studied included transfer back to acute care facilities, stay, and ventilator weaning status.

Within 60 days, 58.6% of subjects were transferred back to an acute care facility. The most common reason for transfer was infection/sepsis (37%). The Charlson Comorbidity Index of subjects transferred to acute care, versus those who were not, was 4.9 ± 3.1 versus 3.6 ± 2.7 (P = .01), an odds ratio of 1.1 for each 1-point increase in Charlson Comorbidity Index (95% CI 1.03-1.71, P = .02). Colonization with acinetobacter was associated with higher incidence of transfer (71% vs 51%, P = .01). The odds ratio for transfer to acute care was 1.3 for each additional organism colonizing a subject (95% CI 1.11-1.53, P = .006).

Higher comorbidity burden and colonization status were associated with increased risk of transfer to acute care. Further investigation is needed to clarify this relationship between comorbidity burden and colonization with change in clinical status.