Comparison of Linezolid and Vancomycin for Methicillin-Resistant Staphylococcus aureus Pneumonia: Institutional Implications.

OBJECTIVE

Recent studies suggesting clinical superiority of linezolid over vancomycin in the treatment of methicillin-resistant Staphylococcus aureus (MRSA) pneumonia led to a change in our institution's clinical pathway/order form for hospital-acquired pneumonia, positioning linezolid as the preferred agent. Our objective was to assess the impact of this change within our institution.

DESIGN

Retrospective electronic medical records review.

METHODS

The analysis for this observational study included eligible patients admitted to our medical center between May 1, 2011, and August 31, 2014, with ICD-9 codes for MRSA and pneumonia. Included patients were at least 18 years of age and had vancomycin or linezolid initiated at least 2 days after admission and continued for at least 2 consecutive days. The primary end points were extent of antibiotic use before and after order form change and length of stay (LOS) and hospital charges in the two treatment groups. A secondary aim was to detect any gross discrepancies in patient outcomes such as treatment duration, mechanical ventilation duration, all-cause mortality rate, nephrotoxicity, and 30-day readmission between the two treatment groups.

MEASUREMENTS AND MAIN RESULTS

Outcomes in 227 patients were assessed. Linezolid use increased 16.2% subsequent to the change in the order form. Although not statistically significant, the median hospital admission charge was $6200 lower in patients treated with linezolid compared with those treated with vancomycin ($25,900 vs $32,100). Hospital LOS was significantly associated with Charlson Comorbidity Index score (p<0.001), type of treatment (p=0.032), duration of treatment (p<0.001), mechanical ventilation (p<0.001), and intensive care unit admission (p<0.001). All-cause mortality favored linezolid treatment, and these patients were more likely to be discharged (shorter LOS).

CONCLUSIONS

Although linezolid use increased markedly with this pathway/order form change, no negative institutional consequences or unfavorable patient outcomes were detected, justifying the change in policy from these perspectives.