Background: The NHSN recently updated risk adjustment models and rebaselined Standardized Infection Ratios (SIRs) for healthcare-associated infections. The CDC expected that hospital SIRs would generally increase. However, the impact of rebaselining on individual hospitals SIRs was unknown. Accordingly, we assessed the impact of rebaselining on SIRs in a network of community hospitals.
Methods: We analyzed 2016 SIR data for CAUTI, MRSA LabID events, CDI LabID events, colon SSIs (COLO), and abdominal hysterectomy SSIs (HYST) from 38 hospitals in the Duke Infection Control Outreach Network (DICON). SIRs calculated using the old and new baselines were compared. Wilcoxon signed rank test was performed to determine if hospitals SIRs changed significantly following rebaselining. Hospitals were ranked by SIR for each metric, and change in rank following rebaselining was determined. Meaningful change in rank was defined as increase or decrease by >=4 places (greater than a decile). Hospitals that did not have an SIR calculated for a given metric were excluded from that metrics analysis.
Results: Median hospital SIRs for CAUTI and CDI increased significantly after rebaselining (0.587 versus 0.307, p<0.001; and 0.825 versus 0.783, p=0.04, respectively). Median MRSA SIRs increased (0.903 versus 0.797, p=0.5), and COLO and HYST SIRs decreased (0.457 versus 0.586, p=0.1; and 0 versus 0.489, p=0.4); however, these changes were not statistically significant (Figure 1). For all metrics, a minority of hospitals had meaningful change in SIR rank following rebaselining (Figure 2).
Conclusion: SIRs increased following rebaselining for CAUTI and CDI but did not change significantly for MRSA, COLO, or HYST. The majority of hospitals SIR rank did not change meaningfully following rebaselining.
Figure 1. Box and whisker plots of 2016 SIRs before and after rebaselining.
*p-value given by Wilcoxon signed rank test
Figure 2. Change in 2016 SIR ranking following NHSN Rebaselining among DICON hospitals.
A. W. Baker, None
B. Smith, None
L. Adcock, None
B. Wood, None
E. Cook, None
L. Crane, None
A. Cromer, None
K. Lockamy, None
S. Louis, None
P. Padgette, None
C. W. Woods, None
D. Sexton, Centers for Disease Control and Prevention: Grant Investigator , Grant recipient
Centers for Disease Control and Prevention Foundation: Grant Investigator , Grant recipient
UpToDate: Collaborator , Royalty Recipient
D. Anderson, None
S. S. Lewis, None