Reference group choice and antibiotic resistance outcomes

Area of Science:

• Infectious Diseases
• Clinical Epidemiology
• Antimicrobial Resistance

Background:

• Methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) are significant healthcare-associated pathogens.
• Accurate assessment of the impact of these resistant organisms on patient outcomes is crucial for effective infection control.

Purpose of the Study:

• To compare the association of MRSA and VRE infections with adverse patient outcomes using different control groups.
• To evaluate the influence of reference group selection on the observed effect size of resistant organism infections.

Main Methods:

• Two cohort studies were conducted involving patients with MRSA and VRE infections.
• Cases were compared against two distinct reference groups: uninfected patients and patients infected with their respective susceptible counterparts.
• Adverse outcomes associated with MRSA and VRE infections were analyzed.

Main Results:

• Both MRSA and VRE infections were significantly associated with adverse patient outcomes.
• The magnitude of the association between resistant infections and adverse outcomes was greater when uninfected control patients were used for comparison.
• The choice of reference group impacts the perceived effect of resistant organism infections.

Conclusions:

• MRSA and VRE infections contribute to poor patient outcomes.
• The selection of an appropriate control group, particularly uninfected patients, is critical for accurately quantifying the impact of antimicrobial-resistant organisms.
• These findings highlight the importance of robust study design in antimicrobial resistance research.