Prevalence, incidence burden, and clinical impact of healthcare-associated infections and antimicrobial resistance: a national prevalent cohort study in acute care hospitals in Greece

Abstract

Background

Assessing the overall burden of healthcare-associated infections (HAIs) is challenging, but imperative in evaluating the cost-effectiveness of infection control programs. This study aimed to estimate the point prevalence and annual incidence of HAIs in Greece and assess the excess length of stay (LOS) and mortality attributable to HAIs, overall and for main infection sites and tracer antimicrobial resistance (AMR) phenotypes and pathogens.

Patients and methods

This prevalent cohort study used a nationally representative cross-section of 8,247 inpatients in 37 acute care hospitals to record active HAIs of all types at baseline and overall LOS and in-hospital mortality up to 90 days following hospital admission. HAI incidence was estimated using prevalence-to-incidence conversion methods. Excess mortality and LOS were assessed by Cox regression and multistate models correcting for confounding and time-dependent biases.

Results

HAIs were encountered with daily prevalence of 9.1% (95% confidence interval [CI] 7.8%–10.6%). The estimated annual HAI incidence was 5.2% (95% CI 4.4%–5.3%), corresponding to approximately 121,000 (95% CI 103,500–123,700) affected patients each year in the country. Ninety-day mortality risk was increased by 80% in patients with HAI compared to those without HAI (adjusted hazard ratio 1.8; 95% CI 1.3–2.6). Lower respiratory tract infections, bloodstream infections, and multiple concurrent HAIs doubled the risk of death, whereas surgical site and urinary tract infections were not associated with increased mortality. AMR had significant impact on the daily risk of 90-day mortality, which was increased by 90%–110% in patients infected by carbapenem-resistant gram-negative pathogens. HAIs increased LOS for an average of 4.3 (95% CI 2.4–6.2) additional days. Mean excess LOS exceeded 20 days in infections caused by major carbapenem-resistant gram-negative pathogens.

Conclusion

HAIs, alongside with increasing AMR, pose significant burden to the hospital system. Burden estimates obtained in this study will be valuable in future evaluations of infection prevention programs.

Keywords:

• nosocomial infections
• antibiotic resistance
• length of stay
• mortality
• prevalence
• incidence

Acknowledgments

We thank the infection control teams in all of the participating hospitals for their cooperation and support.

Author contributions

Study conception: EIK, AG; study design: EIK, EA, MR, EI, AG; data acquisition: EIK, FK, EA, MR, EI, AG; data management and statistical analysis: EIK; drafting of the manuscript: EIK; data interpretation and critical revision of the manuscript: EIK, FK, EA, MR, EI, AG. All authors approved the final manuscript and are accountable for all aspects of this work.

Disclosure

The authors report no conflicts of interest in this work. No external funding was received for this work.