Risk of infective endocarditis in patients with Staphylococcus aureus blood stream infection and declining kidney function
Authors: Kaur K P , Chaudry M S , Chamat-Hedemand S , Larsen A R , Pedersen A , Fosboel E L , Oestergaard L , Torp-Pedersen C , Bruun N E 
Published: October 2021

Abstract

Background
Worldwide, Staphylococcus aureus (S.aureus) is one the most common causes of infective endocarditis (IE), particularly in dialysis patients. However, the association between mildly and moderately decreased kidney function and IE in patients with S.aureus blood stream infection (SAB) has not been examined.

Purpose
In a retrospective nation-wide study, to evaluate the association between IE and declining kidney function in SAB patients.

Methods
All patients with first-time SAB between January 1st, 1996 to December 31st, 2018 were identified from a national database including &gt;90% of all patients with SAB. By cross-linking with other nationwide databases, co-morbidities were recorded. The population was divided into 4 groups according to eGFR: group 1 (eGFR ≥90), group 2 (eGFR 30–89), group 3 (eGFR &lt;30) and group 4 (Renal Replacement Therapy dependent). Patients were followed until the outcome of IE. Changes in co-morbidities across the eGFR groups were tested with the Cochran-Armitage test. In a multivariable logistic regression analysis, the odds ratio (OR) of IE was calculated for each eGFR group while adjusting for age, sex, hypertension, diabetes, native valve disease (NVD), prosthetic valve, and cardiac implantable electronic device (CIED).

Results
Among 17,759 SAB patients, 1,098 were diagnosed with IE. The male population accounted for 60–70% of the IE patients in each eGFR group (Table 1). The overall median age of S.aureus IE patients was 61.5 [48–72] with the highest median age in group 2 (67 [57–76]). Across the eGFR groups, there was a significant increase in the prevalence of diabetes (12.6% in group 1 to 47.0% in group 4), hypertension (18.9% in group 1 to 80% in group 4) and native valve disease (18.7% in group 1 to 36.4% in group 4), p&lt;0.0001. In a multivariate analysis with group 1 as reference, the adjusted OR of S.aureus IE increased significantly with OR 1.16 [95% CI 1.01–1.34] in group 2 to OR 1.42 [95% CI 1.07–1.87] in group 3. The increase was not significant in group 4, OR 1.63 [95% CI 0.95–2.53]. The OR of S.aureus IE decreased with increasing age groups and OR was 0.55 [95% CI 0.43–0.71] among patients &gt;80 years as compared to the reference age group, 18–39 years. A significantly increased OR of S.aureus IE was found among patients with NVD (OR 3.25 [95% CI 2.22–4.76]), prosthetic valve (OR 6.31 [95% CI 5.10–7.79] and CIED (OR 2.88 [95% CI 2.35–3.53]). The overall in-hospital mortality was 16.4% (n=181), with the highest mortality in group 3 (n=11, 22.3%). Overall, the one-year mortality was 26.6% (n=292), and the highest mortality was found in group 4 (n=29, 34.1%). When adjusting for age and sex, mortality did not differ significantly with declining eGFR.

Conclusion
In this study, we found a significant increase in the odds ratio of IE in patients with SAB when kidney function decreased. Both in-hospital and one-year mortality were high, but did not differ significantly across the eGFR groups.

Funding Acknowledgement
Type of funding sources: None.