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ORIGINAL RESEARCH article

Front. Med., 06 December 2022

Sec. Infectious Diseases: Pathogenesis and Therapy

Volume 9 - 2022 | https://doi.org/10.3389/fmed.2022.1053278

Staphylococcus aureus endocarditis: Identifying prognostic factors using a method derived from morbidity and mortality conferences

On behalf of the AEPEI (Association pour l’Etude et la Prévention de l’Endocardite Infectieuse) study group
  • 1. UniversitĂ© de Lorraine, CHRU-Nancy, Service des Maladies Infectieuses et Tropicales, Nancy, France

  • 2. UniversitĂ© de Lorraine, APEMAC, Nancy, France

  • 3. CH AndrĂ©e Rosemon, UnitĂ© de Maladies Infectieuses et Tropicales, Cayenne, France

  • 4. CHRU-Nancy, Service des Maladies Infectieuses et Tropicales, Nancy, France

  • 5. CHRU-Nancy, Institut National de la Sante et de la Recherche Medicale (INSERM), UniversitĂ© de Lorraine, CIC, EpidĂ©miologie Clinique, Nancy, France

  • 6. UMR 6249 CNRS-UFC Chrono-environnement, Service de Maladies Infectieuses, CHRU Besançon, Besançon, France

  • 7. Infectious Diseases and Intensive Care Unit, Pontchaillou University Hospital, Rennes, France

  • 8. CIC-Institut National de la Sante et de la Recherche Medicale (INSERM) 1414, Pontchaillou University Hospital, Rennes, France

  • 9. University of Rennes, Institut National de la Sante et de la Recherche Medicale (INSERM), Bacterial Regulatory RNAs and Medicine, UMR 1230, Rennes, France

  • 10. UFR MĂ©decine, CHU Robert DebrĂ©, Reims, France

  • 11. Institut National de la Sante et de la Recherche Medicale (INSERM) CIC 1425, Bichat–Claude Bernard Hospital, Assistance Publique-HĂ´pitaux de Paris, Paris, France

  • 12. Institut National de la Sante et de la Recherche Medicale (INSERM), UMR-1137, IAME, Paris University, Paris, France

  • 13. UniversitĂ© de Paris, IAME, Institut National de la Sante et de la Recherche Medicale (INSERM), Paris, France

  • 14. Centre for Clinical Investigation, Assistance Publique-HĂ´pitaux de Paris, Bichat-Claude Bernard University Hospital, Paris, France

  • 15. Louis Pradel Hospital, Department of Cardiology, Lyon, France

  • 16. Montpellier University Hospital, Department of Infectious and Tropical Diseases, Montpellier, France

  • 17. CHU Nancy-Brabois, Department of Cardiology, Nancy, France

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Abstract

Objectives:

Lethality of Staphylococcus aureus (Sa) infective endocarditis (IE) is high and might be due to yet unidentified prognostic factors. The aim of this study was to search for new potential prognostic factors and assess their prognostic value in SaIE.

Materials and methods:

We used a two-step exploratory approach. First, using a qualitative approach derived from mortality and morbidity conferences, we conducted a review of the medical records of 30 patients with SaIE (15 deceased and 15 survivors), randomly extracted from an IE cohort database (NCT03295045), to detect new factors of possible prognostic interest. Second, we collected quantitative data for these factors in the entire set of SaIE patients and used multivariate Cox models to estimate their prognostic value.

Results:

A total of 134 patients with modified Duke definite SaIE were included, 64 of whom died during follow-up. Of the 56 candidate prognostic factors identified at the first step, 3 had a significant prognostic value in multivariate analysis: the prior use of non-steroidal anti-inflammatory drugs [aHR 3.60, 95% CI (1.59–8.15), p = 0.002]; the non-performance of valve surgery when indicated [aHR 1.85, 95% CI (1.01–3.39), p = 0.046]; and the decrease of vegetation size on antibiotic treatment [aHR 0.34, 95% CI (0.12–0.97), p = 0.044].

Conclusion:

We identified three potential SaIE prognostic factors. These results, if externally validated, might eventually help improve the management of patients with SaIE.

Introduction

Infective endocarditis (IE) is a rare but serious disease associated with high morbidity and mortality (1, 2). Staphylococcus aureus (Sa) became the most frequent pathogen responsible for IE during the past decades (3, 4). In comparison with other pathogens, lethality of SaIE is higher (4, 5). Its morbidity is also of concern, with 20–60% of embolic events (4, 5), 20–25% of sepsis (6, 7), and 26–38% of cardiac surgery during the initial management (4, 5).

To improve the outcomes of SaIE, identifying new prognostic factors may help tailor IE management to patients’ risk and improve patients’ management accordingly. Prognostic factors have already been identified in IE and SaIE. Among these, patients’ characteristics such as age (4, 8) and comorbidities (1, 8), have a major prognostic impact. Many SaIE clinical characteristics are associated with lethality, including prosthetic valve infection (8, 9), disease severity (septic shock and SOFA score) (9, 10), and heart, valve, or organ failures (1, 11). Higher mortality is also associated with left-sided IE (12), intracardiac abscess (1, 8), and larger vegetations (1, 13). Embolic events (2, 13), neurological complications (1, 10), and cardiac conduction abnormalities (14) are associated with poorer outcome. Methicillin-resistance of Sa (9) and persistent bacteremia are also associated with poorer outcome (4). Finally, deviations from optimal management such as inadequate antibiotic therapy (15) and delayed surgical treatment (8, 16) may also worsen the prognosis of SaIE. The plateauing high mortality observed in SaIE over the last decades (4, 5, 17, 18) suggests that specific prognostic factors may have not yet been identified. Moreover, most of the already identified prognostic factors are not modifiable. Searching for new prognostic factors might lead to identify modifiable factors and help design interventions that could improve SaIE outcome.

Prognostic factors are best identified using longitudinal studies and collecting candidate prognostic factors at baseline and outcomes during the follow-up, and then using Cox models to estimate the prognostic value of each factor. However, such methods require having candidate factors before initiating data collection. Once major factors, such as age and comorbidities, have been tested, identification of newer candidate factors becomes harder. Morbidity and mortality conferences (MMC) are designed to improve the quality of healthcare by addressing errors in patient’s management. In these conferences, healthcare professionals review and discuss, collegially, confidentially, and critically, the charts of patients who developed severe adverse events, to identify healthcare related factors that contributed to their occurrence (19). We thought that this approach could be helpful to identify candidate prognostic factors in SaIE. The aim of this study was to search for new potential prognostic factors and assess their prognostic value in SaIE.

Materials and methods

Study design

We used an exploratory two-step approach that included: (1) a qualitative approach derived from MMC to identify candidate prognostic factors in SaIE, and (2) a conventional quantitative approach to estimate the prognostic value of the factors identified at the end of step 1, using the source data that had been collected for the EI2008 study (NCT03295045) (3).

Setting

The EI2008 study has been extensively described elsewhere (3). Briefly, EI2008 is a longitudinal cohort study conducted in France in 2008, which aimed to describe IE incidence and prognosis, and enrolled 602 patients aged ≥ 18 years with definite (n = 497) or possible (n = 105) IE according to modified Duke criteria. Data collection consisted of demographic characteristics, medical history, medications, IE mode of acquisition, and clinical, biological, and therapeutic characteristics (see Supplementary material). Patients were followed up for 1-year all-cause mortality (3). The identification of all Sa strains had been confirmed by the national reference center for staphylococci (Centre National de Référence des Staphylocoques, Institut des Agents Infectieux, Hospices Civils de Lyon, Lyon, France).

Participants

For the first-step qualitative approach, among 134 patients with modified Duke definite SaIE included in EI2008, we used computer-generated random numbers to sample 15 patients with definite SaIE who had died and 15 patients with definite SaIE who had survived at the end of the 1-year follow-up.

For the quantitative approach, we selected from the EI2008 study database all the 134 patients with modified Duke definite SaIE, of whom 70 survived and 64 died during follow-up (Figure 1).

FIGURE 1

FIGURE 1

Flow chart of patients with Staphylococcus aureus infective endocarditis (SaIE) selected from EI2008. IE, infective endocarditis, Sa, Staphylococcus aureus.

Data collection

For the qualitative approach, we used a method inspired by MMC (19, 20) and conducted an in-depth review of the whole patients’ charts (MB, AL, and BL) to identify factors that were not already collected in the EI2008 case report form (CRF) but could be associated with the outcome (defined as “candidate prognostic factors”). We searched the charts of the 15 patients who died during follow-up for factors deemed unfavorable candidate prognostic factors, and the charts of the 15 patients who survived for factors deemed favorable candidate prognostic factors. Following the guidelines of the French National Authority for Health on MMC (20), each candidate prognostic factor was then collegially and critically reviewed (by MB, AL, BL, NA, and BH) to drop duplicates (i.e., variables that were already collected as part of EI2008 CRF) and to select those that were deemed relevant on a clinical and pathophysiological perspective. All the candidate prognostic factors that were retained at the end of the first step were collected from the medical charts of all the 134 patients included in the quantitative approach and were implemented into an enriched EI2008 database.

For the quantitative approach, we re-used the data that were prospectively collected as part of the EI2008 cohort study protocol and additional data (concerning the candidate prognostic factors identified by the qualitative approach) that were specifically collected from patients’ medical charts for the purpose of the present study.

Statistical analyses

We first described patients’ characteristics and the distribution of candidate factors, using frequencies and percentages for categorical variables, or median and interquartile range for quantitative variables. Second, we used Cox models to identify potential prognostic factors among candidates using bivariate analyses. We retained candidate prognostic factors with a p-value < 0.2 as eligible for multivariate analyses. Third, for each eligible candidate prognostic factor, we conducted a multivariate Cox model, using the given factor as an independent variable and adjusting for confounding factors that were identified among baseline characteristics and candidate prognostic factors by their bivariate association (p-value < 0.2) with both survival and the candidate prognostic factor under scrutiny. P-values were two-sided, and statistical significance level was set at 0.05. All statistical analyses were performed using SAS 9.4 (SAS Institute, Inc., Cary, NC, USA) software.

Ethics

This study complies with the principles outlined in the Declaration of Helsinki. EI2008 was approved by the French Commission Nationale Informatique et des Libertés (CNIL-DR-2010-219). Patients received complete information about the study, and their right to refuse to participate. EI2008 being an observational study, in accordance with the French law, patient written consent was waived (NCT03295045).

Results

Staphylococcus aureus infective endocarditis patients’ characteristics and follow-up

The characteristics of the 134 patients are described in Table 1. Their median age was 62.5 years (IQR 31 years) and there was a majority of men (n = 98, 73.1%). A heart disease at risk of IE was present in 54 (40.3%) patients. Most IE cases were community-acquired (n = 72, 53.7%). Most frequent complications included septic shock (n = 49, 36.6%), cerebral embolisms (n = 48, 35.8%), and heart failure (n = 13, 9.7%).

TABLE 1

Patient’s characteristics N % Median Q1 Q3
Sociodemographic
Age (years) 134 1 62.5 44.0 75.0
Women 36 26.9
Medical history
Obesity 21 15.7
Heart disease without risk of IE 67 50.0
Heart disease at risk of IE 54 40.3
Native valve disease 38 28.4
Intra-cardiac device 20 14.9
Infective endocarditis 6 4.5
Smoker 31 23.1
Alcohol abuse 20 14.9
Anticoagulant or antiplatelet therapy 56 41.8
Charlson comorbidity index 134 1 1.0 0.0 3.0
Clinical characteristics
Acquisition mode Community-acquired 72 53.7
Healthcare-associated 39 29.1
Intravenous drug use 23 17.2
Initial Glasgow score 112 83.6 15.0 14.0 15.0
Heart failure 13 9.7
Cardiac conduction abnormalities 14 10.4
Arterial aneurysm 4 3.0
Vertebral osteomyelitis 13 9.7
Arthritis 16 11.9
Septic shock and sepsis 49 36.6
Extra-cardiac device infection 12 9.0
Acute kidney injury 21 15.7
Embolic complications
Cerebral 48 35.8
Peripheral 61 41.5
Biological characteristics
White blood cells (G/L) 131 97.8 13.1 9.3 16.8
CRP (mg/L) 123 91.8 226.0 131.0 316.0
GFR (ml/min/1.73 m2) 129 96.3 57.6 34.1 80.8
Methicillin resistant Sa 17 12.7
Echocardiographic
Vegetation Size > or = 10 mm 73 54.5
Size < 10 mm 23 17.2
Location Aortic 39 29.1
Mitral 52 38.8
Tricuspid 22 16.4
CIED 7 5.2
Intra-cardiac abscess 21 15.7
New native valve regurgitation/perforation 110 82.1
Prosthetic endocarditis 17 12.7
New prosthetic regurgitation/dehiscence 6 4.5
Therapeutics
Heart surgery and/or CIED removal 62 46.3
Care or surgical complications 30 22.4
Extra-cardiac surgery 8 6.0

Main characteristics of the 134 patients with Staphylococcus aureus infective endocarditis.

Frequencies and percentages used for categorical variables. Median and interquartile range used for quantitative variables. IE, infective endocarditis; Sa, Staphylococcus aureus; CRP, C-Reactive Protein; GFR, Glomerular Filtration Rate; CIED, cardiac implantable electronic device.

Identification of candidate prognostic factors in Staphylococcus aureus infective endocarditis: Results of the qualitative approach

In the charts of the 15 surviving patients, we identified 22 candidate prognostic factors that could be associated with higher survival (Table 2). In the charts of the 15 deceased patients, we identified 34 candidate prognostic factors that could be associated with higher mortality (Table 3). All these candidate prognostic factors were then collected in the medical charts of all the 134 patients included in the quantitative approach (the frequency of each factor was presented in Tables 2, 3).

TABLE 2

Definition N %
Patient medical history
No antibiotic allergy No history of allergy whatever the class of antibiotic 125 93.3
Previous Sa infection Prior history of documented Sa infection 6 4.5
Cardiovascular treatment Drug with cardiovascular effects (antiplatelet therapy, anticoagulant, diuretic, antiarrhythmic, RAAS inhibitors, statins, antihypertensive drug) 61 45.5
Severity upon admission
Immunological sign of IE Splenomegaly, glomerulonephritis, purpura, Osler nods 22 16.4
Initial neurological sign Neurological signs of IE at the first medical examination 50 37.3
Sa susceptible strain Sa strain susceptible to any antibiotic or resistant only to penicillin G 83 61.9
Penicillin G susceptible Sa strain In vitro phenotypic Sa susceptibility against penicillin G 13 9.7
Low blood inflammation First blood analysis: CRP < 150 mg/L + WBC < 15 G/L + neutrophils < 10 G/L 16 11.9
Healthcare management
Ophtalmologist exam Posterior segment eye examination was performed during hospitalization 5 3.7
Low initial inoculum Only one positive blood culture among blood culture performed before antibiotic initiation 9 6.7
Early first echocardiography Echocardiography ≤ 48 h of hospitalization or after first positive blood culture 90 67.2
Decreasing vegetation size on antibiotic treatment Evidence of decreasing vegetation size on antibiotic treatment (at least one millimeter) when comparing diagnosis echocardiography and last in-hospital echocardiography (censored by surgery in operated patient) 23 17.2
Early body computed tomography Computed tomography during the first week of hospitalization or after first positive blood culture 64 47.8
Prolonged antibiotic combined therapy Concomitant administration of two different antibiotics ≥ 14 days 95 70.9
Extracardiac infectious surgery Surgery of an extracardiac infected site to control inoculum 27 20.1
Steroid use Use of steroid during the hospitalization 15 11.2
Hospital organization
IE team Management involving an IE team as described by ESC guidelines (15) 101 75.4
Early IE team Management involving an IE team during the first week of hospitalization 53 39.6
Hospitalization report signed by a senior physician Hospitalization report signed by a physician with a permanent position 97 72.4
Records completed by a physician Hospitalization records completed by a physician with a permanent position 27 20.5
Outcomes of hospitalization
CIED implantation CIED implantation during hospitalization 12 9.0
Oral antibiotic switch Oral antibiotic switch during hospitalization 37 27.6

Description of candidate prognostic factors that could be associated with survival in the 134 Staphylococcus aureus infective endocarditis patients.

Frequencies and percentages used for categorical variables. IE, infective endocarditis; Sa, Staphylococcus aureus; RAAS, renin angiotensin aldosterone system; CRP, C-Reactive Protein; WBC, white blood cells; ESC, European Society of Cardiology; CIED, cardiac implantable electronic device.

TABLE 3

Definition N %
Patient medical history
Prolonged bed rest Uninterrupted bed rest ≥ 48 h 12 9.0
Patient dependent for ADL Patient needing assistance for eating, bathing, getting dressed, toileting, mobility, and continence 10 7.5
Patient dependent for IADL Patient needing assistance for cooking, cleaning, transportation, laundry, and managing finances 10 7.5
Skin pressure ulcer Skin pressure ulcer before hospitalizations for SaIE 12 9.0
Penicillin allergy Penicillin allergy known at hospital admission 6 4.5
COPD Documented history of COPD 8 6.0
Prior use of NSAIDs Use of NSAIDs during the week before the hospital admission 10 7.5
MRSa carriage Documented history of carriage of MRSa at hospital admission 1 0.7
Severity upon admission
Rifampicin resistance Sa strain with in vitro phenotype of rifampicin resistance 2 1.5
Quinolone resistance Sa strain with in vitro phenotype of quinolone resistance 10 7.5
Use of vasoactive drug Use of adrenaline or noradrenaline during the hospitalization 37 27.6
Use of dobutamine Use of dobutamine during the hospitalizations 16 11.9
Healthcare management
No probabilistic antibiotic treatment (PAT) No use of a PAT before Sa identification 50 37.3
No efficient PAT No use of a PAT with an efficient (suboptimal efficacy) scope before Sa identification 62 46.3
No optimal PAT No use of a PAT with an optimal (antibiotic with the higher proved efficacy) scope before Sa identification 119 88.8
Not recommended antibiotic treatment Antibiotic therapy did not follow ESC guidelines (15) more than half the treatment duration 49 36.6
Gentamycin Use of at least one dose of gentamycin during hospitalization 100 74.6
Vancomycin Use of at least one dose of vancomycin during hospitalization 59 44.0
Oxacillin Use of at least one dose of oxacillin during hospitalization 90 67.2
Rifampicin Use of at least one dose of rifampicin during hospitalization 68 50.7
Quinolone Use of at least one dose of quinolone during hospitalization 68 50.7
Persistent deep infected site Deep infected site that persisted in the absence of surgical act 28 20.9
CIED Implantation during septic period CIED is implanted before infection control proved by negative blood culture 10 7.5
Non-performance of valve surgery when indicated No valve surgery was performed during hospitalization despite indication as described in ESC guidelines (15) (Death, patients’ refusal, and contraindications) 26 19.4
Time before surgery respected Time before the valve surgery according to the level of emergency 43 32.1
Extracardiac surgery indication Indication of an extracardiac surgery to control the Sa infection 28 20.9
Palliative care Current Sa infection severity leading to a decision to limit active care 22 16.4
Hospital organization
Unavailable extra-cardiac surgery Extracardiac surgery was indicated but not offered in the concerned hospital 5 3.7
Unavailable cardiac surgery Cardiac surgery was indicated but not offered in the concerned hospital 12 9.0
Outcomes of hospitalization
Adverse event related to anticoagulant A hemorrhagic adverse event due to anticoagulant use occurred 6 4.5
Surgical complication An adverse event due to surgery act occurred whatever its form 10 7.5
Nosocomial infection When a healthcare associated infection occurred during hospitalizations 25 18.7
Antibiotic allergy An anaphylactic adverse event due to antibiotic occurred 9 6.7
Antibiotic toxicity When an adverse event due to antibiotic occurred, whatever is form 23 17.2

Description of factors that could be associated with death in the 134 Staphylococcus aureus infective endocarditis patients.

Frequencies and percentages used for categorical variables. IE, infective endocarditis; Sa, Staphylococcus aureus; COPD, chronic obstructive pulmonary disease; NSAIDs, non-steroidal anti-inflammatory drugs; MRSa, methicillin resistant Staphylococcus aureus; PAT, probabilistic antibiotic treatment (antibiotic treatment when endocarditis is suspected and not proved by microbiologist analysis); ESC, European Society of Cardiology; CIED, cardiac implantable electronic device.

Candidate prognostic factors were sorted out into five categories: patient medical history (3 potentially associated with higher survival vs. 8 potentially associated with higher mortality), severity upon admission (5 vs. 4), healthcare management (8 vs. 15), hospital organization (4 vs. 2), and outcomes of hospitalization (2 vs. 5).

Prognostic value of candidate prognostic factors in Staphylococcus aureus infective endocarditis: Results from the quantitative approach

Eligible factors associated with outcome are presented in Table 4. After adjustment for potential confounders, two eligible candidate prognostic factors remained significantly associated with higher mortality during the 1-year follow-up: the prior use of non-steroidal anti-inflammatory drugs (NSAIDs) [aHR 3.60, 95% confidence interval (95% CI) (1.59–8.15), p = 0.002] and the non-performance of valve surgery when indicated [aHR 1.85, 95% CI (1.01–3.39), p = 0.046]. One eligible candidate prognostic factor was associated with lower mortality: the decrease of vegetation size on antibiotic treatment [aHR 0.34 95% CI (0.12–0.97), p = 0.044].

TABLE 4

One-year follow up mortality Bivariate analysis Multivariate analysis



n rate 95% CI HR 95% CI P-value aHR 95% CI P-value Adjustment variables
Factors that could be associated with survival
Patient medical history
Cardiovascular treatment Yes 47 0.66 0.55–0.76 3.06 1.75–5.34 <0.001
No 17 0.28 0.18–0.41 Ref
Severity upon admission
Immunological sign of IE Yes 6 0.27 0.13–0.51 0.43 0.19–1.01 0.052
No 58 0.52 0.43–0.62 Ref
Initial neurological sign Yes 37 0.75 0.62–0.86 3.67 2.22–6.05 <0.001
No 27 0.32 0.24–0.44 Ref
Healthcare management
Low initial inoculum Yes 2 0.22 0.06–0.64 0.35 0.09–1.44 0.147
No 62 0.50 0.42–0.59 Ref
Early first echocardiography Yes 46 0.51 0.42–0.62 1.58 0.91–2.72 0.102
No 18 0.42 0.29–0.58 Ref
Decreasing vegetation size on antibiotic treatment Yes 4 0.18 0.07–0.41 0.23 0.08–0.64 0.005 0.34 0.12–0.97 0.044 Age, acquisition mode, methicillin resistant Sa, prosthetic infection, oral antibiotic switch, no optimal PAT, oxacillin, quinolone, time before surgery respected
No 60 0.55 0.46–0.64 Ref
Prolonged antibiotic combined therapy Yes 39 0.42 0.33–0.53 0.44 0.26–0.72 0.001
No 25 0.64 0.49–0.79 Ref
Hospital organization
Hospitalization report signed by a senior physician Yes 51 0.53 0.44–0.64 1.68 0.91–3.08 0.097
No 13 0.35 0.22–0.53 Ref
Outcomes of hospitalization
CIED implantation Yes 8 0.69 0.42–0.92 1.72 0.82–3.61 0.153
No 56 0.46 0.38–0.56 Ref
Oral antibiotic switch Yes 9 0.26 0.14–0.44 0.31 0.15–0.62 0.001
No 55 0.57 0.47–0.67 Ref
Factors that could be associated with death
Patient medical history
Prolonged bed rest Yes 3 0.25 0.09–0.59 0.39 0.12–1.23 0.107
No 61 0.51 0.42–0.60 Ref
Patient dependent for ADL Yes 9 0.82 0.56–0.97 2.53 1.25–5.13 0.010
No 55 0.45 0.37–0.55 Ref
Patient dependent for IADL Yes 8 0.80 0.53–0.97 2.17 1.03–4.57 0.041
No 56 0.46 0.37–0.55 Ref
Prior use of NSAIDs Yes 8 0.80 0.53–0.97 2.81 1.33–5.92 0.007 3.60 1.59–8.15 0.002 Age, cerebral embolic complication, mode of acquisition, methicillin resistant Sa, prosthetic infection
No 56 0.46 0.37–0.55 Ref
Severity upon admission
Quinolone resistance Yes 8 0.80 0.53–0.97 2.00 0.95–4.20 0.067
No 56 0.46 0.37–0.55 Ref
Use of vasoactive drug Yes 24 0.65 0.50–0.80 2.36 1.42–3.92 0.001
No 40 0.42 0.33–0.52 Ref
Use of dobutamine Yes 12 0.75 0.53–0.92 2.61 1.38–4.91 0.003
No 52 0.45 0.36–0.54 Ref
Healthcare management
No probabilistic antibiotic therapy (PAT) Yes 13 0.27 0.17–0.43 3.37 1.83–6.21 <0.001
No 51 0.61 0.50–0.71 Ref
No efficient PAT Yes 22 0.37 0.26–0.50 2.13 1.27–3.58 0.004
No 42 0.58 0.47–0.70 Ref
No optimal PAT Yes 53 0.45 0.37–0.55 2.23 1.16–4.29 0.016
No 11 0.73 0.50–0.92 Ref
Not recommended antibiotic treatment Yes 31 0.63 0.50–0.76 0.49 0.30–0.79 0.004
No 33 0.40 0.30–0.51 Ref
Oxacillin Yes 37 0.42 0.32–0.53 0.59 0.36–0.96 0.035
No 27 0.61 0.47–0.76 Ref
Quinolone Yes 27 0.40 0.30–0.53 0.62 0.38–1.01 0.057
No 37 0.56 0.45–0.69 Ref
Non-performance of valve surgery when indicated Yes 21 0.81 0.64–0.93 3.13 1.85–5.31 <0.001 1.85 1.01–3.39 0.046 Age, mitral location, methicillin resistant Sa, prosthetic infection, heart surgery and/or CIED extraction, time before surgery respected, palliative care
No 43 0.40 0.32–0.50 Ref
Time before surgery respected Yes 13 0.31 0.19–0.47 0.45 0.25–0.83 0.011
No 51 0.56 0.47–0.67 Ref
Extracardiac surgery indication Yes 16 0.58 0.40–0.76 1.46 0.83–2.57 0.190
No 48 0.46 0.37–0.56 Ref
Palliative care Yes 22 1.00 1.00–1.00 6.67 3.79–11.73 <0.001
No 52 0.38 0.30–0.48 Ref
Hospital organization
Unavailable extra-cardiac surgery Yes 4 0.80 0.42–0.99 2.39 0.87–6.58 0.093
No 60 0.47 0.39–0.56 Ref
Unavailable valve surgery Yes 9 0.75 0.50–0.94 2.08 1.03–4.22 0.042
No 55 0.46 0.37–0.55 Ref
Outcomes of hospitalization
Adverse event related to anticoagulant Yes 5 0.83 0.48–0.99 2.40 0.96–5.99 0.061
No 59 0.47 0.38–0.56 Ref
Surgical complication Yes 8 0.80 0.53–0.97 2.15 1.02–4.52 0.044
No 56 0.46 0.37–0.55 Ref
Nosocomial infection Yes 17 0.68 0.50–0.85 1.85 1.06–3.22 0.031
No 47 0.44 0.35–0.53 Ref

Prognostic value of factors that could be associated with Staphylococcus aureus infective endocarditis outcome.

Quantitative variables: hazard ratio expressed as per unit increase of the variable. Quantitative variables: hazard ratio expressed as per 10 units-increase of the variable. IE, infective endocarditis; Sa, Staphylococcus aureus; GFR, Glomerular filtration rate; CIED, cardiac implantable electronic device; ADL, activity of the daily life; IADL, instrumental activity of the daily life; NSAIDs, non-steroidal anti-inflammatory drugs; PAT, probabilistic antibiotic treatment.

Discussion

In this study, relying on a method derived from MMC, we identified three potential prognostic factors, two that were associated with higher mortality, i.e., the prior use of NSAIDs and the non-performance of valve surgery when indicated, and one that was associated with lower mortality, i.e., the decrease of vegetation size on antibiotic treatment.

To the best of our knowledge, no published study used a method derived from MMC to identify potential prognostic factors in SaIE. In most instances, it takes the form of a meeting of members of different medical teams who collectively try to retrospectively identify factors that may have contributed to a patient’s unfavorable outcome. The patient’s management is described and analyzed in an attempt to identify the causal factors of complications with the aim to improve the quality and safety of care, without judging individuals or looking for a culprit (21). In an attempt to standardize the course of MMC, Gregor and Taylor recommended that it be based on five essential components: (1) an adverse event (the case presented must include an adverse event that resulted from clinical decisions and/or care provided); (2) anonymity (individuals involved in the case must be afforded anonymity to allow for free and objective discussion); (3) critical analysis (based on reliable, objective data and careful attention to sources of bias in clinical decision making); (4) reframing understanding of errors to prevent their repetition; and (5) projection to practice change (19). Here, in an attempt to suggest practice changes to improve SaIE patients’ outcome, we organized a meeting of members of different medical backgrounds, i.e., infectious disease (MB, BH, AL, and BL), epidemiology (NA), and public health (NA), to collectively reframe the understanding of favorable or unfavorable prognosis relying on a critical analysis of all the data collected in the anonymized medical charts of some patients who died or survived from SaIE. And then, relying on a more classic quantitative approach, we raised hypotheses about factors that could be considered as prognostic factors.

We are aware that an association may not be causal. To establish epidemiologic evidence of a causal relationship between a presumed cause and an observed effect, Hill proposed to examine a set of nine criteria (22). We therefore examined our three potential prognostic factors versus these criteria (Table 5). NSAIDs were strongly associated with death, with a threefold higher risk of death in SaIE patients who had vs. those who had not received NSAIDs. To date, no study assessed the prognostic value of the use of NSAIDs in IE. However, NSAIDs are known to have multiple effects on innate and adaptive immunity (prostaglandin and leukotriene pathways) (23). Several studies showed that NSAID use could worsen the prognosis of infectious conditions, especially respiratory tract, osteoarticular and skin and soft tissue bacterial infection (24–26). The non-performance of valve surgery when indicated was associated with impaired prognosis in SaIE patients. This result was consistent with what was previously reported in other studies focusing on prognostic factors in IE and SaIE (1, 27, 28). In our study, as in previous studies (1, 27, 28), patients who did not undergo cardiac surgery despite indication were old, had many comorbidities, and presented with cardiac, infectious or embolic complications resulting in an unfavorable benefit-risk ratio for undergoing surgery. The decrease of vegetation size on antibiotic treatment was associated with a lower mortality. Decreasing vegetation size on antibiotic treatment was obtained by comparing diagnostic and last in-hospital echocardiography (which was censored by surgery in operated patient). The strength of this association was high, with a threefold decreased risk of death in SaIE patients in whom the vegetation size decreased. Regarding plausibility, our finding is consistent with prior results that showed a correlation between the size of the vegetation, the risk of embolism, and the risk of death in IE (13, 29–31). For this variable, as for the others, it seems essential to confirm our results in other studies. However, before that, it seems essential to find a standardized definition of a significant reduction in the size of the vegetation: how many millimeters? By what echocardiographic method? After what period of antibiotic treatment? An intervention to improve SaIE outcomes could be multidisciplinary meeting to adapt treatment when the vegetation size does not decrease during antibiotic treatment. For example, some authors believe that antibiotics other than those recommended should be tested in Sa infections, including IE, as they may have a better tolerability profile or even greater efficacy (32–38). However, these data are based on meta-analyses from biased observational studies and deserve to be confirmed in a large randomized controlled trial (39, 40). We have therefore identified three potential prognostic factors, two of which have never been identified before in endocarditis. In the future, it would seem interesting to confirm our results in an independent cohort. Ideally, a precise definition of each factor will have to be decided and the prognostic influence of each of them will be studied prospectively. Finally, if these results are confirmed, interventional projects could be developed to change the management of SaIE and improve its poor prognosis.

TABLE 5

Strength Consistency Specificity Temporality Biological gradient Plausibility Coherence Experiment Analogy
Prior use of NSAIDs x x x
Non-performance of valve surgery when indicated x
(1, 16, 27)
x x
(1, 16, 27)
x
(1, 16, 27)
x
Decreasing of vegetation
size on antibiotic treatment
x x x
(13, 29–31)

The potential prognostic factors relevance in Staphylococcus aureus endocarditis assessed by the Hill criteria.

We acknowledge that our work may have some limitations. First, the patients’ medical charts may not include key prognostic information that was therefore missed by our qualitative approach. Second, due to the observational design, residual unmeasured confounding might still threaten the validity of our multivariate analyses. Third, due to the relatively low number of IE cases that were included in this study, we may not have been able to identify factors that had a genuine prognostic value. Fourth, the wording and definition of our candidate prognostic factors may be questioned and our results need now to undergo external validation in an independent dataset with standardized definitions to ensure reproducibility and therefore confirm the possible causality of the factors we identified.

Conclusion

Our results suggest that the management of patients with SaIE could be improved by considering new prognostic factors. Although they need to be confirmed by additional studies, our findings indicate that the outcome of SaIE would be enhanced by limiting the use of NSAIDs, considering valve surgery when indicated even if the likelihood of postoperative death is high, and reconsidering the treatment strategy when the size of the vegetation does not decrease during the antibiotic treatment.

Statements

Data availability statement

This raw data supporting the conclusions of this article are protected by the French law. Requests to access the datasets should be directed to the corresponding author.

Ethics statement

This studies involving human participants were reviewed and approved by the French Commission Nationale de l’Informatique et des Libertés (CNIL-DR-2010-219). The patients/participants provided their written informed consent to participate in this study.

Author contributions

BL, AL, MB, BH, and NA: conception and design of the study. BL, AL, MB, WN-S, BH, and NA: analysis and interpretation of data. All authors acquired of data, drafted the article or revised it critically for important intellectual content, and final approval of the version to be submitted.

Acknowledgments

We would like to acknowledge the AEPEI study group and the whole French National Observatory on Infective Endocarditis team.

Conflict of interest

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Publisher’s note

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.

Supplementary material

The Supplementary Material for this article can be found online at: https://www.frontiersin.org/articles/10.3389/fmed.2022.1053278/full#supplementary-material

Abbreviations

ADL, activity of the daily life; AEPEI, Association pour l’Etude et la Prévention de l’Endocardite Infectieuse; CIED, cardiac implantable electronic device; COPD, chronic obstructive pulmonary disease; CRF, case report form; ESC, European Society of Cardiology; GFR, Glomerular Filtration Rate; HAS, Haute Autorité de Santé; IADL, instrumental activity of the daily life; IE, infective endocarditis; MMC, morbidity and mortality conferences; MRSa, methicillin resistant Staphylococcus aureus; NSAIDs, non-steroidal anti-inflammatory drugs; PAT, probabilistic antibiotic treatment; Sa, Staphylococcus aureus; SaIE, Staphylococcus aureus infective endocarditis.

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Summary

Keywords

Staphylococcus aureus , infective endocarditis, prognostic factors, survival, morbidity and mortality conference method

Citation

Lefèvre B, Legoff A, Boutrou M, Goehringer F, Ngueyon-Sime W, Chirouze C, Revest M, Vernet Garnier V, Duval X, Delahaye F, Le Moing V, Selton-Suty C, Filippetti L, Hoen B and Agrinier N (2022) Staphylococcus aureus endocarditis: Identifying prognostic factors using a method derived from morbidity and mortality conferences. Front. Med. 9:1053278. doi: 10.3389/fmed.2022.1053278

Received

25 September 2022

Accepted

17 November 2022

Published

06 December 2022

Volume

9 - 2022

Edited by

Carlo Tascini, University of Udine, Italy

Reviewed by

Davide Fiore Bavaro, University of Bari Medical School, Italy; Katarina Westling, Karolinska Institutet (KI), Sweden

Updates

Copyright

*Correspondence: Benjamin Lefèvre,

†These authors have contributed equally to this work and share first authorship

‡These authors have contributed equally to this work and share last authorship

This article was submitted to Infectious Diseases: Pathogenesis and Therapy, a section of the journal Frontiers in Medicine

Disclaimer

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.

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