The identification of prognostic factors that are associated with the outcomes of critically ill patients can be helpful to physicians in making treatment plans and discussing goals of care with patients and their relatives. In-hospital mortality is high in critically ill patients with candidemia, and its incidence increases when these patients also have NOAF. Although much remains to be understood, heightened awareness and early intervention may help reduce the suffering of these patients.
The incidence of NOAF varies from 1% to 5% in regular inpatients [22, 23], 4.5% to 29.5% in mixed ICU patients , 8% to 10% in patients with sepsis, 6% to 22% in patients with severe sepsis [25-27], and 23% to 44% in patients with septic shock [28-30]. In our study, we demonstrated that 28.3% of all patients with candidemia developed NOAF which is much higher than the incidence reported in previous studies on NOAF in critically ill patients (1.8% to 10%) and similar to the incidence for patients with septic shock [31-33]. This increasing incidence may support the hypothesis that a systemic inflammatory response, increased physiological stress and autonomic dysfunction are major triggering factors for the development of AF in these patients[34, 35].
Compared with patients who have never developed AF, the duration of mechanical ventilation for patients with NOAF was significantly prolonged, which translated into more resource utilization and higher costs. Patients with NOAF also had an extremely high in-hospital mortality rate (73.1%) and 1 year mortality rate after discharge from hospital (85.7%). In the Kaplan-Meier univariate analysis and multivariate logistic regression analysis, NOAF was significantly associated with higher in-hospital mortality and 1 year mortality in patients with candidemia, which indicated that NOAF could be a predictor for poor outcomes of these patients.
According to a previous study, patients with NOAF had an increased risk of embolic stroke. In our study, NOAF in patients with candidemia was associated with an increased risk of stroke compared with patients without AF. In the multivariate analysis, stroke was also associated with in-hospital mortality. The possible explanations are that AF could cause embolic and ischaemic stroke which could be attributable to haemodynamic instability and biochemical disturbances and lead to clinical deterioration and death [37-39].
The CHA2DS2-VASc score incorporates congestive heart failure, hypertension, age (65-74 years, ≥75 years [doubled]), diabetes, previous stroke or TIA (doubled), vascular disease, and sex. It has been widely used for the assessment of thromboembolic risk and guiding antithrombotic therapy in patients with AF. Several studies have demonstrated that a higher CHA2DS2-VASc score is an independent predictor for mortality in patients with AF [40-44]. In our study, the CHA2DS2-VASc score was higher in patients with AF than those without AF, and multivariate analysis revealed that it was also a risk factor for in-hospital mortality, suggesting that the CHA2DS2-VASc score may be a prognostic factor associated with poor outcomes in critically ill patients with candidemia.
The SOFA score is used to determine the extent of a patient’s organ dysfunction or failure. Unsurprisingly, the SOFA score was closely related to in-hospital mortality [40-44]. Anemia is a common clinical situation which could occur due to many factors, such as blood loss, nutritional deficiency, renal dysfunction, and inflammation. Similar to previous studies, patients with anemia had an increased rate of in-hospital mortality in our study. This result reminded us that we should act quickly to treat anemia appropriately according to the cause.
Strengths and limitations
To our knowledge, this study is the first to demonstrate that NOAF is associated with in-hospital mortality and 1 year mortality in critically illa patients with candidemia, which suggests that NOAF may be considered as an important predictor of deterioration among these patients.
There are several limitations in our study. Firstly, these data were retrospectively collected, and it is possible that the number of prior-AF cases may be inaccurate as many patients may have asymptomatic AF. Secondly, this was a single center study and the number of cases was relatively small, which limits the strength of our conclusions. Thirdly, the majority of patients with NOAF died within 1 year after discharge from hospital, so there was not enough data to assess long-term outcomes. Therefore, the results of our study might not be fully generalizable. Hence, a multicenter prospective, randomized controlled trial should be conducted to overcome these limitations.