Is rosuvastatin protective against sepsis associated encephalopathy? A secondary analysis of the SAILS trial

Sepsis is a common cause of death in emergency departments and sepsis associated encephalopathy is a major complication of sepsis. Rosuvastatin may have a cerebral protective role based on its vascular endothelial protective and anti-inammatory functions. Our study aims to explore the potential for a protective function of rosuvastatin against sepsis associated encephalopathy. Sepsis patients without any neurological dysfunction on admission were prospectively enrolled in the ‘Rosuvastatin for Sepsis-Associated Acute Respiratory Distress Syndrome’ study (SAILS trial, ClinicalTrials.gov number, NCT00979121). Patients were divided into rosuvastatin and placebo groups. This is a secondary analysis of this dataset. Baseline characteristics, therapy outcomes and adverse drug events were reported between groups. fewer placebo the highest CK level was signicantly higher in the rosuvastatin group than in the placebo group (204.8 ± 425.31 vs 89.3 ± 78.29, p = 0.034).


Introduction
Sepsis is a life-threatening disease, de ned as organ dysfunction caused by intense systemic in ammatory and coagulation cascade reactions arising from severe infection(s) [1]. Sepsis associated encephalopathy (SAE), a transient and reversible encephalopathy caused by infection outside of the brain [5][6][7], occurs in 25%-50% of sepsis patients [2,3,4]. However, SAE is closely related to mortality rates of sepsis patients and long-term rates of disability [8,9]. Therefore, early diagnosis and prevention of SAE may be of vital importance to reducing the mortality, disability and public health burden of sepsis.
A 2010 meta-analysis demonstrated statin drugs were able to reduce all-cause mortality in sepsis induced ARDS patients [16]. In recent years, a series of studies were carried out to investigate the role of statins on different types and locations of infections, with varying results. A randomized controlled trial (RCT) consisting of 745 participants showed that rosuvastatin does not reduce mortality rate in sepsis associated acute respiratory dysfunction syndrome (ARDS) patients [17]. Regarding the effect of statin drugs on SAE patients speci cally, there were no clinical trials focusing on just this issue. Therefore, our team looked at a secondary analysis of related study data to investigate any protective role of rosuvastatin for SAE patients. We hypothesized that rosuvastatin can reduce the rate of SAE among sepsis patients.

Study population
Our study is a secondary analysis of the Rosuvastatin for Sepsis-Associated Acute Respiratory Distress Syndrome ('SAILS' study, ClinicalTrials.gov number, NCT00979121). This study was a RCT consisting of 745 patients, investigating any protective effect of rosuvastatin on sepsis patients. The patients were enrolled if their chest radiography showed pulmonary edema and acute respiratory failure. The detailed research methodology of the RCT was shown in the SAILS report [18]. Access to the full database of the original RCT can be requested at the website of the National Institutes of Health (NIH): https://biolincc.nhlbi.nih.gov/studies/rocprimed/?q=primed. Our research team was authenticated by the NIH and was able to download the full database from the NIH website.

Patient enrollment
Patients were enrolled in the original study if they were receiving positive-pressure mechanical ventilation through an endotracheal tube, had a ratio of the partial pressure of arterial oxygen (PaO2) to the fraction of inspired oxygen (FIO2) of 300 or less, and had bilateral in ltrates on chest radiography that were consistent with pulmonary edema, without evidence of left atrial hypertension [19]. were not receiving renal-replacement therapy, the daily dose was reduced to 10mg. Rosuvastatin drug administration terminated on the third day after discharge from the intensive care unit (ICU), study day 28, hospital discharge, or death. The study drug was suspended for safety reasons if the creatine kinase (CK) level exceeded 10 times the upper limit of the normal range or level of alanine aminotransferase (ALT) or aspartate aminotransferase (AST) exceeded eight times the upper limit of the normal range.

Study outcomes
In our study, SAE was de ned as a Glasgow coma scale (GCS) or intensive care unit -confusion assessment method (ICU-CAM) scores lower than on admission, excluding central nervous system infections, cerebrovascular accident, central nervous system organic diseases or patients undergoing cardiopulmonary cerebral resuscitation.
Primary outcome of this analysis was the rate of SAE. Secondary outcomes included: 28-day all-cause mortality, duration of hospital stay, length of ICU stay, and adverse drug events. Adverse drug events were described using the highest level of CK, ALT and AST during the patient's hospitalization period, (symptoms such as muscle pain were not available in the current data set).

Statistical analysis
Baseline characteristics were compared between the rosuvastatin group and the placebo group. Continuous data were described as medians with standard differences (SD), and categorical data were described using absolute numbers with percentages. All statistical calculations were performed using the statistical program SPSS 20.0 (IBM Inc., Armonk, NY, USA). Chi-square tests were used for percentage statistics and t-tests were used for continuous statistics. Kaplan-Meier curves were drawn with time since randomization in the SAILS study. A p-value less than 0.05 was interpreted as statistically signi cant.

Baseline characteristics
Our analysis enrolled 86 sepsis patients in total from the original RCT. Please see Figure 1 for the study ow diagram. Fifty-one patients received rosuvastatin treatment while 31 received placebo. SOFA scores in the rosuvastatin group were 4.6±3.2 and 5.1±4.6 in placebo group (p=0.061). The use of antibiotic, vasoactive, narcotic, and paralytic medications was comparable between the rosuvastatin and placebo groups.
Other baseline characteristics were also comparable between rosuvastatin and placebo group. Complete baseline characteristics are shown in Table 1.  Table 2.

Discussion
In this study comparing SAE incidence in sepsis patients with or without rosuvastatin in a secondary analysis of a prospective RCT, we found that the rosuvastatin group had a statistically signi cant lower incidence of SAE, although at a statistically signi cant higher risk of adverse drug effects. Like in the original SAILS study, our study did not show that rosuvastatin was associated with a shortened length of hospital or ICU stay.
In recent years, a series of observational studies and randomized trials showed a bene cial effect of statins on patients suffering from severe infections [19]. A 2006 retrospective study showed that, regardless of infection site, administration of statins at the time of bacteremia diagnosed was associated with a lower all-cause mortality rate in bacteremic patients, and further administration of statis led to even lower mortality [20].
Concerning the severity of sepsis, the protective effect of statin drugs was also recently highlighted [21]. Yaniv Almog and his colleagues conducted a prospective cohort study in 2004, nding that prior therapy with statins was associated with a lower rate of severe sepsis [22]. In the long term, statin also showed a protective effect on bacteremic patients, reducing the 180-day mortality rate in one study [23]. These results were consistent with our ndings that found a bene cial effect of statin drugs for SAE patients. Nevertheless, the original study did not perform dose-effect research, which is awaiting further investigation.
Another prospective cohort study with 470 ICU patients illustrated that statin drugs were capable of increasing delirium-free ICU days, although the rate of delirium decrease did not show a signi cant difference between groups (40% in statin group VS 33% in statin free group) [24]. Like our ndings, this other study also reported a decreased SAE rate (32.1% in the statin group vs. 57.1% in the placebo group).
Another multicenter prospective cohort study, including 763 ICU patients (263 of which were septic or ARDS patients), showed that in-hospital statin use was associated with a reduced delirium rate while statin use prior to hospitalization did not show a bene t [25].
However, there are also some studies challenging the use of statins for patients with sepsis. A retrospective cohort consisting of 438 septic participants showed worse outcomes in the statin group, with a signi cantly higher in-hospital mortality rate [26]. Speci cally, statins may not attenuate lung injury during sepsis, and the ARDS rate was not signi cantly reduced in sepsis patients when statins were administered [27]. In our study, we still found that rosuvastatin was protective against SAE, while the mortality rate was not signi cantly elevated in patients receiving rosuvastatin. SAE is a central nervous system dysfunction in sepsis caused by an in ammatory cascade [28]. Rosuvastatin is widely used in cardiovascular and cerebral vascular disease patients to lower blood cholesterol levels and rates of disease recurrence [29]. In recent decades, statins such as rosuvastatin were found to possess pleiotropic pharmacologic effects, including anti-in ammatory and immunomodulatory functions [30]. The immunomodulatory effects in particular may contribute to cerebral protection for sepsis patients suffering from an in ammatory cascade.
Up-regulation of IL-1 and IL-6 is associated with reduced inter-endothelial junction proteins [31], leading to BBB disruption, which may also cause SAE in sepsis patients [32]. Statins can reduce the expression of pro-in ammatory factors such as IL-1, IL-6, IL-10, IL-17, IL-18, intracellular adhesion molecule (ICAM) and TNF-α [33], which are closely related to the severity of sepsis in animal models [34]. Similar outcomes were also shown in burn patients treated with statins [35]. Also, statin drugs inhibit the prenylation of Rac and Rho proteins [36], upgrading the expression of endothelium-derived nitric oxide synthetase (eNOS). In turn, eNOS increases NO expression, maintaining endothelial cell function, attenuating BBB damage in sepsis patients [37], thereby reducing the rate of SAE among sepsis patients through an antiin ammatory pathway. However, the exact pharmacological mechanism of immunomodulation caused by statins has not clearly been demonstrated yet.
Although rare, adverse drug events from statins include myopathy, hepatic function damage and rhabdomyolysis [38]. The original SAILS study selected rosuvastatin due to fewer drug interactions than other statins [39]. Symptoms of statins' adverse effects include muscle pain, nausea, and vomiting, among others. Unfortunately, in our current study, these symptomatic descriptions were not included in the original data set. We could only assess adverse drug events by comparing the levels of CK, AST and ALT between the rosuvastatin and placebo groups. Our study showed the rosuvastatin group has a statistically signi cant higher CK level, which may be related to a higher risk of myopathy in the rosuvastatin group than placebo.
Our study still has some limitations. First, bilirubin levels are an important laboratory test for evaluating hepatic function, which may be affected by rosuvastatin. However, bilirubin levels were absent from the SAILS study. Second, regarding baseline drug administration, detailed information such as the type of narcotics and antibiotics was not fully reported in the original study, which could interfere with the SAE outcomes. Statin outcomes may also vary among different types of pathogens.

Conclusions
Rosuvastatin may possess a protective function against SAE in sepsis patients, but at a higher rate of adverse drug events. A future RCT involving varying doses of rosuvastatin may help con rm our ndings and identify future treatment recommendations.   Titlepage.docx