Update on the Preventive Antibiotics in Stroke Study (PASS): a randomised controlled phase 3 clinical trial

Preventive Ceftriaxone in Patients with Stroke Treated with Intravenous Thrombolysis: Post Hoc Analysis of the Preventive Antibiotics in Stroke Study

BACKGROUND

The Preventive Antibiotics in Stroke Study (PASS), a randomized open-label masked endpoint trial, showed that preventive ceftriaxone did not improve functional outcome at 3 months in patients with acute stroke (adjusted common OR 0.95; 95% CI 0.82-1.09). Post-hoc analyses showed that among patients who received intravenous thrombolysis (IVT), patients who received ceftriaxone had a significantly better outcome as compared with the control group. This study aimed to gain more insight into the characteristics of these patients.

METHODS

In PASS, 2,550 patients were randomly assigned to preventive antibiotic treatment with ceftriaxone or standard care. In current post-hoc analysis, 836 patients who received IVT were included. Primary outcome included functional status on the modified Rankin Scale, analyzed with adjusted ordinal regression. Secondary outcomes included infection rate and symptomatic intracerebral hemorrhage (sICH) rate.

RESULTS

For all patients in PASS, the p value for the interaction between IVT and preventive ceftriaxone regarding functional outcome was 0.03. Of the 836 IVT-treated patients, 437 were administered ceftriaxone and 399 were allocated to the control group. Baseline characteristics were similar. In the IVT subgroup, preventive ceftriaxone was associated with a significant reduction in unfavorable outcome (adjusted common OR 0.77; 95% CI 0.61-0.99; p = 0.04). Mortality at 3 months was similar (OR 0.75; 95% CI 0.48-1.18). Preventive ceftriaxone was associated with a reduction in infections (OR 0.43; 95% CI 0.28-0.66), and a trend towards an increased risk for sICH (OR 3.09; 95% CI 0.85-11.31). Timing of ceftriaxone administration did not influence the outcome (aOR 1.00; 95% CI 0.98-1.03; p = 0.85).

CONCLUSIONS

According to the post-hoc analysis of PASS, preventive ceftriaxone may improve the functional outcome in IVT-treated patients with acute stroke, despite a trend towards an increased rate of post-IVT-sICH.

The Preventive Antibiotics in Stroke Study (PASS): a pragmatic randomised open-label masked endpoint clinical trial

BACKGROUND

In adults with acute stroke, infections occur commonly and are associated with an unfavourable functional outcome. In the Preventive Antibiotics in Stroke Study (PASS) we aimed to establish whether or not preventive antimicrobial therapy with a third-generation cephalosporin, ceftriaxone, improves functional outcome in patients with acute stroke.

METHODS

In this multicentre, randomised, open-label trial with masked endpoint assessment, patients with acute stroke were randomly assigned to intravenous ceftriaxone at a dose of 2 g, given every 24 h intravenously for 4 days, in addition to stroke unit care, or standard stroke unit care without preventive antimicrobial therapy; assignments were made within 24 h after symptom onset. The primary endpoint was functional outcome at 3 months, defined according to the modified Rankin Scale and analysed by intention to treat. The primary analysis was by ordinal regression of the primary outcome. Secondary outcomes included death, infection rates, antimicrobial use, and length of hospital stay. Participants and caregivers were aware of treatment allocation but assessors of outcome were masked to group assignment. This trial is registered with controlled-trials.com, number ISRCTN66140176.

FINDINGS

Between July 6, 2010, and March 23, 2014, a total of 2550 patients from 30 sites in the Netherlands, including academic and non-academic medical centres, were randomly assigned to the two treatment groups: 1275 patients to ceftriaxone and 1275 patients to standard treatment (control group). 12 patients (seven in the ceftriaxone group and five in the control group) withdrew consent immediately after randomisation, leaving 2538 patients available for the intention-to-treat-analysis (1268 in the ceftriaxone group and 1270 in the control group). 2514 (99%) of 2538 patients (1257 in each group) completed 3-month follow-up. Preventive ceftriaxone did not affect the distribution of functional outcome scores on the modified Rankin Scale at 3 months (adjusted common odds ratio 0·95 [95% CI 0·82-1·09], p=0·46). Preventive ceftriaxone did not result in an increased occurrence of adverse events. Overgrowth infection with Clostridium difficile occurred in two patients (<1%) in the ceftriaxone group and none in the control group.

INTERPRETATION

Preventive ceftriaxone does not improve functional outcome at 3 months in adults with acute stroke. The results of our trial do not support the use of preventive antibiotics in adults with acute stroke.

FUNDING

Netherlands Organization for Health Research and Development, Netherlands Heart Foundation, and the European Research Council.

The Immune Response to Acute Focal Cerebral Ischemia and Associated Post-stroke Immunodepression: A Focused Review

It is currently well established that the immune system is activated in response to transient or focal cerebral ischemia. This acute immune activation occurs in response to damage, and injury, to components of the neurovascular unit and is mediated by the innate and adaptive arms of the immune response. The initial immune activation is rapid, occurs via the innate immune response and leads to inflammation. The inflammatory mediators produced during the innate immune response in turn lead to recruitment of inflammatory cells and the production of more inflammatory mediators that result in activation of the adaptive immune response. Under ideal conditions, this inflammation gives way to tissue repair and attempts at regeneration. However, for reasons that are just being understood, immunosuppression occurs following acute stroke leading to post-stroke immunodepression. This review focuses on the current state of knowledge regarding innate and adaptive immune activation in response to focal cerebral ischemia as well as the immunodepression that can occur following stroke. A better understanding of the intricate and complex events that take place following immune response activation, to acute cerebral ischemia, is imperative for the development of effective novel immunomodulatory therapies for the treatment of acute stroke.

Update of the Preventive Antibiotics in Stroke Study (PASS): statistical analysis plan

BACKGROUND

Infections occur in 30% of stroke patients and are associated with unfavorable outcomes. Preventive antibiotic therapy lowers the infection rate after stroke, but the effect of preventive antibiotic treatment on functional outcome in patients with stroke is unknown. The PASS is a multicenter, prospective, phase three, randomized, open-label, blinded end-point (PROBE) trial of preventive antibiotic therapy in acute stroke. Patients are randomly assigned to either ceftriaxone at a dose of 2 g, given every 24 h intravenously for 4 days, in addition to standard stroke-unit care, or standard stroke-unit care without preventive antibiotic therapy. The aim of this study is to assess whether preventive antibiotic treatment improves functional outcome at 3 months by preventing infections. This paper presents in detail the statistical analysis plan (SAP) of the Preventive Antibiotics in Stroke Study (PASS) and was submitted while the investigators were still blinded for all outcomes.

RESULTS

The primary outcome is the score on the modified Rankin Scale (mRS), assessed by ordinal logistic regression analysis according to a proportional odds model. Secondary analysis of the primary outcome is the score on the mRS dichotomized as a favorable outcome (mRS 0 to 2) versus unfavorable outcome (mRS 3 to 6). Secondary outcome measures are death rate at discharge and 3 months, infection rate during hospital admission, length of hospital admission, volume of post-stroke care, use of antibiotics during hospital stay, quality-adjusted life years and costs. Complications of treatment, serious adverse events (SAEs) and suspected unexpected serious adverse reactions (SUSARs) are reported as safety outcomes.

CONCLUSIONS

The data from PASS will establish whether preventive antibiotic therapy in acute stroke improves functional outcome by preventing infection and will be analyzed according to this pre-specified SAP.

TRIAL REGISTRATION

Current controlled trials; ISRCTN66140176. Date of registration: 6 April 2010.