Intensive Blood Pressure Reduction in Acute Cerebral Haemorrhage Trial 3 (INTERACT3)

INTERACT3 aims to determine whether a multifaceted Health Improvement of Systems (HIS) intervention designed to enhance delivery of BP lowering treatment early, rapidly, intensively and in a sustained target-driven manner improves health outcomes, processes and costs over usual care, for patients with ICH and elevated BP across a range of health care settings.

  • Primary hypothesis is that compared with control hospitals, those hospitals randomised to the HIS have an increased proportion of ICH patients with good functional outcome at six months (effectiveness) (ie. null hypothesis of no difference in outcome between randomised groups)
  • Secondary hypothesis is that intervention hospitals will have a greater proportion of patients receiving BP lowering treatment to target systolic BP level (<140 mmHg within one hour) (process indicator) than the control hospitals


There is less data available regarding the effectiveness of early intensive BP lowering treatment in patients with large and severe ICH, and in those requiring early surgical decompression of the haematoma, although it is likely that any benefits are less in patients with a poor prognosis.  

There is also uncertainty as to whether earlier and more rapid control of BP than was achieved in INTERACT2 translates into even better outcomes than was demonstrated in the study.  Moreover, there is uncertainty over the resource implications and how well this evidence translates into clinical practice.

Hospitals will be randomised to the HIS or control (usual) care.  All hospitals will be required to undertake consecutive recruitment of 30 ICH patients with systolic BP >150mmHg.  All hospitals will be trained in the study protocol prior to their activation and enrollment of any patients.  Data collection will occur at baseline, 24 hours from admission, Day 7 (or discharge, if earlier), and Days 28, 90 and 180 (end of follow-up).

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