Does the Addition of Non-Approved Inclusion and Exclusion Criteria for RtPA Impact Treatment Rates? Findings in Australia, the UK, and the USA

Background: Strict criteria for recombinant tissue plasminogen activator (rtPA) eligibility are stipulated on licences for use in ischaemic stroke; however, practitioners may also add non-standard rtPA criteria. We examined eligibility criteria variation in 3 English-speaking countries including use of non-standard criteria, in relation to rtPA treatment rates.

Methods: Surveys were mailed to 566 eligible hospitals in Australia (AUS), the UK, and the USA. Criteria were pre-classified as standard (approved indication and contraindications) or non-standard (approved warning or researcher "decoy"). Percentage for criterion selection was calculated/compared; linear regression was used to assess the association between use of non-standard criteria and rtPA treatment rates, and to identify factors associated with addition of non-standard criteria.

Results: Response rates were 74% AUS, 65% UK, and 68% USA; mean rtPA treatment rates were 8.7% AUS, 12.7% UK, and 8.7% USA. Median percentage of non-standard inclusions was 33% (all 3 countries) and included National Institutes of Health Stroke Scale (NIHSS) scores > 4, computed tomography (CT) angiography documented occlusion, and favourable CT perfusion. Median percentage of non-standard exclusions was 25% AUS, 28% UK, and 60% USA, and included depressed consciousness, NIHSS > 25, and use of antihypertensive infusions. No AUS or UK sites selected 100% of standard exclusions.

Conclusions: Non-standard criteria for rtPA eligibility were evident in all three countries and could, in part, explain comparably low use of rtPA. Differences in the use of standard criteria may signify practitioner intolerance for those derived from original efficacy studies that are no longer relevant.