At-risk registers integrated into primary care to stop asthma crises in the UK (ARRISA-UK): study protocol for a pragmatic, cluster randomised trial with nested health economic and... oleh Jane R. Smith, Stanley Musgrave, Estelle Payerne, Michael Noble, Erika J. Sims, Allan B. Clark, Garry Barton, Hilary Pinnock, Aziz Sheikh, Andrew M. Wilson, On behalf of the ARRISA-UK Group