Assessing the impact of selective licencing schemes for private rental housing on mental health and well-being: protocol for a mixed-method natural experiment study in Greater London, UK.

INTRODUCTION: The UK private rental housing market has poorer quality housing compared with other sectors and is subjected to calls for better regulation. Poor quality housing poses risks to mental and physical health, and housing improvement can potentially benefit health and well-being. Local authorities have powers to implement selective licencing (SL) schemes in specific localities. Such schemes involve landlord registration, payment of licence fees, local authority inspection and requirements that landlords conduct any necessary renovation works to ensure housing standards are met. We aim to evaluate SL in Greater London and to test the feasibility of a national evaluation. METHODS AND ANALYSIS: We will measure individual-level and area-level impacts of SL in Greater London between 2011 and 2019. A difference-in-differences approach with propensity score-matched controls will be used. We propose to exploit data from the Annual Population Survey (APS) and health and social benefit registers to measure mental health and well-being at individual (self-reported anxiety) and area (Small Area Mental Health Index) level. We estimate 633 APS participants in our intervention groups compared with 1899 participants in control areas (1:3 ratio of intervention to control). Secondary outcomes will be self-reported well-being and residential stability at the individual level and incidence of police-recorded antisocial behaviour calls and population turnover at the area level. The study size of the area-level analyses will be 3684 lower layer super output areas (including controls). Qualitative semistructured interviews with lead implementers in several London boroughs will produce insights into variations and commonalities between schemes. ETHICS AND DISSEMINATION: Ethical approval was obtained from London School of Hygiene and Tropical Medicine's Ethics Committee (reference number 26481) and London Borough of Hackney. All interviewees will be asked for informed written consent. Study findings will be published in a peer-reviewed journal.