Title: Health impact and economic value of meeting housing quality standards
Funder: Division for Social Care and Health Research (Wales)

Abstract: This proposal seeks to evaluate the impact of a mixture of different types of housing improvements to social housing in Carmarthenshire between 2009 and 2014 on the health of the residents. By using record linkage of routine longitudinal data including such health-related aspects as hospital admissions and GP consultations and prescriptions we plan to compare the health of the residents before and after the interventions and to compare their health changes with those of social housing residents in a nearby region whose properties will not be improved during the study period. The analyses will be conducted in parallel with the results of a series of before and after health and wellbeing surveys already funded by the Council and which is quite separate from this proposal.The intervention participants are the residents of the 9256 properties being improved between 2009 and 2014. The intervention comprises up to four separate work packages (internal works/windows and doors/thermal insulation/gardens and estate environment) which is proceeding stepwise. Properties receiving all four interventions will have different intervention dates for each. The intervention is proceeding stepwise over a considerable period of time complicating the assessment of the impact. By using routine data available for a number of years including the whole of this intervention period and preceding years we hope to overcome the logistical difficulties inherent in other types of evaluation.The outcomes will be discussed fully later but the primary outcome concerns hospital admissions rates for certain conditions. These will be evaluated for the two years before the whole intervention began and compared with the time period following the intervention; the length of this period will vary between households with the timing of the interventions. The information within the SAIL database will allow us to identify similar households (matched on deprivation and demography) from 13000 non-intervention social houses in the nearby region and we will evaluate comparable admission rates for those households over periods matched to those in the intervention group. This will enable us to adjust for any systematic changes over time in admission rates. We will link multiple anonymised datasets at an individual and household level using the Secure Anonymised Information Linkage System (SAIL) operated by the Health Information Research Unit (HIRU).We have an environment GIS database (eGIS) containing a point location for each residence along with address data (Ordnance Survey Master Map Address Layer 2). These data have been used to establish a method of anonymously linking each residence to health data for individuals within the SAIL databank using Residential Anonymous Linking Fields (RALFs). While the environment data are within the eGIS they are completely separate from health data in SAIL. Therefore we are able to know the location and other information about the house and its local environment for example neighbourhood quality (REAT- see next paragraph) without compromising confidentiality and privacy. While in the eGIS we will add house improvement data and other relevant information specifically the work packages and completion dates describing the regeneration process. Each regenerated house and its local area will be linked to a validated reliable objective tool designed by members of this project team to measure the quality of the neighbourhood built environment. The Residential Environmental Assessment Tool (REAT) is used at a postcode level to measure using independent observers the characteristics of the area environment around a home or group of homes. The REAT tool is predictive of mental health over and above deprivation indices. We will undertake a REAT assessment of each of the postcodes in which the regeneration has not started to measure the impacts of interventions undertaken by Carmarthenshire County Council on the outside of the buildings and within the gardens. Under the latest timetable approximately 360 or 50% of the postcodes affected by the intervention will be assessed pre- and post-intervention. These postcode-level data will then be linked to the key data using the RALFs prior to anonymisation. Additionally we will use digital map analysis techniques developed as a result of EPSRC funding together with internet-based tools such as Google Streetview to investigate the possibility of replacing REAT assessments in their current form which require an assessor to visit the area with a computerised analysis including map data. These data will be compared to the REAT scores data to assess the validity of this semi-automatic method of measuring the environment. If this proved successful it would allow the assessment on a much larger scale than is presently possible.These data are sent to Health Solutions Wales where addresses are replaced with a consistent RALF. Now the data may be brought into the SAIL databank and linked to Anonymous Linking Fields (ALFs) for individuals enabling links to health data to be made. We will create links to variables within several different datasets to enable us to explore potential changes in disease burden for individuals nested within houses related to housing improvements. We are using this methodology for other studies currently in particular the development of the Wales Electronic Cohort for Children (circa 700000 children) funded by NISCHR.Variations in the intervention are achieved as a result of the four different work packages and the order in which they are completed for each house. Different types of intervention may have different impacts on health; for example exterior work such as security lighting installation may make residents feel more secure whereas interventions to improve thermal efficiency may have greater effects on general health hospital admissions and overall mortality. Specific hypotheses are:1. Combined housing regeneration improvements will reduce the number of combined condition emergency admissions (see primary outcome measure)2. Improvements in affordable warmth due to insulation and new boilers will result in fewer cardio-respiratory events3. Installation of full central heating and new windows and doors will reduce the presence of mould and lead to a reduction in asthma treatments4. Improved quality of kitchens and bathrooms will improve mental health.5. Improvements to the exterior of properties including security light additions will improve mental health (measured by a reduction in treatments for anxiety and depression)6. Installation of power points in convenient locations upgrades of electrical systems and installation of smoke detectors will reduce the number of fall and burn injuriesOthers may be generated following the comprehensive literature review. The evidence for these pathways is presented in the background section and the detailed project proposal.Economic feasibility study for economic assessment toolThe aim of the economic evaluation is to investigate the economic value of the housing regeneration programme. A feasibility study for a UK-wide Health Economic Assessment Tool for housing similar to the WHO HEAT tool for cycling will be conducted using the health impact economic value data. We will assess the viability of making a tool that can be used by local government and private social housing management to assess the benefits of regeneration programmes. The evaluation will estimate the costs of providing the new regeneration programme and determine the extent to which it can be regarded as an efficient use of public funds. The economic evaluation will inform the feasibility of a UK-wide Health Economic Assessment Tool for Housing.The approach to be adopted in this evaluation of the scheme is to conduct a cost-consequences analysis (CCA) from the perspective of the public sector and the wider social perspective. The costs of delivering the programme will be collected by scrutiny of routinely collected datasets held within the Secure Anonymised Information Linkage (SAIL) system relevant financial documents discussion with key staff involved with the programme and finance staff from the constituent organisations. The costs associated with utilisation of hospital and GP services (NHS reference costs) will be collected to calculate resource utilisation over time in conjunction with the costs of delivering the programme. Primary and secondary outcome measures will be used in the CCA.Cost-consequences will be assessed within the study duration and additional modelling will be undertaken to estimate cost-consequences and outcomes beyond the end date of the study. Future costs and benefits will be discounted at the prevailing rate to bring into present values as required by assessment agencies. Changes in resources utilised over time as well as changes in primary and secondary outcomes will be calculated and used in conjunction with the costs of delivering the programme to generate the net cost of programme delivery. A series of one-way sensitivity analyses will be undertaken to assess the extent to which changes in the variable employed affect the baseline estimates. Probabilistic sensitivity analysis will be undertaken to ascertain the probability that the scheme represents value for money.


Research activity codes: 3.2 INTERVENTIONS TO ALTER PHYSICAL AND BIOLOGICAL ENVIRONMENTAL RISKS
Health categories: GENERIC HEALTH RELEVANCE