Preventing bath water scalds: a cost-effectiveness analysis of introducing bath thermostatic mixer valves in social housing

Aims To assess the cost-effectiveness of installing thermostatic mixer valves (TMVs) in reducing risks of bath water scalds and estimate the costs of avoiding bath water scalds. Methods The evaluation was undertaken from the perspective of the UK public sector, and conducted in conjunction with a randomised control trial of TMVs installed in social housing in Glasgow. Installation costs were borne by the social housing organisation, while support materials were provided by the UK NHS. Effectiveness was represented by the number of families with at-risk bath water temperatures pre- and post-installation, and the number of bath scalds avoided as a result of installation. Differences in the number of families with at-risk temperatures between groups were derived from the RCT. Cost-effectiveness was assessed and a series of one-way sensitivity analyses were conducted. Results Unit costs associated with installation were calculated to be £13.68, while costs associated with treating bath water scalds ranged from £25 226 to £71 902. The cost of an avoided bath water scald ranged from net savings to public purse of £1887 to £75 520 and at baseline produced a net saving of £3 229 008; that is, £1.41 saved for every £1 spent. Conclusion It is very likely that installing TMVs as standard in social housing in new buildings and major refurbishments accompanied by educational information represents value for money. Trial registration number ISRCTN:21179067.