OBJECTIVES: Washington Panel and UK NICE guidelines propose that the health affects of patient care on their carers should be included within the denominator of cost-utility analyses. The impact of patient disability on carers has been demonstrated by directly measuring the quality of life (QoL) of carers in specific patient populations with substantial informal care needs. However, it is possible that a general relationship between patient and carer quality of life exists, whereby any improvements in patient QoL are mirrored by improvements in carer QoL. If such a general relationship does exist, any intervention that generates additional patient quality adjusted life years (QALYs) will also generate additional carer QALYs. We investigated whether a general relationship between patient and carer QoL exists using the Health Outcomes Data Repository (HODaR). METHODS: Using a sample of 15,113 patients we estimated the relationship between utility and time away from normal activities for patients, along with the relationship between patient utility and carer time spent helping patients. For any given patient utility we can then predict carer time, and assuming that this has the same impact on well-being as time away form normal activities has on patients, predict carer utility. RESULTS: A simple relationship shows that a reduction in utility of 0.10 was associated with a 0.017 reduction in carer utility (i.e. QALY gains are increased by 17%). More complex models looked at the type of disabilities that were associated with greater or lesser carer effects. CONCLUSION: This work is preliminary, but points to the possibility of a general relationship between patient and carer QoL. Additional research is required that directly measures carer QoL, and identifies whether it was influenced by the general health of the patient or specific disabilities. Any widespread effect may have a profound effect on the future funding decisions.