Quantifying Family Spillover Effects in Economic Evaluations: Measurement and Valuation of Informal Care Time.

Spillover effects on the welfare of family members may refer to caregiver health effects, informal care time costs, or both. This review focuses on methods that have been used to measure and value informal care time and makes suggestions for their appropriate use in cost-of-illness and cost-effectiveness analyses. It highlights the importance of methods to value informal care time that are independent of caregiver health effects in order to minimize double counting of spillover effects. Although the concept of including caregiver time costs in economic evaluations is not new, relatively few societal perspective cost-effectiveness analyses have included informal care, with the exception of dementia. This is due in part to challenges in measuring and valuing time costs. Analysts can collect information on time spent in informal care or can assess its impact in displacing other time use, notably time in paid employment. A key challenge is to ensure appropriate comparison groups that do not require informal care to be able to correctly estimate attributable informal care time or foregone market work. To value informal care time, analysts can use estimates of hourly earnings in either opportunity cost or replacement cost approaches. Researchers have used widely varying estimates of hourly earnings. Alternatively, stated-preference methods (i.e. contingent valuation, conjoint analysis) can be used to value the effect of informal care on utility, but this can entail double counting with health effects. Lack of consensus and standardization of methods makes it difficult to compare estimates of informal care costs.