Rationale and objectivesEconomic theory classifies an intervention as socially beneficial if the total Willingness to Pay (WTP) of those who gain exceeds the total Willingness to accept (WTA) of those who are harmed. This paper examines the differences in health system users’ valuation of a health care service in primary care setting based on the WTP and WTA perspectives, discussing the impact of personal and service variables, including risk attitudes, on these disparities.MethodSix hundred and sixty two subjects who asked for care in health centres in the Region of Madrid (Spain) were interviewed, using the contingent valuation method to estimate WTP and WTA. Patient sociodemographic characteristics, health needs, satisfaction with the service and risk attitude and behaviour under risk (measured by self-reported scales and lottery games respectively) were collected. Generalised Linear Models were used to estimate the association between the explanatory variables and the WTA/WTP ratio.ResultsWe obtained the WTA/WTP ratio for 570 subjects (mean 1.66 CI 95%: 1.53–1.79; median 1, interquartile range 1–2). People with higher education or in high social groups expressed WTA values closest to WTP. The opposite occurred in patients with the greatest health needs or who were born abroad. Self-reported expression of risk aversion appeared also related to increases in the WTA/WTP ratio. Satisfaction with the service evaluated was the most influential factor in the WTA/WTP ratio.ConclusionHealth need, difficulty in obtaining substitutes and satisfaction with the service could serve for profiling people averse to loss for health care services in primary care setting. Self-reported expression of risk aversion could also be related to increases in the WTA/WTP ratio. This would mean that these characteristics should be taken into account both in the design and implementation of new healthcare interventions, as in the making decision for disinvestment.