A "0" score is attributed to countries with a single national scheme (NHS or single-payer system). Source: OECD Survey on Health System Characteristics 2008-09. Various institutional aspects of the health care systems mediate the impact of competition on hospital costs and patients’ health outcomes. In the United States, competitive pressures have fostered the development of Health Maintenance Organisations (HMOs) since the 1980s (Kessler and McClellan, 2000). However, effective health quality monitoring by regulators is crucial as recorded quality care improvements may be due to hospitals focussing on monitored quality indicators while neglecting unmonitored and unobserved quality aspects (Propper et al., The overall experience is that regulated competition among private insurers has contributed to better align benefit packages to purchasers’ preferences, but health care cost reductions have proved elusive.