Рандомное исследование медицинского страхования: Влияние сооплаты на здоровье и расходы (1974-1982)

US based health care study in 1974 1982

The RAND Health Insurance Experiment (RAND HIE) was an experimental study from 1974 to 1982 of health care costs, utilization and outcomes in the United States, which assigned people randomly to different kinds of plans and followed their behavior. Because it was a randomized controlled trial, it provided stronger evidence than the more common observational studies and concluded that cost sharing reduced "inappropriate or unnecessary" medical care (overutilization) but also reduced "appropriate or needed" medical care.

The RAND HIE was begun in 1971 by a group led by health economist Joseph Newhouse and including health service researchers Robert Brook and John Ware; health economists Willard Manning, Emmett Keeler, Arleen Leibowitz, and Susan Marquis; and statisticians Carl Morris and Naihua Duan. The group set out to answer this question (among others): "Does free medical care lead to better health than insurance plans that require the patient to shoulder part of the cost?" The team established an insurance company using funding from the United States Department of Health, Education, and Welfare. The company randomly assigned 5809 people to insurance plans that had no cost sharing, 25%, 50% or 95% coinsurance rates with a maximum annual payment of $1000. It also randomly assigned 1,149 persons to a staff model health maintenance organization (HMO), the Group Health Cooperative of Puget Sound. That group faced no cost sharing and was compared with those in the fee for service system with no cost sharing as well as an additional 733 members of the Cooperative who were already enrolled in it. Subsequent RAND HIE publications "rule[d] out all but a minimal influence, favorable or adverse, of free care for the average participant" but determined that a "low income initially sick group assigned to the HMO . [had a] greater risk of dying" than those assigned to fee for service (FFS) care. The experiment also demonstrated that cost sharing reduced "appropriate or needed" medical care as well as "inappropriate or unnecessary" medical care. Studies of specific conditions and diseases in the RAND HIE data found, for example, that the decrease in use of medical services had adverse effects on visual acuity and on blood pressure control. A RAND summary said, "The projected effect was about a 10 percent reduction in mortality for those with hypertension." Newhouse, summarizing the RAND HIE in 2004, wrote, "For most people enrolled in the RAND experiment, who were typical of Americans covered by employment based insurance, the variation in use across the plans appeared to have minimal to no effects on health status. By contrast, for those who were both poor and sick—people who might be found among those covered by Medicaid or lacking insurance—the reduction in use was harmful, on average."

The RAND Health Insurance Experiment is considered "one of the best experimental social science studies ever conducted". However, several criticisms of the study have been suggested. Some authors questioned the generalizability of comparisons of HMO and FFS care since data on the former were based on a "single, relatively small but well managed" HMO in Seattle. One 2007 article suggested that the "large number of participants who voluntarily dropped out of the costsharing arms of the experiment" could have invalidated the RAND HIE's findings. In response, Newhouse and colleagues described the argument as "implausible". The RAND HIE did not study people without health insurance and so could not determine how the presence or absence of health insurance affects health. Nevertheless, the study opened the way for increased cost sharing for medical care in the 1980s and 1990s. The RAND HIE is still referenced in the academic literature as a "gold standard" study in research on the effects of health insurance. In summarizing 132 articles, they found that the RAND HIE provided the only relevant experimental data; all other studies they reviewed were observational. "A classic experiment by RAND researchers from 1974 to 1982 found that people who had to pay almost all of their own medical bills spent 30 percent less on health care than those whose insurance covered all their costs, with little or no difference in health outcomes. The one exception was low income people in poor health, who went without care they needed." "The RAND health insurance experiment found that patients cut back equally on both superfluous and necessary visits when asked for small co payments."