Connor J, Rodgers A, Priest P
Department of Medicine, University of Auckland, New Zealand.
J Epidemiol Community Health. 1999 Nov;53(11):725-30. doi: 10.1136/jech.53.11.725.
Despite the wealth of evidence linking low income to ill health, there is little information from randomised studies on how much and how quickly these risks can be reversed by improvements in income.
To conduct a systematic review of randomised studies of income supplementation, with particular reference to health outcomes.
Extensive searches of electronic databases and contact with previous authors. As well as searching for trials that were specifically designed to assess the effects of increased income, studies of winners and losers of lotteries were also sought: if winning is purely chance, such studies are, in effect, randomised trials of increased income.
Ten relevant studies were identified, all conducted in North America, mostly in the late 1960s and 1970s. Five trials were designed to assess the effects of income supplementation on workforce participation and randomised a total of 10,000 families to 3-5 years of various combinations of minimum income guarantees and reduced tax rates. Two trials were designed to assess re-offending rates in recently released prisoners and randomised a total of 2400 people to 3-6 months of benefits. One trial was designed to assess housing allowances and randomised 3500 families to three years of income supplements. One trial assessed the health effects of 12 months of income supplementation in 54 people with severe mental illness. Finally, one study compared three groups of people who won different amounts of money in a state lottery. In all these studies the interventions resulted in increases in income of at least one fifth. However, no reliable analyses of health outcome data are available.
Extensive opportunities to reliably assess the effects of increases in income on health outcomes have been missed. Such evidence might have increased the consideration of potential health effects during deliberations about policies that have major implications for income, such as taxation rates, benefit policies, and minimum wage levels. Randomised evidence could still be obtained with innovative new studies, such as trials of full benefit uptake or prospective studies of lottery winners in which different sized winnings are paid in monthly installments over many years.
尽管有大量证据表明低收入与健康状况不佳有关，但关于收入改善能在多大程度上以及多快逆转这些风险的随机研究却很少。
对收入补充的随机研究进行系统评价，特别关注健康结果。
广泛检索电子数据库并与之前的作者联系。除了搜索专门设计用于评估收入增加影响的试验外，还寻找彩票中奖者和失利者的研究：如果中奖纯粹是偶然的，那么此类研究实际上就是收入增加的随机试验。
共确定了10项相关研究，均在北美进行，大多是在20世纪60年代末和70年代。5项试验旨在评估收入补充对劳动力参与的影响，共将10000个家庭随机分为3至5年不同组合的最低收入保障和降低税率组。2项试验旨在评估近期释放囚犯的再次犯罪率，共将2400人随机分为3至6个月的福利组。1项试验旨在评估住房补贴，将3500个家庭随机分为3年的收入补充组。1项试验评估了54名严重精神疾病患者接受12个月收入补充后的健康影响。最后，1项研究比较了在州彩票中赢得不同金额奖金的三组人群。在所有这些研究中，干预措施使收入至少增加了五分之一。然而，目前尚无对健康结果数据的可靠分析。
错失了可靠评估收入增加对健康结果影响的大量机会。这些证据可能会在审议对收入有重大影响的政策（如税率、福利政策和最低工资水平）时，增加对潜在健康影响的考虑。通过创新的新研究，如全面福利获取试验或对彩票中奖者的前瞻性研究（其中不同规模的奖金在多年内按月分期支付），仍可获得随机证据。
