Government employees in Spain are covered by public Mutual Funds that purchase a uniform basket of benefits, equal to the ones served to the general population, from private companies. Companies apply as private bidders for a fixed per capita premium hardly adjusted by age. Our hypothesis is that this premium does not cover risks, and companies have incentives for risk selection, which are more visible in high-cost patients. We focus on a particularly costly disease, cancer, whose prevalence is similar among government employees and the general population. We compare hospitalisations in the public hospitals of the government employees that have chosen public provision and the general population. We analysed a database of hospital discharges in the Valencian Community from 2010 to 2015 (3 million episodes). Using exact matching and logistic models, we find significant risk selection; thus, in hospitalised government employees, the likelihood for a solid metastatic carcinoma and non-metastatic cancer to appear in the registry is 31% higher than in the general population. Lymphoma shows the highest odds ratio of 2.64. We found quantitatively important effects. This research provides indirect evidence of risk selection within Spanish Mutual Funds for government employees, prompting action to reduce incentives for such a practice. More research is needed to figure out if what we have observed with cancer patients occurs in other conditions.

西班牙的政府雇员受到公共共同基金的保护，这些基金从私营公司购买一篮子统一的福利，与为普通民众提供的福利相同。公司以私人投标人的身份申请固定的人均保费，几乎不根据年龄进行调整。我们的假设是，这种保费并不能覆盖风险，公司有风险选择的动机，这在高费用患者中更为明显。我们关注的是一种代价特别高昂的疾病——癌症，其在政府雇员和普通人群中的患病率相似。我们比较了选择公共服务的政府雇员和一般人群在公立医院的住院情况。我们分析了 2010 年至 2015 年巴伦西亚社区出院数据库（300 万集）。使用精确匹配和逻辑模型，我们发现显着的风险选择；因此，在住院的政府雇员中，实体性转移性癌症和非转移性癌症出现在登记处的可能性比一般人群高出 31%。淋巴瘤的优势比最高，为 2.64。我们发现了数量上重要的影响。这项研究为政府雇员在西班牙共同基金内进行风险选择提供了间接证据，促使人们采取行动减少这种做法的激励。需要更多的研究来弄清楚我们在癌症患者身上观察到的情况是否也会发生在其他情况下。