Importance Trauma is the leading cause of death and disability among young adults in the United States. Young adults are also the age group most likely to be uninsured. Implementation of Medicaid expansion through the Affordable Care Act (ACA) has increased insurance coverage, but its associations with trauma care and outcomes among young adults nationwide remain unknown. We examined whether Medicaid expansion, in its first year, was associated with changes in insurance coverage and improved outcomes in young adults hospitalized for traumatic injury.

Objective To assess the associations of ACA Medicaid expansion with insurance coverage, in-hospital mortality, failure to rescue, access to rehabilitation, and unplanned readmissions among hospitalized young adult trauma patients across many US states.

Design, Setting, and Participants We used the Healthcare Cost and Utilization Project State Inpatient Databases to examine changes in insurance coverage and risk adjusted outcomes among young adults (age 19 to 44 years) who were hospitalized for injuries before and after Medicaid expansion and open enrollment occurred (2012-2013 vs 2014) in 11 US states that expanded Medicaid through the ACA. We also performed difference-in-difference analyses to compare these changes between 3 expansion states and 3 non-expansion states within the same geographic region.

Results Of the 141 187 trauma patients hospitalized across 11 Medicaid expansion states, 43 871 (31.1%) were women, and the mean (SD) age was 31.4 (7.6) years. Medicaid expansion was associated with an increase in Medicaid coverage from 16 229 individuals (16.7%) to 15 358 individuals (34.9%) (difference: 18.2% [95% CI, 16.5%-20.0%]; P < .001), a decrease in lack of insurance from 27 016 individuals (27.8%) to 5589 individuals (12.7%) (difference: −15.1% [95% CI, −16.8% to −13.5%]; P < .001), and an increase in discharge to rehabilitation from 9220 individuals (11.4%) to 4736 individuals (12.6%) (difference: 1.16% [95% CI, 0.55%-1.77%]; P < .001). We found no significant reductions in in-hospital mortality, failure to rescue, or unplanned readmissions. Similar results were found when 3 of these states were compared with 3 geographically and demographically similar states that had not enacted Medicaid expansion.

Conclusions and Relevance The first year of implementation of Medicaid expansion and open enrollment across 11 selected US states was associated with significant increases in Medicaid coverage, reductions in uninsured rates, and increased access to postdischarge rehabilitation among young adults hospitalized for injury. However, this study found no significant reductions in in-hospital mortality, failure to rescue, or unplanned readmissions.

重要性 创伤是美国年轻人死亡和致残的主要原因。年轻人也是最有可能没有保险的年龄组。通过《平价医疗法案》（ACA）实施的医疗补助扩展已经增加了保险覆盖面，但在全​​国范围内其与创伤护理和结局之间的关联仍然未知。我们检查了医疗补助计划扩张的第一年是否与因创伤受伤住院的年轻人的保险范围变更和改善的结局有关。

目的 评估美国许多州住院的年轻成人创伤患者的ACA医疗补助扩展与保险范围，院内死亡率，抢救失败，获得康复服务以及计划外的再次入院的关联。

设计，设置和参与者 我们使用了“医疗保健成本和利用项目状态住院病人数据库”来检查在医疗补助扩展和开放注册之前和之后因伤住院的年轻人（年龄在19至44岁之间）的保险范围变化和风险调整后的结局美国11个州通过ACA扩展了医疗补助计划（2012-2013年与2014年）。我们还进行了差异分析，以比较同一地理区域内3个展开状态和3个非展开状态之间的这些变化。

结果 在11个医疗补助扩张州的141 187名创伤患者中，有43 871名（31.1％）是女性，平均（SD）年龄为31.4（7.6）岁。医疗补助计划的扩展与医疗补助计划的覆盖范围从16229个人（16.7％）增加到15358个人（34.9％）相关（差异：18.2％[95％CI，16.5％-20.0％]；P  <.001），缺乏保险的人数从27,016人（27.8％）减少到5589人（12.7％）（差异：-15.1％[95％CI，-16.8％至-13.5％]；P  <.001），从9220人（11.4％）恢复到康复的4736人（12.6％）（差异：1.16％[95％CI，0.55％-1.77％]; P <.001）。我们没有发现医院内死亡率，抢救失败或计划外再次入院的显着降低。将这些州中的3个州与3个地理上和人口统计学上未制定医疗补助计划扩展的州进行比较时，发现了相似的结果。

结论与相关性 在美国11个选定州实施医疗补助扩展和公开招募的第一年与医疗补助覆盖率的显着增加，未投保率的降低以及因伤住院的年轻成年人出院后康复的机会增加有关。但是，该研究发现住院死亡率，抢救失败或计划外的再入院率均没有显着降低。