A study recently published in Annals of Internal Medicine has found no significant change in hospital use associated with the health insurance coverage expansions of 1966 and 2014. Bed supply in hospitals may have limited increases in use, as the increase in the population gaining coverage was compensated for by the decrease among others. This suggests that a surge in hospital use would likely not result from universal coverage. 

This study included 8 years of data surrounding the 1966 health insurance coverage expansion (4 years before and 4 years after) via the National Health Interview Survey, as well as 8 years surrounding the 2014 expansion (6 years before and 2 years after) via the Medical Expenditure Panel Survey. Measurements included the mean hospital days and discharges among the society at large and among groups stratified by age, health status, and income. Findings were verified with the American Hospital Association and US Census Bureau data, which allowed for calculations of per-capita hospital use, as well as those who were institutionalized and who died while under hospital care. Multivariable negative binomial regression was used to examine changes between pre- and postexpansion periods.

The rate of overall hospital discharges did not change significantly before and after Medicare/Medicaid expansion, with hospital discharges changing from an average of 12.8 per 100 people to 12.7 per 100 people (P =.26). Hospital days were not significantly different in the initial 2 years following implementation but increased slightly by the third and fourth. Compared with nonelderly, adjusted discharges rose by 2.4 (95% CI, 1.7-3.1) per 100 people higher among the elderly (P <.001). A similar increase was observed among low-income persons vs high-income. Use dropped among younger people and those with higher incomes.  

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Hospital use also stayed the same before and after the implementation of the Affordable Care Act, with before and after discharge rates of 9.4 and 9.0 per 100 people, respectively (P =.133), and similar rates of hospital days. Those in good health had significantly fewer hospital days, with a reduction of 3.2 (95% CI, 0.2-6.2) per 100 people (P =.040), as well as fewer discharges, with a reduction of 0.6 (95% CI, 0.2-1.0) per 100 people (P =.006). Those in poor or fair health had statistically nonsignificant increases in both (P =.27). 

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Limitations to this study included a reliance on participant recall and a lack of institutionalized participants, a lack of analysis on factors potentially preventing hospitalizations, the potential impact of secular changes in bed supply, and limited follow up after the Affordable Care Act. 

Study researchers concluded that “[past] coverage expansions were associated with little or no change in society-wide hospital use; increases in groups who gained coverage were offset by reductions among others, suggesting that bed supply limited increases in use. Reducing coverage may merely shift care toward wealthier and healthier persons. Conversely, universal coverage is unlikely to cause a surge in hospital use if growth in hospital capacity is carefully constrained.”


Gaffney A, McCormick D, Bor DH, Goldman A, Woolhandler S, Himmelstein DU. The effects on hospital utilization of the 1966 and 2014 health insurance coverage expansions in the United States [published online July 23, 2019]. Ann Intern Med. doi:10.7326/M18-2806