Universal Health Insurance Coverage in Massachusetts Did Not Change the Trajectory of Arthroplasty Use or Costs

Abstract

Background: The state of Massachusetts enacted universal health insurance in 2006. However it is unknown whether the increased access to care resulted in changes to surgical use or costs.

Questions/purposes: We asked the following related research questions: compared with the United States as a whole, how did the (1) number of cases (as a percentage of the overall population, to account for changes in the overall population during the time surveyed), (2) payer mix, and (3) inpatient costs for arthroplasty change in Massachusetts after introduction of health insurance reform?

Methods: We analyzed the use and cost of primary THAs and TKAs in Massachusetts using the State Inpatient Database (SID) between 2002 and 2011 compared with the Nationwide Inpatient Sample (NIS) during the same years. The SID captures 100% of inpatient procedures in Massachusetts, while the NIS is a nationally representative database of inpatient procedures for the United States. The SID and NIS are publicly available data sources from the Agency for Healthcare Research and Quality, and include information regarding procedure volumes, payer mixes, and costs. Inpatient costs were defined similarly in both databases by using hospital charges and an average cost-to-charge ratio that is unique for each hospital. The incidence of arthroplasties was calculated by dividing the procedure volume by the relevant population (either for Massachusetts or the entire country) based on public data from the United States Census bureau.

Results: The incidence of THAs and TKAs performed in Massachusetts increased steadily throughout the study period, and paralleled a similar increase in the United States as a whole. In Massachusetts, the incidence of THAs increased by 59% between 2002 and 2011, and the incidence of TKAs likewise increased by 80%. The trends for the incidence in total joint arthroplasties were similar to those for Massachusetts for the United States as a whole. The period of health insurance reform in Massachusetts was associated with a greater proportion of patients covered by Medicaid, Commonwealth Care, or Health Safety Net for THAs and TKAs. By 2011, universal health insurance in Massachusetts covered 2.45% of primary THAs and 2.77% of primary TKAs. Coverage for Medicaid in Massachusetts increased from 3.23% and 3.04% of THAs and TKAs in 2002 to 4.06% and 4.34% respectively in 2011. On average, Medicaid coverage was greater for TKAs in Massachusetts than across the United States during the study period. The introduction of health insurance reform had a minimal effect on the cost of total joint arthroplasties in Massachusetts. Although the costs of total joint arthroplasties in the United States were higher than those in Massachusetts, this difference narrowed substantially from 2002 to 2011, with the Massachusetts cost trending upward and the overall United States cost trending downward.

Conclusions: Despite extending insurance coverage to the entire state of Massachusetts, there was little change in actual utilization trends for joint replacement.

Clinical relevance: The enactment of universal health insurance coverage in Massachusetts appears to have been a nonevent insofar as the use and cost of total hip and knee surgeries is concerned in the state. Factors other than health insurance reform appear to be driving the growth in demand for arthroplasties in Massachusetts and are likely to do so as well in the United States under the Affordable Care Act of 2010.

Fig. 1A–B

The incidences of primary (A) THAs and (B) TKAs were generally insensitive to the period before and after 2006 when universal health insurance coverage was mandated in Massachusetts compared with the United States. MA = Massachusetts; US = United States; M = male; F = female.

Fig. 2A–B

Inpatient costs (USD 2014) of primary (A) THAs and (B) TKAs were generally insensitive to the time before and after 2006 when universal health insurance coverage was mandated in Massachusetts compared with the United States. The vertical axis for both figures has units of 10,000 USD 2014. MA = Massachusetts; US = United States.