We compared pre- and post-reform utilization of major therapeutic inpatient surgical procedures predominantly scheduled by outpatient referrals among non-elderly MA adults, and found greater overall increases for lower area income cohorts compared to the highest area income cohort, and for Hispanics compared to Whites. Prior to reform, both Blacks and Hispanics had lower rates of these procedures compared to Whites. We estimated the net change in procedure use associated with health reform among the non-elderly accounting for secular trends, finding significant increases for lower area income groups and Hispanics and Whites but not among Blacks or the highest area income group. As 90 percent of all surgeries came from outpatient physician referral, these findings suggest a meaningful improvement in access to outpatient care for the surgeries studied, especially those living in lower income areas, Hispanics and Whites.
Our findings of greater net increases in procedure use among lower area income groups and Hispanics are consistent with previous randomized(38
) and natural experiments of expanded public insurance programs or similar policy changes; however, few prior studies have explicitly examined whether increased insurance coverage reduces income or racial/ethnic disparities in access to or use of care.(36
) A recent study of Oregon’s lottery-selected expansion of Medicaid to uninsured low-income non-elderly adults in 2008 found that hospital admissions increased by 30 percent in one year; this effect is nearly identical to that found in the RAND randomized study in the 1970s.(38
) More relevant to our study is the finding from Oregon that the increase in inpatient admissions was “disproportionately concentrated” among admissions “that do not originate in the emergency room”; we note that these primarily include admissions based on outpatient physician referral, including those for HRR procedures examined here.(39
More appropriate for comparison to our study are findings of quasi-experimental expansions of public health insurance.(28
) Studies examining the impact of Medicare enrollment at age 65 have noted increased use of inpatient and outpatient care among the previously uninsured(29
) and also the previously insured (due to the relative “generosity” of Medicare)(28
). One study documented a 10 percent increase in hospitalizations in the year following Medicare enrollment, with larger increases in use of “elective” procedures such as bypass surgery and joint replacement.(28
) This suggests that our finding of increased procedure use may reflect a combination of pent-up unmet need and need arising from new diagnoses following increased access to outpatient care.
While the 17 surgical procedures examined represent a broad spectrum of inpatient procedures our main focus here was on their role as markers of access to care. In combining these procedures for evaluating the differential impact of health reform in access to care across subpopulations, we recognize heterogeneity in the procedures in other respects, including acuity of conditions targeted, impact on quality of life and value in terms of clinical benefit per dollar. Reflecting this heterogeneity, we found considerable differences in post-reform changes in rates, with several categories of procedures experiencing decrease in utilization while some others had sharp increases (≥ 25 percent). As estimates of net increases by individual procedure categories had wide confidence intervals due largely to small numbers, we cannot rule out potentially large differences among subpopulations. Nevertheless, statistically significant net increases associated with health reform were found for musculoskeletal and urinary/genital procedures among lower area income cohorts and Whites, and for urinary/genital procedures among Hispanics.
For Hispanics, the overall post-reform increase in procedure use among the non-elderly was considerably higher than that for their elderly counterparts, particularly for musculoskeletal, urinary/genital and nervous system procedures. For Blacks, whereas the changes for both groups were similar for musculoskeletal and urinary/genital procedures, the magnitude of the change is large and comparable to that for the non-elderly Hispanics. Therefore, it is the similar increase in the use of these procedures among the elderly Blacks that leads to the results of no significant net change (for non-elderly) attributable to the reform. Reasons for the similar increase among all Blacks (elderly and non-elderly) are unclear and merit further examination.
There is considerable debate on whether more medical care leads to better health.(43
) However, most studies of natural experimental policy changes have found that expansions of health insurance result in health improvements for individual health measures or subpopulations.(36
) Given the natural experimental setting of MA reform, we instead examined disparities in healthcare utilization and focused on vulnerable subpopulations and selected inpatient procedure categories for which underutilization of care is known to be associated with uninsurance or underinsurance. Research has documented higher rates of clinically unmet need among minorities and lower income patients for many inpatient procedures, including those for cardiac,(44
) and musculoskeletal(22
) care. Our findings are among the first to show that expanded insurance coverage on a population level is associated with increase in use by such vulnerable populations.
Our study has several important limitations. First, we cannot differentiate overuse of procedures from clinically appropriate use. We suspect that our findings of increased procedure use among minorities do not reflect overuse, as Dartmouth Atlas comparisons of regional differences for Medicare beneficiaries for 12 common inpatient surgeries found MA procedure rates were below average for 6, near average for 5 and above average for only one procedure.(47
) Second, since our data is observational, the possibility of potential confounding from unobserved factors remains. However, since we adjust for changes among the elderly, our estimates are robust to unobserved factors (including practice pattern changes) that affect all age groups. Also, comparison of non-elderly and elderly rates of use may not be clinically meaningful for some procedures. However, our findings do include same-age group comparisons by race/ethnicity and area income cohorts. Further, we did not include individual level data on insurance status, because of the inability to infer population rates of insurance status by the subgroups of interest from our data on health care users only. Identification of patient race/ethnicity is not necessarily based on patient self-report and may vary across hospitals; however, as this is likely to affect both non-elderly and elderly patients in each hospital, our methodology of contrasting changes among non-elderly patients with those for elderly patients provides robustness of findings to the potential heterogeneity in race/ethnicity identification. Also, in the absence of data on individual income, we have used zip code –level income as the measure of socioeconomic status; however, this approach has been used in numerous previous studies.(31
) Finally, our focus on the use of inpatient procedures may underestimate use of procedures performed in outpatient settings.
Nonetheless our findings have implications for national health reform (Affordable Care Act, 2010) which shares many key elements with MA health reform.(1
) Notably, prior to health reform, MA had lower uninsurance and better safety-net funding compared to other states.(48
) Depending on the extent to which similar subpopulations gain from insurance expansion from the national reform, the potential for improved access is considerably larger or smaller, as is the potential for higher costs. Our study only examined utilization in the first two years following the reform, and therefore may include sharp increases in utilization from non-elderly patients with prior unmet need. Whether these increases will taper-off in the longer run is unknown. Actual changes also depend on other factors, including provider supply and practice patterns, which also vary considerably across states.
In conclusion, our findings of significant post-reform expansion in procedure use for Hispanics and lower area income patients are consistent with the relatively larger gains in insurance coverage among these subpopulations. These findings suggest potentially improved access to outpatient care and may reflect demand built up prior to reform when individuals were uninsured. Whether such improved access – a crucially important first step to improving equity in access and outcomes – translates into improved clinical outcomes at a reasonable cost merits further study.