The (Portland) Oregon Medicaid Study

A new study today on the Oregon Medicaid experiment (they randomly selected some who applied for coverage while denying others; the difference in the groups is the estimated impact of having Medicaid v. being uninsured in Portland, Oregon; they data reported are only from Portland, and not statewide). Such a study design is as good as it gets on internal validity (does x cause y; in this case does Medicaid make people healthier, measured in a variety of ways, as compared to being uninsured). The external validity of such a study–are these findings applicable to other places depends upon how similar other states are to this study population (Portland).

Based on reading the many tweets this afternoon about the study, I was surprised when I actually read the study. Basically, they find that Medicaid coverage:

• reduced depression, improved or maintained self reported quality of life, increased the likelihood of having a usual source of primary care, increased the uptake of several preventive measures such as cholesterol screening, pap smear and mammography, and increased perceptions that patients received quality care. Again, this is the estimated impact of Medicaid as compared to being uninsured.
• Medicaid also greatly reduced the financial burden of health care and nearly eradicated catastrophic health expenditures that they defined as being greater than 30% of family income (or ~$4,500 for family of two at the federal poverty level in Oregon).

There was bad news too. They found, for example, that Medicaid did not:

• decrease blood pressure, reduce cholesterol, or decrease the proportion of diabetics with A1C levels above 6.5%, or reduce the Framingham risk score significantly (a global measure of 10 year heart disease mortality risk). There was also no significant difference in persons reporting no, or mild pain. There were also some prevention screening procedures that those with Medicaid were not more likely to receive (Table 5), for example: fecal-occult blood test, colonoscopy for those age 50+, flu shot. Again, this is the estimated impact of Medicaid as compared to being uninsured.

In terms of health care use/spending, those with Medicaid:

• had more doctor visits, but there were no differences in hospitalizations, ED visits, or outpatient surgery. Persons with Medicaid had an estimated health care expenditure on their behalf of $4,428, or $1,171 more than someone who was uninsured. Keep in mind other parts of Medicaid that were not a part of this study, or the proposed expansions, cost lots more.

Several things of note:

• This study is focused on Portland, and not even all of Oregon (see 1st para of second column on page 1714). The internal validity of the study (does x cause y) is as good as it gets. The external validity (do these results generalize) depends upon how similar Portland, Oregon is to another state thinking of expanding Medicaid.
• There are a few things about the study subjects that leap out. First, these are some seriously well controlled diabetics in Portland, with 5.1% of the control group (uninsured) having A1C of 6.5%+; those with Medicaid were not statistically better. I honestly think this must be a typo (Table 2) and instead of 5.1% of diabetics in control group with A1C of 6.5% or greater they meant 5.1% with 6.5% A1C or less (though it is repeated in the text). This is a presentation to the results of an incredibly successful diabetes disease management company in Mississippi that is absolutely thrilled to have 64% of patients with A1C less than 7% after one year (see slide 25); the Oregon study says that 95% have levels of 6.5% or less.* Nationally, between 15-30% of diabetics have A1C of greater than 9. I just don’t see how what is written can be true, or if it is, the country should be studying diabetes care in Portland. Update 11:50pm on 5/1; further updated 5/2 at 7:05am: This is a A1C of everyone on the study and not only diabetics. I was thinking in terms of diabetics, so that is my error. This link says prevalence of diabetes over age 20 is 11.3%….but what is needed for comparison to see the similarity of the study population is prevalence between 18-64….going to bed will get after that tomorrow. and this one also has 11.3% prevalence for age 20+, but 26.9% for age 65+. I don’t think the A1C prevalence of 6.5% or greater is that different from the national average, but I can’t find a precise age comparison for the study population (ages 18-64).
• This sample of patients went to the doctor a lot. The uninsured reported an average of 5.5 office visits annually, with those covered by Medicaid having 2.7 more per year, on average. Using this CDC report (Table 10, No. 252, page 115), I found that nationally 69% of persons age 18-44 in the US in 2010 had between 0 and 3 office visits and only 19% had 4-9 visits; for the age group 45-64, it was 57.7% with 0-3 and 25% with 4-9. Yet the mean of the uninsured group in this study is 5.5 visits annually, with those covered by Medicaid having an average of 2.7 more.

The bottom line is that this is a well done study with high internal validity, and it finds some positive health impacts of Medicaid on health as compared to being uninsured. It also finds some areas in which health is no better (or worse) for those covered by Medicaid. The study unambiguously shows that Medicaid reduces the financial burden of health care for beneficiaries. There are some aspects of the study findings that may reduce the applicability of the findings to other parts of the country, but that doesn’t mean it isn’t an important study. It is just another piece of the puzzle.

However, for all the tweeters saying this study showed Medicaid is utterly flawed and there is no way anyone should expand Medicaid coverage I can only think they didn’t actually read the study. More tomorrow on the political and policy ramifications of this study and how people talked about it within 5 minutes of its release.

*Disclosure: I am a consultant for Diabetes Care Group, Inc. and have done cost estimations for them based on their clinical A1C results; some of them are excerpted in that publicly available slide deck.