Abstract
Abstract
Background:
Medicare is a public insurer for whom many autistic adults are eligible in the United States, but little is known about autistic beneficiaries who are covered. A challenge in using claim data is identification of autism spectrum disorder (ASD) cases to ensure accurate characterization. Some work suggests that relying on one claim could identify probable ASD, although other works indicate that two claims are necessary for case identification. The purpose of the current study was to describe the sample of Medicare young adult beneficiaries, and determine whether using a 1+ versus 2+ claim case identification resulted in similar interpretation of sample demographic characteristics and primary care utilization patterns in Medicare professional service claims.
Methods:
We used Medicare Limited Data Sets (2008–2010) claims. After ASD case identification using ICD-9-CM (299.xx), 527 unique beneficiaries in the last claim year of 2010 professional service file were identified as having at least one claim of ASD. Of these, 69% (n = 364) had two or more claims. Proportions and zero-inflated negative binomial regression were used to examine differences in demographic characteristics and primary care utilization and costs for the 1+ and 2+ samples.
Results:
Medicare claims contain a sample of autistic adults with expected demographics identified in historic prevalence cohorts. No differences in age, gender, race/ethnicity, Hispanic status, or dual-eligibility months or Adjusted Clinical Groups (ACG)® concurrent risk scores were identified between the 1+ and 2+ samples. No difference was found in the overall estimation of primary care use or costs between the 1+ and 2+ samples based on Zellner's seemingly unrelated regression methods.
Conclusions:
This study is the first to describe a national sample of Medicare-insured autistic adults. We found that using a 1+ case identification results in a sample that is demographically similar to a 2+ claim sample, and produces similar estimates of utilization as a 2+ claim sample.
Why was this study done?
1. In the United States health care system, Medicare provides health benefits primarily to individuals over the age of 65 years. However, it also includes individuals who have received a disability determination and meet eligibility criteria who are under 65 years. Approximately 25% of Medicare beneficiaries are under the age of 65 years, and these include individuals on the autism spectrum. 2. There are no published studies about the kinds of services used by autistic adults who receive Medicare health insurance benefits. Understanding the kinds of health services used by autistic adults who don't have private insurance will help us make sure that public health care benefits meet the needs of autistic adults in the future. 3. When conducting research using claims-based data sets, such as Medicare data sets, it can be challenging to identify which patients in the data set are autistic. Researchers disagree on whether to include anyone who has had at least one claim with an autism code, or if they should only include patients who have had at least two claims with an autism code.
What was the purpose of this study?
The purpose was to describe young autistic adults who are eligible for Medicare benefits, and to determine the best way that individuals can be identified in the claims records.
What did the researchers do?
We used claims files for Medicare Limited Data Sets in 2010 to identify fee-for-service beneficiaries with the diagnosis ‘autism spectrum disorder’. There were 527 people who had at least 1 claim with a code of ‘autism spectrum disorder’ (1+) and 364 people with at least 2 codes (2+) in the Medicare ‘Carrier’ file. We used statistical tests to look for differences in these two samples for age, gender, race/ethnicity, and use of primary care services and costs.
What did the researchers find?
• Medicare beneficiaries identified on the autism spectrum had similar characteristics as the young adult population we expect- most were men (more than 70%), most were white, non-Hispanic, and most (more than 80%) were also eligible for Medicaid (in addition to Medicare). • We did not find differences in age, gender, race/ethnicity, dual enrollment in Medicaid, primary care services or costs between those with 1 compared with 2 or more claims with ‘autism spectrum disorder’.
What are the weaknesses of the study?
Weaknesses of our study include: lack of demographic information related to reasons for eligibility for Medicare benefits, income, or employment; and lack of any corresponding claims that may have been paid by Medicaid.
How will these findings help future researchers and autistic adults?
• The results help researchers understand that using a 1+ case identification is feasible, and results in a sample that is similar to a 2+ claim sample. • This study will help autistic adults because very little research talks about how health care is used by those with public insurance such as Medicare. This study is the first to talk about this, and will pave the way for future studies.
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