This Commonwealth Fund report from May 2009 examines health insurance and health care access before and after entry into the Social Security Disability Insurance program.

From the report:

This report uses National Health Interview Survey (NHIS) data linked to data from the Social Security Disability Insurance (SSDI) and Medicare programs to create profiles of SSDI beneficiaries during the three years before and after SSDI entry to illustrate changes in insurance status, health care access, and utilization. It finds that SSDI beneficiaries are less likely to be insured, even three years prior to SSDI entry, and that utilization and access problems peak right before and after entry. At the time their SSDI applications were allowed, 11 percent of beneficiaries had completed the entire 24-month Medicare waiting period and about one-third had completed 12 months or more. This implies that eliminating the Medicare waiting period would help many beneficiaries who lack health insurance. However, this policy alone would not be of help to beneficiaries who are uninsured before entry and whose allowances are made at long intervals after SSDI entitlement.

Full report: Health Insurance and Health Care Access Before and After SSDI Entry (PDF|620KB) 

The Commonwealth Fund. (2009). Health insurance and health care access before and after SSDI entry. Livermore, G., Stapleton, D., and Claypool, H.