Correlation Patterns between Primary and Secondary Diagnosis Codes in the Social Security Disability Programs

This paper addresses impairment co-morbidity among participants in programs that provide dis-ability benefits. Co-morbidity in this context is defined as the simultaneous presence of a primary and a secondary medical diagnosis. I fit a high-dimensional Bayesian multivariate probit model with a 10% random sample of 2009 initial claimants (disabled workers, including individuals concurrently applying for Disability Insurance and Supplemental Security Income). The resulting correlation estimates provide evidence of strong impairment co-morbidity patterns at the initial-claim level. Many of the findings mirror the epidemiological evidence, such as associations of diabetes with chronic renal failure, open wounds of a lower limb, peripheral neuropathies, and blindness/low vision. Other results are surprising. For instance, the correlation estimates defy the presumption of high positive association between mental and musculoskeletal-system diagnoses