I think there is a confusion between Social Security Death Index (SSDI) which provides the date of death and the State/City where Social Security benefits were first claimed, and Social Security Disability (SSD, or sometimes refers to as SSDI) which are Social Security benefits granted based on the individual's disability. The application date for this benefit provides demographic information and health information about the applicant. 

Dan Efrat
Cherry Hill, NJ US
Researching Israelit (from Novogrudok, Belarus and Riga area, Latvia), Rabinowitz (Dyatlovo/Zhetl in Belarus( Pruss, in the Ukraine) and Koifman (in the Ukraine)