This info comes directly from the above LINK!

"What to do if the individual gets the long form
The long form (SSA-454-BK) is 10 pages and is very similar to the original forms that the individual filled out when he or she first applied for disability benefits. The form primarily asks for the names and addresses of all medical providers. SSA will obtain the medical records directly from the medical providers. This form not only goes to persons whose condition is expected to improve, it is also sent to persons whose short form was “kicked” by the computer, and is randomly sent to persons as part of a trial or study that the Social Security Administration may be conducting. The long form should be filled out just as thoroughly and completely as when the individual initially applied for disability benefits. On this form, it is important to note any changes in the medical condition, especially new infections, symptoms or diagnoses. Individuals must make sure their doctors are alerted to the review and that they submit new medical records since their last review promptly.

SSA will ask for evidence that it will need for the CDR that is similar to what it needed for the initial claim for Social Security disability benefits. SSA will have the individuals fill out forms describing their current condition and list all of the places where she or he have received treatment. SSA will obtain copies of all recent medical records. SSA may schedule examinations or tests for the individual if more information is needed about their condition. If he individual fails to provide information that SSA asks for or if the individual fails to attend an examination that SSA schedules for that SSA schedules for them, their benefits will be terminated."