Final answer:
The two groups added to Medicare eligibility after its inception are individuals eligible for disability benefits from Social Security and patients with end-stage renal disease.
Step-by-step explanation:
After the initial establishment of Medicare, two groups were added to those eligible for its benefits: individuals eligible for disability benefits from Social Security and patients with end-stage renal disease (ESRD). These expansions were among several amendments to the original act. Initially, Medicare was designed to cover the medical expenses of those over 65, but over time, eligibility criteria broadened.
The widening of eligibility reflected the program's adjustment to changing healthcare needs and demographics, including supporting those with long-term disabilities and specific chronic conditions like ESRD requiring expensive treatment such as dialysis or kidney transplantation. These additions have provided vital support for those with significant healthcare needs who might otherwise be unable to afford necessary treatments.