American Medical Directors Association. AMDA was officially chartered in June, 1977 and is now known as the Society for Post-Acute and Long-Term Care Medicine is the only medical specialty society representing the community of over 50,000 medical directors, physicians, nurse practitioners, physician assistants, and other practitioners working in the various post-acute and long-term care (PALTC) settings. The Society’s 5,500 members work in skilled nursing facilities, long-term care and assisted living communities, CCRCs, home care, hospice, PACE programs, and other settings.