Mo. Rev. Stat. § 334.420

The board shall not renew any certificate of registration unless the anesthesiologist assistant has provided satisfactory evidence that the board's minimum requirements for continuing education have been met. The board's minimum requirements for continuing education shall include, but are not limited to, the successful completion of the examination for continued demonstration of qualifications once every six years, as authorized by the National Commission on Certification * of Anesthesiologist Assistants (NCCAA) or its successor. At the discretion of the board, compliance with the provision of this section may be waived for an anesthesiologist assistant that has discontinued the practice of an anesthesiologist assistant due to retirement.