An algorithm, not a doctor, predicted a rapid recovery for Frances Walter, an 85-year-old Wisconsin woman with a shattered left shoulder and an allergy to pain medicine. In comments to federal regulators and interviews with STAT, many providers described rigid criteria applied by NaviHealth, which exercises prior authorization on behalf of the nation’s largest Medicare Advantage insurers, including its sister company UnitedHealthcare as well as Humana and several Blue Cross Blue Shield plans. ’”This story is part of a series examining the use of artificial intelligence in health care and practices for exchanging and analyzing patient data