Health insurers are crying foul after a study funded by an insurance trade group found that Medicare Advantage, the private insurance version of Medicare, does not receive nearly the money it should get from the federal government for patients with chronic conditions. 

Specifically, the study by Avalere, a health care consulting firm, found that the Centers for Medicare and Medicaid Services (CMS) underestimates the cost it takes to treat seniors with common conditions, such as arthritis and depression. 

"We find that the model under-predicts expenditures for chronic non-cancer pain ($14.3 billion), osteoarthritis ($13.4 billion), depression ($8.9 billion), and [Rheumatoid Arthritis] ($5.3 billion)," the report concludes.