Medicare Part B

To determine whether Medicare carriers in various parts of the country differed significantly in denying coverage for medical treatment they consider unnecessary, GAO analyzed Medicare Part B data on claims processed by six Medicare carriers for 74 services that were either expensive or heavily used. The carriers GAO studied included California Blue Shield, Transamerica Occidental Life Insurance, Connecticut General Life Insurance Company, Blue Shield of South Carolina, Illinois Blue Cross and Blue Shield, and Wisconsin Physicians' Service. GAO found that the magnitude of carrier denial rates for Medicare Part B claims was generally low and persistent for two consecutive years, although rates for some services shifted. Medical necessity denial rates for 74 services across six carriers varied substantially. The main reason was that some carriers used computerized screening criteria for specific services while others did not. Further, a small proportion of the providers accounted for half of the denied claims. To a lesser degree, the varying interpretation of national coverage standards across carriers, differences in the way carriers treated claims with missing information, and reporting inconsistencies also explained the variation in carrier denial rates.