Executives from some of Massachusetts' leading health insurance companies refused to answer key questions from state regulators about why some hospitals and doctors are paid up to three times as much as others for the same services. But some of the company officials acknowledged that provider payments are based on fierce competition among hospitals and doctors in some areas of the state, as well as employers' insistence that a particular hospital or physicians' group be included in their plan. The testimony was part of a probe by the state Department of Insurance into the reasons for soaring increases in insurance costs overall.
