Blue Cross Blue Shield of Massachusetts says its new system of paying doctors a fixed amount per patient improved care during the first year, contrary to critics? fears that patients would be harmed. The state?s largest health insurer said that during 2009, the 6,300 doctors paid under the new method improved care for their patients faster than the 14,200 other doctors in the Blue Cross HMO network. Quality was assessed using dozens of criteria, such as the percentage of diabetics whose glucose, blood pressure, and cholesterol levels were regularly measured and under control. Company executives said they believe the contract is also helping to control medical costs, its primary purpose, but the growth of healthcare spending is slowing overall, making it difficult to draw firm conclusions about the reasons.