Anyone who's gotten into a dispute with a medical insurer knows that working things out can be time-consuming and nerve-wracking.That seems to be the effect that a disagreement between Cook Children's Health Care System and Aetna insurance over reimbursements is having on some of those feeling the ramifications.As of November, Aetna Better Health, a Medicaid managed care network, dropped Cook Children's, which means patients using that coverage have had to switch doctors or go elsewhere for medical services, Star-Telegram business writer Jim Fuquay reported Tuesday. A Cook Children's spokeswoman said that members covered under the Children's Health Insurance Program also are affected.It's not clear how many children have been shuffled, but the potential number affected is 42,500.Families eligible for Medicaid can choose from three managed-care plans in Tarrant County: Aetna, Amerigroup (128,000 members) and Cook Children's Health Plan (108,000).Medicaid managed care is a statewide effort to control costs, encourage preventive healthcare and get low-income people to rely more on regular physicians than emergency rooms for treatment.A comparison of the plans shows that, in addition to a range of basic services that all insurers must provide, the Amerigroup and Cook plans offer several options that Aetna doesn't, such as extras for pregnant women and Boys & Girls Club membership, while Aetna offers extra behavioral health services. (bit.ly/WhXEMc)Representatives of Cook and Aetna are supposed to meet for mediation Feb. 7 with officials from the Texas Health and Human Services Commission, which administers Medicaid in the state.During the impasse, Aetna members from Tarrant County have been able to receive pediatric services at Children's Medical of Dallas or its Southlake clinic. But low-income people could find those locations challenging to reach. Southlake lacks public transit.Meanwhile, Cook says it continues to care for Aetna members who come to the emergency room or whose referral to a specialist is approved by Aetna.A resolution soon would be a healthy outcome for children whose medical well-being is at stake.