SAYRE, Pa.-Guthrie Healthcare System has signed a letter of intent to be the local provider of care for Geisinger Health Plan in the northern tier of Pennsylvania and the southern tier of New York. Guthrie will offer Danville, Pa.-based Geisinger as its preferred managed-care product. Financial terms of the agreement are being negotiated. As part of the agreement, Geisinger will assist the system in physician networking. A year ago, Guthrie and its multispecialty group-practice affiliate, 205-member Guthrie Clinic, Sayre, ended a four-year relationship. The affiliation was discontinued as part of an agreement settling litigation against Guthrie Healthcare System brought by Guthrie Clinic physicians who served on the system's board. Guthrie Clinic currently provides staffing for the system's flagship facility, Robert Packer Hospital in Sayre, under a lease agreement. Standard & Poor's Corp. recently downgraded the system's A+ underlying rating to A- and removed it from CreditWatch. The rating had been watched because of the system's financial position and concerns relating to the litigation (April 11, 1994, p. 17). The underlying rating on the system's AAA credit-enhanced bonds was lowered because of declining utilization, deteriorating financial performance and continued fallout from the litigation, the New York-based credit-rating agency said.