LifePoint Hospitals Inc. might have to wait at least another month to close its purchase of Sumner Regional Health Systems. The state attorney general's office has extended its review of the deal 30 days through July 30. Clearance from the attorney general is the final approval that the Brentwood-based hospital chain needs. The attorney general must review whether the sale is in the public's interest since it involves purchase of a not-for-profit entity by a for-profit company. LifePoint said it still is committed to acquiring Sumner.