Screening Partnership Reform Act of 2018 This bill converts the security screening opt out program (a program providing for private screening companies to conduct security screening at airports) into the screening partnership program and further revises it to: (1) authorize the operator of an airport to select a qualified private screening company; (2) require that a contract with such a private screening company certify to Congress that the cost of providing screening services at the airport is equal to or less than the cost to the federal government of providing screening services at that airport during the term of the contract and that entering into the contract would not compromise aviation security; and (3) authorize consideration of recommendations by private screening companies for improving aviation security.