Democrats’ decisive sweep of the U.S. House and Senate in Tuesday’s elections will reshape the direction of federal health policy — setting the stage for oversight investigations, a legislative push to reverse cuts to the Affordable Care Act and Medicaid, and a focus on lowering costs such as insurance premiums and drug prices. The conclusive string of victories sets up Democrats to argue that voters — who said in preelection surveys that healthcare affordability was a top concern — have given them a clear mandate to overturn historic cuts President Donald Trump and Republicans made to publ...