The Massachusetts House Tuesday night overwhelmingly approved its 278-page plan to curb the soaring cost of medical care. The final vote—148 to 7—sets up what could be difficult negotiations between the House and the Senate, which approved its own cost-control legislation last month. The House debated hundreds of amendments but did not make significant changes to its bill, although it did adopt a $20-million tax on hospitals and insurers that would fund prevention and public health programs.