Europe’s flagging economy got off to a weak start in 2019, as Italy showed few signs of emerging from recession and the uncertainty around Britain’s exit from the European Union dragged on U.K. growth.

The eurozone economy slowed more sharply than expected in 2018 and seems set to cool further this year. In addition, decelerating Chinese growth means the outlook for the global economy has become a big worry for investors and policy makers.

Survey...