The investment bank said that the price gulf has never been greater, with pub prices rising at their fastest rate ever and off-trade prices sinking with the advent of supermarket discounts.
Supermarkets often sell lager as a loss-leader, and pub prices are rising 1.4 times faster in pubs than in the off-trade, the research found.
WestLB Panmure said that tenants and licensees are most at risk. Traditional pubs face the biggest threat because the bigger pub chains have more leverage to negotiate deals on the beer they sell.
JD Wetherspoons said: "Price is important, but pubs have always been more expensive than supermarkets. People go to the pub to socialise."
Ted Tuppen, the chief executive of Enterprise Inns, said: "If your only reason for going to the pub is price, then you might as well buy the drink at the supermarket. If you're going because of the quality of the pub, then frankly price isn't that important."