NEW YORK — McDonald’s Corp. is having a tough time stomaching the competition.
The world’s biggest hamburger chain said a key sales figure fell for the first time in nearly a decade in October, amid a challenging economy abroad and intensifying competition at home. Global revenue at restaurants open at least 13 months fell 1.8 percent. The last time it dropped was in March 2003.
The figure is a key metric because it strips out the impact of newly opened and closed locations.
The figure fell in each of the three regions it reports on. In both the United States and Europe, it fell 2.2 percent. In the region encompassing Asia, the Middle East, and Africa, it dropped 2.4 percent.
Chief executive Don Thompson cited the ‘‘pervasive challenges of today’s global marketplace’’ for the declines.
Canada, which is not included in the monthly figures, was positive for the month.
After years of outperforming its rivals, McDonald’s has been hitting some bumps, with longtime rivals Burger King and Wendy’s Co. reviving their brands with improved menus and new TV ad campaigns. Taco Bell, owned by Yum Brands Inc., is also enjoying growth.
And people are increasingly flocking to Chipotle Mexican Grill Inc. and Panera Bread Co. restaurants, which offer better-quality food for a little more money.
McDonald’s said Thursday that it would remain focused on underscoring its value message.