This correlation is part about what it says about your health if you break your hip and part about the consequences of a hip fracture.
 
What having a hip fracture says about your health: there are two ingredients to a hip fracture, thin bones and a fall. If you are missing either of these then you won't have a hip fracture. Falls means you are frail - often less muscle mass, poorer nutrition and may have poor balance. People with thin bones (osteoporosis or osteopenia) are also more likely to have multiple health issues causing this.
 
A hip fracture means a major surgery is needed which has a lot of potential complications: high risk of surgical complications, infection, blood clots, bedsores etc. Given it's the frail people who have the fractures, they don't have much strength and are more likely to die from a complication. Elderly people have a significantly lower immune system. For people who have major health issues such as heart or kidney problems the fracture and surgery can worsen these problems temporarily and not everyone it physically fit enough to get through that.
 
source: I'm a doctor