Ankylosing spondylitis is an autoimmune system disease mainly caused by various factors, such as genetic factors, environmental factors, trauma to the sacroiliac joint, and allergic reactions. Under the influence of these factors, it leads to inflammation, pain, and stiffness at the sacroiliac joint and spinal attachment points as the main symptoms. It mostly affects young men.

Generally speaking, mild ankylosing spondylitis has little impact on the patient's lifespan. Patients may only experience pain and limited mobility in the sacroiliac joint and spine throughout their lives. Through appropriate treatment and functional exercises, the condition can be controlled, and it is quite common for patients to live to their sixties, seventies, or even eighties.

However, there are also cases of ankylosing spondylitis that start early and progress rapidly in clinical practice. In the early stage, the condition can progress to involve the nervous system, cardiovascular system, etc., resulting in multiple organ dysfunctions, which will greatly shorten the patient's life. The youngest patient seen clinically died of ankylosing spondylitis at around thirty years old. However, this situation is generally very rare, and patients don't need to worry too much.