Surgeons should consider genetic and lifestyle factors to better stratify severe diverticulitis risk and optimize patient selection.

• High-risk individuals, based on polygenic and lifestyle scores, had a hazard ratio of 4.71 for severe diverticulitis, with a cumulative incidence of 3.50% versus 0.75% in lower-risk patients.
• The combined effects of genetic and lifestyle risks surpassed the influence of either alone.

Personalized risk profiles can enhance discussions about operative interventions.