Associations for surgical procedures predating the time point of clinical onset in cases or the corresponding index date in controls by ≥20 years.

Models 1 and 2, anatomic SP classification; models 3 and 4, etiologic SP classification. Other risk SPs encompass three reported etiologic SP categories, i.e., lowest-risk, no-risk, and not reclassified[7]. Age subcategories <30, 30–39, and ≥40 years at first-registered surgery.
aSubsidiary procedures' is a heterogeneous category that includes minor surgery (punctures, needle aspiration or biopsy, superficial incisions), other non-surgical, potentially invasive procedures, such as transluminal endoscopies (with or without biopsy), and, in a few instances in Denmark, blood transfusion.
SP-code distribution by body system groups in exposed cases.
bn = 15. Female genital organs and obstetric SP, 7; Digestive system and spleen, 3; Other groups, 5.
cn = 15. Female genital organs and obstetric SP, 8; Digestive system and spleen, 3, Other groups, 4.
dn = 37. Female genital organs and obstetric SP, 18; Digestive system and spleen, 8; Peripheral vessels and lymphatic system, 5; Other groups, 6.
eHR or LR SPs: acronym for higher-risk or lower-risk SPs [7].
Associations for surgical procedures predating the time point of clinical onset in cases or the corresponding index date in controls by ≥20 years.