Factors Associated With the Presence of Postoperative Headache in Elective Surgery Patients: a Prospective Single Center Cohort Study

A dedicated team interviewed patients preoperatively and during the first five postoperative days and collected data regarding medical history, surgery, anaesthesia and the presence of postoperative headache by manual record review. The frequency of preoperative headache was assessed by asking the subjects on the appearance or not of headache within the last year. Additional information were obtained to distinguish migraine which was deemed present only when the participants reported two or more of the following specific symptoms supporting this diagnosis as proposed by the International Headache Society; episodic headache (4-72 hours) with the following features: moderate or severe throbbing pain, worsened by movement, associated with nausea/vomiting, photophobia or phonophobia, with or without visual aura.

Specifically, preoperative data included patients' demographics, marital status, life-style and habits, as caffeine consumption (>200 mg/day or >2 cups of coffee/day), alcohol (drink equivalent > 15ml absolute alcohol) and tobacco consumption, previous experience or/and family history of headache. Intraoperative data included the type of anaesthesia (general, regional anaesthesia or their combination); anaesthetic drugs used; type and duration of surgery; intraoperative patients' position; and intraoperative adverse events including hypotension (decrease >20% from baseline), hypertension (increase >20% from baseline), hypercarbia (PaCO2 >6 kPa) and hypoxia (SpO2 <90%). Noticeably, the choice of anaesthetic technique and postoperative management were determined by the engaged anaesthesiologist.

Postoperative headache was defined as a dichotomous variable (i.e. present or not present) by asking the participants twice daily for the first five days (or less if discharged earlier) after anaesthesia and surgery.