Metamizole vs. ibuprofen at home after day case surgery A double-blind randomised controlled noninferiority trial

BACKGROUND NSAIDs and paracetamol are the cornerstones of pain treatment after day case surgery. However, NSAIDs have numerous contraindications and consequently are not suitable in up to 25% of patients. Metamizole is a non-opioid compound with a favourable gastro-intestinal and cardiovascular profile compared with NSAIDs.

OBJECTIVES The study aimed to assess if a combination of metamizole and paracetamol is noninferior to a combination of ibuprofen and paracetamol in treating pain at home after painful day case surgery.

DESIGN A double-blind randomised controlled trial.

SETTING Single centre.

PATIENTS Two hundred patients undergoing elective ambulatory haemorrhoid surgery, arthroscopic shoulder or knee surgery, or inguinal hernia repair.

INTERVENTION Patients were randomly allocated to receive either metamizole and paracetamol (n = 100) or ibuprofen and paracetamol (n = 100) orally for four days.

MAIN OUTCOME MEASURES Average postoperative pain intensity using a numerical rating scale and use of rescue medication were measured in the postanaesthesia care unit (PACU) and on postoperative days (POD) 1 to 3. A difference in mean numerical rating scale score of 1 point or less was considered noninferior. Adverse effects of study medication and satisfaction with study medication were measured on PODs 1 to 3 by telephone follow-up.

RESULTS In the PACU, the difference in mean +/- SD pain score between metamizole and paracetamol and ibuprofen and paracetamol was 0.85 +/- 0.78. From POD 1 to 3, this difference was lower than 1, resulting in noninferiority. Rescue opioid consumption in the PACU and on PODs 1 and 3 was not significantly different between treatment groups. Rescue opioid consumption on POD2 was significantly higher in the ibuprofen and paracetamol group (P = 0.042). Adverse effects of study medication and overall patient satisfaction were similar in both groups.

CONCLUSION Paracetamol/metamizole and paracetamol/ibuprofen are equally effective in treatment of acute postoperative pain at home after ambulatory surgery with comparable patient satisfaction levels.