Landwehr 2005.

Methods	Randomized, double‐blinded, placebo‐ and active‐controlled Medications administered 30 min before arrival in the recovery area
Participants	Type of surgery: retinal Propacetamol group Entered/completing: 12/12 Age (mean, SD): 52 ± 18 Sex (male, %): 67 Metamizole group Entered/completing: 13/13 Age (mean, SD): 60 ± 19 Sex (male, %): 31? (data reported in error) Placebo group Entered/completing: 13/13 Age (mean, SD): 58 ± 22 Sex (male, %): 69
Interventions	Intervention: 1 g paracetamol in 100 ml over 15 min Active control: 1 g metamizol Placebo: 100 ml normal saline
Outcomes	Pain intensity at rest and on coughing (VRS, VAS) Opioid consumption (tilidine) Patient satisfaction (categorical)
Source of funding	The study was in part financed by a grant from Bristol‐Myers Squibb GmbH, München, Germany
Were treatment groups comparable at baseline?	Yes: demographics
Details of preoperative pain	Not reported
Notes	—
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated code
Allocation concealment (selection bias)	Low risk	Code prepared at a remote site and sealed in sequentially numbered, opaque envelopes
Blinding (performance bias and detection bias) All outcomes	Low risk	Infusions were made to look identical
Incomplete outcome data (attrition bias) All outcomes	Low risk	5 participants in placebo group had incomplete data, imputed by LOCF. It appears that all other participants contributed data at all time points for all outcomes.
Selective reporting (reporting bias)	Low risk	All outcomes from Methods section reported in Results section. Some adverse event data listed only as P values.
Size	High risk	Fewer than 50 participants per arm of the study (12 propacetamol, 13 metamizole, 13 placebo)