Mitra 2012.

Methods	Randomized, double‐blind, parallel‐group controlled trial, multiple dose, active‐controlled. First dose after spinal block regression to T10.
Participants	Type of surgery: cesarean section Paracetamol group Entered/completing: 101/101 Age (mean, SD): 25.92 ± 3.09 Sex (male, %): 0 Tramadol group Entered/completing: 103/103 Age (mean, SD): 26.04 ± 3.65 Sex (male, %): 0
Interventions	Diclofenac 100 mg suppository for all participants starting at the ‘end of surgery’ and every 8 h for 24 h Paracetamol IV in 10 cc of NS (no mention of injection time), 1 g every 6 h beginning at block regression to T10 Tramadol 75 mg IV in 10 cc NS per the above protocol
Outcomes	Primary: summed pain intensities during the entire observation period, calculated as the sum of time‐weighted pain intensity scores as an area under the curve (AUC). NRS at rest and movement at 0, 1, 2, 4, 8, 12, 24 h Secondary: use of supplementary rescue analgesic (pethidine 30 mg IV, administered if the participant’s NRS scores > 4)
Source of funding	Grant received from the Department of Science & Technology (DST), Ministry of Science & Technology, Government of India
Were treatment groups comparable at baseline?	Yes ‐ age BMI, surgical duration, blood loss, NRS at rest and movement. No ‐ BP and HR lower in acetaminophen group
Details of preoperative pain	Participants receiving long‐term analgesics were excluded
Notes	Primary analysis plan was not pursued because of a non normal distribution of pain scores. Instead medians and interquartile ranges were reported and compared for each time point at rest and at movement. This includes time at 4 h. Use of rescue medications over the entire time period was summarized without specific information as to the time for request.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Using computer‐generated random number tables
Allocation concealment (selection bias)	Low risk	Coded, sealed, opaque envelopes
Blinding (performance bias and detection bias) All outcomes	Low risk	Both the test drugs (tramadol and acetaminophen) were drawn up in similar (Dispovan, Faridabad, Haryana, India) 10 ml coded syringes and diluted with normal saline so as to make the final volume of injection to 10 ml. Participants and assessors were blinded to assignment, but blinding success not tested.
Incomplete outcome data (attrition bias) All outcomes	Low risk	No missing data
Selective reporting (reporting bias)	Low risk	All outcomes from Methods section reported in Results section
Size	Unclear risk	50 to 199 participants per arm of the study (101 paracetamol, 103 tramadol)