Zhou 2016.

Methods	Double‐blinded, placebo controlled, randomized clinical trial Sequence generation not described Follow‐up for 3 months
Participants	Subjects: 106 adults in a university setting in China Operation: craniotomy 2 groups, size: 53/53 Age (± SD), group 1, 2: not described Men/women, group 1, 2: not described Exclusion criteria: not described
Interventions	Group 1 (ropivacaine): after the anesthesia induction, skin along the incision was infiltrated with 0.5% ropivacaine. Morphine was used as rescue analgesic postoperatively. Anaesthetic regimen not further described. Group 2 (control): exactly the same as above except 0.9% saline was substituted for ropivacaine. Adjuvants: none Immediate post‐op pain control: significantly improved
Outcomes	Dichotomous: pain vs no pain Continuous: VAS Other reported: morphine consumption, heart rate and mean arterial pressure were recorded before anesthesia induction, after anesthesia induction, after scalp infiltration, during skull drilling, mater cutting, and skin closure
Notes	We were unable to obtain additional information about randomization and blinding methods from the study author. Funding sources: funding of study not described Conflicts of interest: study authors declare no conflicts of interest
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Randomization methods not described
Allocation concealment (selection bias)	Unclear risk	Concealment of allocation not described
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Sham block was used. Blinding of personnel not described.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Blinding of outcome assessors not described
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Rate of attrition not described
Selective reporting (reporting bias)	Unclear risk	Unclear if subgroup analysis was performed
Null bias	High risk	Quote: "the incidence of pain... showed no difference between groups."

5‐HT3: 5‐hydroxytryptamine; ANOVA: analysis of variance; ASA: American Society of Anesthesiology perioperative risk classification; BPI: brief pain inventory; EMLA: eutectic mixture of local anaesthetics; Epi: epinephrine; GA: general anaesthesia; h: hour; HRQOL: health‐related quality of life; ICBG: iliac crest bone graft harvesting; IM: intramuscular; ITM: intrathecal morphine; ITT: intention‐to‐treat; IV: intravenous; Kg: kilogram; L2: lumbar segment number 2; LA: local anaesthetic; LMA: laryngeal mask airway; MAC: minimum alveolar concentration; mg: milligram; mL: millilitre; NIH: National Institute of Health; NSAID: nonsteroidal anti‐inflammatory drugs; NRS: numerical rating scale; paracetamol: acetaminophen; PACU: postanaesthesia care unit; PCA: participant controlled analgesia; PCEA: patient controlled epidural analgesia; POD: postoperative day; PVB: paravertebral block; RCT: randomized controlled trial; SA: spinal anaesthesia; SAB: subarachnoid block; SC: subcutaneous; SD: standard deviation; SF‐36: Short Form (36) Health Survey; SF‐MPQ‐2: Short Form MacGill Pain Questionaire; T4: thoracic segment 4; TAP: transabdominal plane block; TEA: thoracic epidural analgesia; µg: microgram; VAS: visual analogue scale