Table 1 Characteristics of the reviewed studies
| Â | Author, year | Country | Study design | Sample size | Gender (n) | Age range (year) | Type of operation | Dosage | Forms of drug use | Effectivness |
|---|---|---|---|---|---|---|---|---|---|---|
1 | Snall (2013) | Finland | Single-blinded RCT | 41 | M:40 F:1 | 18–51 | Open reduction/ostheosynthesis of mandibular fractures | 30 mg | IV 10 mg/IM 20 mg | No |
2 | Karaman et al. (2009a) | Turkey | Single-blinded RCT | 100 | NR | NR | Adenotonsillectomy/ tonsillectomy | 0.2Â mg/kg | IV | Yes |
3 | Karaman et al. (2009b) | Turkey | Single-blinded RCT | 100 | NR | NR | Adenotonsillectomy/ tonsillectomy | 0.7Â mg/kg | IV | Yes |
4 | Newhook et al. (2021b) | USA | Retrospective cohort | 373 | M:210 F:163 | 35–88 | Pancreatic ductal adenocarcinoma resection | 4–10 mg | IV | No |
5 | Jacob et al. (2015a) | Netherlands | Double-blinded RCT | 4465 | M:3248 F:1217 | NR | Cardiac surgery with CPB | 1Â mg/kg | IV | Yes |
6 | Dieleman et al. (2012) | Netherlands | Double-blinded RCT | 4482 | M:3250 F:1232 | NR | Cardiac surgery with CPB | 1Â mg/kg | IV | Yes |
7 | Zhang et al. (2019) | China | Double-blinded RCT | 214 | M:51 F:163 | 18–65 | Thyroid | 0.1 mg/kg | IV | Yes |
8 | Pappas et al. (1998) | USA | Double-blinded RCT | 128 | NR | 2–12 | Ambulatory tonsillectomy | 1 mg/kg | IV | Yes |
9 | Shakeel et al. (2010) | Scotland | Retrospective cohort | 333 | M:157 F:176 | NR | Tonsillectomy | NR | NR | Yes |
10 | Tkachenko and Pyasetska (2019) | Ukraine | Double-blinded RCT | 83 | M:0 F:83 | 18–36 | Cesarean section | 4 mg | Intrathecal | Yes |
11 | Tkachenko and Pyasetska (2019) | Ukraine | Double-blinded RCT | 82 | M:0 F:82 | 18–36 | Cesarean section | 8 mg | IV | No |
12 | Blume et al. (2018b) | Germany | Retrospective cohort | 49 | M:32 F:17 | NR | Cervical spondylotic myelopathy | 40Â mg | IV | No |
13 | Ituk and Thenuwara (2018) | USA | Double-blinded RCT | 52 | NR | NR | Post-cesarean delivery analgesia | 8Â mg | IV | No |
14 | Lim et al. (2011) | Korea | RCT | 80 | M:47 F:33 | NR | Gallbladder resection | 8Â mg | IV | Yes |
15 | Hatfield (2017) | USA | Case–control | 200 | M:100 F:100 | 18–64 | Laparoscopic cholecystectomy | 4–8 mg | IV | Yes |
16 | Jacob et al. (2015b) | Netherlands | Double-blinded RCT | 62 | M:47 F:15 |  > 18 | Cardiac surgery | 1 mg/kg | IV | No |
17 | Sauër et al. (2014) | Netherlands | Double-blinded RCT | 737 | M:480 F:257 |  > 18 | Isolated CABG, valve surgery | 1 mg | IV | No |
18 | Corcoran et al. (2017) | 10 countries-ENIGMA II Trial Post hoc | Double-blinded RCT | 5499 | M:3559 F:1940 |  > 45 | Urology, neurology, gastrointestinal, liver, ENT, Orthopedic, plastics, gynecological, vascular, colorectal | NR | NR | No |
19 | Klement et al. (2018) | USA | Retrospective cohort | 7910 | M:3649 F:4261 | NR | Total joint arthroplasty | NR | IV | Yes |
20 | Lomivorotov et al. (2020) | China, Brazil, Russia | Double-blinded RCT | 394 | M:186 F:208 |  < 1 | Cardiac surgery | 1 mg | IV | No |
21 | Samona et al. (2017) | USA | Retrospective cohort | 102 | M:44 F:58 |  > 18 | Total knee arthroplasty | NR | IV | Yes |
22 | Sandini et al. (2018b) | USA | Retrospective cohort | 562 | M:322 F:357 | NR | Pancreaticoduodenectomy | NR | IV | Yes |
23 | Osch et al. (2015) | Netherlands-DECS trial post hoc | Double-blinded RCT | 4482 | M:3250 F:1232 |  > 18 | Cardiac surgery | 1 mg | IV | No |
24 | Khan and Iqbal (2012) | Pakistan | Quasi experiment | 100 | M:66 F:34 | 6_30 | Tonsillectomy | 0.5Â mg/kg | IV | Yes |
25 | Thongrong et al. (2018) | Thailand | Double-blinded RCT | 54 | M:17 F:37 | 29–74 | Microvascular decompression | 4 mg | IV | No |
26 | Bateman et al. (2006) | USA | Retrospective cohort | 65 | NR | 2–120 months | Cleft palate | 4 mg | IV | Yes |
27 | Foulkes (1990) | Georgia | Retrospective cohort | 45 | M:30 F:15 | 24–87 | Lumbar hemilaminectomy/micro diskectomy | 16 mg | NR | Yes |
28 | Splinter and Roberts (1996) | Canada | Double-blinded RCT | 133 | NR | 2–12 | Tonsillectomy | 150 pg/kg | IV | Yes |
29 | Egan et al. (2019b) | USA | Retrospective cohort | 121 | M:87 F:34 | 27–87 | Diabetic patients who underwent surgery due to cutaneous burns | 10–4 mg | IV | No |