| Level I | Good quality evidence |
Systematic review of RCTs with consistent findings High quality individual RCT |
| Level II |
Limited quality patient orientated evidence |
Systematic review of lower quality studies or studies with inconsistent findings Low quality clinical trial Cohort studies Case-control studies |
| Level III | Other |
Consensus guidelines, extrapolations from bench research, usual practice, opinion, disease-oriented evidence (intermediate or physiologic outcomes only), or case series |
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Tramadol - caution: The Royal College of Anaesthetists. Opioid Aware Resource, 2019. [Accessed August 2019]. https://www.rcoa.ac.uk/faculty-of-pain-medicine/opioids-aware
Tramadol - caution: Kaye AD, Jones MR, Kaye AM, Ripoll JG, Galan V, Beakley BD, Calixto F, Bolden JL, Urman RD, Manchikanti L. Prescription Opioid Abuse in Chronic Pain: An Updated Review of Opioid Abuse Predictors and Strategies to Curb Opioid Abuse: Part 1. Pain Physician. 2017 Feb;20(2S):S93-S109. https://www.ncbi.nlm.nih.gov/pubmed/28226333
Tramadol– caution: Beakley BD, Kaye AM, Kaye AD. Tramadol, Pharmacology, Side Effects, and
Serotonin Syndrome: A Review. Pain Physician. 2015 Jul-Aug;18(4):395-400. https://www.ncbi.nlm.nih.gov/pubmed/26218943
Tramadol – caution: Sharma V. Tramadol-Induced Hypomania and Serotonin Syndrome. Prim Care
Companion CNS Disord. 2016 Dec 15;18(6). https://www.ncbi.nlm.nih.gov/pubmed/28002658
Tramadol – caution: Hassamal S, Miotto K, Dale W, Danovitch I. Tramadol: Understanding the Risk of
Serotonin Syndrome and Seizures. Am J Med. 2018 Nov;131(11):1382.e1-1382.e6. https://www.ncbi.nlm.nih.gov/pubmed/29752906