Characteristics of Patients with Tramadol Use or Abuse: A Systematic Review and Meta-Analysis

Recently, an increasing number of studies have reported an association between the incidence of seizures and the use or abuse of tramadol. The aim of this study was to review articles involving patients with tramadol-induced seizures that reported their characteristics and the consumed tramadol dosage. The following databases were searched from their inception until October 30, 2018: PubMed, EMBASE, the Cochrane Library, Scopus, Ovid, Proquest and Science direct. All cross-sectional studies that reported the tramadol dosage and individual characteristics of patients with tramadol-induced seizure were included. The studies were assessed for any bias risk using the adapted Newcastle-Ottawa scale. The pooled estimates were reported using random-effects meta-analysis. Our search identified a total of 3,275 articles, and we finally extracted data from 11 studies involving 970 patients. The included studies were all conducted in developing countries. The pooled data resulted in an estimated mean (+/- standard deviation) of 1,454.5 +/- 333.6 mg for tramadol dosage that induces seizures in patients. The mean minimum tramadol dose causing seizure in the pooled data was 169.5 +/- 131.2 mg. The mean age of the patients was 25.85 +/- 0.86 years. In addition, 83.37 +/- 12.6% of the patients were male, and the manner of poisoning in 70.51 +/- 29.07% of the patients was suicide or abuse. Our findings demonstrated that the prevalence of seizures following the consumption of tramadol was higher among males. Therefore, the probability of seizure should be considered by physicians in prescribing tramadol, and the individuals receiving it, especially the ones at a higher risk of exposure, should be properly informed about its complications.