Who are prone to develop adverse effects with oral tramadol?: A retrospective cohort study

Objective: Oral tramadol is a commonly prescribed analgesic in Hong Kong. Significant adverse effects are frequently observed in our locality. Our study aims to describe the rate of significant adverse effect that warrant discontinuation of oral tramadol and identify the risk factors for development of adverse effect. Design: Retrospective cohort study. Methods: Adult patients aged greater than 18 years old admitted to the emergency medicine ward of a large-scale local hospital in Hong Kong being prescribed with oral tramadol during in-hospital stay were recruited. Significant adverse effects during the hospital stay were observed as the outcome of interest. Results: A total of 575 subjects were recruited. 29.9% experienced significant adverse effects likely related to tramadol. Age (p=0.006; odds ratio [OR]=1.017, 95% confidence interval [CI]=1.005-1.029) and sex (p=0.006; OR=1.696, 95% CI=1.166-2.465) were statistically significant predictors of adverse effects after oral tramadol. Conclusion: Our study suggests that female and increasing age patients are significant predictors for the development of adverse effect after taking oral tramadol. Possible adverse effects should be explained to the patients careful especially the higher risk groups.