Tramadol appears to be associated with higher mortality risk among older patients with osteoarthritis when compared against common NSAIDs, according to findings from a study published online March 12 in.
The findings from the retrospective cohort study are worth noting despite their susceptibility to confounding by indication because “tramadol is a weak opioid agonist and has been considered a potential alternative to NSAIDs and traditional opioids because of its assumed relatively lower risk of serious cardiovascular and gastrointestinal adverse effects than NSAIDs, as well as a lower risk of addiction and respiratory depression compared with other opioids,” wrote Chao Zeng, MD, PhD, of Xiangya Hospital of Central South University, Changsha, China, and his coauthors.
The investigators analyzed data from a combined total of 88,902 individuals aged 50 years and older with knee, hip, or hand osteoarthritis who were seen during 2000-2015 and had visits recorded in the United Kingdom’s The Health Improvement Network (THIN) electronic medical records database. Participants were matched on sociodemographic and lifestyle factors, as well as osteoarthritis duration, comorbidities, other prescriptions, and health care utilization prior to the index date of the study.
Over 1 year of follow-up, researchers saw a 71% higher risk of all-cause mortality in patients taking tramadol than that in seen in those taking naproxen, 88% higher than in those taking diclofenac, 70% higher than in those taking celecoxib, and about twice as high as in patients taking etoricoxib.
However, there was no significant difference in risk of all-cause mortality between tramadol and codeine, the researchers found.
The authors suggested that tramadol may have adverse effects on the neurologic system by inhibiting central serotonin and norepinephrine uptake, which could potentially lead to serotonin syndrome. They also speculated that it could increase the risk of postoperative delirium, cause fatal poisoning or respiratory depression if taken in conjunction with alcohol or other drugs, or increase the risk of hypoglycemia, hyponatremia, fractures, or falls.
The numbers of deaths from cardiovascular, gastrointestinal, infection, cancer, and respiratory diseases were all higher in the tramadol group, compared with patients taking NSAIDs, but the differences were not statistically significant because of the relatively small number of deaths, the authors said.
Overall, 44,451 patients were taking tramadol, 12,397 were taking naproxen, 6,512 were taking diclofenac, 5,674 were taking celecoxib, 2,946 were taking etoricoxib, and 16,922 were taking codeine.
Patients in the tramadol cohort were generally older, with higher body mass index, a longer duration of osteoarthritis, and had a higher prevalence of comorbidities, higher health care utilization, and more prescriptions of other medications.
The authors noted that, while the patients from each medication cohort were matched on propensity score, the results were still susceptible to confounding by indication and should be interpreted with caution.
The study was supported by grants from the National Institute of Arthritis and Musculoskeletal and Skin Diseases and the National Natural Science Foundation of China. One author declared funding from the National Institute on Drug Abuse during the conduct of the study and grants from Optum Labs outside the study. No other conflicts of interest were declared.
SOURCE: Zeng C et al. .