All-Cause Mortality Associated with Tramadol Use: A Case-Crossover Study

Immeasurable Time Bias in Self-controlled Designs: Case-crossover, Case-time-control, and Case-case-time-control Analyses

BACKGROUND

Impact of immeasurable time bias (IMTB) is yet to be examined in self-controlled designs.

METHODS

We conducted case-crossover, case-time-control, and case-case-time-control analyses using Korea's healthcare database. Two empirical examples among elderly patients were used: 1) benzodiazepines-hip fracture; 2) benzodiazepines-mortality. For cases, the date of hip fracture diagnosis or death was defined as the index date, and the inherited date of their matched cases for controls or future cases. Exposure was assessed in the 1-30 day (hazard) and 61-90 day (control) windows preceding the index date. A non-missing exposure setting included in- and outpatient prescriptions and the pseudo-outpatient setting included only the outpatients. Conditional logistic regression was done to estimate odds ratios (ORs) with 95% confidence intervals (CIs), where the relative difference in OR among the two settings was calculated to quantify the IMTB.

RESULTS

The IMTB had negligible impacts in the hip fracture example in the case-crossover (non-missing exposure setting OR 1.27; 95% CI, 1.12-1.44; pseudo-outpatient setting OR 1.21; 95% CI, 1.06-1.39; magnitude 0.05), case-time-control (OR 1.18; 95% CI, 0.98-1.44; OR 1.13; 95% CI, 0.92-1.38; 0.04, respectively), and case-case-time-control analyses (OR 0.99; 95% CI, 0.80-1.23; OR 0.94; 95% CI, 0.75-1.18; 0.05, respectively). In the mortality example, IMTB had significant impacts in the case-crossover (non-missing exposure setting OR 1.44; 95% CI, 1.36-1.52; pseudo-outpatient setting OR 0.72; 95% CI, 0.67-0.78; magnitude 1.00), case-time-control (OR 1.38; 95% CI, 1.26-1.51; OR 0.68; 95% CI, 0.61-0.76; 1.03, respectively), and case-case-time-control analyses (OR 1.27; 95% CI, 1.15-1.40; OR 0.62; 95% CI, 0.55-0.69; 1.05, respectively).

CONCLUSION

Although IMTB had negligible impacts on the drug's effect on acute events, as these are unlikely to be accompanied with hospitalizations, it negatively biased the drug's effect on mortality, an outcome with prodromal phases, in the three self-controlled designs.

Co-prescribing of opioids and benzodiazepines/Z-drugs associated with all-cause mortality—A population-based longitudinal study in primary care with weak opioids most commonly prescribed

Introduction: The risk of mortality associated with the co-prescribing of benzodiazepines and opioids has been explored in a number of papers mainly focusing on strong opioids. The mortality risk associated with the use of weak opioids has not been dealt with to a similar extent.

Objective: To assess the mortality risk in primary care patients with consistent 3-year co-prescribing of benzodiazepine/Z-drugs (benzodiazepine receptor modulators) and mainly weak opioids (codeine, tramadol).

Methods: Of 221,804 patients contacting the primary healthcare centres, 124,436 were selected for further analysis, 88,832 participants fulfilled the inclusion criteria, aged 10–69 years and were divided into four groups with neither any use of benzodiazepines/Z-drugs nor opioids as Group 1, 3 years’ use of opioids and no/minimal benzodiazepines/Z-drugs as Group 2, with benzodiazepines/Z-drugs and no/minimal opioids as Group 3, and finally both benzodiazepines/Z-drugs and opioids as Group 4. Hazard ratios were calculated with the no-drug group as a reference, using Cox proportional hazards regression model adjusted for age, sex, number of chronic conditions and cancer patients excluded (n = 87,314).

Results: Hazard ratios for mortality increased both in Group 3 where it was 2.66 (95% CI 2.25–3.09) and in Group 4 where it was 5.12 (95% CI 4.25–6.17), with increased dose and higher number of chronic conditions. In Group 4 an opioid dose-dependent increase in mortality among persons using >1000 DDDs benzodiazepines/Z-drugs was observed when those on less than ≤300 DDDs of opioids with HR 4.94 (95% CI 3.54–6.88) were compared to those on >300 DDDs with HR 7.61/95% CI 6.08–9.55). This increase in mortality was not observed among patients on <1000 DDDs of benzodiazepines/Z-drugs.

Conclusion: The study supports evidence suggesting that mortality increases in a dose-dependent manner in patients co-prescribed benzodiazepines/Z-drugs and weak opioids (codeine, tramadol). An association between the number of chronic conditions and a rise in mortality was found. Long-term use of these drugs should preferably be avoided. Non-pharmacological therapy should be seriously considered instead of long-term use of benzodiazepines/Z-drugs, and deprescribing implemented for chronic users of these drugs when possible.

Comparison of Online Patient Reviews and National Pharmacovigilance Data for Tramadol-Related Adverse Events: Comparative Observational Study

BACKGROUND

Tramadol is known to cause fewer adverse events (AEs) than other opioids. However, recent research has raised concerns about various safety issues.

OBJECTIVE

We aimed to explore these new AEs related to tramadol using social media and conventional pharmacovigilance data.

METHODS

This study used 2 data sets, 1 from patients' drug reviews on WebMD (January 2007 to January 2021) and 1 from the US Food and Drug Administration (FDA) Adverse Event Reporting System (FAERS; January 2016 to December 2020). We analyzed 2062 and 29,350 patient reports from WebMD and FAERS, respectively. Patient posts on WebMD were manually assigned the preferred terms of the Medical Dictionary for Regulatory Activities. To analyze AEs from FAERS, a disproportionality analysis was performed with 3 measures: proportional reporting ratio, reporting odds ratio, and information component.

RESULTS

From the 869 AEs reported, we identified 125 new signals related to tramadol use not listed on the drug label that satisfied all 3 signal detection criteria. In addition, 20 serious AEs were selected from new signals. Among new serious AEs, vascular disorders had the largest signal detection criteria value. Based on the disproportionality analysis and patients' symptom descriptions, tramadol-induced pain might also be an unexpected AE.

CONCLUSIONS

This study detected several novel signals related to tramadol use, suggesting newly identified possible AEs. Additionally, this study indicates that unexpected AEs can be detected using social media analysis alongside traditional pharmacovigilance data.

Opioid use frequency in early axial spondyloarthritis in Finland - a pharmacoepidemic register study

OBJECTIVES

To evaluate opioid use among incident axial spondyloarthritis (axSpA) patients compared to general population.

METHODS

From the national register, we identified all adult patients with axSpA (ICD-10 codes M45-46), who between 2010 and 2014 (index date, ID) were for the first time granted special reimbursement for any disease-modifying anti-rheumatic drugs (DMARDs). Three matched population controls were identified for each patient. Drug purchases were evaluated between 2009-15, and opioid use was analyzed for one year before and after the ID. The Defined Daily Dose (DDD) was used as a tool to assess the opioid consumption before and after the biological (b) DMARD initiation.

RESULTS

We identified 3,577 axSpA patients and 10,573 controls. Of these patients, 97.2% started a conventional synthetic (cs) DMARD during a year after ID and 23.4% switched later to a self-injected bDMARD between the ID and 31 Dec 2015 (median follow-up 3.4 years). Opioids were purchased at least once by 29.8% and 21.7% of the patients in the years before and after the ID, respectively, compared to 8.1% and 7.8% of the controls. The proportion of opioid-using patients was greatest during the last quarter before the ID [relative risk (RR) 4.72 (95% CI 4.14 to 5.39)] compared to controls, and it remained higher [RR 2.84 (2.59 to 3.11)] also after the start of csDMARDs. DDD of opioid consumption decreased from 7.7 to 1.6/1,000 inhabitants after bDMARD initiation.

CONCLUSION

Considerably more axSpA patients than population controls used opioids. The opioid consumption by dose decreased clearly after bDMARD initiation.

Tramadol versus codeine and the short-term risk of cardiovascular events in patients with non-cancer pain: A population-based cohort study

AIMS

The effect of tramadol on the cardiovascular system is largely unknown. There is concern that, with its multimodal mechanism of action to increase serotonin and norepinephrine levels in the body, it could increase the risk of arterial ischaemia and cardiovascular events. We aimed to compare the short-term risk of cardiovascular events with the use of tramadol to that of codeine among patients with non-cancer pain.

METHODS

We conducted a retrospective population-based cohort study using data from the Clinical Practice Research Datalink (CPRD) with new users of tramadol or codeine from April 1998 to March 2017. Exposure was defined using an approach analogous to an intention-to-treat, with a maximum follow-up of 30 days. The primary endpoint was myocardial infarction, and secondary endpoints were unstable angina, ischaemic stroke, coronary revascularization, cardiovascular death and all-cause mortality. Hazard ratios (HRs) were estimated using Cox proportional hazards models, adjusted for high-dimensional propensity score.

RESULTS

The final cohort included 123 394 tramadol users and 914 333 codeine users. When tramadol was compared to codeine, the adjusted hazard ratio (HR) of myocardial infarction was 1.00 (95% CI 0.81-1.24). There was also no evidence of elevated risks of unstable angina (0.92; 95% CI 0.67-1.27), ischaemic stroke (0.98; 95% CI 0.82-1.17), coronary revascularization (0.97; 95% CI 0.69-1.38), cardiovascular death (1.07; 95% CI 0.93-1.23) or all-cause mortality (1.03; 95% CI 0.94-1.14) when tramadol was compared to codeine.

CONCLUSIONS

Short-term use of tramadol, compared with codeine, was not associated with an increased risk of cardiac events among patients with non-cancer pain.

Repeated Administration of Clinically Relevant Doses of the Prescription Opioids Tramadol and Tapentadol Causes Lung, Cardiac, and Brain Toxicity in Wistar Rats

Tramadol and tapentadol, two structurally related synthetic opioid analgesics, are widely prescribed due to the enhanced therapeutic profiles resulting from the synergistic combination between μ-opioid receptor (MOR) activation and monoamine reuptake inhibition. However, the number of adverse reactions has been growing along with their increasing use and misuse. The potential toxicological mechanisms for these drugs are not completely understood, especially for tapentadol, owing to its shorter market history. Therefore, in the present study, we aimed to comparatively assess the putative lung, cardiac, and brain cortex toxicological damage elicited by the repeated exposure to therapeutic doses of both prescription opioids. To this purpose, male Wistar rats were intraperitoneally injected with single daily doses of 10, 25, and 50 mg/kg tramadol or tapentadol, corresponding to a standard analgesic dose, an intermediate dose, and the maximum recommended daily dose, respectively, for 14 consecutive days. Such treatment was found to lead mainly to lipid peroxidation and inflammation in lung and brain cortex tissues, as shown through augmented thiobarbituric acid reactive substances (TBARS), as well as to increased serum inflammation biomarkers, such as C reactive protein (CRP) and tumor necrosis factor-α (TNF-α). Cardiomyocyte integrity was also shown to be affected, since both opioids incremented serum lactate dehydrogenase (LDH) and α-hydroxybutyrate dehydrogenase (α-HBDH) activities, while tapentadol was associated with increased serum creatine kinase muscle brain (CK-MB) isoform activity. In turn, the analysis of metabolic parameters in brain cortex tissue revealed increased lactate concentration upon exposure to both drugs, as well as augmented LDH and creatine kinase (CK) activities following tapentadol treatment. In addition, pneumo- and cardiotoxicity biomarkers were quantified at the gene level, while neurotoxicity biomarkers were quantified both at the gene and protein levels; changes in their expression correlate with the oxidative stress, inflammatory, metabolic, and histopathological changes that were detected. Hematoxylin and eosin (H & E) staining revealed several histopathological alterations, including alveolar collapse and destruction in lung sections, inflammatory infiltrates, altered cardiomyocytes and loss of striation in heart sections, degenerated neurons, and accumulation of glial and microglial cells in brain cortex sections. In turn, Masson's trichrome staining confirmed fibrous tissue deposition in cardiac tissue. Taken as a whole, these results show that the repeated administration of both prescription opioids extends the dose range for which toxicological injury is observed to lower therapeutic doses. They also reinforce previous assumptions that tramadol and tapentadol are not devoid of toxicological risk even at clinical doses.

Low-Dose Tramadol as an Off-Label Antidepressant: A Data Mining Analysis from the Patients' Perspective

Objectives: The purpose of this analysis was to assess, from the patients' perspective, the effectiveness and relative safety of tramadol as an off-label antidepressant and to determine if patients' views and experiences are consistent with the biomedical literature. Method: A data mining approach was used to analyze databases available at drugs.com. Results: Tramadol was reported to be an effective or very effective antidepressant by 94.6% of patients (123/130) who provided ratings submitted to User Reviews for Tramadol to Treat Depression (https://www.drugs.com/comments/tramadol/for-depression.html). When compared to 34 other antidepressants in the database titled Drugs Used to treat Depression (https://www.drugs.com/condition/depression.html), for which there were ≥100 individual reviews for each drug, tramadol was rated as being the most effective (effectiveness rating = 9.1/10). Phenelzine (effectiveness rating = 8.7/10) was the only other antidepressant having ≥100 individual reviews coupled with a very high (8.0-10.0) effectiveness rating. Eleven patients reported significant symptoms of withdrawal upon cessation of tramadol, and five patients reported loss or reduction of libido as a side effect. Most (57/72, 79.2%) patients who reported a dose consumed experienced relief from depression at low therapeutic doses (25-150 mg/day). Fourteen patients reported taking this antidepressant for 5-10 years, and four patients reported taking tramadol for 10 or more years. Results demonstrated that most patients' comments and beliefs are consistent with the biomedical literature. Conclusions: Patients' reviews coupled with a survey of the biomedical literature indicate that at low therapeutic doses in the absence of interactions with other drugs, adult patients found tramadol to be a generally safe, effective, and fast-acting medication for relief from depression.

Real-World Data on Nonmedical Use of Tramadol from Patients Evaluated for Substance Abuse Treatment in the NAVIPPRO Addiction Severity Index-Multimedia Version (ASI-MV®) Network

INTRODUCTION

Drug safety studies regarding comparative risk of different opioid compounds are important as providers and regulatory agencies in the United States continue to balance pain management with an ongoing opioid epidemic.

OBJECTIVE

The aim of this study was to evaluate nonmedical use (NMU) and diversion of tramadol and comparator opioids using real-world data from the Addiction Severity Index-Multimedia Version (ASI-MV^®).

METHODS

A cross-sectional study design was used to evaluate past 30-day tramadol and comparator opioid NMU among adults assessed for substance abuse treatment using the ASI-MV from 2010 to 2018. Population and drug utilization-adjusted rates were studied, as well as patient characteristics, route of administration, and diversion.

RESULTS

Past 30-day NMU of one or more prescription opioid was reported in 125,048 (22.6%) of ASI-MV assessments (2010-2018); 46.5% reported oxycodone, 43.2% hydrocodone, 8.1% morphine, and 7.2% tramadol. Male respondents ranged from 43.2% in the tramadol group to 51.8% in the oxycodone group. Majority (~ 76%) were Caucasian in all groups, with 86.9% Caucasian in the morphine group. Prevalence of past 30-day tramadol NMU was significantly lower than that of morphine, oxycodone, and hydrocodone for both population and utilization-adjusted rates. Rate of snorting of tramadol was 4-7 times lower than comparator opioids and injection was 14-34 times lower than morphine and oxycodone. Tramadol was most likely to be obtained via the patient's own prescription while the comparator opioids were more often obtained via dealers or family/friends.

CONCLUSION

Tramadol had a significantly lower rate of NMU than comparator opioids and was less likely to be diverted or used via higher-risk non-oral routes. These findings support previous evaluations by WHO and the United States Drug Enforcement Agency that concluded that tramadol has a low potential for abuse.

New methodological approaches were able to effectively reduce immeasurable time bias in case-only designs

OBJECTIVES

The objective of this study was to assess approaches to reduce immeasurable time bias in case-crossover (CCO), case-time-control (CTC), and case-case-time-control (CCTC) designs.

STUDY DESIGN AND SETTING

We used Korea's health care database that has inpatient and outpatient prescriptions and an empirical example of benzodiazepines and mortality among the elderly. We defined our unbiased exposure setting using all prescriptions and a pseudo-outpatient setting using outpatient records only. In the pseudo-outpatient setting, we assessed 10 approaches of restricting, adjusting, stratifying, or weighting on hospitalization-related factors. We conducted conditional logistic regression to estimate odds ratio (OR) with 95% confidence intervals (CI), where an approach was considered effective when its OR was within the unbiased exposure setting OR's 95% CI.

RESULTS

Immeasurable time bias negatively biased the unbiased exposure setting's OR in all three case-only designs, overestimating the protective effect of benzodiazepines on mortality. Of the 10 approaches examined, stratifying the proportion of hospitalized time in 0.01 intervals most effectively repaired the bias in the CCO (OR 1.25, 95% CI 1.10-1.43) and CTC analyses (1.11, 0.95-1.30); no approach was effective in the CCTC analysis.

CONCLUSION

Stratifying the proportion of hospitalized time in 0.01 intervals best approximated the unbiased exposure setting estimate by overcoming the significant impact of immeasurable time bias in CCO and CTC designs.

Repeated Administration of Clinical Doses of Tramadol and Tapentadol Causes Hepato- and Nephrotoxic Effects in Wistar Rats

Tramadol and tapentadol are fully synthetic and extensively used analgesic opioids, presenting enhanced therapeutic and safety profiles as compared with their peers. However, reports of adverse reactions, intoxications and fatalities have been increasing. Information regarding the molecular, biochemical, and histological alterations underlying their toxicological potential is missing, particularly for tapentadol, owing to its more recent market authorization. Considering the paramount importance of liver and kidney for the metabolism and excretion of both opioids, these organs are especially susceptible to toxicological damage. In the present study, we aimed to characterize the putative hepatic and renal deleterious effects of repeated exposure to therapeutic doses of tramadol and tapentadol, using an in vivo animal model. Male Wistar rats were randomly divided into six experimental groups, composed of six animals each, which received daily single intraperitoneal injections of 10, 25 or 50 mg/kg tramadol or tapentadol (a low, standard analgesic dose, an intermediate dose and the maximum recommended daily dose, respectively). An additional control group was injected with normal saline. Following 14 consecutive days of administration, serum, urine and liver and kidney tissue samples were processed for biochemical, metabolic and histological analysis. Repeated administration of therapeutic doses of both opioids led to: (i) increased lipid and protein oxidation in liver and kidney, as well as to decreased total liver antioxidant capacity; (ii) decreased serum albumin, urea, butyrylcholinesterase and complement C3 and C4 levels, denoting liver synthesis impairment; (iii) elevated serum activity of liver enzymes, such as alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase and γ-glutamyl transpeptidase, as well as lipid profile alterations, also reflecting hepatobiliary commitment; (iv) derangement of iron metabolism, as shown through increases in serum iron, ferritin, haptoglobin and heme oxygenase-1 levels. In turn, elevated serum cystatin C, decreased urine creatinine output and increased urine microalbumin levels were detected upon exposure to tapentadol only, while increased serum amylase and urine N-acetyl-β-D-glucosaminidase activities were observed for both opioids. Collectively, these results are compatible with kidney injury. Changes were also found in the expression levels of liver- and kidney-specific toxicity biomarker genes, upon exposure to tramadol and tapentadol, correlating well with alterations in lipid profile, iron metabolism and glomerular and tubular function. Histopathological analysis evidenced sinusoidal dilatation, microsteatosis, mononuclear cell infiltrates, glomerular and tubular disorganization, and increased Bowman's spaces. Although some findings are more pronounced upon tapentadol exposure, our study shows that, when compared with acute exposure, prolonged administration of both opioids smooths the differences between their toxicological effects, and that these occur at lower doses within the therapeutic range.

Safety Events Associated with Tramadol Use Among Older Adults with Osteoarthritis

Tramadol is a low-level opioid increasingly recommended to treat moderate-to-severe acute and chronic pain. Although characterized as having fewer opioid-related adverse events, the longer term safety of tramadol use among older adults has not been thoroughly documented. Thus, the primary objective was to examine the risk of safety events associated with chronic tramadol use compared to other chronic opioid use or no opioids among older adults with osteoarthritis. Safety events considered included: ≥3 emergency room (ER) visits, falls/hip fractures, cardiovascular (CVD) hospitalization, composite safety event hospitalization, and all-cause mortality. The study population included older adults ages ≥65 years diagnosed with osteoarthritis and classified into new or continuing tramadol use, new or continuing other opioid use, or nonuse. Inclusion criteria included: 6-month pre period and up to 33 months post period. Tramadol, other opioid, and no opioid users were 1:1 propensity-matched providing study populations of 25,899 within each category; 72% were new chronic opioid users. Multiple logistic regression or Cox proportional hazard ratios were used to document risk. Generally, tramadol users had fewer adverse event risks compared to other opioid users but higher risks than nonusers. New users of tramadol or other opioids had higher risks than continuing users. Tramadol use was associated with increased risk of multiple ER utilizations, falls/fractures, CVD hospitalizations, safety event hospitalizations, and mortality (new users only) compared to nonuse. Thus, although tramadol use may be appropriately recommended within a pain management strategy for older adults with osteoarthritis, careful monitoring for adverse safety events is warranted.