Overlaps in pharmacology for the treatment of chronic pain and mental health disorders

Global trends and hotspots in pain associated with bipolar disorder in the last 20 years: a bibliometric analysis

Purpose

The prevalence of comorbid pain and Bipolar Disorder in clinical practice continues to be high, with an increasing number of related publications. However, no study has used bibliometric methods to analyze the research progress and knowledge structure in this field. Our research is dedicated to systematically exploring the global trends and focal points in scientific research on pain comorbidity with bipolar disorder from 2003 to 2023, with the goal of contributing to the field.

Methods

Relevant publications in this field were retrieved from the Web of Science core collection database (WOSSCC). And we used VOSviewer, CiteSpace, and the R package "Bibliometrix" for bibliometric analysis.

Results

A total of 485 publications (including 360 articles and 125 reviews) from 66 countries, 1019 institutions, were included in this study. Univ Toront and Kings Coll London are the leading research institutions in this field. J Affect Disorders contributed the largest number of articles, and is the most co-cited journal. Of the 2,537 scholars who participated in the study, Stubbs B, Vancampfort D, and Abdin E had the largest number of articles. Stubbs B is the most co-cited author. "chronic pain," "neuropathic pain," "psychological pain" are the keywords in the research.

Conclusion

This is the first bibliometric analysis of pain-related bipolar disorder. There is growing interest in the area of pain and comorbid bipolar disorder. Focusing on different types of pain in bipolar disorder and emphasizing pain management in bipolar disorder are research hotspots and future trends. The study of pain related bipolar disorder still has significant potential for development, and we look forward to more high-quality research in the future.

Replicability and reproducibility of predictive models for diagnosis of depression among young adults using Electronic Health Records

BACKGROUND

Recent advances in machine learning combined with the growing availability of digitized health records offer new opportunities for improving early diagnosis of depression. An emerging body of research shows that Electronic Health Records can be used to accurately predict cases of depression on the basis of individual's primary care records. The successes of these studies are undeniable, but there is a growing concern that their results may not be replicable, which could cast doubt on their clinical usefulness.

METHODS

To address this issue in the present paper, we set out to reproduce and replicate the work by Nichols et al. (2018), who trained predictive models of depression among young adults using Electronic Healthcare Records. Our contribution consists of three parts. First, we attempt to replicate the methodology used by the original authors, acquiring a more up-to-date set of primary health care records to the same specification and reproducing their data processing and analysis. Second, we test models presented in the original paper on our own data, thus providing out-of-sample prediction of the predictive models. Third, we extend past work by considering several novel machine-learning approaches in an attempt to improve the predictive accuracy achieved in the original work.

RESULTS

In summary, our results demonstrate that the work of Nichols et al. is largely reproducible and replicable. This was the case both for the replication of the original model and the out-of-sample replication applying NRCBM coefficients to our new EHRs data. Although alternative predictive models did not improve model performance over standard logistic regression, our results indicate that stepwise variable selection is not stable even in the case of large data sets.

CONCLUSION

We discuss the challenges associated with the research on mental health and Electronic Health Records, including the need to produce interpretable and robust models. We demonstrated some potential issues associated with the reliance on EHRs, including changes in the regulations and guidelines (such as the QOF guidelines in the UK) and reliance on visits to GP as a predictor of specific disorders.

Prediction and diagnosis of depression using machine learning with electronic health records data: a systematic review

BACKGROUND

Depression is one of the most significant health conditions in personal, social, and economic impact. The aim of this review is to summarize existing literature in which machine learning methods have been used in combination with Electronic Health Records for prediction of depression.

METHODS

Systematic literature searches were conducted within arXiv, PubMed, PsycINFO, Science Direct, SCOPUS and Web of Science electronic databases. Searches were restricted to information published after 2010 (from 1st January 2011 onwards) and were updated prior to the final synthesis of data (27th January 2022).

RESULTS

Following the PRISMA process, the initial 744 studies were reduced to 19 eligible for detailed evaluation. Data extraction identified machine learning methods used, types of predictors used, the definition of depression, classification performance achieved, sample size, and benchmarks used. Area Under the Curve (AUC) values more than 0.9 were claimed, though the average was around 0.8. Regression methods proved as effective as more developed machine learning techniques.

LIMITATIONS

The categorization, definition, and identification of the numbers of predictors used within models was sometimes difficult to establish, Studies were largely Western Educated Industrialised, Rich, Democratic (WEIRD) in demography.

CONCLUSION

This review supports the potential use of machine learning techniques with Electronic Health Records for the prediction of depression. All the selected studies used clinically based, though sometimes broad, definitions of depression as their classification criteria. The reported performance of the studies was comparable to or even better than that found in primary care. There are concerns with generalizability and interpretability.

Prediction of the prognosis of somatoform disorders using the Minnesota Multiphasic Personality Inventory

BACKGROUND

Somatoform disorders are frequently resistant to treatment. This study aimed to determine the utility of the Minnesota Multifaceted Personality Inventory (MMPI) in predicting the prognosis of somatoform disorders.

METHODS

Overall, 125 patients diagnosed with somatoform disorders between January 1, 2013 and December 31, 2017 in the psychiatric department of Fukushima Medical University Hospital were included. Patients with positive outcomes were identified based on a subjective estimation regarding (1) pain and (2) social functions, including activities of daily living. They were divided into the improved group (IG) and the non-improved group (NIG). Each factor was then descriptively compared between the two groups, and the sensitivity and specificity were determined.

RESULTS

The NIG had significantly higher scores but only on the Hy scale. Thus, the optimal Hy scale cutoff score was calculated. The cutoff point was 73.5, with a sensitivity of 55.7% and a specificity of 71.7%.

CONCLUSION

An MMPI Hy scale score higher than a cutoff value of 73.5 predicts a poor response to conventional supportive psychotherapy or drug therapy in patients with somatoform disorders. This cutoff point may be used as an important index for selecting treatment for somatoform disorders.

Indifference or hypersensitivity? Solving the riddle of the pain profile in individuals with autism

ABSTRACT

Excitatory-inhibitory (E/I) imbalance is a mechanism that underlies autism spectrum disorder, but it is not systematically tested for pain processing. We hypothesized that the pain modulation profile (PMP) in autistic individuals is characterized by less efficient inhibitory processes together with a facilitative state, indicative of a pronociceptive PMP. Fifty-two adults diagnosed with autism and 52 healthy subjects, age matched and sex matched, underwent quantitative sensory testing to assess the function of the (1) pain facilitatory responses to phasic, repetitive, and tonic heat pain stimuli and (2) pain inhibitory processes of habituation and conditioned pain modulation. Anxiety, pain catastrophizing, sensory, and pain sensitivity were self-reported. The autistic group reported significantly higher pain ratings of suprathreshold single ( P = 0.001), repetitive (46°C- P = 0.018; 49°C- P = 0.003; 52°C- P < 0.001), and tonic ( P = 0.013) heat stimuli that were cross correlated ( r = 0.48-0.83; P < 0.001) and associated with sensitivity to daily life pain situations ( r = 0.39-0.45; P < 0.005) but not with psychological distress levels. Hypersensitivity to experimental pain was attributed to greater autism severity and sensory hypersensitivity to daily stimuli. Subjects with autism efficiently inhibited phasic but not tonic heat stimuli during conditioned pain modulation. In conclusion, in line with the E/I imbalance mechanism, autism is associated with a pronociceptive PMP expressed by hypersensitivity to daily stimuli and experimental pain and less-efficient inhibition of tonic pain. The latter is an experimental pain model resembling clinical pain. These results challenge the widely held belief that individuals with autism are indifferent to pain and should raise caregivers' awareness of pain sensitivity in autism.

Medicinal cannabis for patients with chronic non-cancer pain: analysis of safety and concomitant medications

OBJECTIVES

This study aimed to explore the incidence of adverse events (AEs) reported by patients when initiating medicinal cannabis treatment for chronic pain, and the association of cannabis constituents, dose and concomitant medicines with AE incidence.

METHODS

Patient demographics, cannabis products and AE data were collected as part of the Cannabis Access Clinics Observational Study, and concomitant medicines were obtained from patient health summaries provided by referring doctors. Cannabis products were grouped by their constituents as either cannabidiol-only or containing both cannabidiol and Δ-9-tetrahydrocannabinol.

KEY FINDINGS

From a total of 275 patients, each had a median of six concomitant medicines, with opioids (n = 179; 65%) the most common. A total of 35.6% patients took 10 or more other medicines, and they were associated with a 3.6 times higher likelihood to report the AE of fatigue (P = 0.048). Patients who received concomitant gabapentinoids were 2.4 times more likely to report dizziness (P = 0.036), patients on tricyclic antidepressants were 1.8 times more likely to report somnolence (P = 0.034) and 3.4 times more likely to report anxiety (P = 0.04), when compared with patients who were not prescribed those classes of medications. Those patients who were prescribed products containing both cannabidiol and Δ-9-tetrahydrocannabinol were 1.5 times more likely (P = 0.004) to have experienced an AE when compared with those prescribed only cannabidiol.

CONCLUSIONS

These findings show that certain concomitant medications and cannabis constituents may be associated with AE incidence when initiating medicinal cannabis. These potential pharmacokinetic and pharmacodynamic interactions require further study to develop guidance for prescribers and pharmacists.

Risks of complicated acute appendicitis in patients with psychiatric disorders

BACKGROUND

Acute appendicitis often presents with vague abdominal pain, which fosters diagnostic challenges to clinicians regarding early detection and proper intervention. This is even more problematic with individuals with severe psychiatric disorders who have reduced sensitivity to pain due to long-term or excessive medication use or disturbed bodily sensation perceptions. This study aimed to determine whether psychiatric disorder, psychotropic prescription, and treatment compliance increase the risks of complicated acute appendicitis.

METHODS

The diagnosis records of acute appendicitis from four university hospitals in Korea were investigated from 2002 to 2020. A total of 47,500 acute appendicitis-affected participants were divided into groups with complicated and uncomplicated appendicitis to determine whether any of the groups had more cases of psychiatric disorder diagnoses. Further, the ratio of complicated compared to uncomplicated appendicitis in the mentally ill group was calculated regarding psychotropic dose, prescription duration, and treatment compliance.

RESULTS

After adjusting for age and sex, presence of psychotic disorder (odds ratio [OR]: 1.951; 95% confidence interval [CI]: 1.218-3.125), and bipolar disorder (OR: 2.323; 95% CI: 1.194-4.520) was associated with a higher risk of having complicated appendicitis compared with absence of psychiatric disorders. Patients who are taking high-daily-dose antipsychotics, regardless of prescription duration, show high complicated appendicitis risks; High-dose antipsychotics for < 1 year (OR: 1.896, 95% CI: 1.077-3.338), high-dose antipsychotics for 1-5 years (OR: 1.930, 95% CI: 1.144-3.256). Poor psychiatric outpatient compliance was associated with a high risk of complicated appendicitis (OR: 1.664, 95% CI: 1.014-2.732).

CONCLUSIONS

This study revealed a close relationship in the possibility of complicated appendicitis in patients with severe psychiatric disorders, including psychotic and bipolar disorders. The effect on complicated appendicitis was more remarkable by the psychiatric disease entity itself than by psychotropic prescription patterns. Good treatment compliance and regular visit may reduce the morbidity of complicated appendicitis in patients with psychiatric disorders.

Mood, sleep and pain comorbidity outcomes in cannabis dependent patients: Findings from a nabiximols versus placebo randomised controlled trial

BACKGROUND

Mood, sleep and pain problems are common comorbidities among treatment-seeking cannabis-dependent patients. There is limited evidence suggesting treatment for cannabis dependence is associated with their improvement. This study explored the impact of cannabis dependence treatment on these comorbidities.

METHODS

This is a secondary analysis from a 12-week double-blind placebo-controlled trial testing the efficacy of a cannabis agonist (nabiximols) against placebo in reducing illicit cannabis use in 128 cannabis-dependent participants. Outcome measurements including DASS-21 (Depression, Anxiety, and Stress subscales); Insomnia Severity Index (ISI); and Brief Pain Inventory (BPI), were performed at weeks 0, 4, 8, 12 and 24. Each was analysed as continuous outcomes and as binary cases based on validated clinical cut-offs.

RESULTS

Among those whose DASS and ISI scores were in the moderate to severe range at baseline, after controlling for cannabis use, there was a gradual decrease in severity of symptoms over the course of the trial. BPI decreased significantly until week 12 and then rose again in the post-treatment period during weeks 12-24. Neither pharmacotherapy type (nabiximols vs placebo) nor number of counselling sessions contributed significant explanatory power to any of the models and were excluded from the final analyses for both continuous and categorical outcomes.

CONCLUSIONS

Participants in this trial who qualified as cases at baseline had elevated comorbidity symptoms. There was no evidence that nabiximols treatment is a barrier to achieving reductions in the comorbid symptoms examined. Cannabis dependence treatment reduced illicit cannabis use and improved comorbidity symptoms, even when complete abstinence was not achieved.

Pain Sensitivity in Schizophrenia Spectrum Disorders: A Narrative Review of Recent Work

Many patients with schizophrenia seem relatively immune to physical pain while others complain of constant pain. This may result from disturbances or alterations of the sensory threshold for pain in populations with psychosis, a possibility for which there is some preliminary evidence. The inconsistency in pain perception may, in part, be explained by the treatments patients receive, but treatment-naïve patients also exhibit differences in response to pain. This suggests that decreased pain sensitivity may represent a specific psychosis endophenotype. Thus far, few experimental studies have investigated sensory thresholds, pain modalities, or other factors contributing to the perception or expression of physical pain in psychosis. A digital search for information on this topic was conducted in PubMed and Google Scholar. The result is a non-systematic, narrative review focusing on recent clinical and experimental findings of pain sensitivity in patients with psychosis. Importantly, physical and mental pain are closely connected constructs that may be difficult to differentiate. Our hope is that the review provides some clarity to the field in the specific context of schizophrenia.

Vortioxetine in the Treatment of Mood Disorders Associated with Burning Mouth Syndrome: Results of an Open-Label, Flexible-Dose Pilot Study

OBJECTIVE

To evaluate the efficacy of a new multimodal antidepressant, vortioxetine (VO), in the management of burning mouth syndrome (BMS).

DESIGN

Longitudinal single-assessment open-label pilot study.

SETTING

University hospital. Subjects. Thirty BMS patients were enrolled.

METHODS

BMS patients were treated with topical clonazepam and a flexible dose of VO (10 mg, 15 mg, or 20 mg). The visual analog scale (VAS), the Total Pain Rating Index (T-PRI), the Hamilton Rating Scales for Depression (HAM-D) and Anxiety (HAM-A), and the Pittsburgh Sleep Quality Index (PSQI) were performed at baseline (time 0) and after two (time 1), four (time 2), six (time 3), and 12 months (time 4) of treatment. Descriptive statistics and the Wilcoxon nonparametric test for two paired samples were used.

RESULTS

The BMS patients showed a statistically significant improvement in VAS and T-PRI scores from baseline (median [interquartile range {IQR}] = 10.0 [10-10] and 22.0 [20-24], respectively) to time 4 (median [IQR] = 0.0 [0-0] and 8.0 [7-9], P < 0.001, respectively). Similarly, the HAM-A and HAM-D and PSQI scores showed an improvement from time 0 (median [IQR] = 20 [15.8-22], 19 [16-20.3], and 4.0 [4-7.3], respectively) to time 4 (median [IQR] = 6.0 [6-7], 6.0 [6-7], and 3.0 [3-4], respectively, P < 0.001).

CONCLUSIONS

VO is efficacious and well tolerated in the treatment of BMS in firstline therapy on account of its better receptor pharmacological profile and in second-line treatment for patients who have only partially responded or have reported adverse effects to previous treatments.

Vortioxetine as a new frontier in the treatment of chronic neuropathic pain: a review and update

Chronic neuropathic pain (CNP) is a disabling medical condition that impairs the health-related quality-of-life of affected patients. A high prevalence of anxiety, depression, sleep disturbance and cognitive impairment has frequently been reported in association with CNP, making the management of this disease complex and often multidisciplinary. Dual-acting agents such as selective serotonin and noradrenalin reuptake inhibitors (SNRIs) are considered particularly useful in the modulation of pain and in treatment of the mood disorders frequently associated with CNP. Recent evidence suggests that the top-down inhibitory control of pain involves the engagement and enhancement of descending endogenous opioidergic, cannabinoid and serotonergic systems, with the effect of serotonin being particularly related to the receptor subtypes that are preferentially activated; indeed serotonin induces analgesia via activation of 5-HT7 receptors and hyperalgesia via activation of 5-HT3 receptors. Vortioxetine (VO) is a novel multimodal serotonergic antidepressant with a unique mechanism of action. It has been demonstrated recently in experimental and clinical studies to have efficacy on pain hypersensitivity and on mood disorders. This drug inhibits the serotonin transporter with a high affinity, antagonises the 5-HT3, 5-HT1D and 5HT7 serotonin receptors, and activates the 5-HT1A and 5-HT1B receptors. In clinical studies, VO has proved effective at a dose of 10-20 mg/daily in short- and long-term treatment of patients with chronic orofacial pain, demonstrating a higher rate of clinical response and remission, a better acceptability, safety rate and tolerability, and a lower latency of action compared with other antidepressants. In the light of these recent findings, VO may be considered as a new pharmacological treatment also in relation to various types of CNP, particularly in elderly patients with concomitant mood disorders and cognitive impairment. The purpose of this review is to provide an up-to-date overview of the pharmacology and clinical applications of VO and to highlight its potential therapeutic properties and advantages in the management of CNP.

Concomitant benzodiazepine and opioids decrease sleep apnoea risk in chronic pain patients

Background

The concurrent use of sedating centrally acting drugs and opioids by chronic pain patients occurs routinely despite concerns of negative impacts on respiration during sleep. The effects of centrally acting drugs and opioids on sleep apnoea have not been well characterised. The objective of this study was to assess the effect of concomitant centrally acting drugs and opioids on the prevalence and severity of sleep apnoea in chronic pain patients.

Methods

We conducted a prospective cohort study at five chronic pain clinics. Each participant underwent an in-laboratory polysomnography and daily morphine milligram equivalents were calculated. Participants were grouped into centrally acting drugs and opioid users versus sole opioid users.

Results

Of the 332 consented participants, 204 underwent polysomnography and 120 (58.8%) had sleep apnoea (72% obstructive, 20% central, and 8% indeterminate sleep apnoea). Overall, 35% (71 of 204) were taking opioids alone, and 65% (133 of 204) were taking centrally acting drugs and opioids. There was a 69% decrease in the odds of having sleep apnoea (apnoea–hypopnoea index ≥5 events·h⁻¹) in participants taking benzodiazepine/opioids versus sole opioid users (OR 0.31, 95% CI:0.12–0.80, p=0.015). Additionally, concomitant benzodiazepine/opioids versus sole opioid use was associated with a decrease in respiratory arousal index scores (p=0.03). Mean overnight S_pO2 was approximately 1% lower in the concomitant benzodiazepine/opioids group versus sole opioid users (93.1±2.5 versus 94.4±2.1%, p=0.01).

Conclusion

In chronic pain patients on opioids, administration of certain benzodiazepine sedatives induced a mild respiratory depression but paradoxically reduced sleep apnoea risk and severity by increasing the respiratory arousal threshold.

There may be potential to reduce sleep apnoea risk and severity in specific chronic pain patients on opioids using certain benzodiazepine sedatives by selecting those with a low respiratory arousal threshold in whom sleep promotion may stabilise breathinghttps://bit.ly/2Zj4WX1

Effects of repeated treatment with monoamine-transporter-inhibitor antidepressants on pain-related depression of intracranial self-stimulation in rats

RATIONALE

Synaptic neurotransmission with dopamine (DA), norepinephrine (NE), and serotonin (5-HT) is terminated primarily by reuptake into presynaptic terminals via the DA, NE, and 5-HT transporters (DAT/NET/SERT, respectively). Monoamine transporter inhibitors constitute one class of drugs used to treat both depression and pain, and therapeutic effects by these compounds often require repeated treatment for days or weeks.

OBJECTIVES

The present study compared antinociceptive effects produced by repeated treatment with monoamine transporter inhibitors in a preclinical assay of pain-related depression of positively reinforced operant responding.

METHODS

Adult Sprague-Dawley rats equipped with microelectrodes targeting a brain-reward area responded for pulses of electrical brain stimulation in an intracranial self-stimulation (ICSS) procedure. Intraperitoneal injection of dilute lactic acid served as a noxious stimulus that repeatedly depressed ICSS and also produced weight loss during 7 days of repeated acid administration.

RESULTS

Acid-induced depression of both ICSS and body weight were completely blocked by repeated pretreatment with the nonsteroidal anti-inflammatory drug ketorolac. The DAT-selective inhibitor bupropion also fully blocked acid-induced ICSS depression and weight loss throughout all 7 days of treatment. The NET-selective inhibitor nortriptyline and the SERT-selective inhibitor citalopram were generally less effective, but both drugs blocked acid-induced ICSS depression by the end of the 7-day treatment. Acid-induced depression of ICSS and body weight were not blocked by the kappa opioid receptor (KOR) agonist U69593 or the KOR antagonist norbinaltorphimine.

CONCLUSIONS

These results support effectiveness of bupropion to alleviate signs of pain-related behavioral depression in rats and further suggest that nortriptyline and citalopram produce significant but less reliable effects.

Effect of Acupuncture on Chronic Pain with Depression: A Systematic Review

Background

Numerous studies suggested that chronic pain and depression were closely related and widespread in the population. When patients have symptoms of chronic pain and depression, the corresponding treatment will become difficult. Acupuncture, a unique therapeutic method of traditional Chinese medicine, has been reported to potentially serve as an alternative treatment for patients with comorbid chronic pain and depression by many research studies.

Methods

A comprehensive search was conducted through the online database, including the Cochrane Library, PubMed, EMBASE, SinoMed, CNKI, and Wanfang database. Trials were RCTs published in the English or Chinese language, recruiting participants with chronic pain and depression comorbidity. The primary outcomes were the Visual Analogue Scale (VAS) and Hamilton Depression Scale (HAMD). Statistical analyses were conducted using Review Manager 5.3. Each trail was quality appraised with the five-point Jadad Score.

Results

7 eligible RCTs involving 535 patients were included. Better therapeutic effect and safety could be observed in the experimental group compared with the control group. There was a significant decrease in the VAS (mean difference (MD) = −0.68 (−1.24, −0.12), P=0.02) and HAMD (MD = −2.18 (−3.09, −1.26), P < 0.00001) scores and the incidence of adverse events between two groups.

Conclusion

In the treatment of chronic pain with depression, acupuncture could not only get better clinical efficacy, but also have higher security compared with medicine therapy, which can be used in patients with poorer response to the conventional medication or suffering from serious side effects.

Accelerated Atherosclerosis in Rheumatoid Arthritis: Mechanisms and Treatment

Background:

Rheumatoid arthritis (RA) is a chronic systemic autoimmune inflammatory disorder that increases the risk of developing cardiovascular disease. There is accumulating evidence that the RA disease state accelerates the formation of atherosclerotic plaques. Treatments for RA improve joint symptomatology and may reduce inflammation, but consideration of their effects on the cardiovascular system is generally low priority.

Objective:

Since cardiovascular disease is the leading cause of mortality in RA patients, the impact of RA therapies on atherosclerosis is an area in need of attention and the focus of this review.

Results:

The drugs used to treat RA may be analgesics, conventional disease-modifying anti-rheumatic drugs, and/or biologics, including antibodies against the cytokine tumor necrosis factor-α. Pain relievers such as nonselective non-steroidal anti-inflammatory drugs and cyclooxygenase inhibitors may adversely affect lipid metabolism and cyclooxygenase inhibitors have been associated with increased adverse cardiovascular events, such as myocardial infarction and stroke. Methotrexate, the anchor disease-modifying anti-rheumatic drug in RA treatment has multiple atheroprotective advantages and is often combined with other therapies. Biologic inhibitors of tumor necrosis factor-α may be beneficial in preventing cardiovascular disease because tumor necrosis factor-α promotes the initiation and progression of atherosclerosis. However, some studies show a worsening of the lipid profile in RA with blockade of this cytokine, leading to higher total cholesterol and triglycerides.

Conclusion:

Greater understanding of the pharmacologic activity of RA treatments on the atherosclerotic process may lead to improved care, addressing both damages to the joints and heart.

Cost-Effectiveness of Treatment Options for Neuropathic Pain: a Systematic Review

BACKGROUND

Neuropathic pain significantly reduces an individual's quality of life and places a significant economic burden on society. As such, many cost-effectiveness analyses (CEAs) have been published for treatments available for neuropathic pain.

OBJECTIVES

The primary objective of this systematic review was to provide a detailed summary of the estimates of cost-effectiveness from published CEAs comparing available treatments for neuropathic pain. The secondary objectives were to identify the key drivers of cost-effectiveness and to assess the quality of published CEAs in neuropathic pain.

METHODS

We searched Embase, MEDLINE, Cochrane CENTRAL and seven other databases to identify CEAs reporting the costs, health benefits (e.g., quality-adjusted life-years or disability-adjusted life-years) and summary statistics, such as incremental cost-effectiveness ratios, of treatments for neuropathic pain. We excluded studies reporting diseases other than neuropathic pain, those for which the full text was not available (e.g., conference abstracts), studies not written in English or not published in peer-reviewed journals, and narrative reviews, editorials and opinion papers. Titles and abstract reviews, full-text reviews, and data extraction were all performed by two independent reviewers, with disagreement resolved by a third reviewer. Mean costs, health benefits, and summary statistics were reported and qualitatively compared across studies, stratified by time horizon. Drivers of cost-effectiveness were assessed using reported one-way sensitivity analyses. The quality of all included studies was evaluated using the Tufts CEA Registry Quality Score and study reporting using the CHEERS (Consolidated Health Economic Evaluation Reporting Standards) checklist.

RESULTS

A total of 22 studies were identified and included in this systematic review. Included studies were heterogeneous in the treatments compared, methodology and design, perspectives, and time horizons considered, making cross-study comparisons difficult. No single treatment was consistently the most cost-effective across all studies, but tricyclic antidepressants were the preferred treatment at a willingness-to-pay threshold of $US50,000 per quality-adjusted life-year in several studies with a short time horizon and a US payer perspective. Among the 14 studies reporting one-way sensitivity analyses, drivers of cost-effectiveness included utility values for health states and the likelihood of pain relief with treatment. The quality of the identified CEAs was moderate to high, and overall reporting largely met CHEERS recommendations.

LIMITATIONS

To assess drivers of cost-effectiveness and quality, we only included studies with the full text available and thus excluded some CEAs that reported cost-effectiveness results. The heterogeneity of the included studies meant that the study results could not be synthesized and comparison across studies was limited.

CONCLUSIONS

Though many pulished studies have evaluated the cost-effectiveness of treatments for neuropathic pain, significant heterogeneity between CEAs prevented synthesis of the results. Standardized methodology and improved reporting would allow for more reliable comparisons across studies.