Guidelines for prescribing opioids for chronic non-cancer pain in Korea

Updated guidelines for prescribing opioids to treat patients with chronic non-cancer pain in Korea: developed by committee on hospice and palliative care of the Korean Pain Society

There are growing concerns regarding the safety of long-term treatment with opioids of patients with chronic non-cancer pain. In 2017, the Korean Pain Society (KPS) developed guidelines for opioid prescriptions for chronic non-cancer pain to guide physicians to prescribe opioids effectively and safely. Since then, investigations have provided updated data regarding opioid therapy for chronic non-cancer pain and have focused on initial dosing schedules, reassessment follow-ups, recommended dosage thresholds considering the risk-benefit ratio, dose-reducing schedules for tapering and discontinuation, adverse effects, and inadvertent problems resulting from inappropriate application of the previous guidelines. Herein, we have updated the previous KPS guidelines based on a comprehensive literature review and consensus development following discussions among experts affiliated with the Committee on Hospice and Palliative Care in the KPS. These guidelines may assist physicians in prescribing opioids for chronic non-cancer pain in adult outpatient settings, but should not to be regarded as an inflexible standard. Clinical judgements by the attending physician and patient-centered decisions should always be prioritized.

Attitudes toward Social Issues Related to Opioid Use among Palliative Care Physicians

Purpose

This study investigated palliative care physicians' attitudes regarding social issues related to opioid use.

Methods

An email survey was sent to 674 physicians who were members of the Korean Society for Hospice and Palliative Care (KSHPC).

Results

Data from 66 physicians were analyzed (response rate, 9.8%). About 70% of participants stated that their prescribing patterns were not influenced by social issues related to opioid use, and 90% of participants thought that additional regulations should be limited to non-cancer pain. Under the current circumstances, pain education for physicians is urgently needed, as well as increased awareness among the public. Half of the respondents identified the KSHPC as the primary organization responsible for providing pain education.

Conclusion

Palliative care physicians' prescribing patterns were not influenced by social issues related to opioid use, and these issues also should not affect cancer pain control.

A population-based study on the risk of prescription opioid abuse in patients with chronic opioid use and cost-effectiveness of prescription drug monitoring program using a patient simulation model in South Korea

BACKGROUND

Concerns regarding the burden of inappropriate opioid use are growing. We examined the association between prescription opioid abuse and patient characteristics and estimated the cost-effectiveness of the prescription drug monitoring program (PDMP) implemented in South Korea, considering patient-level information.

METHODS

A retrospective cohort study was conducted to explore the association between opioid abuse and patient characteristics using the National Health Insurance Service-National Sample Cohort (NHIS-NSC) database. We selected non-cancer patients with chronic opioid use and investigated the incidence of opioid abuse between 2010 and 2015. The association between opioid abuse and patient characteristics was assessed using the Cox proportional hazards model. The cost-effectiveness of the PDMP was assessed using discrete event simulation (DES) with a time horizon of 30 years from a societal perspective. Time-to-event data and event costs were obtained from the NHIS-NSC database. The abuse rate was adjusted for each patient based on the baseline characteristics and history of abuse experienced in the model. Program effectiveness, program costs, and health-state utilities were obtained from the published literature. The incremental cost-utility ratio (ICUR) was estimated at a discount rate of 5% for both costs and quality-adjusted life-years (QALYs).

RESULTS

We identified 22,524 patients with chronic opioid use in the NHIS-NSC database. Every one-year increase in age (hazard ratio: 1.002 [95% CI: 1.000-1.003]), medical aid program (1.130 [95% CI: 1.072-1.191]), high Charlson Comorbidity Index (1.054 [95% CI: 1.044-1.065]), and history of opioid abuse (1.501 [95% CI: 1.391-1.620] and 3.005 [95% CI: 2.387-3.783] for 1-2 and ≥3 abuse events, respectively) significantly increased the risk of opioid abuse. In the DES, the PDMP was cost-effective, with an estimated ICUR of $2,227/QALY, which was most affected by the program's effectiveness.

CONCLUSION

Patient characteristics and history of opioid abuse affected the risk of opioid abuse. Considering patient-level information, the PDMP implemented in South Korea is likely to be cost-effective.

Assessment and nonsurgical management of low back pain: a narrative review

Low back pain (LBP) is a common condition that affects people of all ages and income levels worldwide. The etiology of LBP may be mechanical, neuropathic, systemic, referred visceral, or secondary to other causes. Despite numerous studies, the diagnosis and management of LBP remain challenging due to the complex biomechanics of the spine and confounding factors, such as trivial degenerative imaging findings irrelevant to symptoms and psychological and emotional factors. However, it is imperative to identify the crucial signs ("red flags") indicating a serious underlying condition. While many recent guidelines emphasize non-pharmacologic management approaches, such as education, reassurance, and physical and psychological care, as the first option, LBP patients in many countries, including South Korea, are prescribed medications. Multidisciplinary rehabilitation combined with prudent use of medications is required in patients unresponsive to first-line therapy. The development of practical guidelines apposite for South Korea is needed with multidisciplinary discussion.

Economic burden of opioid misuse focused on direct medical costs

Background: Since their development, synthetic opioids have been used to control pain. With increased opioid use, problematic opioid prescription has also increased, resulting in a growing economic burden. However, there is a paucity of research studies on the economic burden of prescription opioid misuse in Asia, especially South Korea.

Objectives: To estimate the incremental economic burden of prescription opioid misuse for the South Korean population.

Methods: The National Health Insurance Service-National Sample Cohort database, covering 2% of the South Korean population between 2010 and 2015, was analyzed. Outpatients aged 18 or older who took one or more prescription opioids were selected. Based on their opioid prescription patterns, patients were classified into opioid misuse and non-misuse groups. The direct medical costs per person per year (PPPY) and the incremental economic burden of the opioid misuse group were explored using an exponential conditional model with a suitable distribution and log link function. All analyses were performed using SAS® Enterprise Guide version 9.4, and p < 0.05 was considered statistically significant.

Results: The number of patients who had ≥1 opioid prescription was 345,020 including 84,648 (24.53%) in the opioid misuse group and 260,372 (75.47%) in the non-misuse group. The adjusted mean direct medical costs PPPY were estimated to be USD 401 for the opioid misuse group, which is 1.49 times significantly higher than that for the non-misuse group (p < 0.0001). The incremental economic burden of the opioid misuse group in the South Korean population was estimated to be approximately USD 0.52 billion for the period 2010–2015.

Conclusion: Prescription opioid misuse was significantly associated with the increased economic burden. Along with proper policies for using opioids, it is necessary to monitor opioid prescription patterns to prevent opioid misuse and reduce the related economic burden.

Risk of major adverse events associated with gabapentinoid and opioid combination therapy: A systematic review and meta-analysis

Background: The use of opioid-gabapentinoid combinations has increased, raising several safety concerns. However, meta-analysis studies focusing on this issue are limited. Objective: To evaluate the risk of central nervous system (CNS) depression, gastrointestinal (GI) adverse events, and mortality of combination therapy compared with those of opioid therapy and to explore the differences in the results according to study design and indications. Methods: Relevant studies were selected (published before 30 January 2022) by searching the MEDLINE, Embase, and CENTRAL databases. The pooled odds ratios (OR) with 95% confidence intervals (CI) of the outcomes were estimated using the Mantel-Haenszel method. Subgroup and meta-regression analyses were performed according to study characteristics. Quality assessment was conducted using the Risk of Bias 2 tool for randomized controlled trials (RCTs) and Cochrane Collaboration's Risk of Bias in non-RCTs tool for non-randomized trials. Results: Adverse events were reported in 26 RCTs and 7 non-RCTs, and mortality was reported in 10 non-RCTs. Compared to opioid therapy, dizziness, cognitive dysfunction, and respiratory depression in combination therapy significantly increased in non-RCTs (OR 3.26, 95% CI 1.82-5.85; OR 3.13, 95% CI 1.51-6.50; OR 1.71, 95% CI 1.31-2.24, respectively), and a similar trend for dizziness and cognitive dysfunction was also identified in the RCT analysis, although the difference was not significant. Combination therapy for cancer pain was associated with the highest risk of sedation in subgroup analysis. Combination therapy significantly decreased the risk of GI adverse events, including nausea, vomiting, and constipation. The mortality risk associated with combination therapy was higher than that associated with opioid therapy (OR 2.76, 95% CI 1.26-6.05). Conclusion: Opioid-gabapentinoid combination therapy could be associated with an increased risk of CNS depression and mortality, despite tolerable GI adverse events. These data suggest that combination therapy requires close monitoring of CNS depression, especially in cancer patients. Caution is needed in interpreting the clinical meanings owing to the lack of risk difference in respiratory depression in the RCT-only analysis and the absence of RCT or prospective studies investigating mortality.

Actual situation and prescribing patterns of opioids by pain physicians in South Korea

Background

Use of opioids for chronic intractable pain is increasing globally, and their proper use can improve patients’ quality of life. In contrast, opioid use disorders, such as abuse or addiction, caused by prescribing opioids, are a worldwide issue. This study aimed to understand current opioid prescribing patterns and pain physicians’ experiences with opioid use in South Korea.

Methods

Pain physicians in 42 university hospitals in South Korea were asked to complete anonymous questionnaires regarding opioid prescriptions.

Results

A total of 69 surveys were completed. Most pain physicians started prescribing opioids at a pain score of 7/10 and aimed to reduce pain by 50%. Most physicians (73.1%) actively explained the prescribed medications and possible side effects, and 61.2% of physicians preferred the prescription interval of 4 weeks. Immediate-release opioids were the most popular treatment for breakthrough pain (92.6%). The most common side effect encountered by physicians was constipation (43.3%), followed by nausea/vomiting (34.3%). Of the physicians, 56.5% replied that addiction and misuse prevalences were less than 5%. However, the most concerning side effect was addiction (33.0%).

Conclusions

The survey results showed that the prescribing patterns of pain physicians generally followed Korean guidelines. Physicians were most interested in the safety and effectiveness of opioid prescriptions. They were most concerned about respiratory depression and abuse or addiction. A significant number of physicians agreed that the NHIS regulations needed improvement for patient convenience and safe and effective treatment, though there were pros and cons of the NHIS restrictions on prescription conditions.

Long-term opioid use and mortality in patients with chronic non-cancer pain: Ten-year follow-up study in South Korea from 2010 through 2019

BACKGROUND

We aimed to investigate the prevalence and factors associated with long-term opioid use among patients with chronic non-cancer pain (CNCP).

METHODS

We extracted data from the National Health Insurance Service (NHIS) database in South Korea. As a nationwide database, the NHIS database contains information regarding all disease diagnoses and prescriptions for any drug and/or procedures. A total of 2.5% of adult patients (≥20 years of age) who were diagnosed with musculoskeletal diseases and CNCP from 2010 to 2019 were selected using a stratified random sampling technique and included in the analysis. Patients who were prescribed opioids continuously for ≥90 days were classified as long-term opioid users.

FINDINGS

A total of 19,645,161 patients with CNCP were included in the final analysis. The prevalence of long-term opioid use was 0.47% (95% confidence interval [CI]: 0.46%, 0.48%; 8421/1,808,043) in 2010, which gradually increased to 2.63% (95% CI: 2.61%, 2.66%; 49,846/1,892,913) in 2019. Among the 2010 cohort (n = 1,804,019), in multivariable logistic regression: old age, underlying disability, increased Charlson comorbidity index, use of benzodiazepine or Z-drug, rheumatoid arthritis, osteoarthritis, and low back pain were associated with an increased prevalence of long-term opioid use among patients with CNCP. In a multivariable Cox regression, the 10-year all-cause mortality in long-term opioid users was found to be 1·21-fold (hazard ratio: 1.21, 95% CI: 1.13, 1.31; P<0·001) higher than that in opioid-naive patients with CNCP.

INTERPRETATION

Long-term opioid use increased in patients with CNCP in South Korea from 2010 to 2019. Certain factors were potential risk factors for long-term opioid use. Moreover, long-term opioid use was associated with increased 10-year all-cause mortality among patients with CNCP.

FUNDING

None.

Cost-Effectiveness of an Opioid Abuse-Prevention Program Using the Narcotics Information Management System in South Korea

OBJECTIVES

To assess the cost-effectiveness of an opioid abuse-prevention program embedded in the Narcotics Information Management System ("the Network System to Prevent Doctor-Shopping for Narcotics") in South Korea.

METHODS

Using a Markov model with a 1-year cycle length and 30-year time horizon, we estimated the incremental cost-utility ratio (ICUR) of implementing an opioid abuse-prevention program in patients prescribed outpatient opioids from a Korean healthcare payer's perspective. The model has 6 health states: no opioid use, therapeutic opioid use, opioid abuse, overdose, overdose death, and all-cause death. Patient characteristics, healthcare costs, and transition probabilities were estimated from national population-based data and published literature. Age- and sex-specific utilities of the general Korean population were used for the no-use state, whereas the other health-state utilities were obtained from published studies. Costs (in 2019 US dollars) included the expenses of the program, opioids, and overdoses. An annual 5% discount rate was applied to the costs and quality-adjusted life-years (QALYs). Parameter uncertainties were explored via deterministic and probabilistic sensitivity analyses.

RESULTS

The program was associated with 2.27 fewer overdoses per 100 000 person-years, with an ICUR of $227/QALY. The ICURs were generally robust to parameter changes, although the program's effect on abuse reduction was the most influential parameter. Probabilistic sensitivity analysis showed that the program reached a 100% probability of cost-effectiveness at a willingness-to-pay threshold of $900/QALY.

CONCLUSIONS

The opioid abuse-prevention program appears to be cost-effective in South Korea. Mandatory use of the program should be considered to maximize clinical and economic benefits of the program.

Increased risk of death with codeine use in the elderly over 85 years old and patients with respiratory disease: A case-control study using retrospective insurance claims database

To investigate the risk of mortality associated with exposure to codeine, considering various risk groups, using population-based national insurance claims data.National sample cohort data from the National Health Insurance Service of South Korea (2002-2013) was used in this case-control study. Cases were defined as patients with a death record between January 1, 2002 and December 31, 2013. Each case was matched to 10 controls based on age, sex, baseline comorbidities, and year of death. Definition of exposure was codeine prescription in 30 days prior to death and sensitivity analyses were performed for 15 and 60-day exposures. Adjusted odds ratios (aORs) with 95% confidence intervals (CIs) were estimated using conditional logistic regression adjusting for benzodiazepine, other opioids, anesthetics, hypnotics, CYP2D6 inducer, CYP3A4 inducer, and the Charlson comorbidity index.A total of 19,341 cases and 185,700 matched controls were included. The overall risk associated with codeine use and mortality risk was not significant (aOR 1.08, 95% CI 1.00-1.16). Sensitivity analyses with different exposure time window also presented similar insignificant results. However, in the subgroup analyses, codeine use was associated with an increased risk of mortality in the >85-year-old age group (aOR 2.38, 95% CI 1.26-4.48) and patients with respiratory disease (aOR 1.29, 95% CI 1.17-1.42).Although no statistically significant association was found in codeine exposure and mortality risk between cases and controls, we demonstrated that the elderly over 85 years old and patients with respiratory disease are associated with a higher risk with codeine exposure. Therefore, a more cautious practice of codeine prescription in these groups might be needed.

Opioid Pain Medication Prescription for Chronic Pain in Primary Care Centers: The Roles of Pain Acceptance, Pain Intensity, Depressive Symptoms, Pain Catastrophizing, Sex, and Age

Background: Psychological factors of patients may influence physicians’ decisions on prescribing opioid analgesics. However, few studies have sought to identify these factors. The present study had a double objective: (1) To identify the individual factors that differentiate patients who had been prescribed opioids for the management of chronic back pain from those who had not been prescribed opioids and (2) to determine which factors make significant and independent contributions to the prediction of opioid prescribing. Methods: A total of 675 patients from four primary care centers were included in the sample. Variables included sex, age, pain intensity, depressive symptoms, pain catastrophizing, and pain acceptance. Results: Although no differences were found between men and women, participants with chronic noncancer pain who were prescribed opioids were older, reported higher levels of pain intensity and depressive symptoms, and reported lower levels of pain-acceptance. An independent association was found between pain intensity and depressive symptoms and opioid prescribing. Conclusions: The findings suggest that patient factors influence physicians’ decisions on prescribing opioids. It may be useful for primary care physicians to be aware of the potential of these factors to bias their treatment decisions.

Correlation between paravertebral spread of injectate and clinical efficacy in lumbar transforaminal block

The potential paravertebral space includes spinal nerves, dorsal rami, rami communicants, and sympathetic chains. This study evaluated correlations between paravertebral spread of injectate and clinical efficacy in lumbar transforaminal block. We retrospectively analysed the data of 88 patients who received transforaminal blocks for lumbar radicular pain. We categorized patients into two groups: patients with ≥ 50% pain reduction on a numeric rating scale at 30 min following a block (responder group), and patients with < 50% pain reduction (non-responder group). Paravertebral spread of injectate was graded as limited to the anterior, middle, and posterior 1/3 of the anterolateral aspect of vertebral bodies; spread between the posterolateral margins of bodies and the posterior epidural space was considered no spread. Clinical and fluoroscopic data, perfusion index, temperature, and cold sensation were compared between the groups. Among 54 patients analysed, 26 (48.1%) experienced ≥ 50% and 28 (51.9%) < 50% pain reduction. Paravertebral spread occurred in 33 (61.1%) patients; 19 (57.6%) responders and 14 (42.4%) non-responders. On analysis, paravertebral spread, epidural spread patterns, perfusion index change ratios, temperature changes, and cold sensation changes showed no differences between responder and non-responder groups. Paravertebral spread occurred in 61.1%, with no correlation with the clinical efficacy of lumbar transforaminal block.

Patients' perception about opioids and addiction in South Korea

Background

Chronic pain affects approximately 22% of the world’s population. Opioids can be useful in chronic pain management. However, some patients have negative perception of opioids. The purpose of this research was to evaluate patients’ perception about opioids and investigate problems associated with prescribing and taking opioids in South Korea.

Methods

Patients who visited a pain clinic in 14 university hospitals of South Korea from September through October 2018 were asked to complete anonymous questionnaires about taking opioids.

Results

Of the 368 patients that were surveyed (female 53.3%, male 46.7%), 56.8% were prescribed opioids. In the opioid group, 92.8% patients had heard of opioids from their doctor and 72.6% of them had a positive perception about opioids. The side effects associated with opioid use were constipation (35.4%), dizziness (24.6%), nausea and vomiting (17.4%), dysuria (6.2%), and addiction (2.0%). In the no opioid group, the primary sources of information about opioids were doctors (49.2%), mass media (30.8%), and the internet (16.2%). The main reasons why 39.0% patients did not take opioids were fear of addiction (57.7%) and side effects (38.5%). There were 71.5% and 60.9% patients in the opioid and no opioid group, respectively, who wished to take opioids when their numeric rating scale pain score was ≥ 7.

Conclusions

Perception of opioids among patients who take them was either neutral or positive. However, 39.0% patients who have not been prescribed opioids did not want an opioid prescription, citing fear of addiction and side effects as the primary reasons.

Prevalence and Seriousness of Analgesic-Induced Adverse Events in Korea: A 10-Year Nationwide Surveillance

OBJECTIVES

The objectives of this study were to describe the prevalence and seriousness of analgesic-induced adverse events (AEs) and to identify factors associated with serious analgesic-related AEs in Korea.

METHODS

Voluntarily reported analgesic-induced AEs to the Korea Adverse Event Reporting System from 2007 to 2016 were retrospectively reviewed. Analgesic medications were classified into nonopioids and opioids based on the Anatomical Therapeutic Chemical classification system. All AEs were grouped using System Organ Classes according to the World Health Organization-Adverse Reaction Terminology. Logistic regression was performed to identify factors associated with serious AEs.

RESULTS

Overall, 194,566 AEs (32.2% for nonopioids, 67.8% for opioids) were included in this analysis. The most common causative nonopioid and opioid analgesics was ketorolac (n = 10,789) and tramadol (n = 53,727), respectively. The most frequent AEs were skin and appendage disorders for nonopioids (31.8%) and gastrointestinal disorders (59.5%) for opioids. Serious AEs occurred in 6102 (9.7%) and 3326 (2.5%) cases of the nonopioid and opioid groups, respectively. The most common serious AEs were skin and appendage disorders (33.2%) for nonopioids and neurologic disorders (19.3%) for opioids. Serious AEs were significantly associated with male (odds ratio [OR] = 1.423), advanced age (OR = 1.570), certain causality (OR = 2.304), nonopioid analgesics (OR = 4.182), and polypharmacy (OR = 1.009; P <0.001 for all).

CONCLUSIONS

In Korea, analgesic-induced AEs are prevalent with opioids more commonly implicated. Tramadol is the most common etiologic medication. Serious AEs are more frequently caused by nonopioids with skin and appendage disorders most common.

Medicolegal Consideration to Prevent Medical Malpractice Regarding Opioid Administration: An Analysis of Judicial Opinion in South Korea

PURPOSE

Although the use of opioids is increasing in South Korea, there have been no studies on the serious complications caused by the opioids. The aim of this study was to investigate the rare but serious complications through medicolegal analysis.

MATERIALS AND METHODS

From January 1994 to December 2019, we retrospectively reviewed the closed cases of lawsuits involving the complications of opioids using the database of judgments of the Supreme Court of Korea. General characteristics, opioid-induced complications, and judicial characteristics were analyzed.

RESULTS

Of the 46 cases, 31 cases of complications were finally included in the analysis. There were 28 (90.3%) cases of opioid administration for acute pain and 3 (9.7%) cases for chronic pain. The most commonly prescribed opioid was pethidine (n = 13, 41.9%), and the most common complication was respiratory depression (n = 17, 54.8%). All except two cases were associated with permanent injuries, including 18 (58%) deaths. Twelve (38.7%) cases were ruled in favor of the plaintiff in the claims for damages, with a median payment of United States dollar (USD) 126,346 (IQR: USD 77,275-379,219). Of these cases, the most frequently admitted complaint by the court was the neglect of observation (n = 10, 32.3%), followed by the inappropriate drug choice (n = 4, 12.9%). Eleven (36.7%) cases were plaintiffs' claims for violating explanation obligations, of which 2 (6.7%) were recognized in the court.

CONCLUSION

Our results suggest that physicians must be aware of the serious complications related to opioids and health policies to prevent such complications and malpractice should be adopted.