Pharmaceutical treatment patterns for patients with a diagnosis related to chronic pain initiating a slow-release strong opioid treatment in Sweden

The use of uncertain exposure-A method to define switching and add-on in pharmacoepidemiology

PURPOSE

When defining exposure to pharmacological treatments in pharmacoepidemiology, register data often do not provide information regarding if a pharmacological treatment is a switch or an add-on. This study aims to compare two methods defining switching and add-on therapies and their impact on exposure-outcome associations. Additionally, to guide bias reduction, it aims to describe how the methods relate to immortal time bias and selection bias.

METHODS

Cohort study using Swedish population-based health registers to identify antidepressant (AD) prescriptions as exposures while hospitalizations for psychiatric reasons were used as an empirical outcome example. The first method for exposure definition used conditioning on future exposure (FE), the second used the concept of uncertain exposure (UE). To estimate associations between outcome and exposure categories "Use of one AD," "Use of two or more ADs", and "UE" compared to "Unexposed," hazard ratios (HRs) and 95% confidence intervals were estimated using Cox regression adjusted for age and sex.

RESULTS

Using the UE method, 7.2% of time periods were classified as "UE" with a notable proportion of psychiatric hospitalizations (7.7%) occurring during this time, while when using the FE method these hospitalizations were distributed over unexposed time and AD use time. The FE method resulted in slightly higher associations than the UE method. The highest HR was found during "UE": HR (95% CI) 5.54 (5.06-6.07).

CONCLUSIONS

This study suggests that to reduce the potential immortal time bias, selection bias, and exposure misclassification inherent to the FE method, the UE method could be used for identifying switching and add-on therapies. If not used as a main exposure definition, the UE method may be used to investigate the impact of UE time in a sensitivity analysis.

Opioid Prescriptions in Chronic Pain Rehabilitation. A Prospective Study on the Prevalence and Association between Individual Patient Characteristics and Opioids

While against recommendations, long-term opioid therapy (LTOT) for chronic pain is common. This study aimed to describe the prevalence of opioid prescriptions and to study the association of patient characteristics (demographics, pain characteristics, anxiety, depressive symptoms and pain coping) with future LTOT. The sample included N = 1334 chronic musculoskeletal pain patients, aged 18–65, who were assessed for Interdisciplinary Multimodal Pain Rehabilitation (IMMR) in Swedish specialist rehabilitation. Prescriptions were tracked across a two-year target period after assessment. In total, 9100 opioid prescriptions were prescribed to 55% of the sample (M_median = 6, IQR = 14). Prediction of LTOT was analyzed separately for those who did (24%) and did not (76%) receive IMMR. The odds of receiving opioids was similar for these subsamples, after controlling for differences in baseline characteristics. In both samples, there were significant associations between patient characteristics and future opioid prescriptions. Dysfunctional pain coping was a unique predictor of LTOT in those who received IMMR while pain intensity and depressive symptoms were unique predictors in those who did not receive IMMR. The results underscore that opioid treatment is common among patients in chronic pain rehabilitation and relates to pain and psychological factors. Understanding in detail why these factors relate to opioid prescription patterns is an important future study area as it is a prerequisite for better management and fundamental for preventing overuse.

Associations of mental health and family background with opioid analgesic therapy: a nationwide Swedish register-based study

There is evidence of greater opioid prescription to individuals in the United States with mental health conditions. Whether these associations generalize beyond the US prescription environment and to familial mental health and socioeconomic status (SES) has not been examined comprehensively. This study estimated associations of diverse preexisting mental health diagnoses, parental mental health history, and SES in childhood with opioid analgesic prescription patterns nationwide in Sweden. Using register-based data, we identified 5,071,193 (48.4% female) adolescents and adults who were naive to prescription opioid analgesics and followed them from 2007 to 2014. The cumulative incidence of any dispensed opioid analgesic within 3 years was 11.4% (95% CI, 11.3%-11.4%). Individuals with preexisting self-injurious behavior, as well as opioid and other substance use, attention-deficit/hyperactivity, depressive, anxiety, and bipolar disorders had greater opioid therapy initiation rates than did individuals without the respective conditions (hazard ratios from 1.24 [1.20-1.27] for bipolar disorder to 2.12 [2.04-2.21] for opioid use disorder). Among 1,298,083 opioid recipients, the cumulative incidence of long-term opioid therapy (LTOT) was 7.6% (7.6%-7.7%) within 3 years of initiation. All mental health conditions were associated with greater LTOT rates (hazard ratios from 1.66 [1.56-1.77] for bipolar disorder to 3.82 [3.51-4.15] for opioid use disorder) and were similarly associated with concurrent benzodiazepine-opioid therapy. Among 1,482,462 adolescents and young adults, initiation and LTOT rates were greater for those with parental mental health history or lower childhood SES. Efforts to understand and ameliorate potential adverse effects of opioid analgesics must account for these patterns.

Maternal prescribed opioid analgesic use during pregnancy and associations with adverse birth outcomes: A population-based study

BACKGROUND

Published research on prescribed opioid analgesic (POA) use during pregnancy and birth outcomes is limited in scope and has not adequately adjusted for potential confounding factors. To help address these gaps, we estimated associations between maternal POAs during pregnancy and two adverse birth outcomes using a large population-based dataset, multiple definitions of POA exposure, and several methods to evaluate the influence of both measured and unmeasured confounding factors.

METHODS AND FINDINGS

We obtained data by linking information from several Swedish registers and conducted a retrospective cohort study on a population-based sample of 620,458 Swedish births occurring between 2007 and 2013 (48.6% female; 44.4% firstborn). We evaluated associations between prenatal POA exposure and risk for preterm birth (PTB; <37 gestational weeks) and small for gestational age (SGA; birth weight 2 standard deviations below the expected weight for gestational age or lower). We evaluated the influence of confounding by adjusting for a wide range of measured covariates while comparing exposed and unexposed infants. Additionally, we adjusted for unmeasured confounding factors by using several advanced epidemiological designs. Infants exposed to POAs anytime during pregnancy were at increased risk for PTB compared with unexposed infants (6.4% exposed versus 4.4% unexposed; adjusted odds ratio [OR] = 1.38, 95% confidence interval [CI] 1.31-1.45, p < 0.001). This association was attenuated when we compared POA-exposed infants with acetaminophen-exposed infants (OR = 1.18, 95% CI 1.07-1.30, p < 0.001), infants born to women who used POAs before pregnancy only (OR = 1.05, 95% CI 0.96-1.14, p = 0.27), and unexposed siblings (OR = 0.99, 95% CI 0.85-1.14, p = 0.92). We also evaluated associations with short-term versus persistent POA use during pregnancy and observed a similar pattern of results, although the magnitudes of associations with persistent exposure were larger than associations with any use or short-term use. Although short-term use was not associated with SGA (adjusted ORsingle-trimester = 0.95, 95% CI 0.87-1.04, p = 0.29), persistent use was associated with increased risk for SGA (adjusted ORmultiple-trimester = 1.40, 95% CI 1.17-1.67, p < 0.001) compared with unexposed infants. The association with persistent exposure was attenuated when we used alternative comparison groups (e.g., sibling comparison OR = 1.22, 95% CI 0.60-2.48, p = 0.58). Of note, our study had limitations, including potential bias from exposure misclassification, an inability to adjust for all sources of confounding, and uncertainty regarding generalizability to countries outside of Sweden.

CONCLUSIONS

Our results suggested that observed associations between POA use during pregnancy and risk of PTB and SGA were largely due to unmeasured confounding factors, although we could not rule out small independent associations, particularly for persistent POA use during pregnancy.

Prescribed opioid analgesic use developments in three Nordic countries, 2006–2017

Background and aims

While the Nordic countries have considerably stricter controls on opioid prescribing for chronic non-cancer pain than other countries, previous research has warned that prescription of strong opioids is increasing. This study examines consumption of and developments in dispensed prescribed opioids to individuals receiving ambulatory care from 2006 to 2017, using publicly available data from each of three Nordic countries’ national prescription registries.

Methods

Repeated, cross-sectional design. One-year prevalence of all dispensed prescribed opioids in ATC N02A group were reported for Norway, Denmark, and Sweden in the period 2006–2017 by gender. One-year prevalence of the weak opioids tramadol and codeine and the strong opioid oxycodone were then reported separately over this period for each country. The mean defined daily dose (DDD) per user per year, an estimate of the amount of opioids prescribed, was reported for each of the three opioids in 2016.

Results

Patterns of dispensed prescribed opioids differ greatly between 2006 and 2017 and between countries, with tramadol increasing in Norway, codeine declining across the board, and oxycodone increasing in all three countries. Norway exceeded Sweden and Denmark in prevalence of all dispensed prescribed opioids, with 12.1% of the female Norwegian population and 9.2% of the male Norwegian population dispensed at least one prescribed opioid as an outpatient in 2016. Norway’s high overall prevalence rates are tempered by dispensing the lowest mean doses of both weak opioids compared to Sweden. Similarly, Sweden dispenses the lowest mean doses of oxycodone but to the largest proportion of its population (3.0%).

Conclusions

Significant shifts have occurred in the dispensing of prescribed opioids in Norway, Sweden, and Denmark over the past 12 years. The increasing prevalence of oxycodone in all three countries should continue to be monitored. Prescription registries provide a wealth of publicly available data that can be used to monitor and to guide prescribing policies in a more knowledge-based direction.

Abhängigkeitspotenzial und andere Risiken von Opioidanalgetika im Alter

Zusammenfassung. Zielsetzung: Übersicht über Suchtpotenzial und andere Risiken von Opioidanalgetika im höheren Lebensalter. Methodik: Narrativ review. Literaturrecherche in PubMed (Suchbegriffe: opioid analgesics UND abuse; opioid analgesics UND dependence; opioid analgesics UND addiction; opioid analgesics UND adverse effects; jeweils UND elderly) sowie aktuellen einschlägigen Standardwerken; Auswahl nach altersmedizinischer Relevanz und Aktualität. Ergebnisse: Die Verordnung von Opioidanalgetika (OA) hat in den letzten 25 Jahren massiv zugenommen, die weitaus meisten Verordnungen entfallen auf alte Menschen und Menschen mit chronischen Nicht-Tumorschmerzen (CNTS). Die diagnostischen Kriterien für die Opiatabhängigkeit in ICD-10 und DSM-5 sind für die OA-Behandlung von CNTS ungeeignet. Bei langfristiger OA-Behandlung bei CNTS kann eine spezifische Form von Abhängigkeit entstehen, die nicht mit der illegalen Opiat-(Heroin-)Sucht gleichzusetzen ist. Vorbestehende Suchterkrankungen und andere psychische Störungen sind die wesentlichsten Risikofaktoren. Weitere Nebenwirkungen sind zu beachten. Schmerztherapie bei Suchtkranken stellt eine besondere Herausforderung dar. Schlussfolgerungen: Die Anwendung von OA bei CNTS verlangt eine sorgfältige Indikationsstellung. Die besondere Form der Abhängigkeit von OA ist nicht ausreichend erforscht und wird zu wenig beachtet.

Opioid Receptors

Opioids are the oldest and most potent drugs for the treatment of severe pain. Their clinical application is undisputed in acute (e.g., postoperative) and cancer pain, but their long-term use in chronic pain has met increasing scrutiny. This article reviews mechanisms underlying opioid analgesia and other opioid actions. It discusses the structure, function, and plasticity of opioid receptors; the central and peripheral sites of analgesic actions and side effects; endogenous and exogenous opioid receptor ligands; and conventional and novel opioid compounds. Challenging clinical situations, such as the tension between chronic pain and addiction, are also illustrated.

Endogenous opiates and behavior: 2013

This paper is the thirty-sixth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2013 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior, and the roles of these opioid peptides and receptors in pain and analgesia; stress and social status; tolerance and dependence; learning and memory; eating and drinking; alcohol and drugs of abuse; sexual activity and hormones, pregnancy, development and endocrinology; mental illness and mood; seizures and neurologic disorders; electrical-related activity and neurophysiology; general activity and locomotion; gastrointestinal, renal and hepatic functions; cardiovascular responses; respiration and thermoregulation; and immunological responses.

What analgesics do older people use prior to initiating oxycodone for non-cancer pain? A retrospective database study

BACKGROUND

Increased oxycodone use has been associated with adverse drug events, non-medical use and overdose deaths.

OBJECTIVES

To explore patterns of non-opioid, weak opioid and strong opioid use prior to initiation of oxycodone for non-cancer pain in a predominantly older Australian population.

METHODS

A retrospective study was conducted using the Australian Government Department of Veterans' Affairs administrative claims database. Analgesic use 12 months prior to incident dispensing of oxycodone was determined for people in the community and in residential aged-care facilities (RACFs). Log-binomial regression was used to compute adjusted rate ratios (RRs) and 95 % confidence intervals (95 % CIs) for the use of other analgesics prior to initiating oxycodone.

RESULTS

Of 10,791 people who initiated oxycodone in 2010, 26 % in community settings and 13 % in RACFs were not dispensed other analgesics in the 12 months prior to initiating oxycodone. Thirty-four percent and 20 % of those in community settings and RACFs, respectively, were not dispensed other analgesics in the previous 4 months. Co-morbidity had little impact on prior analgesic use. Each additional co-morbid condition was associated with a 1.4 % increased likelihood (RR 1.014, 95 % CI 1.012-1.016; p < 0.0001) and a 1.2 % increased likelihood (RR 1.012, 95 % CI 1.009-1.015; p < 0.0001) of being dispensed another analgesic prior to initiating oxycodone in community and RACF settings, respectively.

CONCLUSIONS

Oxycodone is frequently initiated for non-cancer pain without first trialing other analgesics. This highlights the need for prescribing practices to be reviewed in light of increasing concerns about adverse drugs events and death due to oxycodone, particularly in older people.

Risk of adverse health outcomes with increasing duration and regularity of opioid therapy

PURPOSE

The purpose of this study was to examine trends in frequency and daily dosage of opioid use and related adverse health outcomes in a commercially insured population.

METHODS

We examined medical claims from the Truven Health MarketScan commercial claims database for 789,457 continuously enrolled patients ages 18 to 64 years to whom opioids were dispensed during the first half of 2008. We tracked them every 6 months until either opioid use was discontinued or the end of 2010. We compared outcomes among all opioid users with those for patients who used opioids with only limited interruptions during the index period, referred to as "daily users." We contrasted the experience of daily users, other users, and nonusers for various outcomes.

RESULTS

Of all claimants, 10.7% had at least one opioid prescription during the first 6 months of 2008. Of these, 39.9% continued through a second 6-month period, and 18.0% continued through the end of 2010. Only 9.0% of all users qualified as daily users, but 87.1% of them continued some use of opioids through the end of 2010. Only 43.8% of all users who continued use through 2010 initially qualified as daily users. Among all users who continued use through 2010, days of use and daily dosage increased with duration of use. Among daily users, only dosage increased, rising from 101 to 114 morphine milligram equivalents/day over the 3 years. The prevalence of benzodiazepine use was greater for daily than all users, exceeding 40% among daily users who continued opioid use for 3 years. Drug abuse and overdose rates increased with longer use. Daily users accounted for 25.0%, other users for 43.6%, and nonusers for 31.4% of opioid analgesic overdoses.

CONCLUSIONS

Adverse health outcomes can increase with accumulating opioid use and increasing dosage. Existing guidelines developed by specialty societies for managing patients using opioids daily or nearly daily do not address the larger number of patients who use opioids intermittently over periods of years. Practitioners should consider applying such guidelines to patients who use opioids less frequently.

Long-term opioid treatment of chronic nonmalignant pain: unproven efficacy and neglected safety?

BACKGROUND

For the past 30 years, opioids have been used to treat chronic nonmalignant pain. This study tests the following hypotheses: (1) there is no strong evidence-based foundation for the conclusion that long-term opioid treatment of chronic nonmalignant pain is effective; and (2) the main problem associated with the safety of such treatment - assessment of the risk of addiction - has been neglected.

METHODS

Scientometric analysis of the articles representing clinical research in this area was performed to assess (1) the quality of presented evidence (type of study); and (2) the duration of the treatment phase. The sufficiency of representation of addiction was assessed by counting the number of articles that represent (1) editorials; (2) articles in the top specialty journals; and (3) articles with titles clearly indicating that the addiction-related safety is involved (topic-in-title articles).

RESULTS

Not a single randomized controlled trial with opioid treatment lasting >3 months was found. All studies with a duration of opioid treatment ≥6 months (n = 16) were conducted without a proper control group. Such studies cannot provide the consistent good-quality evidence necessary for a strong clinical recommendation. There were profound differences in the number of addiction articles related specifically to chronic nonmalignant pain patients and to opioid addiction in general. An inadequate number of chronic pain-related publications were observed with all three types of counted articles: editorials, articles in the top specialty journals, and topic-in-title articles.

CONCLUSION

There is no strong evidence-based foundation for the conclusion that long-term opioid treatment of chronic nonmalignant pain is effective. The above identified signs indicating neglect of addiction associated with the opioid treatment of chronic nonmalignant pain were present.

Opioids, sensory systems and chronic pain

Opioids are the oldest and most potent drugs for the treatment of severe pain. Their clinical application is undisputed in acute pain (e.g. associated with trauma or surgery) but their long-term use in chronic pain has met increasing scrutiny. Therefore, this article will review sensory mechanisms related to opioid analgesia and side effects with a special emphasis on chronic pain. Central and peripheral sites of analgesic actions and side effects, as well as conventional and novel opioid compounds will be discussed. Since pain is a complex bio-psycho-social phenomenon, non-pharmacological considerations important for the understanding of opioid analgesic efficacy are also included. Finally, examples of challenging clinical situations such as the perioperative management of patients receiving long-term opioid treatment are illustrated.