Prescription opioid treatment for non-cancer pain and initiation of injection drug use: large retrospective cohort study

Abstract

Objective To assess the association between long term prescription opioid treatment medically dispensed for non-cancer pain and the initiation of injection drug use (IDU) among individuals without a history of substance use. Design Retrospective cohort study. Setting Large administrative data source (containing information for about 1.7 million individuals tested for hepatitis C virus or HIV in British Columbia, Canada) with linkage to administrative health databases, including dispensations from community pharmacies. Participants Individuals age 11-65 years and without a history of substance use (except alcohol) at baseline. Main outcome measures Episodes of prescription opioid use for non-cancer pain were identified based on drugs dispensed between 2000 and 2015. Episodes were classified by the increasing length and intensity of opioid use (acute (lasting <90 episode days), episodic (lasting ≥90 episode days; with <90 days’ drug supply and/or <50% episode intensity), and chronic (lasting ≥90 episode days; with ≥90 days’ drug supply and ≥50% episode intensity)). People with a chronic episode were matched 1:1:1:1 on socioeconomic variables to those with episodic or acute episodes and to those who were opioid naive. IDU initiation was identified by a validated administrative algorithm with high specificity. Cox models weighted by inverse probability of treatment weights assessed the association between opioid use category (chronic, episodic, acute, opioid naive) and IDU initiation. Results 59 804 participants (14 951 people from each opioid use category) were included in the matched cohort, and followed for a median of 5.8 years. 1149 participants initiated IDU. Cumulative probability of IDU initiation at five years was highest for participants with chronic opioid use (4.0%), followed by those with episodic use (1.3%) and acute use (0.7%), and those who were opioid naive (0.4%). In the inverse probability of treatment weighted Cox model, risk of IDU initiation was 8.4 times higher for those with chronic opioid use versus those who were opioid naive (95% confidence interval 6.4 to 10.9). In a sensitivity analysis limited to individuals with a history of chronic pain, cumulative risk for those with chronic use (3.4% within five years) was lower than the primary results, but the relative risk was not (hazard ratio 9.7 (95% confidence interval 6.5 to 14.5)). IDU initiation was more frequent at higher opioid doses and younger ages. Conclusions The rate of IDU initiation among individuals who received chronic prescription opioid treatment for non-cancer pain was infrequent overall (3-4% within five years) but about eight times higher than among opioid naive individuals. These findings could have implications for strategies to prevent IDU initiation, but should not be used as a reason to support involuntary tapering or discontinuation of long term prescription opioid treatment.

Analgesic Effects of Repetitive Transcranial Magnetic Stimulation in Patients With Advanced Non-Small-Cell Lung Cancer: A Randomized, Sham-Controlled, Pilot Study

“…Pain is a complex symptom that affects many aspects of a cancer patient, including physical function, sleep, ability of daily living, psychological and emotional status, and social relations ( 5 ). Therefore, intervention on the pain is of great significance to improve the quality of life and the prognosis of lung cancer patients ( 6 ).…”

Association Between Prescription Opioid Therapy for Noncancer Pain and Hepatitis C Virus Seroconversion

“…This finding supports the well-established association between nonmedical prescription opioid use and heroin, 12 and a recent cohort analysis identifying an association between medically dispensed long-term prescription opioid therapy and initiation of injection drug use. 10 Although we were unable to establish a causal relationship between prescription opioids and HCV seroconversion or formally assess the role of injection drug use initiation as a mediator, several reasons or motivations for transitioning from prescription opioids to heroin or injection drug use (eg, rising tolerance, relief of withdrawal or pain due to discontinuation of therapy, and introduction of tamper-resistant formulations) have been identified in qualitative studies. 15 , 16 , 17 , 18 , 19 To evaluate our hypothesis that injection drug use initiation risk is higher among people dispensed prescription opioids, we used an administrative algorithm with high sensitivity for identifying injection drug use 31 to limit our analysis to individuals who were injection drug use–naive at prescription opioid initiation.…”

“…13 Less is known about medically dispensed prescription opioids, 10 , 14 although a recent cohort study found long-term prescription opioid therapy for pain to be associated with initiation of injection drug use. 10 Although these associations may not be causal, qualitative studies suggest that some people attribute their initiation of heroin/injection drug use to prior medical or nonmedical prescription opioid use. 15 , 16 , 17 , 18 , 19 In particular, sudden discontinuation of prescription opioid therapy, potentially owing to more stringent policies and guidelines, may lead some individuals to initiate heroin/injection drug use and inadvertently increase the risk of harm.…”

Dolor lumbar en el embarazo, aspectos fisiopatológicos y tratamiento

“…Los anticonvulsivantes utilizados como coadyuvantes analgésicos, como la pregabalina y la gabapentina, tiene una clasificación C en la gestación. Existen estudios que demuestran la seguridad de estos medicamentos, pero solo están indicados en dolor neuropático, con un beneficio clínico menor en el dolor nociceptivo, lo que favorece otro tipo de terapias que garanticen un mayor perfil de seguridad 48 .…”