OA10 Factors associated with long-term opioid use in fibromyalgia patients newly started on an opioid: results from Clinical Practice Research Datalink
Authors: Feng Mengyu , Medina Carlos Raul Ramirez , Huang Yun-Ting , Jenkins David , Jani Meghna 
Published: April 2023

Abstract

Background/Aims
The impact of the opioid epidemic in North America has caused concern in the United Kingdom. Long-term opioid use is associated with several opioid-related harms and adverse outcomes. Fibromyalgia is frequently treated with opioids due to limited therapeutic options. Understanding what factors are associated with long-term opioid use in such patients is the first step in helping to develop targeted interventions for deprescribing. Therefore, the objective of this study was to (i) quantify the proportion of new opioid users with fibromyalgia who become long-term opioid users; and (ii) identify risk factors associated with long-term opioid use in fibromyalgia.

Methods
A retrospective cohort study was conducted using data from the Clinical Practice Research Datalink (CPRD). CPRD is a national database of electronic health records within primary care, representation of the general population. Fibromyalgia patients without prior cancer who were new opioid users between 01/Jan/2006 and 31/Aug/2021 were included. Long-term opioid use was defined as at least 3 opioid prescriptions issued within a 90-day period, or ≥ 1 opioid prescription lasting at least 90 days, in the first year of follow-up. Logistic regression analysis and a random forest model were used to identify risk factors related to long-term opioid use. Compared to logistic regression, random forest variable importance measures covered both the effects of individual predictor variables as well as multivariate interactions with other predictor variables. In the random forest model, the mean decrease accuracy (MDA) index to measure the variables’ importance was used; the larger the value of the mean decrease accuracy, the more important the variable is.

Results
Of the 28,552 fibromyalgia patients who were new opioids users, 7,375 (26%) became long-term opioid users in the first year. In the fully adjusted logistic regression model, suicide and self-harm (adjusted odds ratio [aOR]: 1.98, 95% confidence interval (CI): 1.72-2.27, p &lt; 0.001), substance use disorder (aOR: 2.07, 95%CI: 1.62-2.66, p &lt; 0.001), most deprived (Index of Multiple Deprivation (IMD) quintile 5/most deprived, aOR: 1.98, 95%CI: 1.69-2.33, p &lt; 0.001, compared with quintile 1/least deprived), obesity (aOR: very severely obese, OR: 2.35, 95%CI: 1.76-3.18, p &lt; 0.001) and mean daily morphine milligram equivalents (MME) at the initiation (High (120-199 MME/day): aOR: 34.81, 95%CI: 18.00-78.05, p &lt; 0.001 compared to mean daily MME: Low (&lt;50 MME/day)) were associated with higher risk of long-term opioid use. The three most important variables using the random forest model were mean MME/day at initiation (MDA 140), history of suicide and self-harm (MDA 40) and IMD (MDA 30).

Conclusion
Almost 1 in 4 patients with fibromyalgia starting opioids became a long-term opioid user in this nationally representative dataset within the first year. The dose of initial opioid prescription, high deprivation score, history of suicide and self-harm, substance use disorder and obesity were associated with long-term opioid use.
Disclosure
M. Feng: None. C. Ramirez Medina: None. Y. Huang: None. D. Jenkins: None. M. Jani: None.