Background & Aims
Chronic pain is found to be prevalent and more frequently severe among opioid agonist therapy (OAT) users than general population. Assessment and management of chronic pain in this group is complex and less understood owing to intertwined opioid use, concomitant psychiatric disorder and reluctance on the part of providers to prescribe opioids to these patients. Furthermore, chronic pain can be a major risk factor for opioid relapse alongside the adverse health consequences of under treatment.
This study aims to evaluate the prevalence of chronic pain and its characteristics among adults under OAT in the opioid substitution therapy clinic in a tertiary hospital of Eastern Nepal. The data obtained may be of value to highlight the importance of integrated care of both pain and addiction, patient focused management and the need for development of guidelines for multidisciplinary pain management in this group of patients.
Methods
This was a cross sectional study done among 140 adults under opioid agonist therapy in the opioid substitution therapy clinic in a tertiary hospital of Eastern Nepal from October to December 2023.
All participants above 18 years under therapy were included after verbal and written information. Exclusion criteria was the client refusal and inability to comprehend or communicate. Individual interview with semi-structured questionnaire was used for socio-demographic data and relevant medical history. Pain characteristics were assessed for severity (Numerical rating scale), location and type. Use of prescription or illicit drugs or substance abuse for pain relief was elicited. Validated DN4 questionnaire translated into Nepali was used for assessment of neuropathic pain.
Results
All clients were under methadone maintenance therapy. 32 participants declined to take part in the study (response rate 77%). Mean age of participants was 31 ± 9 (19-55) years, mostly males (92%). Few had a significant medical or psychiatric comorbidities (5%). The prevalence of chronic pain was around 20%. About a third were married, and were engaged in occupation or education while rest were jobless. Only six percent reported having increasing requirement of methadone while the rest had decreasing requirements. Most complained of non-cancer nociceptive pain, with few complaining of neuropathic pain (6%), of mild to moderate pain severity (80%). Pain was musculoskeletal localized mostly to lower back (42%). Other sites were lower limbs, lower abdomen, upper limbs in decreasing order and few with multiple pain sites (8%). There was non significant trend of use of some form of illicit drug abuse or cannabis use in clients with higher NRS (?2 =3.54, p=0.315).
Conclusions
The prevalence of chronic pain among our OAT clients was comparatively lower than other studies which ranged from 23.6% (14.6-46.2) to 32.1 % (28.6-36.3). Pain severity was mostly mild to moderate in contrast to moderate to severe in other studies, where severity was also assessed in terms of pain interference in daily life. Other studied variables showed non significant association with chronic pain. These patients are vulnerable in the sense of addiction, psychiatric disorder and pain. Further larger studies with geographical, socioeconomic and cultural diversities included can give a better picture.
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