Prevalence of suboptimal dosing of methadone and buprenorphine and associated factors in opioid dependent patients

Background. Optimal methadone and buprenorphine dosing is the cornerstone in the treatment of opioid dependence for achieving the foremost treatment outcomes. However, little is known about the prescribing of both medications in treating opioid-dependent patients in communities served by NHS Lanarkshire, Scotland. 
Objectives. This study assesses the prevalence of suboptimal methadone and buprenorphine dosing and examines the role of sociodemographic factors, lifestyle characteristics, health conditions, and the use of medications in suboptimal dosing among opioid-dependent patients in hospitals, clinics and health centres connected to NHS Lanarkshire. 
Method. The approach involved retrospective analysis of pre-collected data by the addiction and substance misuse teams spanning a period from April 2018 to March 2019 in NHS Lanarkshire, Scotland. Binary logistic regression analysis was conducted to identify and examine the association between suboptimal methadone and buprenorphine dosing, and demographic and clinical factors among a total of 410 adult patients (age ≥ 18 years) with a confirmed diagnosis of opioid dependence. 
Results. Among opioid-dependent patients in NHS Lanarkshire (n = 410), the prevalence of suboptimal methadone and buprenorphine dosing was estimated to be 16.3%. Patients aged > 40 years old (OR, 1.45; 95% CI, 0.82-2.56), the presence of COPD comorbidity (OR, 2.23; 95% CI, 1.02-4.89), the use of two concomitant medications (OR, 1.70; 95% CI, 0.88- 3.28), and the use of anti-depressants (OR, 1.48; 95% CI, 0.88-2.52) significantly increased the likelihood of suboptimal OAT dosing. 
Conclusion. These results provide important clues in identifying possible risk factors for suboptimal OAT dosing in opioid-dependent patients, highlighting the need to optimise OAT dosing in those with modifiable risk factors. This will help achieve better treatment outcomes while consistently monitoring patients with unmodifiable risk factors to minimise their likelihood of experiencing adverse events, including the risk of drug overdose or toxicity.