The rising threat of illicit amphetamine-type stimulant use among methadone maintenance treatment patients in East Coast Malaysia: a retrospective observational study

Background: In recent years, amphetamine-type-stimulants (ATS) have been extensively misused in South-East Asia, inducing major problems among methadone-maintenance-treatment (MMT) patients.Objective: We examine ATS-misuse prevalence and its determinants among MMT patients in East-Coast-Malaysia.Methods: A retrospective-observational study was conducted on government-subsidized medication for opioid-use-disorder (MOUD) treatment clinics involving 292 MMT-patients (98% males) who were selected using a multilevel-proportional-stratified random sampling technique. Information obtained during the mandatory monitoring procedure from January 1 to December 31 2019, was utilized to determine ATS misuse prevalence from consecutive random urine drug screening. The determinants associated with its use, namely sociodemographics, social networks, comorbidities, and pharmacological assessments were analyzed via a logistic model.Results: Overall, 52.2% of the MMT-patients (95% CI: 0.42-0.54) had misused ATS at least once during their methadone treatment. These misusing patients were active smokers, hepatitis B and C seronegative, concurrently misused opioids, and had received suboptimum prescribed doses of methadone. Multiple logistic regression analysis demonstrated that the odds of misusing ATS during methadone treatment were 37 times higher among those who concurrently misused opioids (AOR: 37.60, 95% CI: 14.03-100.74) and 12 times higher among those who received suboptimal methadone doses (<60 mg/day) (AOR: 12.24, 95% CI: 5.58-25.43).Conclusion: This study demonstrated the significant prevalence of ATS misuse among MMT-patients in East-Coast-Malaysia, especially among patients who were prescribed suboptimal doses of methadone and/or demonstrated concomitant opioid-misuse. Stringent urine-monitoring is crucial to prevent diversion to ATS misuse. Nonetheless, to avoid negligence and improve physician engagement, the relevant authorities should immediately plan a comprehensive national-standard training module comprising support activities for professional methadone-prescribers.