Patterns of Polysubstance use among Adults in Malaysia – A Latent Class Analysis

Introduction Polysubstance use is the use of more than one non-prescribed licit or illicit substance at one time. This is a common phenomenon, but little is known about the severity and the various substances used by adults in Malaysia. Objective To determine the pattern of polysubstance use and its associated factors among general adults in Malaysia. Methodology This was a secondary data analysis from the National Health and Morbidity Survey (NHMS) 2019), a cross-sectional population survey with a two-stage stratified random sampling design. A total of 10,472 Malaysians aged 18 years and above participated in this survey. Polysubstance use was defined as concurrent use of more than one substance, either alcohol, tobacco, or drugs (opioid, marijuana, amphetamine/ methamphetamine or kratom). A latent class analysis (LCA) was used to identify the membership of polysubstance groups. The association of class membership with demographic profiles was examined using Multinomial Logistic Regression analysis. Results Fit indices (AIC =16458.9, BIC = 16443.6) from LCA supported 3 classes solution: i) Combination of tobacco and alcohol (Tob+Alc) use (2.4%), ii) multi-drug use including kratom (0.3%) and iii) non/negligible user (97.3%). The multinomial model showed young adults (18-40 years) had a higher likelihood of being polysubstance users both for Tob+Alc class (OR=4.1) and multi-drug class (OR=3.9) compared to older age (≥60 years). Chinese (OR = 18.9), Indian (OR =23.3), Indigenous Sabah & Sarawak (OR =34.6) and others ethnicity (OR =8.9) showed higher odds of being Tob+Alc users than Malays. The greater odds of Tob+Alc. use for male (OR =35.5), working group (OR =1.5) and low education level group (OR=3.2). Conclusion Our study highlights patterns and demographics related to the use of polysubstance among adults in Malaysia. These results would help formulate specific prevention programmes for these high risk groups.