Trends in the use of illicit substances in Thailand: Results from national household surveys.

INTRODUCTION AND AIMS: Thailand borders some of the world's largest methamphetamine and opioid producing countries and trafficking routes. Thailand's 'War on Drugs' campaign was launched in 2003. This study reports trends in illicit substance use in Thailand over the period 2001-2011.

DESIGN AND METHODS: National Household surveys on illicit drug use were conducted in 2001, 2003, 2007, 2008 and 2011. A stratified multi-stage cluster random sampling technique was implemented for each survey. Provinces in four regions were systematically selected using a probability proportionate to the size of the targeted population. Participants were interviewed using structured questionnaires on their history of substance use.

RESULTS: The prevalence of illicit drug use within the past drastically decreased from 4.5% in 2001 to 1.0% in 2003 (P < 0.05). Since 2003, the prevalence of illicit use within the past year varied between 1.0% and 1.3%. By 2011, it was estimated that 0.84% have used kratom (a substance derived from Mitragyna speciosa) within the past year. Around 0.20% and 0.19% reported using cannibis and yaba (metamphetamine tablet) within a year of the 2011 survey. Other types of illicit drugs were less commonly used in Thailand.

DISCUSSION AND CONCLUSIONS: There was a decrease in prevalence of illicit drug use within the past year between 2001 and 2003 in Thailand. Since 2003, the past year prelavence of illicit drug use has remained relatively stable. From 2001 to 2011, cannabis, kratom and yaba have remained the three most commonly reported types of illicit drugs used in Thailand.