RESUMEN
INTRODUCTION AND AIMS: A population estimation study was performed in 2009-2010 to understand the apparent decrease in people who inject drugs (PWID) attending needle syringe programs (NSPs) and to calculate the number of PWID in Bali for service planning. DESIGN AND METHODS: The multiplier method was applied to the results of a survey of 125 PWID using data from 16 institutions to calculate benchmarks for five events. Respondents were also asked to nominate other PWID and the services they used and to name PWID who had died in the previous 3 years. RESULTS: There was consistency in the estimates calculated using the multipliers for police arrests, voluntary counselling and testing and NSP which produced estimates of 700, 723 and 769 PWID, respectively. The nominator method identified 529 PWID. The number of reported PWID deaths had decreased over the past 3 years and may reflect a shrinking in the population of PWID in Bali. Police data revealed a dramatic shift in arrests for drug possession in 2002-2003 compared with arrests during 2009. Heroin possession was recorded in 37.4% of 2002-2003 arrests but decreased to 3.1% in 2009, whereas amphetamine possession increased from 11% to 30.9% in the same period. DISCUSSION AND CONCLUSIONS: Bali appears to have experienced a decrease in the number of PWID, which is likely to be related to death and to a pronounced shift to non-injected drug use.