Mapping and Estimating the Size of Key Affected Populations in Iran: Methodological Issues

Area of Science:

• Epidemiology
• Public Health
• Social Sciences

Background:

• Accurate estimation of key affected populations (KAPs), such as people who inject drugs (PWID) and people who use drugs (PWUD), is critical for effective HIV/AIDS prevention and harm reduction initiatives.
• This study addresses the need for reliable population size estimates in Iran, focusing on PWID and PWUD.

Purpose of the Study:

• To compare the collective impact of three methodological adjustments on PWID and PWUD size estimates in four Iranian cities.
• To enhance the accuracy of population size estimations for harm reduction programming.

Main Methods:

• Utilized mapping exercise data from Ahvaz, Sari, Yazd, and Tehran, Iran.
• Applied three adjustments: frequency (for infrequent attendance), duplication (for multiple site visits), and hidden population (for those avoiding sites).
• Derived input parameters from field surveys and national studies, including the Iranian Mental Health Survey.

Main Results:

• Frequency adjustment substantially increased initial PWID estimates.
• Duplication adjustment reduced estimates by 29%–37%.
• Hidden population adjustment, assuming 76% of PWID avoid hotspots, resulted in final estimates (e.g., Ahvaz: 1966, Tehran: 28), with PWUD estimates showing similar trends but limited by data gaps.

Conclusions:

• Standard hotspot mapping underestimates KAP sizes without methodological bias correction.
• The three-step adjustment framework improves accuracy but has limitations, including reliance on mobility assumptions and national survey data quality.
• Integrating correction factors into KAP surveillance is recommended for optimizing harm reduction resource allocation.