National Survey on Magnitude of Substance Use in India: Survey Methodology

Background: In 2019, a large population-based National Drug Use Survey (NDUS) was performed in India. This was the first-ever national survey on the magnitude of substance use in India, generating national and state-level estimates of various forms of substance use. In this communication, we describe in detail the survey methodology and the implementation strategies that enabled its successful conduct and completion. Methods: This was a large population-based epidemiological exercise that adopted a multi-stage sampling procedure to select districts, primary sampling units (PSUs), rural villages, and census enumeration blocks in urban areas. The estimates for alcohol and other illicit substances were obtained from a door-to-door household survey (HHS) (in 186 districts) and respondent-driven sampling (RDS) (in 135 districts). Results: A total of 473,569 individuals (10–75) were surveyed in 186 districts, from 5808 PSUs [rural: 3533 (61%), urban: 2275 (39%)] for the HHS and 70,293 respondents (drug-dependent individuals on any illicit substance). The analyses were performed on 470,892 (99.4%) and 68,705 (97.7%) respondents, respectively, for the HHS and RDS surveys. Conclusions: In a developing nation like India, undertaking and completing such a massive exercise poses a significant challenge. This article comprehensively describes all aspects of the national survey, from the design stage to completion. Such a methodological approach to scholarly communication might be very useful to researchers, particularly in the context of large-population-based epidemiological exercises in the time to come.