International monitoring of capacity of treatment systems for alcohol and drug use disorders: Methodology of the Service Capacity Index for Substance Use Disorders.

Objectives: We aimed to develop a Service Capacity Index for Substance Use Disorders (SCI-SUD) that would reflect the capacity of national health systems to provide treatment for alcohol and drug use disorders, in terms of the proportion of available service elements in a given country from a theoretical maximum.

Methods: Data were collected through the WHO Global Survey on Progress with Sustainable Development Goals (SDG) Health Target 3.5, conducted between December 2019 and July 2020 to produce the SCI-SUD, based on 378 variables overall.

Results: The SCI-SUD was directly derived for 145 countries. We used multiple imputation to produce comparable SCI-SUD estimates for countries that did not submit data (40 countries) or had very high level of missingness (9 countries). The final SCI-SUD demonstrates considerable consistency and internal stability and is strongly associated with the macro-level economic, healthcare-related and epidemiologic (such as prevalence rates) variables.

Conclusion: The presented methodology represents a step forward in monitoring the global situation in regard to the development of treatment systems for SU disorders, however, further work is warranted to improve the external validity of the measure (e.g., in-depth data generation in countries) and ensure its feasibility for regular reporting (e.g., reducing the number of variables).