About the Authors

Victoria Pattison de Menil

v.p.de-menil@lse.ac.uk

Affiliation Department of Social Policy, London School of Economics and Political Science, London, United Kingdom

Martin Knapp

Affiliation Personal Social Services Research Unit, London School of Economics and Political Science, London, United Kingdom

David McDaid

Affiliation Personal Social Services Research Unit, London School of Economics and Political Science, London, United Kingdom

Frank Gitau Njenga

Affiliation Chiromo Lane Medical Centre, Nairobi, Kenya

Competing Interests

Dr. Frank Njenga is a member of the Board of Directors of Chiromo Lane Medical Center and chairs the AAR health management organization in Kenya. He also heads the National Campaign Against Drug Abuse (NACADA), the government authority on the prevention and treatment of substance use disorders. This does not alter the authors' adherence to all the PLOS ONE policies on sharing data and materials.

Author Contributions

Conceived and designed the experiments: VdM MK DM FN. Performed the experiments: VdM. Analyzed the data: VdM MK DM FN. Wrote the paper: VdM. Contributed to revising the article for important intellectual content and approved the final version: MK DM FN.