title: Diffusion of subsidized ACTs in accredited drug shops in Tanzania: determinants of stocking and characteristics of early and late adopters.
abstract: BACKGROUND
  Many households in sub-Saharan Africa utilize the private sector as a primary source of treatment for malaria episodes. Expanding access to effective treatment in private drug shops may help reduce incidence of severe disease and mortality. This research leveraged a longitudinal survey of stocking of subsidized artemisinin combination therapies (ACTs), an effective anti-malarial, in Accredited Drug Dispensing Outlets (ADDOs) in two regions of Tanzania. This provided a unique opportunity to explore shop and market level determinants of product diffusion in a developing country retail market.
  
  
  METHODS
  356 ADDOs in the Rukwa and Mtwara regions of Tanzania were surveyed at seven points between Feb 2011 and May 2012. Shop level audits were used to measure the availability of subsidized ACTs at each shop. Data on market and shop level factors were collected during the survey and also extracted from GIS layers. Regression and network based methodologies were used. Shops classified as early and late adopters, following Rogers' model of product diffusion, were compared. The Bass model of product diffusion was applied to determine whether shops stocked ACTs out of a need to imitate market competitors or a desire to satisfy customer needs.
  
  
  RESULTS
  Following the introduction of a subsidy for ACTs, stocking increased from 12% to nearly 80% over the seven survey rounds. Stocking was influenced by higher numbers of proximal shops and clinics, larger customer traffic and the presence of a licensed pharmacist. Early adopters were characterized by a larger percentage of customers seeking care for malaria, a larger catchment and sourcing from specific wholesalers/suppliers. The Bass model of product diffusion indicated that shops were adopting products in response to competitor behavior, rather than customer demand.
  
  
  CONCLUSIONS
  Decisions to stock new pharmaceutical products in Tanzanian ADDOs are influenced by a combination of factors related to both market competition and customer demand, but are particularly influenced by the behavior of competing shops. Efforts to expand access to new pharmaceutical products in developing country markets could benefit from initial targeting of high profile shops in competitive markets and wholesale suppliers to encourage faster product diffusion across all drug retailers.
authors.affiliation: Department of Epidemiology, School of Public Health, University of Michigan, 1415 Washington Heights, Ann Arbor, MI 48109-2029, USA. anfangen@umich.edu.
authors.forename: Peter S
authors.initials: PS
authors.lastname: Larson
authors.forename: Prashant
authors.initials: P
authors.lastname: Yadav
authors.forename: Sarah
authors.initials: S
authors.lastname: Alphs
authors.forename: Jean
authors.initials: J
authors.lastname: Arkedis
authors.forename: Julius
authors.initials: J
authors.lastname: Massaga
authors.forename: Oliver
authors.initials: O
authors.lastname: Sabot
authors.forename: Jessica L
authors.initials: JL
authors.lastname: Cohen
mesh_terms: D000068:Accreditation / Q000706:statistics & numerical data; D000962:Antimalarials / Q000600:supply & distribution* / Q000627:therapeutic use; D037621:Artemisinins / Q000600:supply & distribution* / Q000627:therapeutic use; D004465:Economic Competition; D005380:Financing, Government / Q000706:statistics & numerical data; D006301:Health Services Needs and Demand / Q000706:statistics & numerical data; D006801:Humans; D008288:Malaria / Q000188:drug therapy; D010594:Pharmacies / Q000706:statistics & numerical data*; D013636:Tanzania / Q000453:epidemiology
chemical_list: D000962:Antimalarials; D037621:Artemisinins; C031327:artemisinin