Interim modelling analysis to validate reported increases in condom use and assess HIV infections averted among female sex workers and clients in southern India following a targeted HIV prevention programme
- Michael Pickles1,2,
- Anna M Foss2,
- Peter Vickerman2,
- Kathleen Deering3,
- Supriya Verma4,
- Eric Demers5,
- Reynold Washington4,6,7,
- BM Ramesh4,7,
- Stephen Moses7,8,
- Jamie Blanchard7,
- Catherine M Lowndes2,5,9,
- Michel Alary5,
- Sushena Reza-Paul7,
- Marie-Claude Boily1
- 1Department of Infectious Disease Epidemiology, Imperial College, London, UK
- 2Health Policy Unit, London School of Hygiene and Tropical Medicine, London, UK
- 3School of Population and Public Health, University of British Columbia, Vancouver, Canada
- 4Karnataka Health Promotion Trust, Bangalore, India
- 5Centre Hospitalier Affilié Universitaire de Québec, Québec, Canada
- 6St. John's Medical College and Hospital, Bangalore, India
- 7Department of Community Health Sciences, University of Manitoba, Winnipeg, Canada
- 8Department of Medical Microbiology, University of Manitoba, Winnipeg, Canada
- 9Health Protection Agency, London, UK
- Correspondence to Michael Pickles, Imperial College St Mary's Campus, Praed Street, London W2 1PG, UK;
Contributors MP participated in the planning of the analysis, developed the mathematical model, performed the simulations and uncertainty analysis, interpreted results and wrote the manuscript; AMF participated in the planning of the analysis, helped in developing the mathematical model and in writing the manuscript; PV and MCB designed the analysis and helped in developing the mathematical model and in interpreting results and writing the manuscript; KD and SV performed analysis of the epidemiological and behavioural data, and carried out explanatory analyses which contributed in designing the model; ED preformed analyses of epidemiological and biological data; RW, BMR, SM, JB, CML, MA and SRP all provided published and unpublished epidemiological and behavioural data, and helped with interpretation of the data and revising the manuscript.
- Accepted 14 November 2009
Objectives This study assesses whether the observed declines in HIV prevalence since the beginning of the ‘Avahan’ India HIV/AIDS prevention initiative are consistent with self-reported increases in condom use by female sex workers (FSWs) in two districts of southern India, and provides estimates of the fraction of new infections averted among FSWs and clients due to increases in condom use in commercial sex after 2004.
Methods A deterministic compartmental model of HIV/sexually transmitted infection (STI) transmission incorporating heterogeneous sexual behaviour was developed, parameterised and fitted using data from two districts in Karnataka, India. Three hypotheses of condom use among FSWs were tested: (H0), that condom use increased in line with reported FSW survey data prior to the Avahan initiative but remained constant afterwards; (H1) that condom use increased following the Avahan initiative, in accordance with survey data; (H2) that condom use increased according to estimates derived from condom distribution data. The proportion of fits to HIV/STI prevalence data was examined to determine which hypothesis was most consistent.
Results For Mysore 0/36/82.7 fits were identified per million parameter sets explored under hypothesis H0/H1/H2, respectively, while for Belgaum 9.7/8.3/0 fits were identified. The HIV epidemics in Belgaum and Mysore are both declining. In Mysore, increases in condom use during commercial sex between 2004 and 2009 may have averted 31.2% to 47.4% of new HIV infections in FSWs, while in Belgaum it may have averted 24.8% to 43.2%, if there was an increase in condom use.
Discussion Increased condom use following the Avahan intervention is likely to have played a role in curbing the HIV epidemic in Mysore. In Belgaum, given the limitations in available data, this method cannot be used alone to decide if there has been an increase in condom use.
Supplementary figures, tables and appendix are published online only at http://sti.bmj.com/content/vol86/issue1
Funding The Bill and Melinda Gates Foundation, Seattle, Washington, USA.
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.