Assessment of intervention outcome in the absence of baseline data: ‘reconstruction’ of condom use time trends using retrospective analysis of survey data
- C M Lowndes1,2,
- M Alary2,
- S Verma3,
- E Demers2,
- J Bradley3,
- A A Jayachandran3,
- B M Ramesh4,
- S Moses5,
- R Adhikary6,
- M K Mainkar7
- 1Department of HIV & Sexually Transmitted Infections, Health Protection Agency, London, UK
- 2URESP, Centre de recherche FRSQ du CHA universitaire de Québec, Québec, Canada
- 3CHARME-India Project, Bangalore, India
- 4Karnataka Health Promotion Trust, Bangalore, India
- 5Department of Medical Microbiology, University of Manitoba, Winnipeg, Canada
- 6Family Health International, New Delhi, India
- 7National AIDS Research Institute, Pune, India
- Correspondence to Dr Catherine Lowndes, Department HIV & STIs, Centre for Infections, Health Protection Agency, 61 Colindale Avenue, London NW9 5EQ, UK;
Contributors CML developed the idea for the study and wrote the manuscript. MA is PI of the CHARME-India Project; he supervised the data and statistical analyses and assisted with writing and revision of the manuscript. SV, ED and AAJ carried out data and statistical analyses, and reviewed the manuscript. JB managed the data analysis and reviewed the manuscript. BMR, SM, RA and MKM were responsible for survey data collection and reviewed the manuscript.
- Accepted 1 December 2009
Background Avahan, the India AIDS Initiative, is a large-scale targeted intervention. Data on condom use prior to Avahan are unavailable. The authors used a novel method of analysing cross-sectional survey data to ‘reconstruct’ condom use rates in presurvey years, and to assess the relationship between Avahan and time trends in condom use among female sex workers (FSWs).
Methods Among FSWs reporting consistent condom use (CCU) with clients in surveys from 21 districts in southern India (n=7358), data on length of time using condoms, and length of time selling sex, were converted into number of FSWs using condoms (numerator) and selling sex (denominator) by year, to give yearly rates of CCU from 2001 to year of survey. Linear regression with generalised estimating equations was used to assess time trends and to compare the rate of increase in condom use before and after Avahan initiation in 2003.
Results In all 21 districts, the rate of increase in CCU from 2001 to time of the surveys was highly significant. Overall CCU increased from 27% (22%) with occasional (regular) clients in 2001, to 76% (68%) in 2006, respectively. The yearly rate of increase in CCU was significantly greater after (slope 2003–2006: 12.7% (12.0%) per year for occasional (regular) clients) than prior to Avahan (slope 2001–2003: 5.1% (5.3%) per year for occasional (regular) clients) implementation (p<0.0001).
Conclusions The findings indicate a positive relationship between implementation of the Avahan programme and rates of CCU increase among FSW. This method of analysis may be useful in other contexts where preintervention data are lacking.
- Female sex workers
- condom use
- programme evaluation
- baseline data
- Avahan, condoms
- developing world
Supplementary figures/tables/appendix are published online only at http://sti.bmj.com/content/vol86/issue1
Funding Bill and Melinda Gates Foundation, PO Box 23350, Seattle, WA 98102, USA.
Competing interests None.
Ethics approval Ethics approval was provided by the Centre hospitalier affilié universitaire de Québec, Québec, Canada; University of Manitoba, Winnipeg, Canada; St John's Medical College, Bangalore, India.
Provenance and peer review Not commissioned; externally peer reviewed.