Article Text
Abstract
Objective To develop a tool for estimating national trends in adult prevalence of sexually transmitted infections by low- and middle-income countries, using standardised, routinely collected programme indicator data.
Methods The Spectrum-STI model fits time trends in the prevalence of active syphilis through logistic regression on prevalence data from antenatal clinic-based surveys, routine antenatal screening and general population surveys where available, weighting data by their national coverage and representativeness. Gonorrhoea prevalence was fitted as a moving average on population surveys (from the country, neighbouring countries and historic regional estimates), with trends informed additionally by urethral discharge case reports, where these were considered to have reasonably stable completeness. Prevalence data were adjusted for diagnostic test performance, high-risk populations not sampled, urban/rural and male/female prevalence ratios, using WHO's assumptions from latest global and regional-level estimations. Uncertainty intervals were obtained by bootstrap resampling.
Results Estimated syphilis prevalence (in men and women) declined from 1.9% (95% CI 1.1% to 3.4%) in 2000 to 1.5% (1.3% to 1.8%) in 2016 in Zimbabwe, and from 1.5% (0.76% to 1.9%) to 0.55% (0.30% to 0.93%) in Morocco. At these time points, gonorrhoea estimates for women aged 15–49 years were 2.5% (95% CI 1.1% to 4.6%) and 3.8% (1.8% to 6.7%) in Zimbabwe; and 0.6% (0.3% to 1.1%) and 0.36% (0.1% to 1.0%) in Morocco, with male gonorrhoea prevalences 14% lower than female prevalence.
Conclusions This epidemiological framework facilitates data review, validation and strategic analysis, prioritisation of data collection needs and surveillance strengthening by national experts. We estimated ongoing syphilis declines in both Zimbabwe and Morocco. For gonorrhoea, time trends were less certain, lacking recent population-based surveys.
- GONORRHOEA
- SYPHILIS
- SURVEILLANCE
- AFRICA
- MATHEMATICAL MODEL
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Supplementary materials
Abstract in French
This web only file has been produced by the BMJ Publishing Group from an electronic file supplied by the author(s) and has not been edited for content.
- Abstract in French - Online abstract
Abstract in Arabic
This web only file has been produced by the BMJ Publishing Group from an electronic file supplied by the author(s) and has not been edited for content.
- Abstract in Arabic - Online abstract
Footnotes
Contributors ELK and TW conceived the project; ELK, GM and NN designed the Spectrum approach; GM, NN and CP designed the statistical methodology; ELK, GM, NN, LA-R, FN and JR analysed results; FN, JR, LA-R, PM, RMC, AE-K and HE-R provided country data; LAR, PM, RMC, FN and TW provided biomedical modelling assumptions; KH, GM and CP programmed the Spectrum user interface software; ELK and JR wrote the article; all authors analysed the final results, reached consensus in the interpretation and contributed to writing the final article.
Funding The project was funded by the WHO, Department of Reproductive Health and Research. LA-R acknowledges the support of Qatar National Research Fund (NPRP 9-040-3-008), which provided the main funding for generating the data provided for this study.
Competing interests None declared.
Provenance and peer review Commissioned; externally peer reviewed.
More info The views expressed in this paper are those of the authors and do not necessarily represent the position of Avenir Health, the WHO, the Joint United Nations Programme on HIV and AIDS, Morocco's Ministry of Health or any other affiliated organisation.
Data sharing statement All data used were provided within the manuscript and its three supplementary files.