Table 4. Approach used to generate 2016 regional estimates for chlamydia, gonorrhoea and trichomoniasis.

Estimation region	Women				Men
	Chlamydia	Gonorrhoea	Trichomoniasis		Chlamydia	Gonorrhoea	Trichomoniasis
Central, eastern and western sub-Saharan Africa	Meta-analysis	Meta-analysis	Meta-analysis		Global male-to-female ratio	Global male-to-female ratio	Global male-to-female ratio
Southern sub-Saharan Africa	Meta-analysis	Meta-analysis	Meta-analysis		Global male-to-female ratio	Global male-to-female ratio	Global male-to-female ratio
Andean, central, southern and tropical Latin America and Caribbean	Meta-analysis	Meta-analysis	Meta-analysis		Special casea	Global male-to-female ratio	Global male-to-female ratio
High-income North Americab	United States estimate for 2012	United States estimate for 2008	United States estimate for 2008		United States estimate for 2012	United States estimate for 2008	United States estimate for 2008
North Africa and Middle East	Meta-analysis	Meta-analysis	Meta-analysis		Global male-to-female ratio	Global male-to-female ratio	Global male-to-female ratio
Australasia and high-income Asia Pacific	Meta-analysis	Gonorrhoea to chlamydia ratio	Trichomoniasis to chlamydia ratio		Global male-to-female ratio	Global male-to-female ratio	Global male-to-female ratio
Western, central and eastern Europe and central Asia	Meta-analysis	Meta-analysis	Trichomoniasis to chlamydia ratio		Meta-Analysis	Global male-to-female ratio	Global male-to-female ratio
Oceania	Meta-analysis	Meta-analysis	Meta-Analysis		Global male-to-female ratio	Global male-to-female ratio	Global male-to-female ratio
South Asia	Meta-analysis	Gonorrhoea to chlamydia ratio	Trichomoniasis to chlamydia ratioc		Global male-to-female ratio	Global male-to-female ratio	Global male-to-female ratio
East Asia and south-east Asia	Meta-analysis	Gonorrhoea to chlamydia ratiod	Meta-analysis		Global male-to-female ratio	Global male-to-female ratio	Global male-to-female ratio

^a In consultation with advisors on sexual transmitted infections for the World Health Organization (WHO) Region of the Americas, we decided to use the midpoint between the 2016 estimate generated by applying the global male-to-female ratio (7.5%) and the 2012 estimate for the region (2.1%). We deemed the former to be too high and the latter too low.

^b Following discussions with the United States Centers for Disease Control and Prevention, we based our estimates on the latest published United States national estimates^21,22 and assumed they remained constant over time and that estimates for 15–39-year-old people could be extrapolated to the 15–49-year age range. We did not apply the adjustments used for other Regions in the WHO estimates process. The figures for the United States were also applied to Canada.

^c The estimate based on the three available data points was over 4%, considerably higher than the 2012 estimate. Following discussions with regional experts we decided not to use this estimate, but instead to use the trichomoniasis to chlamydia ratio for low and lower middle-income countries, territories and areas.

^d This estimation region is made up of countries from East Asia and South East Asia. We used the higher and upper-middle income gonorrhoea to chlamydia ratio for East Asia and the low and lower-middle income ratio for South East Asia.”