TY - JOUR
T1 - Has Chlamydia trachomatis prevalence in young women in England, Scotland and Wales changed? Evidence from national probability surveys
AU - Kounali, Daphne-Zacharenia
AU - Welton, Nicky
AU - Soldan, Kate
AU - Woodhall, Sarah C
AU - Dunbar, J Kevin
AU - Migchelsen, Stephanie J
AU - Mercer, C
AU - Horner, Paddy J
AU - Ades, Tony
PY - 2019
Y1 - 2019
N2 - We evaluate the utility of the National Surveys of Attitudes and Sexual Lifestyles (Natsal) undertaken in 2000 and 2010, before and after the introduction of the National Chlamydia Screening Programme, as an evidence source for estimating the change in prevalence of Chlamydia trachomatis (CT) in England, Scotland and Wales. Both the 2000 and 2010 surveys tested urine samples for CT by Nucleic Acid Amplification tests (NAATs). We examined the sources of uncertainty in estimates of CT prevalence change, including sample size and adjustments for test sensitivity and specificity, survey non-response, and informative non-response. In 2000, the unadjusted CT prevalence was 4.22% in women aged 18-24 years; in 2010, CT prevalence was 3.92%, a non-significant absolute difference of 0.30 percentage points (95% CrI -2.8 - 2.0). In addition to uncertainty due to small sample size, estimates were sensitive to specificity, survey non-response or informative non-response, such that plausible changes in any one of these would be enough to either reverse or double any likely change in prevalence. Alternative ways of monitoring changes in CT incidence and prevalence over time, are discussed.
AB - We evaluate the utility of the National Surveys of Attitudes and Sexual Lifestyles (Natsal) undertaken in 2000 and 2010, before and after the introduction of the National Chlamydia Screening Programme, as an evidence source for estimating the change in prevalence of Chlamydia trachomatis (CT) in England, Scotland and Wales. Both the 2000 and 2010 surveys tested urine samples for CT by Nucleic Acid Amplification tests (NAATs). We examined the sources of uncertainty in estimates of CT prevalence change, including sample size and adjustments for test sensitivity and specificity, survey non-response, and informative non-response. In 2000, the unadjusted CT prevalence was 4.22% in women aged 18-24 years; in 2010, CT prevalence was 3.92%, a non-significant absolute difference of 0.30 percentage points (95% CrI -2.8 - 2.0). In addition to uncertainty due to small sample size, estimates were sensitive to specificity, survey non-response or informative non-response, such that plausible changes in any one of these would be enough to either reverse or double any likely change in prevalence. Alternative ways of monitoring changes in CT incidence and prevalence over time, are discussed.
KW - chlamydia trachomatis
KW - prevalence
KW - sexually transmitted infections (STIs)
U2 - 10.1017/S0950268819000347
DO - 10.1017/S0950268819000347
M3 - Article (Academic Journal)
C2 - 30869031
SN - 0950-2688
VL - 147
SP - e107
JO - Epidemiology and Infection
JF - Epidemiology and Infection
M1 - e107
ER -