An evaluation of economics and acceptability of screening for Chlamydia trachomatis infection, in women attending antenatal, abortion, colposcopy and family planning clinics in Scotland, UK

Abstract

Objective: The aims of this study were to determine cost effectiveness of screening for Chlamydia trachomatis in hospital-based antenatal and gynaecology clinics, and community-based family planning clinics. Additionally, women's views of screening were determined in the hospital-based clinics.

Design: Cost effectiveness based on decision model. Model probabilities were generated for a hypothetical sample of 250 women in each age group in each setting, based on prevalence studies, published data and expert opinion. A prospective observational study was used to generate data on prevalence and acceptability.

Setting: Antenatal, gynaecology and family planning clinics in Aberdeen, Edinburgh and Glasgow.

Sample: Prevalence was estimated in 2817 women. Acceptability was determined in 484 women.

Methods: An economic evaluation was performed using prevalence data from this and a previous study, and using outcome data from the literature and observational work. Incremental cost effectiveness ratios were estimated for each age group and clinical setting. Sensitivity analyses were performed to determine the robustness of incremental cost effectiveness ratios to changes in the incidence of long term sequelae and costs. The prevalence of infection was determined by nucleic acid amplification of urine samples or endocervical swabs. Knowledge of C. trachomatis and women's views of screening were determined using structured questionnaires.

Main outcome measures: Direct health service costs of screening, incidence and costs associated with adverse sequelae, women's views of screening and prevalence of infection.

Results: The estimated cost of screening 250 women in each age group in each the four sample populations (total population of 3750) is 49,367 UK pounds, while preventing 64 major sequelae. This represents a net cost of 771.36 UK pounds in preventing one major sequela. Selective screening of all women under 20 years and all patients attending abortion clinics were shown to be the most cost effective strategies. These results were relatively insensitive to changes in estimated parameters, such as uptake rate, probabilities and unit costs of all major sequelae averted. Prevalence (95% CI) of infection in the highest risk groups (those aged under 20 in both antenatal and abortion clinics) was 12.1% (8.6-16.7) and 12.7% (7.3-21.2), respectively. The majority (>95%) of women agreed with a policy of regular screening for C. trachomatis, and screening in the settings employed in this study was largely acceptable.

Conclusions: A single episode of screening for C. trachomatis does not result in net cost savings. Currently recommended strategies of screening for C. trachomatis in women under 25 years of age in abortion clinics are supported by our data on prevalence and acceptability. These data also suggest that hospital-based screening strategies should be further extended to include younger women attending antenatal clinics and all women of reproductive age attending colposcopy clinics.