Potential for Point-of-Care Tests to Reduce Chlamydia-associated Burden in the United States: A Mathematical Modeling Analysis

Abstract

Background: Point-of-care testing (POCT) assays for chlamydia are being developed. Their potential impact on the burden of chlamydial infection in the United States, in light of suboptimal screening coverage, remains unclear.

Methods: Using a transmission model calibrated to data in the United States, we estimated the impact of POCT on chlamydia prevalence, incidence, and chlamydia-attributable pelvic inflammatory disease (PID) incidence, assuming status quo (Analysis 1) and improved (Analysis 2) screening frequencies. We tested the robustness of results to changes in POCT sensitivity, the proportion of patients getting treated immediately, the baseline proportion lost to follow-up (LTFU), and the average treatment delay.

Results: In Analysis 1, high POCT sensitivity was needed to reduce the chlamydia-associated burden. With a POCT sensitivity of 90%, reductions from the baseline burden only occurred in scenarios in which over 60% of the screened individuals would get immediate treatment and the baseline LTFU proportion was 20%. With a POCT sensitivity of 99% (baseline LTFU 10%, 2-week treatment delay), if everyone were treated immediately, the prevalence reduction was estimated at 5.7% (95% credible interval [CrI] 3.9-8.2%). If only 30% of tested persons would wait for results, the prevalence reduction was only 1.6% (95% CrI 1.1-2.3). POCT with 99% sensitivity could avert up to 12 700 (95% CrI 5000-22 200) PID cases per year, if 100% were treated immediately (baseline LTFU 20% and 3-week treatment delay). In Analysis 2, when POCT was coupled with increasing screening coverage, reductions in the chlamydia burden could be realized with a POCT sensitivity of 90%.

Conclusions: POCT could improve chlamydia prevention efforts if test performance characteristics are significantly improved over currently available options.

Keywords: chlamydia; diagnostics; mathematical model; point-of-care; screening.

Figure 1.

Impact of POCT in Analysis 1. Outcomes of the chlamydia burden among women aged 15–24, presented under different assumptions about POCT sensitivity (varied between 90–99%), the proportion of patients treated immediately (30–100%), the baseline proportion of LTFU (5–20%), and the average baseline delay between testing positive and being treated (1–3 weeks). (A) Prevalence reductions relative to baseline, (B) annual infections, and (C) annual PID cases averted are shown. Samples of 8000 simulations are plotted for each scenario. Abbreviations: LTFU, loss to follow-up; PID, pelvic inflammatory disease; POCT, point-of-care testing; wk, week.

Figure 2.

Impact of POCT if screening frequency is increased by 20% in Analysis 2. Outcomes of the chlamydia burden among women aged 15–24 are presented under different assumptions about POCT sensitivity (varied 90–99%), the proportion of patients treated immediately (30–60%), the baseline proportion of LTFU (5–20%), and the average baseline delay between testing positive and being treated (1–3 weeks). (A) Prevalence reductions relative to baseline, (B) annual infections, and (C) annual PID cases averted are shown. Samples of 8000 simulations are plotted for each scenario. Abbreviations. LTFU, loss to follow-up; PID, pelvic inflammatory disease; POCT, point-of-care testing; wk, week.