Objective The objective of this study was to estimate the cost and cost-effectiveness of opportunistic screening for Chlamydia trachomatis in Ireland.

Methods Prospective cost analysis of an opportunistic screening programme delivered jointly in three types of healthcare facility in Ireland. Incremental cost-effectiveness analysis was performed using an existing dynamic modelling framework to compare screening to a control of no organised screening. A healthcare provider perspective was adopted with respect to costs and included the costs of screening and the costs of complications arising from untreated infection. Two outcome measures were examined: major outcomes averted, comprising cases of pelvic inflammatory disease, ectopic pregnancy and tubal factor infertility in women, neonatal conjunctivitis and pneumonia, and epididymitis in men; and quality-adjusted life-years (QALY) gained. Uncertainty was explored using sensitivity analyses and cost-effectiveness acceptability curves.

Results The average cost per component of screening was estimated at €26 per offer, €66 per negative case, €152 per positive case and €74 per partner notified and treated. The modelled screening scenario was projected to be more effective and more costly than the control strategy. The incremental cost per major outcomes averted was €6093, and the incremental cost per QALY gained was €94 717. For cost-effectiveness threshold values of €45 000 per QALY gained and lower, the probability of the screening being cost effective was estimated at <1%.

Conclusions An opportunistic chlamydia screening programme, as modelled in this study, would be expensive to implement nationally and is unlikely to be judged cost effective by policy makers in Ireland.