Cost-Effectiveness Analysis of Screening for Chlamydia, Gonorrhea, and M. Genitalium: Monovalent Versus Multivalent Testing

Background: Screening and treating Chlamydia trachomatis (CT), Neisseria gonorrhoeae (GC), and Mycoplasma genitalium(MG) infections can prevent pelvic inflammatory disease (PID) in women.  Multivalent testing may result in an economy of scale —i.e., multivalent tests may be cheaper than the sum of the costs of performing multiple, separate tests.    However, individual payers may pay per-test prices that do not reflect this economy.

Methods:  We constructed a fixed incidence Markovian model of CT, GC, and MG (with incidences of 5%, 2%, and 7%, respectively) to estimate the annual PID incidence, and total cost associated with screening 35% of high-prevalence women annually.  We included direct medical costs for clinic visits, testing, and treatment. We calculated incremental cost effectiveness ratios (ICERs) for the following scenarios:  three monovalent, three bivalent, and one trivalent test.  Our study outcome was quality-adjusted life years (QALYs) lost due to PID and its sequelae.  We assumed monovalent, bivalent and trivalent tests respectively cost $20, $25, and $30 with an economy of scale, and $20, $40, and $60 without any economy of scale. Medicaid test pricing was $48 per organism.

Results:  The ICER of CT-GC-MG screening  versus CT-GC screening was  ~$17,000/QALY gained (economy of scale),  ~$48,000 per QALY gained (no economy of scale), or >$150,000/QALY gained (Medicaid pricing).   These results are sensitive to the underlying infection risk in the population screened and PID incidence rates associated with each infection—lower risk, lower PID incidence, and higher testing costs all increase the cost per QALY gained.

Conclusions: In high-prevalence populations, the addition of MG to ongoing CT-GC testing is likely to be an efficient use of resources , but this result is contingent on having economy of scale.  This efficiency diminishes when no economy of scale exists, which may better reflect prices paid by some payers (such as Medicaid).