An early evaluation of clinical and economic costs and benefits of implementing point of care NAAT tests for Chlamydia trachomatis and Neisseria gonorrhoea in genitourinary medicine clinics in England

Abstract

Objectives: To estimate the costs and benefits of clinical pathways incorporating a point of care (POC) nucleic acid amplification test (NAAT) for chlamydia and gonorrhoea in genitourinary medicine (GUM) clinics compared with standard off-site laboratory testing.

Method: We simulated 1.2 million GUM clinic attendees in England. A simulation in Microsoft Excel was developed to compare existing standard pathways of management for chlamydia and gonorrhoea with a POC NAAT. We conducted scenario analyses to evaluate the robustness of the model findings. The primary outcome was the incremental cost-effectiveness ratio. Secondary outcomes included the number of inappropriate treatments, complications and transmissions averted.

Results: The baseline cost of using the point of POC NAAT was £103.9 million compared with £115.6 million for standard care. The POC NAAT was also associated with a small increase of 46 quality adjusted life years, making the new test both more effective and cheaper. Over 95 000 inappropriate treatments might be avoided by using a POC NAAT. Patients receive diagnosis and treatment on the same day as testing, which may also prevent 189 cases of pelvic inflammatory disease and 17 561 onward transmissions annually.

Discussion: Replacing standard laboratory tests for chlamydia and gonorrhoea with a POC test could be cost saving and patients would benefit from more accurate diagnosis and less unnecessary treatment. Overtreatment currently accounts for about a tenth of the reported treatments for chlamydia and gonorrhoea and POC NAATs would effectively eliminate the need for presumptive treatment.

Keywords: Chlamydia Trachomatis; Cost-Effectiveness; Diagnosis; Gonorrhoea; Mathematical Model.

Figure 1

Influence diagrams showing the flow of patients through the model, assuming standard care (A) or point of care (B) pathways for chlamydia and gonorrhoea testing and treatment for genitourinary medicine clinic attendees. (A) Standard care genitourinary medicine clinic attendees based on data from Genitourinary Medicine Clinic Activity Dataset (GUMCAD) 2011, illustrated using chlamydial infection in men. Numbers based on a hypothetical cohort of 1000 male attendances and are rounded to the nearest whole number for illustration. Values <1 are not shown for simplicity. (Note: Attendees who report being a sexual partner of an infected individual are also presumptively treated (partner treatment). These can be explicitly included in the model as ‘partners’, but are not incorporated in this illustration of ‘index’ individuals, but in the complete model are added to the total of overtreatment and effective presumptive treatment.) (a) 1000 men attend of whom 350 have any symptoms at entry into clinic (ie, costed as symptomatic pathway). (b) 956 not treated presumptively, await test result=650 without symptoms (65%)+306: 87%*350 with symptoms. (c) 44=13%*350 with specific symptoms are treated presumptively. This assumes 70% of infections are correctly treated presumptively and that 5% of those not infected (but symptomatic of something else) are overtreated. (d), (e), (k), (n), (o) Show progression to development of complications, numbers not shown as <1. (e) See (d). (f) Repeat tests. (g) 881=956–75 (94% of those tested are negative). (h) 57 (6.0% of those not presumptively treated) are infected=(650*6.9% asymptomatic + 306*4.0% symptomatic) (not chlamydial). (i). 15 of those presumptively treated (35%*44) were not infected. (j) 29 of those presumptively treated (65%*44) were infected. (k), (n), (o) All relate to progression to complications which are rare events dealt with in the model not enumerated for simplicity here (<1). (l) 82 of those receiving treatment for chlamydia recover and become negative (95% treatment effectiveness). (m) Four fail treatment and remain positive (5% failure. Note: these would not routinely receive test of cure for chlamydia). From this illustration we can calculate outcomes: (1) Total chlamydial infections are 86 (8.6%)=29 (presumptive) +57 (wait result). (2). Proportion of infections treated presumptively is 33%=29/86. (3) Number of unnecessary treatments 15: represents 15%=15/(86+15). (B) Pathway for point of care GUM clinic attendees based on profiles from GUMCAD 2011, illustrated using chlamydial infection in men. Numbers based on attendance of 1000 men and are rounded to nearest whole number for illustration. Values <1 are not shown for simplicity. (a) 1000 men attend. (b) 914 (91.3% are not infected and do not have complications in the same day). (c) 86 are correctly diagnosed and treated (8.6%). (d), (g), (h) Show progression to development of complications, numbers not shown as <1. (e) 82 of those receiving treatment for chlamydia recover and become negative (95% treatment effectiveness). (f) Four fail treatment and remain positive (5% failure. Note: these would not routinely receive test of cure for chlamydia). From this illustration we can calculate outcomes: (1) Total chlamydial infections are 86 (8.6%). (2) Proportion of infections treated presumptively is 0. (3) Number of unnecessary treatments is 0.