Cost-effectiveness of microscopy of urethral smears for asymptomatic Mycoplasma genitalium urethritis in men in England

Introduction
Over the past decade, there has been a change in the clinical investigation and management of men attending sexual health services in the UK. Previously, all men, regardless of symptoms, underwent urethral smears, a process by which a sample is taken from inside the urethra and Gram stained for examination by light microscopy (1). This allowed for the immediate diagnosis of two conditions: presumptive gonorrhoea and non-gonococcal urethritis (inflammation of the urethra in the absence of gonorrhoea). Men with either of these conditions, and their sexual partners, were then offered immediate treatment with appropriate antibiotics whilst waiting several days for more definitive results.
With the widespread use of sensitive and specific non-invasive urine testing for chlamydia and gonorrhoea, and in order to streamline services in line with emerging evidence that it is not needed, guidelines now recommend only performing urethral microscopy in symptomatic men (1). A consequence of this change in practice is that asymptomatic men with urethritis, caused by neither chlamydia nor gonorrhoea (known as non-chlamydial, non-gonococcal urethritis or NCNGU), no longer receive empirical antimicrobial therapy. Their sexual partners are also left untreated. However, at the time of the most recent national audit (1), a small number of clinics continued to provide routine urethral microscopy to asymptomatic men, contrary to the guidelines.
The potential impact of this change in practice on costs and patients outcomes is not clear and has not yet been explored in any depth. Asymptomatic urethritis has many causes, both infectious and non-infectious (1). Notably, Mycoplasma genitalium is present in 8-10% of men with asymptomatic urethritis (1) and is associated with both cervicitis and pelvic inflammatory disease in women (2). There is limited access to testing for M. genitalium in the UK and few men are tested for this organism. Therefore, whereas previously, men with asymptomatic urethritis secondary to M. genitalium and their partners may have received successful treatment as part of empirical therapy for urethritis, this is no longer the case.
The focus of this study is on the potential cost implications of this change in clinical practice assuming that some men with asymptomatic NCNGU have M. genitalium, which can have adverse and costly reproductive health outcomes in their female sexual partners. Specifically, the objective of this economic evaluation is to determine whether the screening landscape at the time of the last national audit, in which a small number of clinics continued to perform routine microscopy in asymptomatic men is a cost-effective approach to diagnosing and treating asymptomatic NCNGU compared to the national guideline recommending not performing microscopy for this patient group. While it is acknowledged that there may be other causes of asymptomatic NCNCU other M. genitalium, there is little robust evidence that some of these may lead to important potential consequences. A previous study by Saunders et al. (2011) (3) found a paucity of high quality evidence that asymptomatic NCNGU is associated with significant consequences for men or their sexual partners. Thus, this study only considers cases caused by M. genitalium.