Introduction Our Sexual Health service covers a county-wide population, including large numbers of Army personnel. Despite military personnel being recognised as high risk for sexually-transmitted infections (STIs), accurate data on STI and HIV epidemiology within the military is lacking (1).The latter is compounded by difficulties differentiating military from civilian patients attending Sexual Health clinics. We introduced a local code (‘ARMY’) from April 2016. This has enabled us to monitor numbers of Army attendees and compare STI rates and risk factors with non-military patients.

Methods Local ‘ARMY’ code added by clinicians at time of consultation, based on information including: patient self-reported occupation, garrison address, military uniform.

Electronic patient records for all male new or rebook attendees between 15/4/16 and 31/10/16 with an ‘ARMY’ code were reviewed (n = 234). These were compared with a non-military group of patients (n=234) attending during same time period and were matched for age group, gender, sexuality and presence/absence of symptoms.

Results Army personnel were found to have significantly higher levels of chlamydia positivity (19.2%) compared with non-military attendees (11.1%) (p= 0.020, Fisher’s exact 2-tail). This higher rate of chlamydia was found despite comparable numbers of: sexual partners in prior three months, presentations as chlamydia contacts and high-risk alcohol users. Rates of gonorrhoea, warts, HSV, HIV and syphilis did not differ significantly. Army personnel were significantly more likely to be of non- white British ethnicity (11.1%) than non-military attendees (2.1%), reflecting local population (p =0.0001, Fisher’s exact 2-tail).

Discussion Our findings support promotion of sexual health screening for military personnel and targeting of chlamydia testing. Military personnel often go home to other areas of UK and overseas during leave and could disseminate infections.