B P Stoner

Estimating duration in partnership studies: issues, methods and examples

Background and objectives Understanding the time course of sexual partnerships is important for understanding sexual behaviour, transmission risks for sexually transmitted infections (STI) and development of mathematical models of disease transmission. Study design The authors describe issues and biases relating to censoring, truncation and sampling that arise when estimating partnership duration. Recommendations for study design and analysis methods are presented and illustrated using data from a sexual-behaviour survey that enrolled individuals from an adolescent-health clinic and two STD clinics. Survey participants were queried, for each of (up to) four partnerships in the last 3 months, about the month and year of first sex, the number of days since last sex and whether partnerships were limited to single encounters. Participants were followed every 4 months for up to 1 year. Results After adjustment for censoring and truncation, the estimated median duration of sexual partnerships declined from 9 months (unadjusted) to 1.6 months (adjusted). Similarly, adjustment for censoring and truncation reduced the bias in relative risks for the effect of age in a Cox model. Other approaches, such as weighted estimation, also reduced bias in the estimated duration distribution. Conclusion Methods are available for estimating partnership duration from censored and truncated samples. Ignoring censoring, truncation and other sampling issues results in biased estimates.

P3.161 Triple-Dip: Expanded Extragenital Testing For Neisseria Gonorrhoeae and Chlamidia Trachomatis Identifies High Rates of Asymptomatic Infection in Persons Living with HIV

Background US guidelines now call for expanded extragenital testing for Neisseria gonorrhoeae (GC) and Chlamydia trachomatis (Ct) in HIV infected individuals. In January 2012, we instituted a new policy to promote routine three-site testing (genital, oropharyngeal, rectal) for GC/Ct among HIV-infected persons in our clinic population. The purpose of this study is to assess implementation of the “triple-dip” programme, as well as the prevalence and incidence of STI at each site. Methods We conducted a retrospective chart review of HIV-infected patients seen in our clinic before (Jan.-Dec. 2011) and after (Jan.-Dec. 2012) implementation of a routine three-site testing policy, to compare GC/Ct prevalence during these two time periods. Self-reported behavioural data were also evaluated. Results For the three months after the transitioning from symptom-triggered testing to routine three-site screening for GC/Ct, the number of oropharyngeal tests performed increased from 38 to 325, and the number of rectal tests increased from 32 to 290, an 8 to 9 fold increase in testing. Although the rate of infection at most sites decreased with increased screening, the rate of rectal GC/Ct remained unchanged (13% pre-expanded testing verses 12% after initiating broader testing, p = n.s.). This suggests that the prevalence of asymptomatic rectal infections in patients living with HIV in our clinic is high. Preliminary analyses indicate that rectal infections are more common in our tested patient population (12%) than at other sites of testing (4.5% oropharyngeal tests were positive, 1.5% genital tests were positive). Conclusion Although extragenital testing increased with expanded testing, not all patients at risk were screened. Given the higher percentage of positive rectal tests, enhanced testing should focus on increasing awareness of rectal infection, treatment intervention, and risk counselling.

O3-S3.06 Rescreening for chlamydial infection using home-based, self-obtained vaginal swabs: a randomised controlled trial in family planning clinic clients

Background Family planning clinics provide contraceptive and preventive services for millions of low-income individuals. Screening and treatment for Chlamydia trachomatis infection in these clinics is a major part of the chlamydia control program in the USA. For women diagnosed with chlamydia, rescreening 3 months after treatment is recommended according to national guidelines. However, rescreening rates are low. The time and effort needed for patients to return to the clinic and the lack of access to follow-up care may contribute to the poor adherence to the rescreening recommendation. Methods We conducted a randomised controlled trial in family planning clinics in three cities. After informed consent, women/girls >16 years treated for laboratory-confirmed chlamydial infection were randomly assigned to the Home Group (mailed a vaginal swab kit for self collection at home) or the Clinic Group (made a clinic appointment) for rescreening at 3 months following treatment. Reminder calls were made about 2 weeks before scheduled rescreening. The endpoint was rescreening within a 7 week window, 1 week before to 6 weeks after, the scheduled rescreening date. Results 404 women were enrolled and their group assignments were randomised by opening centrally stuffed envelops. Women assigned to the Home Group had higher rescreening rate than those in the Clinic Group: Overall, 40.8% of 196 in the Home Group and 20.7% of 208 in the Clinic Group were rescreened (p<0.001). The rescreening rates were 38.4% (Home) vs 19.8% (Clinic) among those living with parents, and 48.2% (Home) vs 21.2% (Clinic) among those with a history of chlamydia infection prior to the treated episode at enrolment (both p<0.001). Among women reached by a reminder call, rescreening rates were significantly higher in the Home Group (59.2% of 130) than in the Clinic Group (37.8% of 111) (p<0.001). Among 163 women not reached by the reminder call, the rescreening rate were low (<5%) in both groups. In the Home Group, 12 tested positive for chlamydia compared to 8 in the Clinic Group, and the rate of reinfection was 12.9% in the Home Group and 14.6% in the Clinic Group (p=0.8). Conclusions Use of home-based, self-obtained vaginal swabs resulted in a significant increase in rescreening rates compared to rescreening in the clinic. Our findings indicate a role for home-based specimen collection as an alternative to clinic-based rescreening for chlamydia in women.

P3.95 Quality of care and incidence of stis in a cohort of transgender women living with hiv

Introduction Transgender women are at high risk for HIV infection, but less is understood about their rates of sexually transmitted infections (STIs) and the quality of sexual health services they receive. The Washington University Virology Clinic (St. Louis, MO USA) serves patients living with HIV; 2% of patients report being transgender women. Methods We conducted a retrospective cohort study of transgender women living with HIV (n=41) to document frequency of testing for incident bacterial STIs [syphilis, gonorrhoea (GC), chlamydia (Ct)], with demographic information, markers of HIV care, and STI test results from 2011–2015. Results Most patients were African American (91%) and on antiretroviral medications (>88%), although only 56% maintained HIV viral load suppression. Health challenges included a history of disrupted antiretroviral treatment (66%) and STIs (65%). Incident syphilis was diagnosed in 7.3% patients, and GC and Ct were diagnosed in 19.5% and 9.8% of patients, respectively. For syphilis screening, 90% of patients were tested at least once a year, and 53% of patients were tested more than once a year. For GC/Ct screening, 89% of patients were tested at least once a year and 49.3% of patients were tested more than once a year. For patients with GC or Ct infection, only 44% of patients were retested at the site of infection 3–6 months after treatment. Reinfection with GC or Ct was subsequently diagnosed in 19.5% of patients. Frequency of three site testing for GC/Ct (genital, rectal, pharyngeal) increased over the course of the study period (from 3% of patients to 34% of patients, X2=17.69, p=0.001). Conclusion Transgender women living with HIV are at high risk for incident bacterial STIs. Frequency of testing for STIs increased over a five-year period, but many patients with documented infection were not re-tested after treatment as recommended by current guidelines. Understanding STI rates, primary locations of infection, and lack of retesting in patients will improve patient education and standardise care for patients.

P2.56 A reminder from the great imitator – gummatous syphilis of the nasal cavity with septal perforation

Introduction Gummatous syphilis presenting as nasal septal perforation is well described in the classic literature, but rarely encountered in the current antibiotic era. We present a man with a destructive nasal process with a delayed diagnosis of tertiary (late benign) syphilis. Case Description A 45 year old Eritrean gentleman presented with an ulcero-nodular lesion of the left nares, progressive over the previous six months. He denied trauma or illicit drug inhalation. Exam was remarkable for left nasal cavity with an eroding destructive lesion perforating through the nasal septum and left nasal ala. He had no clinical signs or symptoms of neurosyphilis. Multiple biopsies revealed acute-on-chronic inflammation with focal necrosis and no evidence of malignancy. Fungal, treponemal and routine bacterial stains were negative, and tissue cultures were negative. Imaging indicated no bony destruction. The patient was treated for presumed cellulitis with multiple courses of oral antibiotics (cephalexin, amoxicillin) with no improvement in symptoms. At follow up, the patient tested negative for human immunodeficiency virus (HIV) infection and negative for anti-neutrophil cytoplasmic antibodies (ANCA). Serologic tests for syphilis were ultimately performed, revealing a rapid plasma reagin (RPR) titer of 1:512 with a reactive florescent treponemal antibody absorption test (FTA-ABS). A CSF evaluation was normal, with no pleocytosis and normal protein and glucose. Treatment was initiated with benzathine penicillin G, three doses of 2.4 million units each at one-week intervals. Clinical response to treatment is pending at the time of this report. Discussion Gummatous syphilis is of clinical importance because of its potential for local destruction and disfigurement of the nasal structures. Early recognition and management has important individual and public health implications and this case would remind contemporary physicians that “the great imitator” could lurk behind unusual presentations.

P3.069 Enhanced Oropharyngeal and Rectal Testing For Neisseria Gonorrhoeae and Chlamydia Trachomatis at a Public STI Clinic

Background Saint Louis, Missouri (USA) consistently reports high per capita rates of Neisseria gonorrhoeae (GC) and Chlamydia trachomatis (Ct). Asymptomatic testing for these STIs has traditionally involved genital testing alone. U.S. screening guidelines recommend GC/Ct testing at all sites of sexual exposure in men who have sex with men (MSM) and other high-risk groups. We instituted a policy to promote extragenital screening, in addition to genitourinary screening, for higher risk patients in a public health STI clinic. The purpose of this study is to assess implementation of this programme as well as the prevalence of STI at each site in our population. Methods We conducted a retrospective study to compare rates of GC and Ct under enhanced testing conditions (genital plus rectal/pharyngeal if exposed) from October 2012–January 2013. As part of the routine intake interview, patients presenting for testing were asked about sexual history and behavioural information. Results Of 441 patients seen during the study period, 68.9% (N = 304) were tested at an extragenital site. Among persons undergoing extragenital testing, 99.7% (N = 303) had an oropharyngeal test, and 7.2% (N = 22) had a rectal test performed. Extragenital testing showed that 4.6% of patients (N = 14) had oropharyngeal GC, 1.0% (N = 3) had oropharyngeal Ct. Of the patients that underwent rectal testing, 9.1% (N = 2) had GC and 4.5% (N = 1) had Ct. Oral GC was found in 20.0% of patients with genital gonorrhoea (N = 15). In addition, 12.0% of the positive tests were in patients that had negative genital site testing. Conclusion Implementation of an enhanced GC/Ct testing policy identified significant numbers of patients with isolated oropharyngeal and rectal infection. The incidence of men with concurrent genital and oropharyngeal GC as well as the predominance of men accounting for the discordant oropharyngeal GC infection, may indicate the need for increased oropharyngeal testing in the general population.

P3.240 Does the Prevalence of Sexually Transmitted Diseases Adequately Reflect Sexual Transmission of Hepatitis C in the HIV-Infected Population?

Background Recent data suggest sexual transmission of hepatitis C virus (HCV). However, data on the association between HCV and sexually transmitted disease (STD) prevalence are limited. Methods This was a retrospective cohort study of treatment-naïve HIV-infected adults ≥ 18 years first engaging at Washington University HIV Clinic from 2001 to 2009, who had routine STD and HCV antibody testing done. Gonorrhea, chlamydia, syphilis, and HCV cases were defined by positive urine nucleic acid amplification test for Neisseria gonorrhoeae, Chlamydia trachomatis, reactive serum rapid plasma reagin, and positive HCV antibody, respectively. Associations with HCV and STD using χ2, Student’s t, and Wilcoxon tests were determined. Discussion Of 926 subjects (median age 32 years, 70% African American, 44% heterosexual, 42% men-who-have-sex-with-men [MSM], 4% injection drug users [IDU]), 8% had HCV (range 5–11%/year). Baseline STD was prevalent in 27% (18–34%/year). The prevalence of gonorrhoea, chlamydia and syphilis were 12% (7–21%/year), 12% (6–17%/year) and 10% (5–16%/year), respectively. Subjects with HCV were older (42 years, interquartile range [IQR 38–48] versus 31 years, [IQR 24–40]) (p < 0.001) and more likely to report past IDU (30% versus 2%) (p < 0.001) than those without. Male subjects with HCV were less likely to be MSM (28% vs 66%) (p < 0.001) and 36% of subjects with HCV were heterosexuals without past IDU. Subjects with HCV were less likely to have STD (17% vs 28%, p = 0.06), although this finding did not reach statistical significance. Furthermore, the number and type of STDs at presentation were not associated with prevalent HCV. Conclusion Hepatitis C was prevalent in approximately 1 in 10 persons engaging in HIV outpatient care over nine years. A high prevalence of HCV among heterosexuals without past IDU suggests a possible role for sexual transmission of HCV not reflected by STD prevalence. Continued universal HCV screening among HIV-infected adults is imperative.