Retesting and repeat positivity following diagnosis of Chlamydia trachomatis and Neisseria gonorrhoea in New Zealand: a retrospective cohort study

Abstract

BackgroundTesting for reinfection at 3 to 6 months following treatment for Chlamydia Trachomatis or Neisseria gonorrhoea is recommended in best practice sexual health management guidelines. This study aimed to describe rates of retesting and repeat positivity following diagnosis of chlamydia or gonorrhoea in a defined geographic region of New Zealand.MethodsRetrospective cohort study in Wellington, New Zealand involving analysis of laboratory data for chlamydia and gonorrhoea tests performed in primary care and sexual health clinics (July 2012–July 2015). Outcome measures: rate of retesting and rate of repeat positivity 6 weeks to 6 months after a positive result (index event). Kaplan-Meier curves were used to plot time from first index event to retest. Logistic regression modelling was used to determine the odds of retesting and repeat positivity between 6 weeks and 6 months of follow-up, adjusting for potential confounders (age, gender, ethnicity and socioeconomic deprivation).ResultsOverall 29.4% (1919/6530) of the cohort was retested between 6 weeks and 6 months, with 18% (347/1919) of those retested returning positive results. Lower odds of retesting were observed for males (OR 0.4, 95% CI 0.34–0.48), and individuals of NZ Maori (OR 0.72, 0.61–0.85) and Pacific ethnicities (OR 0.49, 0.39–0.62, reference European). Factors associated with higher odds of repeat positivity on retesting included male gender (OR 2.0, 1.14–2.82), age 15–19 years (OR 1.78, 1.32–2.41, reference 20–24 years), chlamydia/gonorrhoea co-infection (OR 2.39, 1.32–4.35, reference chlamydia only), Maori (OR 1.6, 1.18–2.17) and Pacific ethnicities (OR 1.88, 1.22–2.9, reference European).ConclusionsWe observed low adherence to STI retesting guidelines, and marked gender and ethnic disparities in rates of retesting and repeat positivity. Low retesting rates are suggestive of low levels of awareness of this aspect of patient management, and an absence of a systematic approach to retesting. High rates of repeat positivity reinforce the importance of advising patients about reducing their risk of reinfection, including notification and treatment of all recent sexual partners. Greater priority needs to be placed on increasing retesting and reducing rates of reinfection, with strategies implemented to improve these important aspects of patient care and population STI control.

Partner notification and retesting for Chlamydia trachomatis and Neisseria gonorrhoeae: a case-note review in New Zealand primary care

“…although a relatively small proportion of cases were retested in this study, the reinfection rate was high, consistent with local and international research. 8,9,22,23 low overall retesting rates and early retesting (within 6 weeks) may be indicative of lack of awareness of guideline recommendations regarding the timing of retesting. 14 improved re-attendance for retesting following the use of text message (SmS) reminders for a test of reinfection, 24,25 with the added provision of a postal home sample collection kit (as well as an SmS) further improving retesting rates.…”

“…5,7 effective partner notification identifies and treats people with infection who may not otherwise have presented for health care (often males), reduces the chances that index cases become reinfected by untreated partners and thus can potentially reduce onward population transmission. 7 Chlamydia reinfection rates are high; 18% of people retested within 6 months of diagnosis were positive on retesting in one region of New Zealand, 8 and 19% of people aged 16-29 years retested positive in an australian general practice population. 9 Untreated and repeat infection may be associated with more serious long-term reproductive health complications, 10 so timely detection and treatment are vital.…”

The Characteristics of Patients Frequently Tested and Repeatedly Infected with Neisseria gonorrhoeae

“…In contrast, patients who are not retested after their initial NG diagnosis could also have impact on circulating STIs within a population. For example, from previous studies it is known that NG retesting rates of STI clinics and general practitioners (GPs) are relatively low, ranging from 15−22.8%, while reinfection rates are relatively high (up to 16%) [7,11]. Therefore, NG reinfections are likely to be missed leading to ongoing transmission of NG.…”

Pathogenic Interplay Between Chlamydia trachomatis and Neisseria gonorrhoeae that Influences Management and Control Efforts—More Questions than Answers?

“…Factors associated with CT/NG co-infection vary across studies/populations and include sex, age, sex work, and drug/alcohol use [70][71][72]. MSM have been reported as more likely to harbor co-infections than heterosexual males, with the co-infection rate increasing with age in MSM, but decreasing with age in heterosexual men [73], while others have found similar co-infection rates for MSM and heterosexual men [74].…”

“…Coinfection has, in most cases, been linked with increased risk of re-infections. Co-infection increases risk of (i) re-infection with CT or NG when retested between 6 weeks and 6 months [70], (ii) NG re-infection in a high NG prevalence population [71], and (iii) CT re-infection in women [75]. However, a study that collected daily samples for 28 days after antibiotic treatment, evaluating 23 patients with NG/CT co-infection for CT clearance, noted 100% clearance with no re-infections [17].…”