Re-evaluating selective screening criteria for chlamydial infection among women in the U S Pacific Northwest

Identifying youth at high risk for sexually transmitted infections in community-based settings using a risk prediction tool: a validation study

BACKGROUND : Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) are the most common bacterial sexually transmitted infections (STIs) worldwide. In the absence of affordable point-of-care STI tests, WHO recommends STI testing based on risk factors. This study aimed to develop a prediction tool with a sensitivity of > 90% and efficiency (defined as the percentage of individuals that are eligible for diagnostic testing) of < 60%.

METHODS

This study offered CT/NG testing as part of a cluster-randomised trial of community-based delivery of sexual and reproductive health services to youth aged 16-24 years in Zimbabwe. All individuals accepting STI testing completed an STI risk factor questionnaire. The outcome was positivity for either CT or NG. Backwards-stepwise logistic regression was performed with p ≥ 0.05 as criteria for exclusion. Coefficients of variables included in the final multivariable model were multiplied by 10 to generate weights for a STI risk prediction tool. A maximum likelihood Receiver Operating Characteristics (ROC) model was fitted, with the continuous variable score divided into 15 categories of equal size. Sensitivity, efficiency and number needed to screen were calculated for different cut-points.

RESULTS

From 3 December 2019 to 5 February 2020, 1007 individuals opted for STI testing, of whom 1003 (99.6%) completed the questionnaire. CT/NG prevalence was 17.5% (95% CI 15.1, 19.8) (n = 175). CT/NG positivity was independently associated with being female, number of lifetime sexual partners, relationship status, HIV status, self-assessed STI risk and past or current pregnancy. The STI risk prediction score including those variables ranged from 2 to 46 with an area under the ROC curve of 0.72 (95% CI 0.68, 0.76). Two cut-points were chosen: (i) 23 for optimised sensitivity (75.9%) and specificity (59.3%) and (ii) 19 to maximise sensitivity (82.4%) while keeping efficiency at < 60% (59.4%).

CONCLUSIONS

The high prevalence of STIs among youth, even in those with no or one reported risk factor, may preclude the use of risk prediction tools for selective STI testing. At a cut-point of 19 one in six young people with STIs would be missed.

Validation of a Clinical Prediction Rule to Predict Asymptomatic Chlamydia and Gonorrhea Infections Among Internet-Based Testers

BACKGROUND

Clinical prediction rules (CPRs) can be used in sexually transmitted infection (STI) testing environments to prioritize individuals at the highest risk of infection and optimize resource allocation. We previously derived a CPR to predict asymptomatic chlamydia and/or gonorrhea (CT/NG) infection among women and heterosexual men at in-person STI clinics based on 5 predictors. Population differences between clinic-based and Internet-based testers may limit the tool's application across settings. The primary objective of this study was to assess the validity, sensitivity, and overall performance of this CPR within an Internet-based testing environment (GetCheckedOnline.com).

METHODS

We analyzed GetCheckedOnline online risk assessment and laboratory data from October 2015 to June 2019. We compared the STI clinic population used for CPR derivation (data previously published) and the GetCheckedOnline validation population using χ2 tests. Calibration and discrimination were assessed using the Hosmer-Lemeshow goodness-of-fit test and the area under the receiver operating curve, respectively. Sensitivity and the fraction of total screening tests offered were quantified for CPR-predicted risk scores.

RESULTS

Asymptomatic CT/NG infection prevalence in the GetCheckedOnline population (n = 5478) was higher than in the STI clinic population (n = 10,437; 2.4% vs. 1.8%, P = 0.007). When applied to GetCheckedOnline, the CPR had reasonable calibration (Hosmer-Lemeshow, P = 0.90) and discrimination (area under the receiver operating characteristic, 0.64). By screening only individuals with total risk scores ≥4, we would detect 97% of infections and reduce screening by 14%.

CONCLUSIONS

The application of an existing CPR to detect asymptomatic CT/NG infection is valid within an Internet-based STI testing environment. Clinical prediction rules applied online can reduce unnecessary STI testing and optimize resource allocation within publicly funded health systems.

Prevalence and factors associated with Chlamydia trachomatis infection among women with HIV in São Paulo

INTRODUCTION

This study aimed to estimate the prevalence and risk factors associated with Chlamydia trachomatis (CT) infection among women with HIV in São Paulo.

METHODS

This cross-sectional study included women with HIV who were receiving care from sixteen public health services in São Paulo (October 2013 to March 2014). All participants answered a questionnaire regarding their sociodemographic, behavioral, and clinical characteristics. A urine sample was tested for CT and Neisseria gonorrhoeae (NG) using the polymerase chain reaction. The chi-square test and a logistic regression model were used to test the associations with CT or NG infections.

RESULTS

We evaluated 853 women and ultimately included 836 (98%) women. The mean age was 40.5 ± 0.34 years, and the prevalences of CT and NG infections were 1.8% and 0.5%, respectively. CT infection was associated with CD4+ T-cell counts of <350 cells/mm3 [adjusted odds ratio (ORadj): 24.5], age of 18-25 years (ORadj: 23.2), the non-use of condoms during the last 6 months (ORadj: 10.2), a self-reported history of a sexually transmitted infection (ORadj: 9.4), and having two or more sexual partners during the last year (ORadj: 6.1).

CONCLUSIONS

Although we observed a low prevalence of CT infection among women with HIV, younger age was associated with a high risk of infection. Therefore, it may be appropriate to include screening for CT as part of the routine care for this population.

Enteric disease episodes and the risk of acquiring a future sexually transmitted infection: a prediction model in Montreal residents

OBJECTIVE

The sexual transmission of enteric diseases poses an important public health challenge. We aimed to build a prediction model capable of identifying individuals with a reported enteric disease who could be at risk of acquiring future sexually transmitted infections (STIs).

MATERIALS AND METHODS

Passive surveillance data on Montreal residents with at least 1 enteric disease report was used to construct the prediction model. Cases were defined as all subjects with at least 1 STI report following their initial enteric disease episode. A final logistic regression prediction model was chosen using forward stepwise selection.

RESULTS

The prediction model with the greatest validity included age, sex, residential location, number of STI episodes experienced prior to the first enteric disease episode, type of enteric disease acquired, and an interaction term between age and male sex. This model had an area under the curve of 0.77 and had acceptable calibration.

DISCUSSION

A coordinated public health response to the sexual transmission of enteric diseases requires that a distinction be made between cases of enteric diseases transmitted through sexual activity from those transmitted through contaminated food or water. A prediction model can aid public health officials in identifying individuals who may have a higher risk of sexually acquiring a reportable disease. Once identified, these individuals could receive specialized intervention to prevent future infection.

CONCLUSION

The information produced from a prediction model capable of identifying higher risk individuals can be used to guide efforts in investigating and controlling reported cases of enteric diseases and STIs.

Prediction of Chlamydia trachomatis infection to facilitate selective screening on population and individual level: a cross-sectional study of a population-based screening programme

OBJECTIVES

To develop prediction models for Chlamydia trachomatis (Ct) infection with different levels of detail in information, that is, from readily available data in registries and from additional questionnaires.

METHODS

All inhabitants of Rotterdam and Amsterdam aged 16-29 were invited yearly from 2008 until 2011 for home-based testing. Their registry data included gender, age, ethnicity and neighbourhood-level socioeconomic status (SES). Participants were asked to fill in a questionnaire on education, sexually transmitted infection history, symptoms, partner information and sexual behaviour. We developed prediction models for Ct infection using first-time participant data-including registry variables only and with additional questionnaire variables-by multilevel logistic regression analysis to account for clustering within neighbourhoods. We assessed the discriminative ability by the area under the receiver operating characteristic curve (AUC).

RESULTS

Four per cent (3540/80 385) of the participants was infected. The strongest registry predictors for Ct infection were young age (especially for women) and Surinamese, Antillean or sub-Saharan African ethnicity. Neighbourhood-level SES was of minor importance. Strong questionnaire predictors were low to intermediate education level, ethnicity of the partner (non-Dutch) and having sex with casual partners. When using a prediction model including questionnaire risk factors (AUC 0.74, 95% CI 0.736 to 0.752) for selective screening, 48% of the participating population needed to be screened to find 80% (95% CI 78.4% to 81.0%) of Ct infections. The model with registry risk factors only (AUC 0.67, 95% CI 0.656 to 0.675) required 60% to be screened to find 78% (95% CI 76.6% to 79.4%) of Ct infections.

CONCLUSIONS

A registry-based prediction model can facilitate selective Ct screening at population level, with further refinement at the individual level by including questionnaire risk factors.

Deriving and validating a risk estimation tool for screening asymptomatic chlamydia and gonorrhea

BACKGROUND

There has been considerable interest in the development of innovative service delivery modules for prioritizing resources in sexual health delivery in response to dwindling fiscal resources and rising infection rates.

METHODS

This study aims to derive and validate a risk scoring algorithm to accurately identify asymptomatic patients at increased risk for chlamydia and/or gonorrhea infection. We examined the electronic records of patient visits at sexual health clinics in Vancouver, Canada. We derived risk scores from regression coefficients of multivariable logistic regression model using visits between 2000 and 2006. We evaluated the model's discrimination, calibration, and screening performance. Temporal validation was assessed in visits from 2007 to 2012.

RESULTS

The prevalence of infection was 1.8% (n = 10,437) and 2.1% (n = 14,956) in the derivation and validation data sets, respectively. The final model included younger age, nonwhite ethnicity, multiple sexual partners, and previous infection and showed reasonable performance in the derivation (area under the receiver operating characteristic curve = 0.74; Hosmer-Lemeshow P = 0.91) and validation (area under the receiver operating characteristic curve = 0.64; Hosmer-Lemeshow P = 0.36) data sets. A risk score cutoff point of at least 6 detected 91% and 83% of cases by screening 68% and 68% of the derivation and validation populations, respectively.

CONCLUSIONS

These findings support the use of the algorithm for individualized risk assessment and have important implications for reducing unnecessary screening and saving costs. Specifically, we anticipate that the algorithm has potential uses in alternative settings such as Internet-based testing contexts by facilitating personalized test recommendations, stimulating health care-seeking behavior, and aiding risk communication by increasing sexually transmitted infection risk perception through the creation of tailored risk messages to different groups.

A validation study of a clinical prediction rule for screening asymptomatic chlamydia and gonorrhoea infections among heterosexuals in British Columbia

BACKGROUND

One component of effective sexually transmitted infections (STIs) control is ensuring those at highest risk of STIs have access to clinical services because terminating transmission in this group will prevent most future cases. Here, we describe the results of a validation study of a clinical prediction rule for identifying individuals at increased risk for chlamydia and gonorrhoea infection derived in Vancouver, British Columbia (BC), against a population of asymptomatic patients attending sexual health clinics in other geographical settings in BC.

METHODS

We examined electronic records (2000-2012) from clinic visits at seven sexual health clinics in geographical locations outside Vancouver. The model's calibration and discrimination were examined by the area under the receiver operating characteristic curve (AUC) and the Hosmer-Lemeshow (H-L) statistic, respectively. We also examined the sensitivity and proportion of patients that would need to be screened at different cut-offs of the risk score.

RESULTS

The prevalence of infection was 5.3% (n=10 425) in the geographical validation population. The prediction rule showed good performance in this population (AUC, 0.69; H-L p=0.26). Possible risk scores ranged from -2 to 27. We identified a risk score cut-off point of ≥8 that detected cases with a sensitivity of 86% by screening 63% of the geographical validation population.

CONCLUSIONS

The prediction rule showed good generalisability in STI clinics outside of Vancouver with improved discriminative performance compared with temporal validation. The prediction rule has the potential for augmenting triaging services in STI clinics and enhancing targeted testing in population-based screening programmes.

A critical appraisal of risk models for predicting sexually transmitted infections

BACKGROUND

Prediction rules have been proposed as alternatives to screening recommendations and have potential applications in sexual health decision making. To our knowledge, there has been no review undertaken providing a critical appraisal of existing prediction rules in sexual health contexts. This review aims to identify and characterize prediction rules developed and validated for sexually transmitted infection (STI) screening, describe the methodological issues essential to the suitability of derived models for clinical or public health application, and synthesize the literature on the performance of these models.

METHODS

We searched MEDLINE (2003-2012) to identify studies that reported on models predicting STIs. We explored the methodological quality of the studies based on a 16-item quality assessment checklist. We also evaluated the studies based on data extracted on model discrimination, calibration, sensitivity, and testing efficiency.

RESULTS

We identified 16 publications reporting on STI prediction rules. The most poorly addressed quality items were missing values, calibration measures, and variable definition. Overall, the performance of risk models as measured by discrimination (area under the receiver operating characteristic curve range, 0.64-0.88) and calibration was found to be generally good or satisfactory. Eight studies attained or were close to attaining the performance benchmark of testing less than 60% of the target population to achieve 90% sensitivity. The 2 risk models that were externally validated displayed adequate discrimination in new settings.

CONCLUSIONS

Although we identified several well-performing STI risk prediction rules, few have been validated. Future developments in the use of prediction rules should address their clinical consequence, comparative usefulness, external validity, and implementation impact.

Predictors identifying those at increased risk for STDs: a theory-guided review of empirical literature and clinical guidelines

SummarySexually transmitted diseases (STDs) are leading causes of substantial morbidity worldwide. Identification of risk factors for estimating STD risk provides opportunities for optimising service delivery in clinical settings, including improving case finding accuracy and increasing cost-efficiency by limiting the testing of low-risk individuals. The current study was undertaken to synthesise the evidence supporting commonly cited chlamydia and gonorrhoea risk factors. The level of empirical support for the following predictors was strong/moderate: age, race/ethnicity, multiple lifetime sexual partners, sex with symptomatic partners and concurrent STD diagnosis. The following predictors had weak evidence: socio-economic status, transactional sex, drug/alcohol use, condom use and history of STD diagnosis. The most frequently listed predictors among nine clinical guidelines were younger age and multiple sexual partners; the least consistently listed predictor was inconsistent condom use. We found reasonably good concordance between risk factors consistently listed in the recommendations and predictors found to have strong empirical support in the literature. There is a need to continue building the evidence base to explicate the mechanisms and pathways of STD acquisition. We recommend periodic reviews of the level of support of predictors included in clinical guidelines to ensure that they are in accordance with empirical evidence.

Risk prediction in sexual health contexts: protocol

BACKGROUND

In British Columbia (BC), we are developing Get Checked Online (GCO), an Internet-based testing program that provides Web-based access to sexually transmitted infections (STI) testing. Much is still unknown about how to implement risk assessment and recommend tests in Web-based settings. Prediction tools have been shown to successfully increase efficiency and cost-effectiveness of STI case finding in the following settings.

OBJECTIVE

This project was designed with three main objectives: (1) to derive a risk prediction rule for screening chlamydia and gonorrhea among clients attending two public sexual health clinics between 2000 and 2006 in Vancouver, BC, (2) to assess the temporal generalizability of the prediction rule among more recent visits in the Vancouver clinics (2007-2012), and (3) to assess the geographical generalizability of the rule in seven additional clinics in BC.

METHODS

This study is a population-based, cross-sectional analysis of electronic records of visits collected at nine publicly funded STI clinics in BC between 2000 and 2012. We will derive a risk score from the multivariate logistic regression of clinic visit data between 2000 and 2006 at two clinics in Vancouver using newly diagnosed chlamydia and gonorrhea infections as the outcome. The area under the receiver operating characteristic curve (AUC) and the Hosmer-Lemeshow statistic will examine the model's discrimination and calibration, respectively. We will also examine the sensitivity and proportion of patients that would need to be screened at different cutoffs of the risk score. Temporal and geographical validation will be assessed using patient visit data from more recent visits (2007-2012) at the Vancouver clinics and at clinics in the rest of BC, respectively. Statistical analyses will be performed using SAS, version 9.3.

RESULTS

This is an ongoing research project with initial results expected in 2014.

CONCLUSIONS

The results from this research will have important implications for scaling up of Internet-based testing in BC. If a prediction rule with good calibration, discrimination, and high sensitivity to detect infection is found during this project, the prediction rule could be programmed into GCO so that the program offers individualized testing recommendations to clients. Further, the prediction rule could be adapted into educational materials to inform other Web-based content by creating awareness about STI risk factors, which may stimulate health care seeking behavior among individuals accessing the website.

Chlamydia trachomatis infection among HIV-infected women attending an AIDS clinic in the city of Manaus, Brazil

This was a cross-sectional study aimed to determine the prevalence of and to identify risk factors for Chlamydia trachomatis (CT) among human immunodeficiency virus (HIV)-infected women attending the acquired immunodeficiency syndrome (AIDS) clinic in the city of Manaus, Brazil, in 2009-2010. Participants answered a questionnaire containing demographic, epidemiological, and clinical data. A genital specimen was collected during examination to detect CT-DNA by hybrid capture, and blood samples were taken to determine CD4(+)T and HIV viral load. There were 329 women included in the study. Median age was 32 years (IQR=27-38) and median schooling was nine years (IQR=4-11). The prevalence of CT was 4.3% (95%CI: 2.1-6.5). Logistic regression analysis showed that age between 18-29 years [OR=4.1(95%CI: 1.2-13.4)] and complaint of pelvic pain [OR=3.7 (95%CI: 1.2-12.8)] were independently associated with CT. The use of condom was inversely associated with CT [OR=0.39 (95%CI: 0.1-0.9)]. The results showed that younger women who did not use condoms are at a higher risk for CT. Screening for sexually transmitted infections must be done routinely and safe sexual practices should be promoted among this population.

Chlamydia trachomatis, Mycoplasma genitalium, and Trichomonas vaginalis infections in men with nongonococcal urethritis: predictors and persistence after therapy

BACKGROUND

Chlamydia trachomatis (CT), Mycoplasma genitalium (MG), and Trichomonas vaginalis (TV) are sexually transmitted infections (STIs) associated with nongonococcal urethritis (NGU). We assessed their predictors and persistence after treatment.

METHODS

We analyzed data from an NGU treatment trial among symptomatic heterosexual men aged 16-45 years from STI clinics. Nucleic acid amplification tests detected CT, MG, and TV at baseline and at 1 and 4 weeks after therapy. Associations between variables and STI detection were investigated.

RESULTS

Among 293 participants, 44% had CT, 31% had MG, and 13% had TV at baseline. In multivariate analysis, CT infection was associated with young age and STI contact. Young age was also associated with MG, and having ≥ 1 new partner was negatively associated with TV. We detected persistent CT in 12% and MG in 44% of participants at 4 weeks after therapy, which were associated with signs and symptoms of NGU. Persistent CT was detected in 23% of participants after azithromycin treatment vs 5% after doxycycline treatment (P = .011); persistent MG was detected in 68% of participants after doxycycline vs 33% after azithromycin (P = .001). All but 1 TV infection cleared after tinidazole.

CONCLUSIONS

Persistent CT and MG after treatment of NGU are common, and were associated with clinical findings and drug regimen.

Female genital Chlamydia trachomatis infection: where are we heading?

INTRODUCTION

Urogenital infection by Chlamydia trachomatis is the most common bacterial sexually transmitted disease in the world. C. trachomatis is the etiologic agent of several common genital tract syndromes such as urethritis, cervicitis, and pelvic inflammatory disease in women.

MATERIALS AND METHODS

In this review, the pathophysiology of a chlamydial infection as well as diagnosis, therapy and prevention strategies regarding female chlamydial infection are reviewed.

RESULTS

A chlamydial infection results in minimal or even no symptoms in approximately two-thirds of women, remaining therefore clinically apparent and undiagnosed. C. trachomatis infections are of great socioeconomic and public health concern due to the potential for severe long-term consequences in women, including an increased risk of ectopic pregnancy, tubal infertility and chronic pelvic pain. Moreover, if the bacterium is transmitted during labor to a newborn, it can cause ophthalmia neonatorum and atypical neonatal pneumonia. Due to the documented increased risk of morbidity, several national guidelines are available, including a routine screening for young women and screening during pregnancy that is recommended in several countries.

DISCUSSION

A routine screening for young women and screening during pregnancy is recommended in several countries. However, additional prospective studies of the effectiveness of chlamydia screening are warranted and might be feasible within established screening programs. Moreover, the transition from cervicitis to infertility should be also evaluated in future controlled studies to underline the existing evidence. Additionally, there is an urgent need to educate and inform health-care providers about implementation of screening programs to reduce the spread of chlamydial infection. Moreover, awareness and use of screening programs by the public is needed, which requires informational campaigns for the general public using different media. For improved screening strategies and public awareness, novel approaches have to be developed and evaluated. Finally, guidelines should be actively disseminated to all medical practitioners to increase their use in daily practice. Although the major socioeconomic and public health concerns of C. trachomatis infection are recognized, several considerations and additional measures for addressing this increasingly urgent health problem remain.

'The difference in determinants of Chlamydia trachomatis and Mycoplasma genitalium in a sample of young Australian women'

BACKGROUND

Differences in the determinants of Chlamydia trachomatis ('chlamydia') and Mycoplasma genitalium (MG) genital infection in women are not well understood.

METHODS

A cohort study of 16 to 25 year old Australian women recruited from primary health care clinics, aimed to determine chlamydia and MG prevalence and incidence. Vaginal swabs collected at recruitment were used to measure chlamydia and MG prevalence, organism-load and chlamydia-serovar a cross-sectional analysis undertaken on the baseline results is presented here.

RESULTS

Of 1116 participants, chlamydia prevalence was 4.9% (95% CI: 2.9, 7.0) (n = 55) and MG prevalence was 2.4% (95% CI: 1.5, 3.3) (n = 27). Differences in the determinants were found - chlamydia not MG, was associated with younger age [AOR:0.9 (95% CI: 0.8, 1.0)] and recent antibiotic use [AOR:0.4 (95% CI: 0.2, 1.0)], and MG not chlamydia was associated with symptoms [AOR:2.1 (95% CI: 1.1, 4.0)]. Having two or more partners in last 12 months was more strongly associated with chlamydia [AOR:6.4 (95% CI: 3.6, 11.3)] than MG [AOR:2.2 (95% CI: 1.0, 4.6)] but unprotected sex with three or more partners was less strongly associated with chlamydia [AOR:3.1 (95%CI: 1.0, 9.5)] than MG [AOR:16.6 (95%CI: 2.0, 138.0)]. Median organism load for MG was 100 times lower (5.7 × 104/swab) than chlamydia (5.6 × 106/swab) (p < 0.01) and not associated with age or symptoms for chlamydia or MG.

CONCLUSIONS

These results demonstrate significant chlamydia and MG prevalence in Australian women, and suggest that the differences in strengths of association between numbers of sexual partners and unprotected sex and chlamydia and MG might be due to differences in the transmission dynamics between these infections.

Risk factors and algorithms for chlamydial and gonococcal cervical infections in women attending family planning clinics in Thailand

AIM

To identify risk factors associated with and evaluate algorithms for predicting Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) cervical infections in women attending family planning clinics in Thailand.

METHODS

Eligible women were recruited from family planning clinics from all regions in Thailand. The women were followed at 3-month intervals for 15-24 months. At each visit, the women were interviewed for interval sexually transmitted infection (STI) history in the past 3 months, recent sexual behavior, and contraceptive use. Pelvic examinations were performed and endocervical specimens were collected to test for CT and NG using polymerase chain reaction.

RESULTS

Factors associated with incident CT/NG cervical infections in multivariate analyses included region of country other than the north, age <or=25 years, polygamous marriage, acquiring a new sex partner in the last 3 months, abnormal vaginal discharge, mucopurulent cervical discharge, and easily induced bleeding of the endocervix. Three models were developed to predict cervical infection. A model incorporating demographic factors and sexual behaviors had a sensitivity of 61% and a specificity of 71%. Incorporating additional factors did not materially improve test performance. Positive predictive values for all models evaluated were low.

CONCLUSION

In resource-limited settings, algorithmic approaches to identifying incident cervical infections among low-risk women may assist providers in the management of these infections.

Incidence of pelvic inflammatory disease in a large cohort of women tested for Chlamydia trachomatis: a historical follow-up study

Background

Chlamydia trachomatis is a highly prevalent sexually transmitted disease. Testing rates among young Norwegian women are high. Young women diagnosed with C. trachomatis are often worried about future complications.

Methods

Our cohort consisted of 24,947 women born 1970–1984 who were tested for C. trachomatis infection during 1990–2005. We linked C. trachomatis laboratory data to data on hospitalizations for pelvic inflammatory disease during 1990–2005. Cox regression analysis with time-dependent covariates adjusted for age at first test was used to assess the association between C. trachomatis history and pelvic inflammatory disease.

Results

Follow-up until the end of 2005 included 201,387 woman-years. The incidence rate of hospitalization for pelvic inflammatory disease was higher among women with prior C. trachomatis infection than among women with negative tests only (48 events during 32,057 person-years and 143 events during 169,192 person-years, corresponding to 0.15 and 0.08 per 100 person-years, respectively). The corresponding hazard ratio adjusted for age at first test was 1.69 (95% CI, 1.21–2.36).

Conclusion

Our data show a link between a diagnosis of C. trachomatis infection and subsequent pelvic inflammatory disease. However, pelvic inflammatory disease was a rare event irrespective of C. trachomatis status. These, together with other recent findings, can be used to reassure women worried about their future reproductive health following a diagnosis of C. trachomatis.

Incidence and risk factors for genital Chlamydia trachomatis infection: a 4-year prospective cohort study

BACKGROUND

Few long-term studies reporting incidence and behavioral data for Chlamydia trachomatis (CT) infection in the general population have been published. Such studies are important to understand risk factors associated with infection and to develop screening recommendations.

METHODS

A fixed prospective 4-year cohort study of 898 sexually active Norwegian women, aged 16 to 23 years at study start, was conducted to assess incidence, repeat infection, and risk factors associated with genital CT infection. Participants were interviewed at study start and at 6-month intervals thereafter for behavioral characteristics. The women were tested for CT infection at 12-month intervals beginning at study start. Risk factors were assessed using Fisher exact test and conditional logistic regression. Person-time was estimated in survival analyses and incidence of CT infection was reported as events per 100 woman-years.

RESULTS

Median duration of observation was 48.0 months (range 10-74) whereas 4.4 specimens were collected per woman (range 2-5). Of the 836 women eligible for the analysis, 19 (2.2%) had a prevalent infection at baseline. The 4-year cumulative incidence of CT infection was 7.7 (95% CI: 6.7-8.7) with annual incidences ranging from 1.2 to 2.9 per 100 woman-years. The 2-year cumulative incidence of repeat CT infection was 11.2 (95% CI: 9.3-13.1) per 100 woman-years. In multivariate analyses, factors associated with incident CT infection were young age (< or =24 years) and number of new partners over the last 12 months prior being tested.

CONCLUSION

The annual incidences observed for women 24 years or younger with 1 or more new partners over the last 12 months support recommendations for annual testing for CT in this age group in Norway.

Births and Ectopic Pregnancies in a Large Cohort of Women Tested for Chlamydia trachomatis

BACKGROUND

Recent studies show divergent results concerning the risk of ectopic pregnancy following Chlamydia trachomatis (CT) infection.

GOAL

Our goal was to investigate future reproductive health outcomes (births and ectopic pregnancies) among women tested for CT.

METHODS

Our cohort consisted of 20,762 women born during 1970-1984 who were tested for CT during 1990-2003. We linked CT data to data on ectopic pregnancies and births during 1990-2004. Cox regression with time-dependent covariates was used to assess the association between CT history and births/ectopic pregnancies adjusted for age at first test. Analyses with ectopic pregnancy as outcome were also adjusted for parity.

RESULTS

We observed 9.6 births per 100 person-years of observation among women with negative tests only and 10.2 per 100 person-years among women with at least 1 positive test (hazard ratio adjusted for age at first test, 1.07; 95% CI, 1.01-1.12). Ectopic pregnancy incidence rates were higher for women with positive test(s) compared with women with negative test only (0.24 vs. 0.13 per 100 person-years; hazard ratio adjusted for age at first test and parity, 1.82; 95% CI, 1.27-2.60). Among women with at least 1 registered pregnancy, the adjusted hazard ratio was 2.03; 95% CI, 1.28-3.22).

CONCLUSION

Although women diagnosed with CT were at higher risk for ectopic pregnancy than women with negative test results only, our study suggest that their fertility prospects were better than they would have been had CT screening not been implemented in this population. Opportunistic CT screening is an appropriate method for maintaining female reproductive health.

Prediction of Chlamydia trachomatis Infection: Application of a Scoring Rule to Other Populations

BACKGROUND

Active case finding is crucial to reduce transmission and consequences of Chlamydia trachomatis (CT) infections. We previously proposed the use of a prediction rule for CT infection for selective screening of high-risk individuals in a population. To support such an application, the prediction rule needs to be validated in other populations.

METHODS

We studied participants aged 15 to 29 years in a population-based study in Amsterdam (n = 1,788) and an outreach screening project among high-risk youth in Rotterdam (n = 172). Validity was indicated by discriminative ability (area under the receiver operating characteristic curve [AUC]) and by calibration, which was visualized in plots and tested with the Hosmer-Lemeshow (H-L) goodness-of-fit test. Cutoffs of predicted risk were examined for their effect on sensitivity and the fraction of participants that would need to be screened.

RESULTS

Discriminative ability was reasonable both for the Amsterdam study (AUC 0.66; 95% confidence interval [CI], 0.58-0.74) and for the Rotterdam study (AUC 0.68; 95% CI, 0.58-0.79). The observed CT prevalence was lower than predicted in Amsterdam (H-L P = 0.02) and nonsignificantly higher in Rotterdam (H-L P = 0.20). By screening 77% of the Amsterdam population, 93% of the cases would have been detected, whereas in the Rotterdam study, no cases would be missed by screening 75%.

CONCLUSION

The chlamydia prediction rule showed a reasonable external validity in two studies. These findings support the use of the rule as a tool for selective chlamydia screening, although only a limited fraction of participants can be excluded when a high sensitivity is required.

Sexually transmitted infections among pregnant women attending an antenatal clinic in Fuzhou, China

OBJECTIVE

To determine the prevalence of sexually transmitted infections (STIs) among women attending an antenatal clinic in urban China and to show whether reported symptoms and findings on clinical examination predicted STIs in this population.

STUDY DESIGN

Cross-sectional descriptive study was conducted among 504 pregnant women attending an antenatal clinic in Fuzhou, China. Structured questionnaires were used to collect demographic and behavioral information, and clinical and gynecologic examinations were performed to detect clinical signs of STIs. Blood samples, vaginal swabs, and cervical swabs were collected, respectively, to test for antibodies to syphilis, culture Trichomonas vaginalis (T. vaginalis), and perform PCR to detect Chlamydia trachomatis (C. trachomatis) and Neisseria gonorrhoeae (N. gonorrhoeae).

RESULTS

C trachomatis was detected in 51 (10.1%), N gonorrhoeae in 4 (0.8%), T vaginalis in 16 (3.2%), and syphilis in 1 (0.2%) of the 504 pregnant women. Fifty-two (73%) of 71 women with any STI were asymptomatic. Multiple logistic regression analysis indicated that age <or=25 years (OR=2.72) and monthly income >RMB 2000 yuan (OR=3.57) were significant independent risk factors for chlamydial infection (P<0.05). The reported symptom of vaginal discharge or the clinical sign of either vaginal or cervical discharge poorly predicted infection with C trachomatis, N gonorrhoeae, or T vaginalis, with a positive predictive value <25% for each STI.

CONCLUSION

A substantial prevalence of STIs, including a large proportion of asymptomatic infections, was found among pregnant women in the study area. These results support a strategy of screening pregnant women for bacterial STIs (followed by treatment of infections), which could be integrated into routine pregnancy care in China.

Chlamydia trachomatis Testing Patterns and Prevalence of Genital Chlamydial Infection Among Young Men and Women in Central Norway 1990–2003: A Population-Based Registry Study

OBJECTIVE

The study objective was to investigate Chlamydia trachomatis (CT) testing patterns, prevalence, and incidence among men and women in Sør-Trøndelag county, central Norway, 1990-2003.

GOAL

The goal of this study was to obtain data for recommendations regarding CT screening.

STUDY DESIGN

Laboratory data on CT tests for persons 15 to 24 years old were retrieved and analyzed.

RESULTS

Four percent of men and 44% of women had been CT tested at least once by the age of 20. By the age of 25, 44% of men and 84% of women had been tested. Prevalence at first test was at its peak in 2000-2002 (men: 15-19 years 18%, 20-24 years 23%; women: 15-19 years 11%, 20-24 years 9%). Incidence estimates were higher for persons with a positive first test than for persons with a negative first test.

CONCLUSIONS

More men and more female teenagers need to be tested. Repeat testing is particularly important among people who have been diagnosed with CT.

Innovative Approaches to the Prevention and Control of Bacterial Sexually Transmitted Infections

Bacterial STI continues to be a major problem in developed nations. Research and evolving standards of public health practice are cause for optimism and concern. Innovations in case-finding and treatment, particularly the application of NAATs to test for chlamydial infection in nonclinical settings, are successes that merit more widespread application. EPT, selective STI screening in men, and rescreening are all promising, but are not yet in widespread use and may face significant operational barriers. To date, public health efforts to alter sexual behavior, at least through specific interventions, are more discouraging. Although some behavioral interventions have been effective, none has been widely instituted. Moreover, the likelihood that existing behavioral interventions will be widely applied seems remote. Future research efforts in this area will need to focus less on proof-of-concept efficacy trials and more on developing and testing sustainable, cost-effective interventions that focus on those at greatest risk and that can be scaled-up within the existing public health infrastructure.

Do the characteristics of sexual health centre clients predict chlamydia infection sufficiently strongly to allow selective screening?

Objectives: This study aimed to estimate chlamydia prevalence and risk factors for infection and to assess the performance of chlamydia-selective screening criteria among clients attending a large sexually transmitted infection (STI) clinic. Methods: Computerised records for all attendances between 1 July 2002 and 30 June 2003 were analysed. Chlamydia prevalence and risk factors for infection were determined for all new clients. The sensitivity and specificity of risk factors for chlamydia were assessed. Results: 2642 male and 2084 female new clients were tested for chlamydia with a prevalence of 7.3% (95% CI: 6.3%, 8.4%) among men and 3.9% (95% CI: 3.1%, 4.9%) among women. Screening heterosexual men based on a positive contact or symptoms of non-specific urethritis or any two of age < 25 years, 4+ partners last 12 months, inconsistent condom use or not presenting for an asymptomatic screen detected 88% of infections by screening 62%. Screening women based on a positive contact or injecting drug use or any two of age < 25 years, 2+ partners last 12 months or inconsistent condom use would detect 86% of infections by screening 57%. Conclusions: Selective screening could be used to more efficiently identify heterosexual men and women at risk of chlamydia.