Vulvovaginal-swab or first-catch urine specimen to detect Chlamydia trachomatis in women in a community setting?

Screening for chlamydia in women is widely recommended. We evaluated the performance of two nucleic acid amplification tests for detecting Chlamydia trachomatis in self-collected vulvovaginal-swab and first-catch urine specimens from women in a community setting and a strategy for optimizing the sensitivity of an amplified enzyme immunoassay on vulvovaginal-swab specimens. We tested 2,745 paired vulvovaginal-swab and urine specimens by PCR (Roche Cobas) or strand displacement amplification (SDA; Becton Dickinson). There were 146 women infected with chlamydia. The assays detected 97.3% (95% confidence interval [CI], 93.1 to 99.2%) of infected patients with vulvovaginal-swab specimens and 91.8% (86.1 to 95.7%) with urine specimens. We tested 2,749 vulvovaginal-swab specimens with both a nucleic acid amplification test and a polymer conjugate-enhanced enzyme immunoassay with negative-gray-zone testing. The relative sensitivities obtained after retesting specimens in the negative gray zone were 74.3% (95% CI, 62.8 to 83.8%) with PCR and 58.3% (95% CI, 46.1 to 69.8%) with SDA. In community settings, both vulvovaginal-swab and first-catch urine specimens from women are suitable substrates for nucleic acid amplification tests, but enzyme immunoassays, even after negative-gray-zone testing, should not be used in screening programs.

Opportunistic and systematic screening for chlamydia: a study of consultations by young adults in general practice

BACKGROUND: Opportunistic screening for genital chlamydia infection is being introduced in England, but evidence for the effectiveness of this approach is lacking. There are insufficient data about young peoples' use of primary care services to determine the potential coverage of opportunistic screening in comparison with a systematic population-based approach. AIM: To estimate use of primary care services by young men and women; to compare potential coverage of opportunistic chlamydia screening with a systematic postal approach. DESIGN OF STUDY: Population based cross-sectional study. SETTING: Twenty-seven general practices around Bristol and Birmingham. METHOD: A random sample of patients aged 16-24 years were posted a chlamydia screening pack. We collected details of face-to-face consultations from general practice records. Survival and person-time methods were used to estimate the cumulative probability of attending general practice in 1 year and the coverage achieved by opportunistic and systematic postal chlamydia screening. RESULTS: Of 12 973 eligible patients, an estimated 60.4% (95% confidence interval [CI] = 58.3 to 62.5%) of men and 75.3% (73.7 to 76.9%) of women aged 16-24 years attended their practice at least once in a 1-year period. During this period, an estimated 21.3% of patients would not attend their general practice but would be reached by postal screening, 9.2% would not receive a postal invitation but would attend their practice, and 11.8% would be missed by both methods. CONCLUSIONS: Opportunistic and population-based approaches to chlamydia screening would both fail to contact a substantial minority of the target group, if used alone. A pragmatic approach combining both strategies might achieve higher coverage.

Partner notification of chlamydia infection in primary care: randomised controlled trial and analysis of resource use

OBJECTIVE: To evaluate the effectiveness of a practice nurse led strategy to improve the notification and treatment of partners of people with chlamydia infection. DESIGN: Randomised controlled trial. SETTING: 27 general practices in the Bristol and Birmingham areas. PARTICIPANTS: 140 men and women with chlamydia (index cases) diagnosed by screening of a home collected urine sample or vulval swab specimen. INTERVENTIONS: Partner notification at the general practice immediately after diagnosis by trained practice nurses, with telephone follow up by a health adviser; or referral to a specialist health adviser at a genitourinary medicine clinic. MAIN OUTCOME MEASURES: Primary outcome was the proportion of index cases with at least one treated sexual partner. Specified secondary outcomes included the number of sexual contacts elicited during a sexual history, positive test result for chlamydia six weeks after treatment, and the cost of each strategy in 2003 sterling prices. RESULTS: 65.3% (47/72) of participants receiving practice nurse led partner notification had at least one partner treated compared with 52.9% (39/68) of those referred to a genitourinary medicine clinic (risk difference 12.4%, 95% confidence interval -1.8% to 26.5%). Of 68 participants referred to the clinic, 21 (31%) did not attend. The costs per index case were 32.55 pounds sterling for the practice nurse led strategy and 32.62 pounds sterling for the specialist referral strategy. CONCLUSION: Practice based partner notification by trained nurses with telephone follow up by health advisers is at least as effective as referral to a specialist health adviser at a genitourinary medicine clinic, and costs the same. Trial registration Clinical trials: NCT00112255.

Screening for Chlamydia trachomatis: a systematic review of the economic evaluations and modelling

OBJECTIVE: To review systematically and critically, evidence used to derive estimates of costs and cost effectiveness of chlamydia screening. METHODS: Systematic review. A search of 11 electronic bibliographic databases from the earliest date available to August 2004 using keywords including chlamydia, pelvic inflammatory disease, economic evaluation, and cost. We included studies of chlamydia screening in males and/or females over 14 years, including studies of diagnostic tests, contact tracing, and treatment as part of a screening programme. Outcomes included cases of chlamydia identified and major outcomes averted. We assessed methodological quality and the modelling approach used. RESULTS: Of 713 identified papers we included 57 formal economic evaluations and two cost studies. Most studies found chlamydia screening to be cost effective, partner notification to be an effective adjunct, and testing with nucleic acid amplification tests, and treatment with azithromycin to be cost effective. Methodological problems limited the validity of these findings: most studies used static models that are inappropriate for infectious diseases; restricted outcomes were used as a basis for policy recommendations; and high estimates of the probability of chlamydia associated complications might have overestimated cost effectiveness. Two high quality dynamic modelling studies found opportunistic screening to be cost effective but poor reporting or uncertainty about complication rates make interpretation difficult. CONCLUSION: The inappropriate use of static models to study interventions to prevent a communicable disease means that uncertainty remains about whether chlamydia screening programmes are cost effective or not. The results of this review can be used by health service managers in the allocation of resources, and health economists and other researchers who are considering further research in this area.

Does population screening for Chlamydia trachomatis raise anxiety among those tested? Findings from a population based chlamydia screening study

BACKGROUND: The advent of urine testing for Chlamydia trachomatis has raised the possibility of large-scale screening for this sexually transmitted infection, which is now the most common in the United Kingdom. The purpose of this study was to investigate the effect of an invitation to be screened for chlamydia and of receiving a negative result on levels of anxiety, depression and self-esteem. METHODS: 19,773 men and women aged 16 to 39 years, selected at random from 27 general practices in two large city areas (Bristol and Birmingham) were invited by post to send home-collected urine samples or vulvo-vaginal swabs for chlamydia testing. Questionnaires enquiring about anxiety, depression and self-esteem were sent to random samples of those offered screening: one month before the dispatch of invitations; when participants returned samples; and after receiving a negative result. RESULTS: Home screening was associated with an overall reduction in anxiety scores. An invitation to participate did not increase anxiety levels. Anxiety scores in men were lower after receiving the invitation than at baseline. Amongst women anxiety was reduced after receipt of negative test results. Neither depression nor self-esteem scores were affected by screening. CONCLUSION: Postal screening for chlamydia does not appear to have a negative impact on overall psychological well-being and can lead to a decrease in anxiety levels among respondents. There is, however, a clear difference between men and women in when this reduction occurs.

Cost effectiveness of home based population screening for Chlamydia trachomatis in the UK: economic evaluation of chlamydia screening studies (ClaSS) project

OBJECTIVE: To investigate the cost effectiveness of screening for Chlamydia trachomatis compared with a policy of no organised screening in the United Kingdom. DESIGN: Economic evaluation using a transmission dynamic mathematical model. SETTING: Central and southwest England. PARTICIPANTS: Hypothetical population of 50,000 men and women, in which all those aged 16-24 years were invited to be screened each year. MAIN OUTCOME MEASURES: Cost effectiveness based on major outcomes averted, defined as pelvic inflammatory disease, ectopic pregnancy, infertility, or neonatal complications. RESULTS: The incremental cost per major outcome averted for a programme of screening women only (assuming eight years of screening) was 22,300 pounds (33,000 euros; $45,000) compared with no organised screening. For a programme screening both men and women, the incremental cost effectiveness ratio was approximately 28,900 pounds. Pelvic inflammatory disease leading to hospital admission was the most frequently averted major outcome. The model was highly sensitive to the incidence of major outcomes and to uptake of screening. When both were increased the cost effectiveness ratio fell to 6200 pound per major outcome averted for screening women only. CONCLUSIONS: Proactive register based screening for chlamydia is not cost effective if the uptake of screening and incidence of complications are based on contemporary empirical studies, which show lower rates than commonly assumed. These data are relevant to discussions about the cost effectiveness of the opportunistic model of chlamydia screening being introduced in England.

Healthcare and patient costs of a proactive chlamydia screening programme: the Chlamydia Screening Studies project

BACKGROUND AND OBJECTIVE: Most economic evaluations of chlamydia screening do not include costs incurred by patients. The objective of this study was to estimate both the health service and private costs of patients who participated in proactive chlamydia screening, using mailed home-collected specimens as part of the Chlamydia Screening Studies project. METHODS: Data were collected on the administrative costs of the screening study, laboratory time and motion studies and patient-cost questionnaire surveys were conducted. The cost for each screening invitation and for each accepted offer was estimated. One-way sensitivity analysis was conducted to explore the effects of variations in patient costs and the number of patients accepting the screening offer. RESULTS: The time and costs of processing urine specimens and vulvo-vaginal swabs from women using two nucleic acid amplification tests were similar. The total cost per screening invitation was 20.37 pounds (95% CI 18.94 pounds to 24.83). This included the National Health Service cost per individual screening invitation 13.55 pounds (95% CI 13.15 pounds to 14.33) and average patient costs of 6.82 pounds (95% CI 5.48 pounds to 10.22). Administrative costs accounted for 50% of the overall cost. CONCLUSIONS: The cost of proactive chlamydia screening is comparable to those of opportunistic screening. Results from this study, which is the first to collect private patient costs associated with a chlamydia screening programme, could be used to inform future policy recommendations and provide unique primary cost data for economic evaluations.

Effectiveness of chlamydia screening: systematic review

BACKGROUND: Screening programmes are promoted to control transmission of and prevent female reproductive tract morbidity caused by genital chlamydia. The objective of this study was to examine the effectiveness of register-based and opportunistic chlamydia screening interventions. METHODS: We searched seven electronic databases (Cinahl, Cochrane Controlled Trials Register, DARE, Embase, Medline, PsycINFO and SIGLE) without language restrictions from January 1990 to October 2007 and reference lists of retrieved articles to identify studies published before 1990. We included studies examining primary outcomes (pelvic inflammatory disease, ectopic pregnancy, infertility, adverse pregnancy outcomes, neonatal infection, chlamydia prevalence) and harms of chlamydia screening in men and non-pregnant and pregnant women. We extracted data in duplicate and synthesized the data narratively or used random effects meta-analysis, where appropriate. RESULTS: We included six systematic reviews, five randomized trials, one non-randomized comparative study and one time trend study. Five reviews recommended screening of women at high risk of chlamydia. Two randomized trials found that register-based screening of women at high risk of chlamydia and of female and male high school students reduced the incidence of pelvic inflammatory disease in women at 1 year. Methodological inadequacies could have overestimated the observed benefits. One randomized trial showed that opportunistic screening in women undergoing surgical termination of pregnancy reduced post-abortal rates of pelvic inflammatory disease compared with no screening. We found no randomized trials showing a benefit of opportunistic screening in other populations, no trial examining the effects of more than one screening round and no trials examining the harms of chlamydia screening. CONCLUSION: There is an absence of evidence supporting opportunistic chlamydia screening in the general population younger than 25 years, the most commonly recommended approach. Equipoise remains, so high-quality randomized trials of multiple rounds of screening with biological outcome measures are still needed to determine the balance of benefits and harms of chlamydia screening.

Emergence and spread of Chlamydia trachomatis variant, Sweden

A variant of Chlamydia trachomatis that had escaped detection by commonly used systems was discovered in Sweden in 2006. In a nationwide study, we found that it is now prevalent across Sweden, irrespective of the detection system used. Genetic analysis by multilocus sequence typing identified a predominant variant, suggesting recent emergence.

Predicting the population impact of chlamydia screening programmes: comparative mathematical modelling study

BACKGROUND: Published individual-based, dynamic sexual network modelling studies reach different conclusions about the population impact of screening for Chlamydia trachomatis. The objective of this study was to conduct a direct comparison of the effect of organised chlamydia screening in different models. METHODS: Three models simulating population-level sexual behaviour, chlamydia transmission, screening and partner notification were used. Parameters describing a hypothetical annual opportunistic screening program in 16-24 year olds were standardised, whereas other parameters from the three original studies were retained. Model predictions of the change in chlamydia prevalence were compared under a range of scenarios. RESULTS: Initial overall chlamydia prevalence rates were similar in women but not men and there were age and sex-specific differences between models. The number of screening tests carried out was comparable in all models but there were large differences in the predicted impact of screening. After 10 years of screening, the predicted reduction in chlamydia prevalence in women aged 16-44 years ranged from 4% to 85%. Screening men and women had a greater impact than screening women alone in all models. There were marked differences between models in assumptions about treatment seeking and sexual behaviour before the start of the screening intervention. CONCLUSIONS: Future models of chlamydia transmission should be fitted to both incidence and prevalence data. This meta-modelling study provides essential information for explaining differences between published studies and increasing the utility of individual-based chlamydia transmission models for policy making.

Valuing the Health States Associated with Chlamydia trachomatis Infections and Their Sequelae: A Systematic Review of Economic Evaluations and Primary Studies

OBJECTIVES Economic evaluations of interventions to prevent and control sexually transmitted infections such as Chlamydia trachomatis are increasingly required to present their outcomes in terms of quality-adjusted life-years using preference-based measurements of relevant health states. The objectives of this study were to critically evaluate how published cost-effectiveness studies have conceptualized and valued health states associated with chlamydia and to examine the primary evidence available to inform health state utility values (HSUVs). METHODS A systematic review was conducted, with searches of six electronic databases up to December 2012. Data on study characteristics, methods, and main results were extracted by using a standard template. RESULTS Nineteen economic evaluations of relevant interventions were included. Individual studies considered different health states and assigned different values and durations. Eleven studies cited the same source for HSUVs. Only five primary studies valued relevant health states. The methods and viewpoints adopted varied, and different values for health states were generated. CONCLUSIONS Limitations in the information available about HSUVs associated with chlamydia and its complications have implications for the robustness of economic evaluations in this area. None of the primary studies could be used without reservation to inform cost-effectiveness analyses in the United Kingdom. Future debate should consider appropriate methods for valuing health states for infectious diseases, because recommended approaches may not be suitable. Unless we adequately tackle the challenges associated with measuring and valuing health-related quality of life for patients with chlamydia and other infectious diseases, evaluating the cost-effectiveness of interventions in this area will remain problematic.