Impact and cost-effectiveness of chlamydia testing in Scotland: a mathematical modelling study

BACKGROUND: Chlamydia is the most common sexually transmitted bacterial infection in Scotland, and is associated with potentially serious reproductive outcomes, including pelvic inflammatory disease (PID) and tubal factor infertility (TFI) in women. Chlamydia testing in Scotland is currently targeted towards symptomatic individuals, individuals at high risk of existing undetected infection, and young people. The cost-effectiveness of testing and treatment to prevent PID and TFI in Scotland is uncertain. METHODS: A compartmental deterministic dynamic model of chlamydia infection in 15–24 year olds in Scotland was developed. The model was used to estimate the impact of a change in testing strategy from baseline (16.8% overall testing coverage; 0.4 partners notified and tested/treated per treated positive index) on PID and TFI cases. Cost-effectiveness calculations informed by best-available estimates of the quality-adjusted life years (QALYs) lost due to PID and TFI were also performed. RESULTS: Increasing overall testing coverage by 50% from baseline to 25.2% is estimated to result in 21% fewer cases in young women each year (PID: 703 fewer; TFI: 88 fewer). A 50% decrease to 8.4% would result in 20% more PID (669 additional) and TFI (84 additional) cases occurring annually. The cost per QALY gained of current testing activities compared to no testing is £40,034, which is above the £20,000-£30,000 cost-effectiveness threshold. However, calculations are hampered by lack of reliable data. Any increase in partner notification from baseline would be cost-effective (incremental cost per QALY gained for a partner notification efficacy of 1 compared to baseline: £5,119), and would increase the cost-effectiveness of current testing strategy compared to no testing, with threshold cost-effectiveness reached at a partner notification efficacy of 1.5. However, there is uncertainty in the extent to which partner notification is currently done, and hence the amount by which it could potentially be increased. CONCLUSIONS: Current chlamydia testing strategy in Scotland is not cost-effective under the conservative model assumptions applied. However, with better data enabling some of these assumptions to be relaxed, current coverage could be cost-effective. Meanwhile, increasing partner notification efficacy on its own would be a cost-effective way of preventing PID and TFI from current strategy. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/1742-4682-12-2) contains supplementary material, which is available to authorized users

Soroprevalência de anticorpos contra vírus herpes simples 1-2 no Brasil Seroprevalencia de anticuerpos contra virus herpes simples 1-2 en Brasil Seroprevalence of herpes simplex 1-2 antibodies in Brazil

OBJETIVO: Estimar a soroprevalência de anticorpos por vírus herpes simples (HSV-1 e HSV-2) e analisar fatores associados no Brasil. MÉTODOS: Estudo transversal realizado entre 1996 e 1997 em 1.090 indivíduos com idade entre um e 40 anos da população geral, em quatro diferentes regiões geográficas no Brasil. Foram analisadas amostras sangüíneas para detecção de anticorpos para HSV-1 e HSV-2 com teste tipo-específico Elisa. Foram descritas freqüências e proporções, comparadas entre grupos utilizando o teste de Fisher bilateral exato. Foi realizada análise de regressão logística para avaliar influência das variáveis sociodemográficas e histórico de DST, sobre a soroprevalência de HSV-1 e/ou HSV-2. RESULTADOS: As soroprevalências de anticorpos para HSV-1 e HSV-2, ajustadas por idade, foram 67,2% e 11,3% respectivamente, sem diferença quanto ao sexo e maiores na Região Norte. As soroprevalências aumentaram com a idade, e para HSV-2 o maior aumento ocorreu na adolescência e entre adultos jovens. Indivíduos soropositivos para HSV-1 apresentaram maior risco de serem positivos para HSV-2 (15,7%) quando comparados com os negativos para HSV-1 (4,7%). Na análise multivariada, o histórico de DST aumentou significativamente (OR=3,2) a probabilidade de soropositividade para HSV-2. CONCLUSÕES: As soroprevalências para HSV-1 e para HSV-2 variam com a idade e entre as regiões do Brasil. História pregressa de DST é importante fator de risco para aquisição de infecção por HSV-2.<br>OBJETIVO: Estimar la seroprevalencia de anticuerpos por virus herpes simples (HSV-1 y HSV-2) en diferentes áreas geográficas en Brasil y analizar factores asociados. MÉTODOS: Estudio transversal realizado entre 1996 y 1997 con individuos de la población en general en cuatro diferentes áreas geográficas en Brasil y estratificados por edad (de uno a 40 años) y sexo, de los cuales 1.090 fueron incluidos en el análisis final. Fueron analizadas muestras de sangre para detección de anticuerpos para HSV-1 y HSV-2 con prueba tipo-específica ELISA gG1-gG2. Fueron descritas frecuencias y proporciones y comparadas entre grupos utilizando la prueba de Fisher bilateral exacta. Fue realizado análisis de regresión logística para evaluar influencia de las variables edad, sexo, geografía, grupo económico, histórico de DST, seropositividad para anti-HSV-1 o anti-HSV-2 e interacciones de cualquiera de esos factores sobre la seroprevalencia de HSV-1 y/o HSV-2. RESULTADOS: La tasa de seroprevalencia de anticuerpos para HSV-1 ajustada por edad fue de 67,2%, sin diferencia con relación al sexo, siendo mayor en la Región Norte. Las seroprevalencias aumentaron con la edad, y para HSV-2, hube un aumento significativo en la adolescencia y entre adultos jóvenes. Individuos seropositivos para HSV-1 presentaron mayor riesgo de ser positivos para HSV-2 (15,7%) cuando se compararon con los negativos para HSV-1 (4,7%). En el análisis multivariado, el histórico de DST aumentó significativamente (OR=3,2) la probabilidad de seropositividad para HSV-2. CONCLUSIONES: Las seroprevalencias para HSV-1 y para HSV-2 varían con la edad y presentan diferencias significativas entre las regiones de Brasil. Historia anterior de DST es importante factor de riesgo para adquisición de infección por HSV-2.<br>OBJECTIVE: To estimate the seroprevalence of HSV-1 and HSV-2 antibodies in Brazil and to analyze factors associated. METHODS: Cross-sectional study including subjects aged 1-40 years from the general population in four different geographical areas in Brazil between 1996 and 1997. All subjects were stratified by age and gender and 1,090 of them were included in the final analysis. Blood samples were tested for HSV-1 and HSV-2 antibodies by type-specific (gG1 and gG2) ELISA. Frequencies and proportions were described and compared among groups using two-sided Fisher's exact test. A logistic regression analysis was performed to assess the influence of the variables age, gender, geographical area, socioeconomic condition, past history of STD, seropositivity for anti-HSV-1 or anti-HSV-2 and interactions of any of these factors on the seroprevalence of HSV-1 and/or HSV-2. RESULTS: The age-adjusted seroprevalences of HSV-1 and HSV-2 antibodies were 67.2% and 11.3%, respectively, without sex differences and being higher in the North region. Seroprevalences increased with age and, for HSV-2 infection, the higher increase was observed among adolescents and young adults. Subjects who tested positive for HSV-1 were more likely to also test positive for HSV-2 (15.7%) compared to HSV-1 negative subjects (4.7%). In the multivariate analysis past history of STD significantly (OR=3.2) increased the likelihood of HSV-2 infection whereas socioeconomic condition did not affect the results. CONCLUSIONS: HSV-1 and HSV-2 seroprevalences vary with age and among Brazilian regions. Past history of STD is a major risk factor for HSV-2 infection