Deriving and Validating A Risk Estimation Tool for Screening Asymptomatic Chlamydia and Gonorrhea

Abstract

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.

Use of a risk quiz to predict infection for sexually transmitted infections: a retrospective analysis of acceptability and positivity

“…Their sum scores were added similarly to the method used by Gotz et al 15 and were derived from regression coefficients of a multivariable logistic regression model using visits between 2000 and 2006 and included younger age, non-white ethnicity, multiple sexual partners and previous infection. They showed reasonable performance in the derivation (area under the receiver operating characteristic curve=0.74) in the evaluation from 2007 to 2012 11. Our expert panel similarly used risk factors previously estimated from our earlier IWTK and other studies, which indicated independent associations with young age, lack of condom use, concurrency, number of partners and previous diagnosis of an STI to design our risk quiz and scoring algorithm 7 8.…”

“…They indicated that eight studies attained a performance benchmark of testing <60% of the population with achieving 90% sensitivity. Their own validation of their risk estimation tool in Canada achieved a sensitivity of 91% and 83% of cases for screening for chlamydia and gonorrhoea, with only screening 68% and 68% of the derivation and validation populations, respectively, by using a cut-off point of at least 6 on their scale 11. Their sum scores were added similarly to the method used by Gotz et al 15 and were derived from regression coefficients of a multivariable logistic regression model using visits between 2000 and 2006 and included younger age, non-white ethnicity, multiple sexual partners and previous infection.…”

Can psychosocial and socio-demographic questions help identify sexual risk among heterosexually-active women of reproductive age? Evidence from Britain’s third National Survey of Sexual Attitudes and Lifestyles (Natsal-3)

“…This reflects that only one has been developed for use in primary care (specifically for identifying STIs among paediatric primary care attenders in the United States [32]). Secondly existing tools focus primarily on sexual behaviour, symptoms and socio-demographics [33–35]. Where psychosocial items have been included in other tools, selection was not empirically-based but reflected service intentions to identify and address adjunct issues such as intimate partner violence [36].…”

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

“…The aim of optimising service provision could be facilitated by the use of risk estimation algorithms. In a previous paper,5 a risk estimation algorithm for optimising asymptomatic chlamydia and gonorrhoea case finding was derived using electronic medical records of patient visits at two sexual health clinics in Vancouver, British Columbia (BC). This algorithm combines five risk factors: younger age, non-white race/ethnicity, multiple sexual partners, previous chlamydia diagnosis and previous gonorrhoea diagnosis.…”

“…Before making recommendations regarding the widespread use of the risk estimation algorithm derived through our previous work,5 we conducted an external validation study in an independent setting to further test the parameters of the tool. It is essential to confirm that the algorithm is generalisable to a plausibly related setting (in addition to the previous comparisons conducted with the derivation population) that reflects the level of heterogeneity that will be encountered in real-life applications of the algorithm 10.…”