Score cut-points* | MSM | Heterosexual males | Heterosexual females | |||||||||
Sensitivity† | Specificity‡ | Fraction positive§ | PPV¶ | Sensitivity† | Specificity‡ | Fraction positive§ | PPV¶ | Sensitivity† | Specificity‡ | Fraction positive§ | PPV¶ | |
≥5 | 99.4% | 2.5% | 99.0% | 11.1% | 100.0% | 0.0% | 100.0% | 7.6% | 100.0% | 1.8% | 99.8% | 5.9% |
≥10 | 98.0% | 9.0% | 98.0% | 11.7% | 100.0% | 0.5% | 99.3% | 8.6% | 98.4% | 11.8% | 97.5% | 6.4% |
≥15 | 93.0% | 24.0% | 93.0% | 13.0% | 99.3% | 11.2% | 99.0% | 9.2% | 90.3% | 33.3% | 88.5% | 7.6% |
≥20 | 80.0% | 52.0% | 77.0% | 18.0% | 96.8% | 23.3% | 96.0% | 10.1% | 70.0% | 62.3% | 67.0% | 9.8% |
≥25 | 57.0% | 75.0% | 54.0% | 23.3% | 88.8% | 42.1% | 87.0% | 12.0% | 43.1% | 86.1% | 40.0% | 15.2% |
≥30 | 33.4% | 88.5% | 31.0% | 27.1% | 74.4% | 62.2% | 72.0% | 14.6% | 27.3% | 95.2% | 25.0% | 24.5% |
≥35 | 12.0% | 97.9% | 10.0% | 40.1 | 50.8% | 82.5% | 48.0% | 20.0% | 19.4% | 97.9% | 17.0% | 33.7% |
≥40 | 3.4% | 99.7% | 3.0% | 56.7% | 29.0% | 93.2% | 26.0% | 23.7% | 11.8% | 99.2% | 10.0% | 42.9% |
* For MSM: 4×(age<25)+5×(age 25–29)+4×(age 30–39)+3×residence (not metropolitan/interstate)+0×(never married/divorced/other)+0×(CALD)+0×(travellers)+0×(sex in Asia)+0×(current sex worker)+2×(current smoker)+11×(genital or anal symptoms)+3×(STI testing)+17×(STI contact)+4×(inconsistent condom use)+0×(past chlamydia)+5×(one male sex partner in last 3 months)+10×(two male sex partners in last 3 months)+12×(three or more male sex partners in last 3 months)+0×(two or more female sex partners in last 3 months)+0×(knowledge of HIV status: not tested/unsure).
For heterosexual males: 0×(age<25)+0×(age 25–29)+0×(age 30–39)+4×(never married/divorced/other)+0×residence (not metropolitan/interstate)+3×(CALD)+3×(travellers)+5×(sex in Asia)+0×(current sex worker)+3×(current smoker)+9×(genital or anal symptoms)+3×(STI testing)+20×(STI contact)+8×(inconsistent condom use)+4×(past chlamydia)+9×(two or more female sex partners in last 3 months)+3×(knowledge of HIV status: not tested/unsure).
For females: 0×(age<25)+0×(age 25–29)+0×(age 30–39)+2×(never married/divorced/other)+3×residence (not metropolitan/interstate)+4×(CALD)+0×(travellers)+0×(sex in Asia)+6×(current sex worker)+2×(current smoker)+4×(genital or anal symptoms)+2×(STI testing)+22×(STI contact)+4×(contraception-oral)+5×(contraception-none)+4×(inconsistent condom use)+0×(past chlamydia)+3×(one male sex partner in last 3 months)+6×(two male sex partners in last 3 months)+9×(three or more male sex partners in last 3 months)+0×(two or more female sex partners in last 3 months)+4×(knowledge of HIV status: not tested/unsure).
† Percentage of detected chlamydia infection in the population (heterosexual males, MSM or heterosexual females).
‡ Percentage of chlamydia negative participants in the population (heterosexual males, MSM or heterosexual females) who would not be screened justly.
§ Percentage of the total population (heterosexual males, MSM or heterosexual females) eligible for screening under the given selection criterion.
¶ Prevalence of chlamydia infection in the screened population (heterosexual males, MSM or heterosexual females).
CALD, culturally and linguistically diverse; MSM, men who have sex with men; PPV, positive predictive value; STI, sexually transmissible infection.