Results
chlamydia infection
CHLAMYDIA INFECTION, ECTOPIC PREGNANCY
Participants (n = 328) were randomly assigned to methotrexate/placebo (n = 163) and methotrexate/gefitinib (n = 165) groups. Both randomized groups had similar participant characteristics at study enrolment (Following randomization, three participants withdrew, one had hCG <1000 IU/l prior to methotrexate treatment and two had surgery prior to methotrexate treatment. Thus, 322 women received their initial dose of methotrexate and were followed up until resolution of pregnancy.For the analysis, most participant characteristics including risk factors for ectopic pregnancy (age, smoking status, prior chlamydia infection and IVF treatment) were similar among single-dose methotrexate treatment success and failure groups. Day 1 and Day 4 serum hCG were both significantly lower in the treatment success groups (see Participant characteristics for methotrexate treatment success and failure groups.Data presented as mean (SD); median [IQR]; n (% excluding not stated/unknown), number where number different from group.BMI: body mass index; hCG: human chorionic gonadotrophin; IVF: The rate of treatment success with single-dose methotrexate was 59% (n = 189/322). In the single-dose methotrexate treatment failure group, 65% (n = 86/133) had surgery only, 26% (n = 34/133) had a second-dose methotrexate only and 7% (n = 9/133) had surgery after a second-dose methotrexate. Four participants did not have hCG follow-up to point of resolution (<30 IU/l); of these, one woman was lost to follow-up, and three women withdrew from follow-up, with one reporting a negative urine pregnancy test. Allowing for additional methotrexate doses, the success rate of methotrexate was 69% (n = 222/322).ROC curve analysis was performed (see 
Receiver operating characteristic (ROC) summary statistics.AUC: area under curve.Test performance characteristics presented across ranges of percentual change of serum hCG.Test performance characteristics.Optimal threshold (in bold type) identified via maximization of Youden's index. An <18% rise is inclusive of any fall in serum hCG.ROC curve analysis showed that Days 1–4 hCG percentual change predicted single-dose methotrexate treatment success, with an AUC of 0.80 (95% CI 0.74–0.85) (Among those with a falling Days 1–4 hCG, the median hCG change in the 24-h prior to treatment was a 4.2% rise (IQR 11.9; n = 95), establishing that the falling Days 1–4 hCG was not a product of a pre-existing downwards trend but more likely a consequence of the treatment effect.Days 1–7 and Days 4–7 hCG had predictive value in determining treatment success with AUC of 0.86 (95% CI 0.81–0.91) and 0.89 (95% CI 0.85–0.93) respectively. Optimal thresholds for Days 1–7 and Days 4–7 hCG were identified as a 5% fall and a 15% fall respectively (A subgroup analysis examined the predictive value of hCG trends in the methotrexate/gefitinib and methotrexate/placebo arms of the GEM3 study. In the methotrexate/placebo group, the rate of single-dose methotrexate treatment success was 58% (n = 92/159). In this group, ROC curve analysis was used to calculate the AUC for each marker. The AUC was 0.78 (95% CI 0.70–0.86), 0.84 (95% CI 0.77–0.92) and 0.91 (95% CI 0.86–0.97) for Days 1–4, 1–7, and 4–7 serum hCG change respectively (see 