Pelvic Inflammatory Disease

External validation of the POP score for predicting obstetric and gynecological diseases in the emergency department

BACKGROUND

The POP score was developed as an easy screening tool for predicting obstetrics and gynecological (OBGYN) diseases in the emergency department (ED), and consists of three predictors, each representing one point: past history of OBGYN diseases, no fever or digestive symptoms, and peritoneal irritation signs). However, its external validity has not yet been evaluated. We aimed to perform the external validation of the POP score.

METHODS

This is a multi-center, retrospective cohort study using ED data of three tertiary care hospitals in Japan between Jan 2017 and October 2020. Young adult women aged 16-49 years with abdominal pain were included in the analysis. The probability of OBGYN diseases was calculated using a logistic regression model of the POP score. Predictions were compared with observations to evaluate the calibration of the model. Further, the diagnostic ability (sensitivity, specificity, and likelihood ratio) of the POP score was evaluated.

RESULTS

Of 66,599 ED visits, 1026 young adult women (median age [interquartile range]: 31 [23-41] years) were included for the analysis. The c-statistic was 0.645 [95% confidence interval (CI): 0.603-0.687]. The predicted probabilities of OBGYN diseases was generally well-calibrated to the observations. When the cut-off was set between 2 and 3 points for the ruling in of OBGYN diseases, the positive likelihood ratio was 9.72 [95% CI: 3.33-28.4]. When the cut-off was set between 0 and 1 points for ruling out of OBGYN diseases, negative likelihood ratio was 0.181 [95% CI: 0.059-0.558].

CONCLUSIONS

Using ED data of three tertiary care hospitals, we externally validated the POP score for prediction of OBGYN diseases in the ED. The POP score likely has clinical value for screening OBGYN diseases in young adult women with abdominal pain in the ED.

The natural history of Chlamydia trachomatis infection in women: a multi-parameter evidence synthesis

BACKGROUND AND OBJECTIVES

The evidence base supporting the National Chlamydia Screening Programme, initiated in 2003, has been questioned repeatedly, with little consensus on modelling assumptions, parameter values or evidence sources to be used in cost-effectiveness analyses. The purpose of this project was to assemble all available evidence on the prevalence and incidence of Chlamydia trachomatis (CT) in the UK and its sequelae, pelvic inflammatory disease (PID), ectopic pregnancy (EP) and tubal factor infertility (TFI) to review the evidence base in its entirety, assess its consistency and, if possible, arrive at a coherent set of estimates consistent with all the evidence.

METHODS

Evidence was identified using 'high-yield' strategies. Bayesian Multi-Parameter Evidence Synthesis models were constructed for separate subparts of the clinical and population epidemiology of CT. Where possible, different types of data sources were statistically combined to derive coherent estimates. Where evidence was inconsistent, evidence sources were re-interpreted and new estimates derived on a post-hoc basis.

RESULTS

An internally coherent set of estimates was generated, consistent with a multifaceted evidence base, fertility surveys and routine UK statistics on PID and EP. Among the key findings were that the risk of PID (symptomatic or asymptomatic) following an untreated CT infection is 17.1% [95% credible interval (CrI) 6% to 29%] and the risk of salpingitis is 7.3% (95% CrI 2.2% to 14.0%). In women aged 16-24 years, screened at annual intervals, at best, 61% (95% CrI 55% to 67%) of CT-related PID and 22% (95% CrI 7% to 43%) of all PID could be directly prevented. For women aged 16-44 years, the proportions of PID, EP and TFI that are attributable to CT are estimated to be 20% (95% CrI 6% to 38%), 4.9% (95% CrI 1.2% to 12%) and 29% (95% CrI 9% to 56%), respectively. The prevalence of TFI in the UK in women at the end of their reproductive lives is 1.1%: this is consistent with all PID carrying a relatively high risk of reproductive damage, whether diagnosed or not. Every 1000 CT infections in women aged 16-44 years, on average, gives rise to approximately 171 episodes of PID and 73 of salpingitis, 2.0 EPs and 5.1 women with TFI at age 44 years.

CONCLUSIONS AND RESEARCH RECOMMENDATIONS

The study establishes a set of interpretations of the major studies and study designs, under which a coherent set of estimates can be generated. CT is a significant cause of PID and TFI. CT screening is of benefit to the individual, but detection and treatment of incident infection may be more beneficial. Women with lower abdominal pain need better advice on when to seek early medical attention to avoid risk of reproductive damage. The study provides new insights into the reproductive risks of PID and the role of CT. Further research is required on the proportions of PID, EP and TFI attributable to CT to confirm predictions made in this report, and to improve the precision of key estimates. The cost-effectiveness of screening should be re-evaluated using the findings of this report.

FUNDING

The Medical Research Council grant G0801947.