Discussion
Main findings
In this study, a RF model was made to predict surgical re-intervention within two years after EA. Comparison of the predictive value of a RF model with the existing logistic regression model of Stevens et al. was made (1).
The existing logistic regression model has a C-index of 0.71 (95% CI 0.64-0.78) (1). The RF model, developed in this study, shows a C-index of 0.65 (95% CI 0.56-0.74) after hyperparameter optimization. This shows that the LR prediction model developed by Stevens et al. probably performs better in predicting surgical re-intervention within two years after EA than the newly developed RF model. However, this difference in performance is not statistically significant when we look at the confidence intervals. Significant predictors of the model are age, duration of menstruation >7 days, dysmenorrhea, parity ≥5 and previous caesarean section(1).
In our database, high parity (≥5) is a predictive variable for surgical re-intervention. This can be related to the larger uterine cavity of grand multiparous women. However, when considering our RF model, parity has no large impact on the AUC. This is in line with previously reported studies that show no significant increased risk of treatment failure with increasing parity (2,17).
Previous caesarean section is also related to higher rates of surgical re-intervention which can be explained by irregularity of the uterine wall caused by the uterine scar (44). This can inhibit complete contact of the ablation device with the uterine wall, leading to residual active endometrium.
In our cohort, pre-operative dysmenorrhea is associated with a higher risk of surgical re-intervention. There is evidence that gynaecologic pathology causing this dysmenorrhea (adenomyosis and endometriosis) reduces the success of endometrial ablation (9,18,32,45,46). This can be explained by the fact that EA is not an appropriate treatment for these diseases due to the superficial effect of energy to the uterine wall of ablation. It could help to diagnose these diseases before performance of EA. However, sensitivity and specificity of the diagnostic tools for determining these diseases in the pre-operative setting are still low (47).
In line with previous studies, we found that younger age was associated with a higher risk of surgical re-intervention (8,10–14,31).
The duration of menstruation > 7 days is also a negative predictive factor for surgical re-intervention after EA. This may be caused by a thicker endometrium which is more difficult to completely remove by the device (8,11).