Main findings
Translating the main findings of this DCE with women suffering from DE and bowel involvement towards the clinical setting we can conclude that 1) In the general ranking, osteoporosis is ranked as least important attribute, while in the DCE, a lower chance of osteoporosis is one of the most important drivers for making a choice in the conservative treatment. 2) Osteoporosis, fatigue symptoms, pain symptoms, pregnancy rates and the presence of endometriosis nodules all have a significant impact on the preference for conservative treatment. The three most important drivers for conservative treatment are lower chance of developing osteoporosis (gonadotropin-releasing hormone (GnRH) analogues), higher chance of improving fatigue symptoms and higher chance of reducing pain symptoms. For surgery, the attributes with a significant impact are getting intestinal symptoms (LARS), pain symptoms, fatigue symptoms, pregnancy rates and getting a temporary stoma. The three most important drivers for surgery are lower chance of getting bowel symptoms (LARS), higher chance of reducing pain symptoms and higher chance of improving fatigue symptoms. 3) The chance of getting a temporary stoma plays a less important role in the context of this study compared to pain reduction and the risk of LARS. 4) Women with a future child wish put pain reduction above possible improvement of fertility chances. 5) Women with previous surgery have significant lower fear for surgery compared to women without a surgical history (DE surgery).
Comparing the results of the direct ranking method and those of the relative importance of the DCE shows discrepancy between both methods. In particular the attribute chance of osteoporosis is considered least important in the ranking exercise while one of the most important attributes when choosing conservative treatment in the DCE. However, as described by Louviere and Islam (29), explicit context like in this case information about the type of treatment, the description of the attributes and the associated levels might explain the difference between the methods. For the ranking exercise, no levels were provided and thus, in contrast with the discrete choice experiment, a trade-off between levels of different attributes when making a choice for conservative treatment or surgery was not required. We believe that the DCE in this study provides more detailed and reliable outcomes, but also requires more intellectual effort from the participants and therefore more challenging to make. Solely ranking attributes is easy, but it should be kept in mind that no considerations about the levels are taken into account.
The risk of permanent intestinal symptoms being almost equally important as pain reduction is an important finding, since the debate about radical DE bowel surgery (resection) versus conservative surgery (shaving/discoid) is ongoing and still undecided. Believers of radical surgery have an approach (radical as possible) almost similar to oncological surgical approaches (30) (31) and aim to reduce pain, prevent recurrence and perhaps even cure women with DE. The potential price they have to pay for this approach is theoretically more severe complications and the risk of permanent intestinal symptoms (LARS) (32). Surgeons who believe in a more reluctant approach aim to reduce pain symptoms and accept possible recurrence/incomplete removal of endometriosis, but try to reduce severe complications and prevent possible permanent bowel symptoms (LARS) (33) (34) (35). However, regarding the good results from the more reluctant surgical approach from Donnez it has to be noted that these patients were treated with progesterone afterwards and only followed up for one year. Long term effects and patients without progesterone should be studied as well to support the more reluctant surgical DE approach.