Participant recruitment
Inclusion took place between January 2019 and October 2020 in
six Dutch academic hospitals
(23.7% of the patients) and eight non-academic hospitals (46.7%) and
also by the Dutch and Belgian endometriosis foundation (29.6%). Women
who were interested could visit the website (www.endokeuze.com) for
information about the study. It was especially noted that only women
with DE and bowel involvement could participate in this study. Women
willing to participate had to pass three inclusion questions, which are
commonly used and accepted in endometriosis questionnaire studies (15)
(16) (17). For this DCE only women with surgically or radiologically
(ultrasound and/or MRI) diagnosed DE with bowel involvement, prior to a
treatment decision and currently not in any fertility treatment
trajectory could participate. Women could not see which answer would in-
or exclude them. The first question was: “Do you have deep
endometriosis with bowel involvement, which is diagnosed by a doctor by
ultrasound, MRI or surgery?” Patients who answered this with ‘yes’
received a second question; “Are you prior to a treatment choice
with medication or surgery?” Patients who answered this with ‘yes’
received a final question; “Are you currently in a trajectory to
become pregnant (e.g. hormonal treatment for ovulation induction,
IVF)?” Patients who answered these questions with ‘no’ were included
in the study prior to a digital informed consent form. Patients who did
not meet the inclusion criteria, were acknowledged for their interest in
the study, but could not further participate. Further exclusion criteria
were low health literacy, this was tested with three questions (18).
Further exclusion criteria were low health literacy, this was tested
with three questions (18). We excluded patients who indicated to always
have difficulties with understanding medical information about their
disease and treatment, always need help with reading information about
their disease and treatment and have no confidence at all in filling in
medical forms. Furthermore, patients with no informed consent, patients
who did not complete the 10 DCE questions, patients who completed the
whole survey in ≤ 10 minutes time (this ‘too fast’ threshold was set
after the pilot) and patients who gave the same answer on all questions
in the first section of the survey and DCE, were excluded. A total of
641 patients started the survey (Supplementary table S1), 141 patients
were excluded at inclusion question one (no DE with bowel involvement),
152 patients were excluded at inclusion question two (not prior to a
treatment decision), 53 patients were excluded at inclusion question
three (patients in fertility treatment). A total of 91 patients who met
the inclusion criteria but stopped after reading the information were
also excluded, five patients with no informed consent were excluded. One
patient who filled in the same answer at all questions (survey fatigue),
24 patients who did not complete the DCE task, three patients with poor
health literacy were excluded. One patient indicated to always have
difficulties with understanding medical information about her disease
and treatment, one patient always needed help with reading information
about her disease and treatment and one patient who had no confidence at
all in filling in medical forms. Furthermore, two patients were excluded
who completed the DCE within 10 minutes. This
resulted in 169 patients who met
all inclusion criteria (26.4% of the initial amount of patients who
started the survey).