68 / 242
68
Chapter 6
METHODS
Design
We performed a prospective multi-centre randomised double-blind placebo-controlled
trial to evaluate whether a single bolus intravenous alfentanil has a clinically relevant
analgesic effect in patients scheduled for elective CT colonography. We evaluated possible
differences between alfentanil and placebo at different time points. This study was
approved by the institutional review board of the Academic Medical Centre; all participants
gave their written informed consent. The study protocol has previously been described
in detail
29
and the trial was registered in the Dutch Trial Register: NTR2902. The study was
conducted in accordance with the protocol and in compliance with the moral, ethical,
and scientific principles governing clinical research as set out in the Declaration of Helsinki
(1989) and Good Clinical Practice (GCP). The CONSORT 2010 Statement was used as guide
for our reporting.
30
Outcomes measures
The primary outcome was the difference in maximum pain score between patients
receiving alfentanil compared with placebo. We had defined a clinically relevant effect as a
pain reduction of at least 1.3 point on an 11-point numeric rating scale, as this is considered
the minimally important difference using this scale.
26-28
Secondary outcome measures were differences between patients receiving alfentanil
and placebo regarding: pain scores per insufflation position, pain and burden of the CT
colonography procedure and individual CT colonography aspects (e.g. insufflation, bowel
preparation etc.), side effects, vital parameters, procedure time, and recovery time.
Population
Consecutive patients aged 18–85 years and scheduled for elective CT colonography were
assessed for eligibility in two institutions in Amsterdam, the Netherlands: Academic Medical
Centre, University of Amsterdam (academic institution) and Onze Lieve Vrouwe Gasthuis
(teaching hospital). Patients were assessed for eligibility by telephone by one of the research
physicians (T.N.B., M.P.P. or L.J.S.). CT colonography was performed in symptomatic and
surveillance patients only. We used the following exclusion criteria: heart rate < 50 beats per
minute; systolic blood pressure < 90 mmHg; severe chronic obstructive pulmonary disease;
liver disease defined as a Child-Pugh score of > 4; alfentanil allergy; pregnancy; increased
intracranial pressure; use of MAO-inhibitors within two weeks before CT colonography;
daily use of barbiturates, opiates, or benzodiazepines.