Methods
The study was conducted in accordance with the Declaration of Helsinki
and was reviewed by the local ethics advisory committee. All
participants gave their informed consent.
Design
This is a placebo-controlled single-blind randomized controlled trial on
the effects of standardized written information in comparison with a
placebo intervention on patient anxiety and satisfaction with
information among adults undergoing an MRI examination for the first
time.
Sample
Study participants were consecutively recruited during 18 months at the
Department of Medical Imaging and Physiology at University Hospital in
Malmö, Sweden. The department has 4 MRIs and performs approximately 5000
outpatient MRI examinations each year. The inclusion criteria were
outpatients aged 18-70 years who were to undergo an MRI examination
using a non-open camera Siemens Symphony 1.5 Tesla MRI scanner.
Inpatients, those who previously had undergone an MRI examination, those
who were to undergo MRI in anesthesia, patients with cognitive
impairment, and those who did not speak Swedish were excluded. The study
participants were randomized to either an intervention or control group.
The flow chart of the study sample is presented in Figure 1.
Figure 1 about here
The sample size was estimated a priori based on previous study results
regarding anxiety, as assessed using the State Trait Anxiety Inventory
(STAI); pre-scanning mean scores in the intervention and control groups
were estimated to be 37 and 41, respectively, and scores after MRI were
estimated to be 32 and 37, respectively, with a common SD of 10. Based
on these parameters, which give effect sizes of 0.4 and 0.5,
respectively, approximately 99 and 64 individuals were required per
group for 80% power at a two-tailed alpha level of 0.0533.
Intervention
The active intervention consisted of an information booklet on MRI that
was developed based on clinical experience, relevant literature, and
patient input 31. Briefly, the booklet contained the
following information:
- explanation of how an MRT examination is conducted (procedure
information)
- description of what might be expected by the patient in connection to
the MRI procedure (behavior information)
- examples of potential reactions and experiences in connection to MRT
(sensory information)
The placebo intervention consisted of an information booklet of the same
size and layout as the intervention booklet, but only containing general
information about the department and no specific information about the
MRI procedure.
In addition to the booklets, both groups received standard care. This
consists of checking responses to a safety questionnaire that patients
complete before the appointment. This is followed by oral information
about the examination (e.g., duration of the examination, the need to
lie still, and that a loud noise will be heard when images are taken).
If the procedure requires the patient to hold her/his breath, this is
practiced prior to the examination. Ear protection is applied and those
who wish so are offered to listen to music. Everyone gets an alarm clock
to call on the staff if needed. Relatives are welcome to be present in
the examination room but have no opportunity to communicate with the
patient. The time to give the above information is limited to
approximately 5 minutes. Upon completion of the MRI, the patient is
informed that the results will be sent to the referring physician.
Instruments and other study data
Anxiety was assessed using the STAI, which consists of two parts: STAI
FORM Y-2 T and STAI FORM Y-1 S 34. STAI FORM Y-2 T
(”trait anxiety”), assesses the individual’s general tendency to
experience stressful situations as worrying, and STAI FORM Y-1 S (”state
anxiety”) assesses the current anxiety levels (ibid). STAI FORM Y-1 S is
available in two different designs; one is worded in present tense and
intends to assess the respondent’s anxiety right now and the other is
worded in past tense and intends to assess recently perceived anxiety.
These STAI forms are hereinafter referred to as STAI-T (trait anxiety),
STAI-SB and STAI-SA (state anxiety before and immediately after MRI,
respectively, where the STAI-SA was intended to assess anxiety
experienced during the MRI). All STAI forms comprise 20 items each with
four ordered response categories scored 1-4, yielding possible total
scores between 20 (less anxiety) and 80 (more anxiety). A total score of
40 or higher is considered to indicate a high level of anxiety16, 32. In cases of ≤10% missing item responses,
scores are imputed by averaging item scores across available item
responses 34.
The STAI has been used in a variety of areas, including the assessment
of anxiety in the context of MRI scanning 12-13, 16-17,
19, 23-24, 32, 35. There is general support for the validity and
reliability of scores on the different STAI forms 36.
In the present study, the Swedish version 37 of the
instrument was used. Cronbach’s coefficient alpha in the control and
intervention groups in this study was 0.94 and 0.92 for STAI-T, 0.93 and
0.94 for STAI-SB, and 0.94 and 0.93 for STAI-SA, respectively.
Satisfaction with the information about MRI was assessed using three
study specific items. The first question concerned the agreement between
the patient’s expectations of the examination and the actual experience.
The two other questions were adapted from the Quality from the Patient’s
Perspective questionnaire for mammography 38 and
concerned whether the pre-scan information made them understand what was
going to happen, and how important the patient considers such
information to be. All three questions had four ordered response
categories scored 1-4, where 4 represents a higher degree of
satisfaction.
In addition, it was recorded whether or not sedatives were taken prior
to the MRI examination, relatives were present in the examination room,
and if the patient listened to music during the examination. Other data
recorded were age, gender, duration of the examination, scanned body
part, if the patient called or visited the MRI department before the
examination, if the patient aborted the examination, and medical history
(classified as malignant or other disease) at referral.
Data collection
An invitation to participate was sent together with the call letter for
the MRI examination. Those who wished to participate were asked to sign
and return a written informed consent together with the completed
STAI-T. To mimic routine clinical use of the written MRI information as
far as possible, those randomized to the intervention group received the
MRI information booklet together with the call letter and the control
group received the placebo booklet.
All staff at the MRI unit were fully informed about the study but were
blinded to which group patients belonged to. Prior to MRI, all patients
were asked to complete the STAI-SB and sealed it in an envelope, before
being provided standard care (see above). Immediately after completion
of the MRI, patients were asked to complete the STAI-SA as well as the
three satisfaction questions, which also were returned in sealed
envelopes. Patients who aborted the examination prematurely were also
asked if they were willing to answer the questionnaires.
Data analysis
Data were analyzed using IBM SPSS Statistics 25, with the two-tailed
significance level set to P<0.05. Demographic data, intake of
sedatives, the presence of relatives in the MRI room, whether the
patients listened to music in connection to the examination, STAI-T
scores, and other baseline data were analyzed using chi-square/Fisher’s
exact tests, Mann-Whitney U tests and independent t-tests, as
appropriate. Mann-Whitney U and Wilcoxon signed-rank tests were used for
between and within group comparisons of STAI-SB and STAI-SA scores, and
Mann-Whitney U tests were used to compare satisfaction scores.
The proportion of patients with STAI-SB and STAI-SA total scores of 40
or more was compared between the intervention and control groups using
chi-square tests. To examine whether the intervention booklet was
associated with a lower risk of high anxiety immediately before and
during MRI scanning, a multivariate logistic regression (forward
stepwise) was performed, using dichotomized STAI-SB and STAI-SA total
scores (<40 = 0; ≥40 = 1) as dependent variables. Group
assignment (intervention or control), high trait anxiety (STAI-T ≥40),
gender, telephone contact or visiting MRI prior to the examination, use
of sedatives prior to MRI, presence of relatives in the examination
room, music during the examination, and medical history were entered as
independent variables.