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.