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1 Department of Clinical Epidemiology and Biostatistics, 2 Department of Radiology and 3 Department of Gastroenterology from the Academic Medical Center, Amsterdam, The Netherlands
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Abstract |
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Introduction |
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Diagnostic tools are used to determine the exact cause of the faecal incontinence complaints and aim to guide future therapy. In the evaluation of faecal incontinence clinicians can use a large variety of diagnostic tools, including anorectal function tests and anorectal imaging techniques after medical history and physical examination.
Treatment guidance appears to be problematic as there exists debate in the value of diagnostic tests with respect to treatment outcomes [9]. It has been shown that the existence of sphincter atrophy has a negative predictive value on the success of sphincter repair [10]. About 10 years ago, endoluminal MRI of the rectum and the anus was introduced [11]. It appeared that, although endoanal MRI was comparable with endoanal ultrasound for identifying defects of the sphincter, only endoanal MRI could reveal thinning of the external sphincter reflecting muscle atrophy [12].
Its ability to identify sphincter defects as well as external sphincter atrophy makes endoanal MRI a likely candidate for a diagnostic strategy to guide treatment decisions in patients with faecal incontinence. Yet an optimal diagnostic strategy should also try to minimize patient burden, as extensive testing may be taxing to patients.
It has been shown in a review that anxiety-related reactions occur in approximately 4% to 30% of patients undergoing MRI, ranging from apprehension to severe reactions that interfere with the performance of the test [13]. These findings were from studies using non-invasive MRI techniques. It could be hypothesized that the use of an endoluminal coil could be even more bothersome for patients, but there exist no data to either refute or confirm this hypothesis.
We designed a study to evaluate and compare the patient burden of diagnostic tests used in the work-up of patients with faecal incontinence as part of a clinical cohort study aiming to identify prognostic factors for treatment success by physiotherapy.
We studied the perceived burden of endoanal MRI, defecography and an anorectal function test combination consisting of anorectal manometry, pudendal nerve terminal motor latency, rectal capacity measurement, anal and rectal sensitivity measurement and endoanal ultrasound.
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Materials and methods |
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Patients were identified by surgeons, gastroenterologists and a gynaecologist participating in the large diagnostic cohort study. Patients were referred to these physicians by general practitioners or by physicians who were not participating in the cohort study. After receiving signed informed consent from patients, data concerning medical history were collected by physicians. All participating physicians used the same structured forms for medical history. Patients were questioned about the duration of their faecal incontinence complaints. The severity of faecal incontinence was assessed by means of an incontinence scale developed by Vaizey [14]. This scale contains items about the type (gas, fluid, solid) and frequency of incontinence and additional items addressing social invalidation, the need to wear a pad or plug, the use of constipating medication and the presence of urge incontinence. The total score on the Vaizey scale ranges from 0 (complete continence) to 24 (complete incontinence).
Inclusion criteria for the cohort study were the existence of faecal incontinence complaints for 6 months or more, a Vaizey incontinence score of at least 12, and failure of conservative treatment, based on diet recommendations and/or antidiarrhetics. Excluded were patients aged below 18 years, patients diagnosed less than 2 years ago with an anorectal tumour and patients with a previous ileoanal or coloanal anastomosis. As the clinical cohort study investigated the treatment effect of physiotherapy, patients with chronic diarrhoea (always fluid stools, three or more times a day), overflow incontinence, proctitis, soiling (leakage of faecal material out of the anus after normal defecation leading to perineal eczema) and rectal prolapse were also excluded from participation.
Some patient categories were excluded from one or more tests. Defecography was not performed in females younger than 45 years without sterilization, except on indication based on clinical symptoms (e.g. lower abdominal pain and/or false urge to defecate) and clinical findings (e.g. symptoms of prolapse) because of the cumulative radiation doses of somatic and genetic effects. Before the MRI examination, patients were questioned about claustrophobia and had to complete a questionnaire comprising exclusion criteria for a MRI examination, such as a pacemaker, claustrophobia and other contraindications. Patients with a pacemaker were excluded from the MRI examination, a pacemaker being an absolute contraindication for MRI.
Only the data of patients who experienced all three test sessions were analysed in this study.
Diagnostic tests
Patients underwent three diagnostic sessions: one with endoanal MRI, a second with defecography and a third with a combination of anorectal function tests consisting of anorectal manometry, pudendal nerve terminal motor latency, rectal capacity measurement, anal and rectal sensitivity measurement, and endoanal ultrasound. None of the patients received sedation for any of the tests. The decision to evaluate the burden of the latter anorectal function test combination was made because these tests are usually performed in a single testing session and we expected that patients would find it difficult to differentiate the tests. Logistical considerations prevented us from randomizing the order of the tests.
All diagnostic tests were performed according to a standard procedure that had been established during joint meetings of the research group members of all participating hospitals. Not all centres were equipped to perform all tests, therefore not all patients could be tested at a single site. Prior to testing, all patients received standard written information concerning the tests.
MRI
Endoanal MRI visualizes the muscles of the pelvic floor. Endoanal imaging was performed with 1 T or 1.5 T MR (General Electric Horizon Echospeed; General Electric, Milwaukee, IL; Philips Gyroscan ACS-NT; Philips Medical Systems, Best, The Netherlands) clinical closed bore units and a dedicated endoanal coil with a diameter of 18 mm. All patients were asked to fast 4 h prior to the MR examinations to minimize artefacts from bowel peristalsis. In all hospitals except one, the patients were injected intramuscularly with an antiperistaltic drug to reduce bowel motion before the start of imaging. No intravenous contrast medium was used. The endoanal coil was covered with a condom and, after lubrication, inserted into the anal canal with the patient in a left lateral position. After positioning of the endoanal coil, the patients were turned to the supine position and moved into the magnet. The patient was instructed not to squeeze to prevent artefacts of movement. The scan period took on average 20 min. As this test was performed as part of a larger study, patients were also studied with a phased array coil in the same session after removal of the endoanal coil. No intravenous contrast medium was used and no dynamic sequences were performed with external phased array coil MRI. The burden expressed by the patients for MRI was the burden for the combination of endoanal and phased-array MRI. The total duration for this combination was around 40 min.
Defecography
Defecography allows an evaluation of the movements of the rectum, insufficiency of the sphincter, presence or absence of rectoceles, enteroceles and intussusceptions. Patients were instructed to drink contrast medium diluted in water prior to the examination. The test started with the patient in left decubital position. Through an injection, pistol barium paste (200–300 ml barium sulphate prepared by the hospital pharmacy or Evacu-Paste (E-Z-EM® Inc., Westbury, NY)) was injected manually into the rectum. In female patients, amidotrizoide acid 50% gel was also injected via a syringe into the vagina. The perineum was located with amidotrizoide acid 50% gel solution or located by a catheter with leadmark. Subsequently, the entire X-ray table was tilted upright 90° and the patient was seated on a specially developed radiolucent defecography chair. Defecography took approximately 15 min (room time). After the test was performed, the patient was instructed to drink extra to eliminate the contrast.
Anorectal function test combination
All tests were performed in left lateral position with hips flexed to 90°. Anal manometry evaluates the muscular contraction and relaxation of the anal sphincters by the measurement of pressures in the anal canal. Anal manometry took place according to the solid-state or water perfused technique, without or with sleeve. The catheter (Konigsberg Instrument Inc., Pasadena, CA; Medtronic, Skolvunde, Denmark; Dentsleeve Pty Ltd, Parkside, Australia) was introduced and stabilized in the anal sphincter complex. After positioning of the catheter, the basal sphincter pressure, maximum squeeze pressure and rectal anal inhibitory reflex were measured.
Pudendal nerve terminal motor latency determines the integrity of the pudendal nerve. The finger with a glove-mounted St Mark's Hospital electrode (Dantec; Skovlunde, Denmark) was inserted into the rectum. The pudendal nerve was electrically stimulated (supra maximum stimulus of 0.05 ms) on each side near the ischial spine.
With rectal and anal sensitivity measurements the threshold sensation of the rectum and anus was determined, respectively. The stimulation electrode (Dantec Keypoint, Skovlunde, Denmark) was mounted on a catheter and introduced into the rectum. A constant current was increased gradually to a maximum of 20 mA. The same procedure was performed in the anus to determine the threshold sensation of the anus.
The capacity measurement of the rectum was performed by introducing a single use urinary catheter (female, 14 Ch) with a latex balloon tied to the end, covered with a lubricant and connected to a 50 ml syringe, into the rectum. The balloon catheter was inflated with air in gradual increments of 50 ml until the maximum tolerable volume was reached. The minimal rectal sensation perceived (sensory threshold), the volume associated with the initial urge to defecate (urge sensation) and the volume at which the patient experienced discomfort and an intense desire to defecate (the maximal tolerated volume) were determined.
Endoanal ultrasound was performed with an ultrasound scanner (3535 Bruel and Kjaer, Gentfofte, Denmark; SDD-2000 Multiview Aloka, Tokyo, Japan) with radial endoscopic probe and a 7.5 MHz transducer. The probe was covered with a condom and, after application of a lubricant, introduced into the anal canal with the patient in left lateral or prone position. The probe was slightly withdrawn so all the different levels of the anal sphincter complex could be visualized. The total duration of the anorectal function test combination was between 30 min and 55 min.
Test questionnaire
The self-administered questionnaire was handed out by a physician before the first test was performed. Patients were requested to take the questionnaire home and to complete the questionnaire after their last test. One researcher (MD) collected all completed questionnaires and contacted patients when no questionnaires were returned. When necessary, extra questionnaires were sent out. The questionnaire consisted of three modules. First, a standard formatted Likert scoring module was used with four items concerning pain, embarrassment, discomfort, and anxiety. The first three items have previously been used in a study of the acceptance of CT colonoscopy by patients [15]. Based on literature data, we added anxiety as the fourth item [13, 16, 17]. Responses were scored on a five-point scale with 1 indicating "none" and 5 indicating "extreme". By adding the item scores, an overall burden score was determined. Second, a comparative assessment module was used, forcing patients to rank the different tests from least to most inconvenient. Finally, a behavioural intent module was used by asking patients whether or not they, if opportune, would recommend each test to friends or relatives. The different modules were collated into one comprehensive questionnaire.
Statistical analyses
The general linear model for related samples was used to compare the burden of the different tests. When a statistical difference was found, paired t-tests were used as post hoc tests. Subgroup analyses were performed based on age, duration of faecal incontinence (using a median split) and gender. Unpaired t-tests were used to test for differences between groups of patients with respect to sum burden scores. We also investigated with unpaired t-tests if burden values were different depending on whether patients received their tests in a single centre or in multiple centres. We analysed whether test order and the time lag between date of last test and date of completed questionnaire affected experienced burden, using Pearson correlation coefficients.
Additional analyses were performed to study the association between the subjective ranking of a test and the burden variables. For each of the three tests, patients were categorized according to position of that test in their inconvenience ranking. We used analysis of variance to examine differences in the amount of burden between the different patient groups. p-values below 0.05 were considered to represent a statistically significant difference.
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Results |
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Order and timing of the tests
Information on the date of testing was available in 157 patients (74%). The mean duration between the first and last test was 62 days (SD±92). Many tests were performed on the same day. The mean time between last test and completion of the questionnaire was 27 days (SD±50). As the exact testing times were absent from a number of patient records, the exact test order could be derived for 108 patients (Table 1
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Younger patients (below 59 years) had a significantly higher total burden sum score for MRI (6.6 versus 5.7), defecography (7.4 versus 6.3) and anorectal function tests (7.1 versus 6.1) than older patients (Table 2). No differences with respect to the total burden sum scores of the three tests were observed between subgroups characterized by gender or duration of incontinence. Whether patients received their tests in a single centre (63%) or in multiple centres (37%) did not influence experienced burden.
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Patients reporting a high burden score for at least one of the items of MRI and anorectal function combination were significantly younger then patients who did not report a high burden score (55 years versus 60 years (p = 0.045) and 54 years versus 60 years (p = 0.015), respectively). There were no other significant associations between medical history and the group of patients that gave a high burden score on at least one item of a test.
In a subset of 137 we analysed the effect of time lag between last test and completed questionnaire. No relationship was observed between total burden of any of the tests and time-lag (MRI (r = –0.13; p = 0.14); anorectal function tests (r = –0.07; p = 0.44); defecography (r = –0.002; p = 0.98)).
Order of testing was present in 108 patients. Analysis showed that test order did not influence the amount of experienced burden (MRI (p = 0.36); anorectal function tests (p = 0.83); defecography (p = 0.63)).
Only a small number of patients would not recommend one of the tests to a friend or relative: 7 for MRI (3.3%), 12 for defecography (5.6 %), and 6 for the anorectal function test combination (2.8%). Reasons for not advising MRI were possibly anxious reactions (n = 4), fear of loss of stool (n = 1), headache (n = 1) and unknown (n = 1).
Defecography was not advised for various reasons: the dislike of the ingestion of the contrast medium before defecography (n = 3), experienced pain (n = 5), unclearness about use of results (n = 2), anxiety (n = 1) and the lack of privacy (n = 1). Reasons for not recommending the anorectal function test combination were pain (n = 5) and long duration (n = 1).
Not all patients responded to the ranking question, therefore analyses were done on the 174 respondents (82%). On the ranking question MRI scored best, with 120 (69%) patients scoring MRI as least inconvenient (Figure 2). Further analysis of all three tests revealed an association between the position in the ranking question (from least to most inconvenient) and the reported burden (Figure 3). Higher rankings (more inconvenient) corresponded with a significant higher burden sum score for that test (MRI: p<0.001, anorectal function combination: p = 0.03, and defecography: p<0.001).
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Discussion |
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TopAbstractIntroductionMaterials and methodsResultsDiscussionReferences |
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Despite the significant differences in burden between tests, we should note that the differences were small and that absolute levels of burden were low for all tests. There existed a group of patients (24%) that reported a high score on at least one aspect of a test. These patients were on average younger, but it appeared to be impossible to identify on this group of patients basis of medical history. Only a small percentage of patients would not recommend one of the tests to a friend or relative.
It could be hypothesized that larger differences in perceived burden exist across subgroups. We therefore performed a series of subgroup analyses defined by gender, age, and duration of incontinence. Younger patients (below 59 years) reported a significantly higher total burden sum score for all three tests. This finding could possibly be explained by a diminished pelvic floor sensory enervation in the older patient population or to less anxiety or embarrassment related to the procedure itself. Gender, duration of faecal incontinence complaints, order of tests, single or multiple site testing and location played no significant role in the amount of perceived burden of the tests.
A number of potential limitations of this study should be taken into account. The obtained results were derived from data of patients voluntarily seeking help. It is possible that there exists a group of patients who do not request medical care, as they are less willing to undergo diagnostic testing, probably having higher burden scores if ever tested. As patients seeking medical attention may suffer more severely from their complaints they could downgrade the burden of the testing in comparison with the burden of their illness.
The observed imbalance between men and women in our study is not due to a form of selection bias but is inherent to the disorder of faecal incontinence [18].
We were forced to combine five tests into an anorectal function combination, as these tests are usually performed in a single testing session. When designing the study we learned that patients found it difficult to differentiate the tests during the testing sequence. We anticipated that in between measurement might interfere with the experience of the testing sequence and decided to rely on a post hoc assessment of the overall burden of the combination of tests. Unfortunately, this prevents us from making separate statements on endosonography. As endosonography and endoanal MRI produce comparable information, it would be interesting to compare the burden of these two imaging modalities.
Although some have questioned the role of defecography in the diagnostic work up of faecal incontinence, our research group had decided to include this diagnostic modality within the cohort study. Some authors have underscored the importance of the role of defecography for accurately diagnosing intussusceptions and anterior rectoceles [19] or for determining the aetiology of outlet obstruction symptoms in patients with combined faecal incontinence [20]. In a suggested work-up of faecal incontinent patients by Felt [21], defecography was one of the components of the diagnostic procedures. MR-defecography is primarily employed in patients with prolapse or constipation, while the role of MR-defecography in incontinent patients is unclear. For this reason MR-defecography was not part of this diagnostic cohort study evaluating current practice.
Another possible limitation is the non-random test order. The order in which tests were offered to patients varied considerably, but the results of our analysis showed that test order did not significantly affect experienced burden.
It has been shown that past experience with testing can influence the perception of patients of a test [22–24]. It is unusual for patients to undergo repeated testing, so we expected very few of our patients to have undergone one or more of these tests previously. The low prevalence and the lack of data prevent us from exploring explicitly any bias due to prior experience. We believe that in our questionnaire study total, bias is kept to a minimum. Non-response bias is negligible as we achieved a response rate of 89%. The questionnaires were self-administered so there is no potential for interviewer bias. Response bias was minimized by assuring anonymity of the patient. Furthermore, the questionnaires were handed out by a physician, but patients were requested to complete the questionnaire at home. Finally, due to the subject of the questionnaire we did not expect patients to respond in a sociably desirable manner.
We have tried to standardize the information given to patients by handing out a written information sheet prior to testing. However, we cannot claim that all patients received exactly the same oral information by their specialists.
To our knowledge this is the first study to investigate the patient burden of endoanal MRI, defecography and anorectal function test combination. The burden of MRI has been studied before, mostly with respect to patient anxiety. In a review by Melendez et al [13] it has been shown that anxiety-related reactions occur in approximately 4–30% of patients undergoing MRI. In this study, three patients did not undergo an MRI because of claustrophobia. None of the other patients became anxious up to a level that the test could not be executed, and none of the examinations had to be discarded because of motion artefacts, also associated with high patient anxiety in the past [17, 25–27].
The percentage of patients reporting high anxiety levels was low in comparison with other studies. One possible reason for this could be that anxiety was measured after the test had been performed. Various studies have reported lower anxiety levels post-MRI compared with pre-MRI [16, 25, 27]. Another possible explanation for the lower number of patients with anxiety reactions could lie in the fact that patients suffered from their incontinence for a long duration and were not afraid that MRI would reveal a certain malignant disease. Studies have shown that test anxiety could result from insecurity about what the test would reveal [16, 28]. Although the amount of anxiety of MRI in this study was low in comparison with earlier studies, the observed values were slightly higher than those for defecography and the anorectal function combination.
MRI scored better with respect to other variables than defecography and the anorectal function combination. Small but significantly lower scores for MRI were seen for pain, embarrassment and discomfort. Total burden sum score was also significantly lower for MRI. Because all tests were performed as part of a larger study designed to evaluate the diagnostic performance of these tests, patients received phased-array MRI as well as endoanal MRI in a single session. The present study addressed the burden of that total MRI session. It can be expected that the burden for a diagnostic session with endoanal MRI only would be even somewhat smaller, because of the shorter duration of this single procedure.
Overall, MRI was preferred more often than defecography and functional testing, with 120 (69%) patients scoring MRI as least inconvenient. For every test we observed a significant relationship between the given inconvenience rank and the burden sum score. Patients ranking a test as least inconvenient reported significantly less burden than patients who ranked this test as most inconvenient. We feel confident in concluding that the burden sum score, based on a combination of embarrassment, pain, anxiety and discomfort, is a reflection of relative inconvenience. The observed relation between the burden values and the ranking question supports the construct validity of this short and apprehensive questionnaire.
In summary, in this study, set up to investigate the burden of diagnostic tests used in the assessment of faecal incontinence, we found significant differences between tests, with MRI scoring significantly better than defecography and the anorectal function combination. As the differences were small and the average burden values were low for all tests, we find it safe to say that the role of burden of testing in the search for an optimal strategy in faecal incontinence will be limited. The preferred diagnostic pathway will most likely be based on maximizing diagnostic accuracy at acceptable costs. Efforts to collect more information on test accuracy and costs are underway.
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Footnotes |
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Received for publication May 26, 2005. Revision received June 15, 2005. Accepted for publication June 22, 2005.
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