Int Urogynecol J (2013) 24:469–478 DOI 10.1007/s00192-012-1886-9
ORIGINAL ARTICLE
Responsiveness and interpretability of incontinence severity scores and FIQL in patients with fecal incontinence: a secondary analysis from a randomized controlled trial E. M. J. Bols & H. J. M. Hendriks & L. C. M. Berghmans & C. G. M. I. Baeten & R. A. de Bie
Received: 16 September 2011 / Accepted: 30 June 2012 / Published online: 18 July 2012 # The International Urogynecological Association 2012
Abstract Introduction and hypothesis This study aims to assess the responsiveness and interpretability of the Vaizey score, Wexner score, and the Fecal Incontinence Quality of Life Scale (FIQL) for use in the evaluation of patients with fecal incontinence (FI). Methods Eighty patients with FI with a mean age of 59.3 (SD±11.9) were enrolled in a randomized controlled trial. The patient-reported outcomes were tested for internal and external responsiveness, longitudinal construct validity, and interpretability. Results All total scores proved to have both adequate to excellent responsiveness and longitudinal construct validity, and changes were in agreement with subjective improvement. Due to variability in minimally important change estimates (Vaizey score −5 to −3, Wexner score −3 to −2, FIQL 1.1 to 1.2), they should be used as indicators. All patient-reported outcomes showed psychometric or practical limitations.
E. M. J. Bols : H. J. M. Hendriks : R. A. de Bie Department of Epidemiology, School for Public Health and Primary Care (CAPHRI), Maastricht University Medical Centre (MUMC+), PO Box 616, 6200 MD Maastricht, The Netherlands E. M. J. Bols (*) : H. J. M. Hendriks : R. A. de Bie Centre for Evidence Based Physiotherapy, MUMC+, PO Box 616, 6200 MD Maastricht, The Netherlands e-mail:
[email protected] L. C. M. Berghmans Pelvic care Center Maastricht, MUMC+, PO Box 5800, 6202 AZ Maastricht, The Netherlands C. G. M. I. Baeten Department of Surgery, MUMC+, PO Box 5800, 6202 AZ Maastricht, The Netherlands
Conclusions The instruments available to date to evaluate severity and quality of life in FI do not yet attain the highest levels of psychometric soundness. As the focus of patients may differ from that of physicians, it is recommended that several measures should be included for evaluation. So far, there are suggestions that the Wexner score is most suitable for severity assessment and the FIQL for evaluating quality of life. Keywords Fecal incontinence . Fecal Incontinence Quality of Life Scale . Minimally important change . Psychometrics . Vaizey score . Wexner score Abbreviations MIC Minimally important change FIQL Fecal Incontinence Quality of Life Scale FI Fecal incontinence SRM Standardized response mean QOL Quality of life PRO Patient-reported outcome SD Standard deviation GPE Global perceived effect
Introduction Fecal incontinence (FI) is defined as the complaint of involuntary loss of feces [1]. Affected patients often suffer in silence and only one third seeks medical advice [2]. Reporting severity of FI and its consequences for quality of life (QOL) are of great relevance, although no consensus exists on the optimal patient-reported outcome (PRO) [3]. In evaluating a patient, one should assess the patients’ subjective perception of improvement for example by using the global perceived effect (GPE) score [4]. Furthermore, grading
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scales assessing type of stool loss are in general use, however lack information on frequency of bowel accidents and are therefore unable to discriminate between patients with small differences [5]. Other multi-item scoring systems have emerged [6–8], of which the Vaizey score [7] and Wexner score [6] are most often used as PRO in trials on physical therapy for FI [9–11]. Both scales combine items regarding frequency and type of stool loss, pad use, and alteration in lifestyle. Additionally, the Vaizey score assesses the ability to defer defecation and the use of constipating medication, and reduces the emphasis on the need to wear a pad [7]. Since FI is a major stressor in life, QOL outcomes are frequently used in evaluating FI. The Fecal Incontinence Quality of Life Scale (FIQL) is a condition-specific QOL questionnaire [12] and more commonly used as secondary outcome in evaluating patients with FI [9]. Besides evaluating treatment, PROs may be of use with regard to clinical decision making as well as communication among health providers and involved insurance companies. However, the application of the Vaizey and Wexner scores and the FIQL in standard practice is hampered since the psychometric properties, in terms of validity, reliability, and responsiveness, have not been rigorously evaluated before. Avery et al. concluded that the Vaizey and Wexner scores were in the early stage of development, and the FIQL was recommended as some validity, reliability, and responsiveness was indicated [11]. In the meantime, efforts by our research group to validate the Vaizey score in patients undergoing physical therapy resulted in the conclusion that the psychometric properties of the Vaizey score are inconclusive [13]. Additionally, it is important that the numerical value of a PRO is interpretable. Thus far, it is unclear which change scores are minimally important, which is of significance in calculating the sample size of a trial and interpreting results of effectiveness studies on physical therapy in FI. We performed secondary analyses based on a recently completed randomized controlled trial [14], which evaluated the add-on effect of rectal balloon training to pelvic floor muscle training, with the aim of critically evaluating the responsiveness and interpretability of the Vaizey score, Wexner score, and the FIQL for use in the evaluation of patients with FI.
Materials and methods Study design and subjects The study population consisted of participants included in a randomized controlled trial [14]. Adult patients with FI were included at Maastricht University Medical Centre between August 2006 and May 2009 when they reported having had FI for more than 6 months, with a Vaizey incontinence score ≥12 (range 0–24), and failure of dietary measures and
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medication. Patients were excluded if diagnosed with an anorectal tumor within the past 2 years, absent squeeze pressure of the anal sphincter, chronic diarrhea (always fluid stool three or more times a day), overflow incontinence, proctitis, ulcerative colitis, Crohn’s disease, previous ileoanal or coloanal anastomosis, and/or rectal prolapse in situ. Participants who had received physiotherapy during the previous 6 months or who were considered unable to comply with therapy were excluded as well. The Medical Ethics Committee of the Maastricht University Medical Centre approved the study. Outcome measures Baseline measurements consisted of medical history taking, physical examination, anal manometry (measurement of sphincter pressure during rest and squeezing), rectal capacity measurement (evaluation of threshold of first detectable sensation, urge sensation, and maximum tolerable volume), anorectal sensitivity, endoanal ultrasound (assessment of internal and external abnormalities), and defecography (imaging of rectum during rectal evacuation). After the diagnostic workup, patients were referred for a standardized physiotherapy program, comprising 12 sessions within a maximum of 9 weeks and were followed up at a mean of 6.8 weeks (SD5.3). Patient-reported outcomes Three questionnaires were completed at baseline and four at follow-up (including the GPE). All versions were in Dutch. The primary outcome was based on the Vaizey score, which was completed by an independent physician during the patient’s hospital visit, and ranges from 0 (complete continence) to 24 (complete incontinence). The Vaizey score assesses the severity of FI (Table 1). The Wexner score was derived from the Vaizey score (without the items “urgency” and “medication use” and a higher weighting for “pad use”) and ranges from 0 (complete continence) to 20 (complete incontinence) (Table 1). A 9-point GPE score asked patients to score their perceived change after physiotherapy treatment. Categories (in wording) ranged from “very much improved” to “very much worse.” The FIQL is a 29-item condition-specific QOL questionnaire, ranging from 4 to 16 and composed of four multi-item subscales: lifestyle (10 items), coping/behavior (9 items), depression/self-perception (7 items), and embarrassment (3 items) [12]. A higher score indicates better QOL. Next to one question on general health and one on self-perception, items are partly scored on a 4-point scale ranging from “most of the time” to “none of the time” and partly from “strongly agree” to “strongly disagree.” The FIQL was
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Table 1 Fecal incontinence score according to Vaizey and Wexner Incontinent
Never Rarely Sometimes Weekly Daily
Solid stoola Liquid stoola Gasa Alteration in lifestylea Wears padb
0 0 0 0 0
Need to wear a pad or plugc Taking constipating medicationc Lack of ability to defer defecation for 15 minc
1 1 1 1 1
2 2 2 2 2 No 0
3 3 3 3 3 Yes 2
0
2
0
4
4 4 4 4 4
Never: no episodes in the past 4 weeks; rarely: 1 episode in the past 4 weeks; sometimes: >1 episode in the past 4 weeks, but
