Background
Multiple sclerosis (MS) is a progressive neurologic disorder that causes demyelination of affected nerves in the central nervous system [
1‐
3]. MS can cause almost any neurological symptom, and it often progresses to cognitive and neurological disabilities in the patient, including a decline in mobility [
1]. MS affects women three times as often as it affects men. It affects approximately 1 in 1000 people in the US and is the most common cause of neurological disability in individuals 20–45 years old [
4,
5]. A majority of MS patients develop some form of lower urinary tract dysfunction due to disconnection between the brainstem and the lower spinal cord [
6‐
8]. In particular, up to 75% of MS patients have neurogenic detrusor overactivity (NDO), a bladder disorder characterized by spontaneous overactivity of the detrusor muscle [
9]. Symptoms of this disorder include urinary urgency, urinary frequency, and/or urinary incontinence [
2,
10]. Incontinence has been identified as one of the worst aspects of the disease from the patient’s perspective [
8]. High intravesical pressures may also lead to serious complications, including kidney infection, and reflux, ultimately causing irreversible damage [
7]. Additionally, given all of the issues with NDO in MS it is noted that research groups are establishing guidelines for the evaluation of urinary disorders in MS [
7,
8,
11]. Therefore, despite the high prevalence of urinary incontinence, urological evaluation and treatment are significantly under-accessed in this population [
10]. This study outlines the development and validation of a shortened form of a new screening tool, the Actionable Bladder Symptom Screening Tool (ABSST), that healthcare providers can use to identify MS patients with urinary incontinence who may be in need of a more precise diagnosis and/or treatment for their urologic symptoms, including referral to a urologist. The objectives of this study were twofold: 1) to adapt the previously validated 17-item ABSST to a short form for ease and brevity of application in a medical setting that is clinically meaningful; and 2) to develop a scoring algorithm that would be interpretable in terms of referring/considering diagnosis and treatment. Novel item response and classical test methods were used to identify optimally performing items for inclusion in the short form assessment.
In view of recent research suggesting that patients and clinicians are more likely to use shorter instruments [
12‐
15], it was decided to develop a short form version of the ABSST that is clinically meaningful from the clinician’s perspective. The development of this short form version of the instrument is described here. In addition, a scoring algorithm was developed for the ABSST, with a identification of a score that would recommend further diagnosis or referral to a urologist. The novel approach of developing the scoring algorithm presented here is based on pivot anchoring as a means of demonstrating clinical meaningfulness.
Discussion
The goal of this study was to validate the short form Actionable Bladder Symptom Screening Tool (ABSST) as a patient driven, clinically useful measure that is easy to administer and score. The goals were to develop a tool that is sensitive, MS-specific, easy to interpret, easy to use in a clinical setting, and multidimensional, all of which encourage patient-clinician interaction. The unique application of a mixed methods approach was used to select the best items from the long form, using both qualitative and quantitative techniques.
The original, long form ABSST was developed as a de novo measure after it was determined that existing measures did not appropriately assess the symptoms and impacts of NDO on MS patients. The long form of the ABSST is a 17-item instrument (16 items with an additional “Yes/No” item asking patients if they would like to receive help for their bladder problems) that covers three domains: Bladder Symptoms, Coping Strategies, and Impact of Bladder Symptoms. It was developed using established qualitative methods [
25,
26], including a literature review and clinician input to identify potential symptoms, open-ended concept elicitation interviews with MS patients who have OAB, and face and content validity testing through cognitive interviews (face-to-face debriefing interviews on the ABSST – details to be reported in another publication) with another group of MS patients with OAB. Once the qualitative phase was completed, a US-based, non-randomized, multi-center, stand-alone observational study was carried out to evaluate the measurement properties of the newly developed instrument. Analysis of item completion, item and scale distribution, and predictive validity of the long form ABSST demonstrated strong psychometric properties (details reported in another publication) [
17,
19,
27‐
30]. The ABSST total score also demonstrated predictive validity, identifying patients who would receive a referral. In order to demonstrate that this screening tool was valid and reliable as a short form, classical test theory and item response theory approaches were taken to ensure that each item included provided the most information, was clinically meaningful, and demonstrated predictive attributes for patient referral to a urologist. Overall, concurrent validity for each subscale as well as predictive and concurrent validity of the total instrument were shown, demonstrating strong psychometric properties.
The simplified scoring method for bladder problem assessment developed here will make it easier for clinicians to identify patients with MS who may have potential problems. The approach used to develop the scoring algorithm adheres to the FDA guidance, is psychometrically valid, and appropriately utilizes pivot anchoring [
31], which has been widely used in the interpretation of clinically meaningful points along a categorical continuum. This methodology allowed for synthesis of meaningful cut-points along the continuum where patients are likely to demonstrate urinary problems, as reported by clinicians. This mixed statistical methods approach to item reduction and scoring optimizes selection of items for making sound clinical decisions based on clinicians’ assessment of the need for patient referral. These data, when subjected to predictive validity calculations, provided very strong results indicating that clinicians could use it to refer patients appropriately.
This study has several limitations. First, the ABSST is a screening tool and was not designed for diagnostic purposes. Second, although it was identified as being clinically meaningful, the relevance in overall clinical practice has not yet been tested. Lastly, because of the error range on the tool itself, it is possible that some patients’ symptoms may go untreated (under-sensitive results) while other patients may incur unnecessary tests and costs (under-specified results). However, the specificity and sensitivity are strong which indicates that the ABSST Short Form is able to differentiate patients who would likely benefit from a referral from those who would not.
Other questionnaires have been developed such as an 8-item screening tool to aid in identifying patients who may have OAB in a busy primary care setting which has a sensitivity of 98% and specificity of approximately 83% [
32]. Moreover, the 3-Item OAB awareness tool (which is a short version of the 8-item screening tool) has recently been validated with a sensitivity of 82% and specificity of 91%. In addition, the International Prostate Symptom Score IPSS has been used to identify the severity of bladder symptoms in an MS population (All patients had an Expanded Disability Status Scale score of <6.5, with a mean of 3.4). The 8-item IPSS was originally developed to measure symptom severity in benign prostate hyperplasia. It has also been utilized to measure the prevalence of bladder problems over 2–3 years [
33]. Only the ABSST Short Form has been developed or psychometrically tested to the scientific rigor of the FDA Guidance for PRO development. Overall the short form ABSST demonstrated good sensitivity and specificity as it has a positive predictive value of approximately 86% and a negative predictive value of approximately 93%. This shows that the short form ABSST maintains the integrity of the longer form tool which had a positive predictive value of approximately 76% and a negative predictive value of approximately 95% [
16]. The sensitivity and specificity of the short form ABSST are in-line with other validated tools in the field and demonstrate its strength and potential positive impact in a clinic and primary care setting [
34]. Of particular importance is the ability of the tool to detect more true-positive cases which increase the cost-effectiveness of screening and early detection of OAB problems as opposed to the false-positive cases, which can be detrimental to the screening process.
Acknowledgements
The authors would like to acknowledge the following for their help in the development of this manuscript:
Vasudha Mukherjee Bal and Marcy Fitzrandolph for managing and overseeing the qualitative design and development of the ABSST.
Benjamin Banderas for managing the quantitative phase of the study.
Beth Anderson and Jeanne Cloppse of Lawrence and Company for their assistance in site-identification, publication strategy and manuscript development through-out study.
No medical writer was used in the development of this manuscript.
Competing interests
Bates, D.: ‘The authors declare that they have no competing interests’.
Burks, J.: Consultant; Speaker’s Bureau for Acorda, Allergan (financed manuscript), Avanir, Bayer, Novartis, Sanofi-Aventis, and Serono. Consultant for Genzyme.
Globe, D.: Employed by Allergan (financed manuscript).
Signori, M.: Employed by Allergan (financed manuscript).
Hudgens, S.: Senior Lead on Research Study, funded by Allergan (financed manuscript).
Denys, P.: Advisor and investigator for Allergan (financed manuscript) and Ipsen, advisor and lecturer for Medtronic, Astellas, Coloplast and Astratech.
MacDiarmid, S.: Consultant; Speaker’s Bureau for Pfizer, Allergan (financed manuscript), Astellas, Uroplasty.
Nitti, V.: Astellas, Allergan (financed manuscript), Pfizer.
Odderson, I.: Speaker for Allergan (financed manuscript).
Perrin Ross, A: ‘The authors declare that they have no competing interests’.
Chancellor, M: Consultant and investigator, Allergan (financed manuscript).
Authors’ contributions
SH and DG were involved in conducting the analyses and drafting the manuscript. JB, MC, SH, DG and MS were involved in developing the draft measures, developing the analysis plan and interpreting the results. All authors were involved in the design of the studies, review of the analysis and review, editing and approval of the manuscripts.