Development of the Incontinence Utility Index: estimating population-based utilities associated with urinary problems from the Incontinence Quality of Life Questionnaire and Neurogenic Module

A scoping review to create a framework for the steps in developing condition-specific preference-based instruments de novo or from an existing non-preference-based instrument: use of item response theory or Rasch analysis

BACKGROUND

There is no widely accepted framework to guide the development of condition-specific preference-based instruments (CSPBIs) that includes both de novo and from existing non-preference-based instruments. The purpose of this study was to address this gap by reviewing the published literature on CSPBIs, with particular attention to the application of item response theory (IRT) and Rasch analysis in their development.

METHODS

A scoping review of the literature covering the concepts of all phases of CSPBI development and evaluation was performed from MEDLINE, Embase, PsychInfo, CINAHL, and the Cochrane Library, from inception to December 30, 2022.

RESULTS

The titles and abstracts of 1,967 unique references were reviewed. After retrieving and reviewing 154 full-text articles, data were extracted from 109 articles, representing 41 CSPBIs covering 21 diseases or conditions. The development of CSPBIs was conceptualized as a 15-step framework, covering four phases: 1) develop initial questionnaire items (when no suitable non-preference-based instrument exists), 2) establish the dimensional structure, 3) reduce items per dimension, 4) value and model health state utilities. Thirty-nine instruments used a type of Rasch model and two instruments used IRT models in phase 3.

CONCLUSION

We present an expanded framework that outlines the development of CSPBIs, both from existing non-preference-based instruments and de novo when no suitable non-preference-based instrument exists, using IRT and Rasch analysis. For items that fit the Rasch model, developers selected one item per dimension and explored item response level reduction. This framework will guide researchers who are developing or assessing CSPBIs.

Developing the Breast Utility Instrument to Measure Health-Related Quality-of-Life Preferences in Patients with Breast Cancer: Selecting the Item for Each Dimension

Introduction. Generic preference-based instruments inadequately measure breast cancer (BrC) health-related quality-of-life preferences given advances in therapy. Our overall purpose is to develop the Breast Utility Instrument (BUI), a BrC-specific preference-based instrument. This study describes the selection of the BUI items. Methods. A total of 408 patients from diverse BrC health states completed the EORTC QLQ-C30 and BR45 (breast module). For each of 10 dimensions previously assessed with confirmatory factor analysis, we evaluated data fit to the Rasch model based on global model and item fit, including threshold ordering, item residuals, infit and outfit, differential item functioning (age), and unidimensionality. Misfitting items were removed iteratively, and the model fit was reassessed. From items fitting the Rasch model, we selected 1 item per dimension based on high patient- and clinician-rated item importance, breadth of item thresholds, and clinical relevance. Results. Global model fit was good in 7 and borderline in 3 dimensions. Separation index was acceptable in 4 dimensions. Item selection criteria were maximized for the following items: 1) physical functioning (trouble taking a long walk), 2) emotional functioning (worry), 3) social functioning (interfering with social activities), 4) pain (having pain), 5) fatigue (tired), 6) body image (dissatisfied with your body), 7) systemic therapy side effects (hair loss), 8) sexual functioning (interest in sex), 9) breast symptoms (oversensitive breast), and 10) endocrine therapy symptoms (problems with your joints). Conclusions. We propose 10 items for the BUI. Our next steps include assessing the measurement properties prior to eliciting preference weights of the BUI.

Highlights

A previous confirmatory factor analysis established 10 dimensions of the European Organisation for Research and Treatment of Cancer (EORTC) core quality of life questionnaire (QLQ-C30) and its breast module (BR45). In this study, we selected 1 item per dimension based on fit to the Rasch model, patient- and clinician-rated item importance, breadth of item thresholds, and clinical relevance. These items form the core of the future Breast Utility Instrument (BUI). The future BUI will be a novel breast cancer–specific preference-based instrument that potentially will better reflect women’s preferences in clinical decision making and cost utility analyses.

Randomized Cross-over Comparison of Icon™ Reusable Underwear to Disposable Pads for the Management of Mild to Moderate Urinary Incontinence

OBJECTIVE

The objective of this study was to compare disposable pads to Icon™ reusable underwear for the management of urinary incontinence on dimensions of quality of life and product performance.

METHODS

This randomized cross-over trial included women with mild to moderate urinary incontinence as defined by baseline responses to the International Consultation on Incontinence Questionnaire-Short Form. Excluded were patients who had fecal incontinence or an active urinary tract infection. Participants were randomized to 2 days of Icon™ underwear or disposable pads use and then completed another 2 days using the alternate product. Outcome measures were responses to Incontinence Quality of Life Instrument (I-QOL) and Product Performance Questionnaire for each product.

RESULTS

Of the 70 women who were randomized, 52 completed the study. There was no significant difference between Icon™ underwear and disposable pads with regards to I-QOL total scores (66.2 ± 23.4 vs 65.5 ± 24.5, P = 0.71) or I-QOL subscores: avoidance and limiting behaviors (62.1 ± 24.4 vs 62.4 ± 25.0, P = 0.88), psychosocial impacts (74.4 ± 25.0 vs 73.4 ± 25.6, P = 0.51), and social embarrassment (57.8 ± 27.8 vs 56.1 ± 29.5, P = 0.43). Icon™ underwear scored significantly better than disposable pads on the Product Performance Questionnaire, with regards to overall impression (P = 0.0002), fit (P < 0.0001), discreteness (P < 0.0001), comfort when dry (P < 0.0001), comfort when wet (P = 0.0008), ability to keep skin dry (P = 0.0034), and kindness to skin (P < 0.0001). There was no difference between products in ability to hold urine without leaking (P = 0.40) or prevent odor when worn (P = 0.41).

CONCLUSIONS

There was no difference in quality of life measures between Icon™ underwear and disposable pad users; however, Icon™ underwear was preferred on product performance.

The Role of Condition-Specific Preference-Based Measures in Health Technology Assessment

A condition-specific preference-based measure (CSPBM) is a measure of health-related quality of life (HRQOL) that is specific to a certain condition or disease and that can be used to obtain the quality adjustment weight of the quality-adjusted life-year (QALY) for use in economic models. This article provides an overview of the role and the development of CSPBMs, and presents a description of existing CSPBMs in the literature. The article also provides an overview of the psychometric properties of CSPBMs in comparison with generic preference-based measures (generic PBMs), and considers the advantages and disadvantages of CSPBMs in comparison with generic PBMs. CSPBMs typically include dimensions that are important for that condition but may not be important across all patient groups. There are a large number of CSPBMs across a wide range of conditions, and these vary from covering a wide range of dimensions to more symptomatic or uni-dimensional measures. Psychometric evidence is limited but suggests that CSPBMs offer an advantage in more accurate measurement of milder health states. The mean change and standard deviation can differ for CSPBMs and generic PBMs, and this may impact on incremental cost-effectiveness ratios. CSPBMs have a useful role in HTA where a generic PBM is not appropriate, sensitive or responsive. However, due to issues of comparability across different patient groups and interventions, their usage in health technology assessment is often limited to conditions where it is inappropriate to use a generic PBM or sensitivity analyses.

OnabotulinumtoxinA in the treatment of overactive bladder: a cost-effectiveness analysis versus best supportive care in England and Wales

The cost-effectiveness of onabotulinumtoxinA (BOTOX(®)) 100 U + best supportive care (BSC) was compared with BSC alone in the management of idiopathic overactive bladder in adult patients who are not adequately managed with anticholinergics. BSC included incontinence pads and, for a proportion of patients, anticholinergics and/or occasional clean intermittent catheterisation. A five-state Markov model was used to estimate total costs and outcomes over a 10-year period. The cohort was based on data from two placebo-controlled trials and a long-term extension study of onabotulinumtoxinA. After discontinuation of initial treatment, a proportion of patients progressed to downstream sacral nerve stimulation (SNS). Cost and resource use was estimated from a National Health Service perspective in England and Wales using relevant reference sources for 2012 or 2013. Results showed that onabotulinumtoxinA was associated with lower costs and greater health benefits than BSC in the base case, with probabilistic sensitivity analysis indicating an 89 % probability that the incremental cost-effectiveness ratio would fall below £20,000. OnabotulinumtoxinA remained dominant over BSC in all but two scenarios tested; it was also economically dominant when compared directly with SNS therapy. In conclusion, onabotulinumtoxinA appears to be a cost-effective treatment for overactive bladder compared with BSC alone.

Checklist to operationalize measurement characteristics of patient-reported outcome measures

BACKGROUND

The purpose of this study was to advance a checklist of evaluative criteria designed to assess patient-reported outcome (PRO) measures' developmental measurement properties and applicability, which can be used by systematic reviewers, researchers, and clinicians with a varied range of expertise in psychometric measure development methodology.

METHODS

A directed literature search was performed to identify original studies, textbooks, consensus guidelines, and published reports that propose criteria for assessing the quality of PRO measures. Recommendations from these sources were iteratively distilled into a checklist of key attributes. Preliminary items underwent evaluation through 24 cognitive interviews with clinicians and quantitative researchers. Six measurement theory methodological novices independently applied the final checklist to assess six PRO measures encompassing a variety of methods, applications, and clinical constructs. Agreement between novice and expert scores was assessed.

RESULTS

The distillation process yielded an 18-item checklist with six domains: (1) conceptual model, (2) content validity, (3) reliability, (4) construct validity, (5) scoring and interpretation, and (6) respondent burden and presentation. With minimal instruction, good agreement in checklist item ratings was achieved between quantitative researchers with expertise in measurement theory and less experienced clinicians (mean kappa 0.70; range 0.66-0.87).

CONCLUSIONS

We present a simplified checklist that can help guide systematic reviewers, researchers, and clinicians with varied measurement theory expertise to evaluate the strengths and weakness of candidate PRO measures' developmental properties and the appropriateness for specific applications.

A Systematic Review of the Literature on the Development of Condition-Specific Preference-Based Measures of Health

BACKGROUND

Health state utility values (HSUVs) are required to calculate quality-adjusted life-years (QALYs). They are frequently derived from generic preference-based measures of health. However, such generic measures may not capture health attributes of relevance to specific conditions. In such cases, a condition-specific preference-based measure (CSPBM) may be more appropriate.

OBJECTIVE

This systematic review aimed to identify all published accounts of developing CSPBMs to describe and appraise the methods used.

METHOD

We undertook a systematic search (of Embase, MEDLINE, PsycINFO, Web of Science, the Cochrane Library, CINAHL, EconLit, ASSIA and the Health Management Information Consortium database) to identify published accounts of CSPBM development up to July 2015. Studies were reviewed to investigate the methods used to design classification systems, estimate HSUVs, and validate the measures.

RESULTS

A total of 86 publications were identified, describing 51 CSPBMs. Around two-thirds of these were QALY measures; the remainder were designed for clinical decision making only. Classification systems for 33 CSPBMs were derived from existing instruments; 18 were developed de novo. HSUVs for 34 instruments were estimated using a 'composite' approach, involving statistical modelling; the remainder used a 'decomposed' approach based on multi-attribute utility theory. Half of the papers that described the estimation of HSUVs did not report validating their measures.

CONCLUSION

Various methods have been used at all stages of CSPBM development. The choice between developing a classification system de novo or from an existing instrument may depend on the availability of a suitable existing measure, while the choice between a decomposed or composite approach appears to be determined primarily by the purpose for which the instrument is designed. The validation of CSPBMs remains an area for further development.

Psychometric properties of the incontinence utility index among patients with idiopathic overactive bladder: data from two multicenter, double-blind, randomized, Phase 3, placebo-controlled clinical trials

BACKGROUND

Overactive bladder is a prevalent and burdensome condition. Generic utility measures may fail to reflect its full impact on patients' health status. The Incontinence Utility Index (IUI) is a community-based preference index derived from the Incontinence Quality of Life Questionnaire (I-QOL) developed to value health states related to urinary symptoms in patients with neurogenic detrusor overactivity. This study assessed the measurement properties of the IUI in patients with idiopathic overactive bladder (OAB).

METHODS

Data were used from two clinical trials which recruited patients with OAB whose symptoms were inadequately managed with ≥ 1 anticholinergic medication. Psychometric evaluation included: Differential Item Functioning (DIF) analysis, concordance between I-QOL and IUI (Intraclass correlation coefficient [ICC], criterion and convergent validity according to relevant patient reported outcomes and clinical variables (Spearman's correlation coefficient, rho), responsiveness, and agreement between utility measures (ICC and Bland-Altman method).

RESULTS

A total of 1,105 idiopathic OAB patients were included. Mean age (range) was 60.4 years (18-90), 87.8% (n = 970) were female. DIF was identified in 3 items, none of which are contained in the IUI. ICC (CI95%) was 0.944 (0.936-0.950). Statistically significant differences (p < 0.001) were found in IUI scores for patients improving according to the Treatment Benefit Scale (TBS). Moderate to strong correlations (rho > |0.6|) were found in the expected direction with daily incontinence, urgency episodes and disease-specific domains of King's Health Questionnaire (KHQ). Low to moderate correlations (rho:<|0.6|) were found with Short Form version 2 (SF-12v2) summary components. A large effect size was found for patients reporting improvement (0.98-1.21) or great improvement (1.87-2.56) in the TBS, as well as in patients responding to treatment (1.19-2.40). Across utility measures, directional trends were consistent with OAB symptom profile, however, a lack of agreement in absolute values was observed.

CONCLUSIONS

The IUI presents good psychometric properties for valuing the impact of UI-related problems in idiopathic OAB patients.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT00910845 and NCT00910520.

Cost-effectiveness analysis of onabotulinumtoxinA (BOTOX(®)) for the management of urinary incontinence in adults with neurogenic detrusor overactivity: a UK perspective

OBJECTIVES

To evaluate the cost effectiveness of onabotulinumtoxinA (BOTOX(®), 200 units [200 U]) for the management of urinary incontinence (UI) in adults with neurogenic detrusor overactivity (NDO) due to subcervical spinal cord injury or multiple sclerosis that is not adequately managed with anticholinergic drugs (ACHDs).

PERSPECTIVE

UK National Health Service (NHS) perspective.

METHODS

A Markov state-transition model was developed, which compared onabotulinumtoxinA + best supportive care (BSC) with BSC alone (comprising behavioural therapy and pads, alone or in combination with clean intermittent catheterization and possibly with ACHDs). Non-responders were eligible for invasive procedures. Health states were defined according to the reduction in UI episodes. Efficacy data and estimates of resource utilization were pooled from 468 patients on onabotulinumtoxinA in two phase III clinical trials. Drug costs (2013) and administration costs (NHS Reference Costs 2011-2012) were obtained from published sources. The time horizon of the model was 5 years, and costs and benefits were discounted at 3.5%. Scenario, one-way and probabilistic sensitivity analyses (PSAs) were conducted to explore uncertainties around the assumptions.

RESULTS

In the base case, treatment with onabotulinumtoxinA + BSC over 5 years was associated with an increase in costs of £1,689 and an increase in quality-adjusted life-years (QALYs) of 0.4, compared with BSC alone, resulting in an incremental cost-effectiveness ratio of £3,850 per QALY gained. Sensitivity analyses showed that utility values had the greatest influence on model results. PSA suggests that onabotulinumtoxinA + BSC had a 100 % probability of being cost effective at a willingness to pay of <£20,000.

CONCLUSION

For adult patients with NDO who are not adequately managed with ACHDs, onabotulinumtoxinA + BSC appears to be a cost-effective use of resources in the UK NHS.