Disease-specific health related quality of life patient reported outcome measures in Genodermatoses: a systematic review and critical evaluation

Translation, cultural adaptation and validation of the German Quality of Life in Epidermolysis Bullosa (QOLEB) questionnaire

Epidermolysis bullosa (EB) is a rare disease characterised by skin fragility and a wide variety of symptoms. The Quality of Life in Epidermolysis Bullosa (QOLEB) score is an English 17-item EB-specific validated measurement tool with two dimensions: functioning and emotions. The aim of this cross-sectional study was to develop and validate a culturally adapted German QOLEB. The following steps were carried out: translation, expert evaluation, back translation, linguistic and cultural adaptation, sample-based psychometric testing and evaluation. Data analysis was performed with n = 46 patients across all EB types. The reliability and internal consistency of the translated German QOLEB were excellent (α = 0.901). Regarding convergent validity, the QOLEB correlated highly with the iscorEB (r = 0.879; p < 0.001). Structural similarity with the English original version was confirmed through exploratory factor analysis. In conclusion, the German QOLEB demonstrates internal reliability and construct validity and is suitable to assess the quality of life in German-speaking EB patients.

Understanding the impact of tuberous sclerosis complex: development and validation of the TSC-PROM

BACKGROUND

Tuberous sclerosis complex (TSC) is a rare and complex genetic disorder, associated with tumor growth in various organ systems, epilepsy, and a range of neuropsychiatric manifestations including intellectual disability. With improving patient-centered care and targeted therapies, patient-reported outcome measures (PROMs) are needed to measure the impact of TSC manifestations on daily functioning. The aim of this study was to develop a TSC-specific PROM for adults that captures the impact of TSC on physical functions, mental functions, activity and participation, and the social support individuals with TSC receive, called the TSC-PROM.

METHODS

COSMIN methodology was used to develop a self-reported and proxy-reported version. Development and validation consisted of the following studies: PROM development, content validity, structural validity, internal consistency, and construct validity. The International Classification of Functioning and Disability was used as a framework. Content validity was examined by a multidisciplinary expert group and cognitive interview study. Structural and construct validity, and internal consistency were examined in a large cohort, using confirmatory factor analysis, hypotheses testing, and Cronbach's alpha.

RESULTS

The study resulted in an 82-item self version and 75-item proxy version of the TSC-PROM with four subscales (physical functions 18 and 19 items, mental functions 37 and 28 items, activities and participation 13 and 14 items, social support 13 items, for self version and proxy version respectively). Sufficient results were found for structural validity with sufficient unidimensionality for each subscale. With regard to construct validity, 82% of the hypotheses were met for the self version and 59% for the proxy version. The PROM showed good internal consistency (Cronbach's alpha 0.78-0.97).

CONCLUSIONS

We developed a PROM for adults with TSC, named TSC-PROM, showing sufficient evidence for reliability and validity that can be used in clinical and research settings to systematically gain insight into their experiences. It is the first PROM in TSC that addresses the impact of specific TSC manifestations on functioning, providing a valuable, patient-centered addition to the current clinical outcomes.

Measurement of patient-reported outcomes. 2: Are current measures failing us?

All instruments designed to measure latent (unobservable) variables, such as patient-reported outcomes (PROs), have three major requirements; a coherent construct theory, a specification equation, and the application of an appropriate response model. The theory guides the selection of content for the questionnaire and the specification equation links the construct theory to scores produced with the instrument. For the specification equation to perform this role, the patient-reported outcome measure (PROM) must employ a response model that generates values for its individual items. The most commonly applied response model in PROM development is the Rasch model. To date this level of measurement sophistication has not been achieved in PRO measurement. Consequently, it is not possible to establish a PROM's true construct validity. However, the development of the Lexile Framework for Reading has demonstrated that such objective measurement is possible for latent variables. This article argues that higher quality PROM development is needed if meaningful and valid PRO measurement is to be achieved. It describes the current state of PROM development, shows that published reviews of PROMs adopt inappropriate criteria for judging their quality, and illustrates how the use of traditional PROMs can lead to incorrect (and possibly dangerous) conclusions being drawn about the efficacy of interventions.

Association between patient-reported outcomes and objective disease indices in people with NF2

Objective

The association between patient-reported outcomes and currently used clinical trial endpoints, including total vestibular schwannoma (VS) volume and word recognition score (WRS) in neurofibromatosis type 2 (NF2), is not known.

Methods

A prospective observational study enrolling adult patients with NF2 was conducted at a single specialty center. Measures included: NF2 impact on quality of life (NFTI-QOL), short form (SF)-36; total VS volume, WRS; provider- and patient-reported disease severity (ProvSev, PatSev) measured with an institutionally derived multi-item (e.g., symptom burden, age-of-onset, and fatality-risk) and single-item Likert (mild, moderate, severe) scale.

Results

Fifty-one patients were enrolled between June 2014 and August 2017. Mean age was 42.1 ± 18.2 years and 37.3% patients were male. Mean WRS was 74.4 ± 37.3%; mean total VS volume was 4.2 ± 5.2 cc. Additional lesions were common including meningioma (79.2%) and spinal ependymoma (39.6%). Mean NFTI-QOL score was 7.6 ± 4.9 and correlated with responses on the SF-36. NFTI-QOL also correlated well with PatSev (r = 0.63, p < 0.001) and both multi- and single-item ProvSev (r = 0.62, p < 0.001; r = 0.52, p < 0.001, respectively). A weak correlation was observed between NFTI-QOL and WRS (r = -0.34, p = 0.0156). There was no correlation with VS volume (r = 0.23, p = 0.15).

Conclusions

The NFTI-QOL correlated well with multiple measures of disease severity but not commonly accepted endpoints for NF2 clinical trials including total VS volume in this US cohort of patients with NF2. This suggests that the NFTI-QOL captures components of the patient experience not sufficiently represented by objective measures of disease and underscores the important and complementary role of patient-focused measures in therapeutic outcome assessment in people with NF2.

Measuring quality of life of primary antibody deficiency patients using a disease-specific health-related quality of life questionnaire for common variable immunodeficiency (CVID_QoL)

Background

Common variable immunodeficiency (CVID) and other primary antibody deficiencies (PAD) are a heterogeneous group of > 300 congenital disorders affecting the immune system. Until recently, efforts to measure health-related quality of life (QoL) in PAD patients have utilised generic QoL tools and disease-specific tools for other conditions. Still, the full impact of the disease is probably not understood. We evaluated the performance of the CVID_QoL, a novel disease-specific QoL instrument for adults with CVID, on Norwegian PAD patients and compared the results to those of the generic WHOQOL-BREF.

Methods

Respondents were recruited through the Norwegian Centre for Rare Disorders’ patient database. Included patients fulfilled the following criteria (all three): 1.) Age ≥18 years, 2.) a PAD diagnosis, 3.) currently on immunoglobulin therapy. The CVID_QoL is a 32-item questionnaire. Global CVID_QoL scores were compared between Norwegian PAD patients and Italian CVID patients.

Results

In total, 83 PAD patients filled out the CVID_QoL, 63% had CVID, 76% were females. 32 patients filled out the WHOQOL-BREF. Feasibility was high (<1% missing). Internal consistency for the emotional- (Cronbach’s α-value = 0.91) and relational functioning (α =  0.77) subscales was high, but questionable for the gastrointestinal and skin symptoms subscale (α =  0.66). Convergent validity varied from weak to strong (range 0.3–0.8). Floor and ceiling effects were present.

Conclusions

Although many disease-specific characteristics are probably shared with CVID and other PAD, the CVID_QoL captures some, but not all, dimensions of PAD patients’ QoL. More evaluations of the CVID_QoL’s performance in different contexts are needed.

Electronic supplementary material

The online version of this article (10.1186/s41687-019-0101-x) contains supplementary material, which is available to authorized users.