Reliability of the Quality of Life Inventory-Disability Measure in Children with Intellectual Disability

Beyond the Diagnosis: Evaluation of Quality-of-Life Measures and Family Functioning in SLC6A1-Related Neurodevelopmental Disorder

BACKGROUND

SLC6A1-related neurodevelopmental disorder (SLC6A1-NDD) is a rare genetic disorder linked to autism spectrum disorder, epilepsy, and developmental delay. In preparation for future clinical trials, understanding how the disorder impacts patients and their families is critically important. Quality-of-life (QoL) measures capture the overall disease experience of patients. This study presents QOL findings from our SLC6A1-NDD clinical trial readiness study and the Simons Searchlight SLC6A1-NDD registry.

METHODS

We compiled QoL data from participants with SLC6A1-NDD enrolled in our clinical trial readiness study (n = 20) and the Simons Searchlight registry (n = 32). We assessed the distribution of scores on the Quality-of-Life Inventory-Disability (QI Disability), Quality of Life of Childhood Epilepsy (QOLCE-55), and Pediatric Quality of Life Inventory Family Impact Module (PedsQL-FIM) administered to caregivers.

RESULTS

In our cohort of 52 participants, the mean QI Disability total score was 73 ± 12.3, the QOLCE-55 mean total score was 49 ± 17.1, and the mean total PedsQL score was 51 ± 17.6. Longitudinal QoL scores for a subset of participants (n = 7) demonstrated a reduction in the Family Relationship domain of PedsQL-FIM (Δ-10.0, P = 0.035). Bootstrap resampling of total scores displays nonoverlapping 95% confidence intervals for the 10th, 50th, and 90th percentiles on all three measures.

CONCLUSIONS

This is the first study to investigate QoL measures for SLC6A1-NDD. Findings suggest that scores within the 10th percentile's confidence interval could be clinically significant, referring to QI-Disability scores of <61, QOLCE-55 scores of <46, and PedsQL-FIM scores of <42. Future validation studies are needed.

Improvement in quality of life with continuous positive airway pressure outweighs the treatment burden in children with obstructive sleep apnea

INTRODUCTION

Continuous positive airway pressure (CPAP) for treatment of obstructive sleep apnea (OSA) may pose a significant burden on families. We assessed the impact of CPAP for children on quality of life (QOL) and caregiver treatment burden.

METHODS

Prospective cohort study of children commencing outpatient CPAP in a specialist sleep centre 2020-2022. Questionnaires regarding sleep-related symptoms (PROMIS Pediatric Sleep Disturbance and Sleep-Related Impairment), QOL (OSA-18, QI-Disability), caregiver burden (Caregiver Strain Questionnaire) and overall health impact (Glasgow Children's Benefit Inventory) were completed by caregivers at CPAP commencement and 6 weeks later.

RESULTS

Twenty-six patients completed follow-up (7 female; median age 11.4 year, baseline obstructive apnea hypopnea index 10.3/h; 77% overweight or obese, 73% comorbidity other than obesity). OSA-related QOL (OSA-18) significantly improved at follow-up (p < 0.01), as did child general QOL (p < 0.001), sleep disturbance (p < 0.01) and sleep-related impairment (p < 0.001). Caregivers mostly rated CPAP as beneficial to their child's health but 19% rated CPAP as harmful or having no effect. Caregiver strain reduced at follow-up (p < 0.001) and benefit outweighed inconvenience (p < 0.0001) in 81%. CPAP adherence was correlated with overall health impact (r = 0.67, p < 0.01) but not with caregiver rating of inconvenience.

CONCLUSIONS

CPAP resulted in improvements in QOL and sleep-related symptoms, and reduced caregiver strain. Perceived benefits outweighed the burden of treatment for most but not all families. CPAP adherence was moderately correlated with family-reported measures of benefit but not related to perceived inconvenience. This study provides reassuring evidence regarding the benefits and impacts of CPAP for children, many of whom already have complex health care needs.

FDA Patient-Focused Drug Development Guidances: Considerations for Trial Readiness in Rare Developmental and Epileptic Encephalopathies

Developmental and epileptic encephalopathies (DEE) are rare, often monogenic neurodevelopmental conditions. Most affected individuals have refractory seizures. All have multiple severe impairments which can be as life-limiting as or more limiting than the seizures themselves. Mechanism- and gene-targeted therapies for these individually rare, genetic conditions hold hope for treatment, amelioration of disease expression, and even cure. The near absence of fit-for-purpose (FFP) clinical outcome assessments (COA) to establish the benefits for nonseizure outcomes of these new therapies in clinical trials poses significant challenges to drug development. The Food and Drug Administration Patient-Focused Drug Development guidance series provides direction for how to overcome these challenges and to ensure FFP measures are available for trials. The goal is to have measures that address outcomes of importance to patients and caregivers, reliably and accurately measure the outcome in the spectrum of abilities for the target disease, and are sensitive to meaningful change over time. The guidances identify 3 primary strategies: (1) directly adopting and implementing available outcome measures; (2) creating measures de novo; and (3) a middle path of adapting or modifying existing measures. Emphasized throughout the guidances is the indispensable and extensive role of the patient or caregiver to assuring the goal of having fit measures is achieved. This review specifically considers the difficulties of adopting available COAs in severely impaired patient groups and ways to adapt or modify existing COAs to be FFP as encouraged in the guidances. Adaptations include alternative scoring, use of assessments in out-of-intended age ranges, and modifications for individuals with sensory or motor impairments. Some additional considerations that may facilitate achieving adequate clinical outcome measures, especially for rare diseases, include use of personalized endpoints, merging of existing COAs, and developing a consortium of rare DEE advocates and researchers to ensure fitness of adapted COAs across multiple rare disease groups. The FDA guidances help ensure that clinical trials targeting nonseizure outcomes, especially in severely impaired populations, will have adequately valid and sensitive outcome measures. This in turn will strengthen the ability of trials to provide informative tests of whether treatments provide meaningful therapeutic efficacy.

Measuring psychological, cognitive, and social domains of physical literacy in school-aged children with neurodevelopmental disabilities: a systematic review and decision tree

PURPOSE

To identify and assess the clinimetric properties of psychological, cognitive, and social competence assessment tools relevant to physical activity for school-aged children (5-17 years) with neurodevelopmental disabilities.

METHODS

Seven electronic databases were searched. Study findings and methodologies were evaluated using the COnsensus-based Standards for the selection of health Measurement Instruments (COSMIN) checklist. Psychometric strength of assessment tools was determined using Grading of Recommendations Assessment, Development and Evaluation principles (GRADE) (Trial registration: CRD42020180616).

RESULTS

Study criteria were met by eight subscales from the BRIEF2, DMQ17, QI-Disability, SAID, and SDQ. Most subscales examined psychological competence (n = 5), with fewer addressing social competence (n = 2), or cognitive competence (n = 1). Validity was moderate to high strength for most subscales. Reliability was of moderate and unclear strength for two subscales. A five-level decision tree was devised to summarise: (1) physical literacy domains/elements, (2) populations, (3) assessment focus, (4) required resources, and (5) psychometric evidence.

CONCLUSIONS

Subscales are available to assess psychological, cognitive, or social competence. For school-aged children with neurodevelopmental disabilities, these have moderate to high strength psychometric support. A decision tree will assist practitioners in subscale selection. Future studies are needed to establish gold standard assessment of physical literacy for this population.IMPLICATIONS FOR REHABILITATIONPsychological Activity Competence can be measured for children with neurodevelopmental disabilities, subscales from The Behaviour Rating Inventory of Executive Function, Second Edition (BRIEF2; The Dimensions of Mastery Questionnaire 17.0 (DMQ17); and The Quality of Life Inventory-Disability (QI-Disability).Cognitive Activity Competence can be measured using a subscale from The Scale of Attention in Intellectual Disability (SAID).Social Activity Competence can be measured using subscales from the BRIEF2, and The Strengths and Difficulties Questionnaire (SDQ).Clinicians can use the Physical Literacy decision tree to guide selection of these tools.

Psychometric properties of QI-Disability in CDKL5 Deficiency Disorder: Establishing readiness for clinical trials

CDKL5 Deficiency Disorder (CDD) is a rare genetic disorder with symptoms of epilepsy, developmental impairments, and other comorbidities. Currently, there are no outcome measures for CDD with comprehensive evidence of validation. This study aimed to evaluate the psychometric properties of the Quality of Life Inventory-Disability (QI-Disability) in CDD. Quality of Life Inventory-Disability was administered to 152 parent caregivers registered with the International CDKL5 Disorder Database (ICDD). Confirmatory factor analysis was conducted and the goodness of fit of the factor structure was assessed. Fixed-effects linear regression models examined the responsiveness of QI-Disability to reported changes in child health. A subset of parent caregivers (n = 56) completed QI-Disability, as well as additional health-related questions, on two occasions separated by four weeks to evaluate test-retest reliability. Test-retest reliability was assessed using intra-class correlations (ICCs) calculated from QI-Disability scores. Based upon adjustments for changes in child health, ICCs were recalculated to estimate responsiveness to change. Confirmatory factor analysis, internal consistency, and divergent validity were mostly satisfactory, except divergent validity was not satisfactory for the Social Interactions and Independence domains. The Physical Health, Social Interactions, Leisure, and Total scores responded to changes in the child's Physical health, and the Negative Emotions and Leisure domains responded to changes in the child's behavior. Unadjusted and adjusted ICC values were above 0.8 for the Positive Emotions, Negative Emotions, Social Interactions, Leisure, Independence domains and Total score, and above 0.6 for the Physical Health domain. Findings suggest that QI-Disability is suitable to assess the quality of life of children and adults with CDD and could be of value for upcoming clinical trials.

Quality of life beyond diagnosis in intellectual disability - Latent profiling

OBJECTIVE

To compare quality of life (QOL) across diagnoses associated with intellectual disability, construct QOL profiles and evaluate membership by diagnostic group, function and comorbidities.

METHOD

Primary caregivers of 526 children with intellectual disability (age 5-18 years) and a diagnosis of cerebral palsy, autism spectrum disorder, Down syndrome, CDKL5 deficiency disorder or Rett syndrome completed the Quality of Life Inventory-Disability (QI-Disability) questionnaire. Latent profile analysis of the QI-Disability domain scores was conducted.

RESULTS

The mean (SD) total QOL score was 67.8 (13.4), ranging from 60.3 (14.6) for CDD to 77.5 (11.7) for Down syndrome. Three classes describing domain scores were identified: Class 1 was characterised by higher domain scores overall but poorer negative emotions scores; Class 2 by average to high scores for most domains but low independence scores; and Class 3 was characterised by low positive emotions, social interaction, and leisure and the outdoors scores, and extremely low independence scores. The majority of individuals with autism spectrum disorder and Down syndrome belonged to Class 1 and the majority with CDKL5 deficiency disorder belonged to Class 3. Those with better functional abilities (verbal communication and independent walking were predominately members of Class 1 and those with frequent seizures were more often members of Class 2 and 3.

CONCLUSION

The profiles illustrated variation in QOL across a diverse group of children. QOL evaluations illustrate areas where interventions could improve QOL and provide advice to families as to where efforts may be best directed.

Modelling quality of life in children with intellectual disability using regression trees

AIM

To identify factors associated with quality of life (QoL) in children with intellectual disability. We aimed to identify patterns of association not observable in previous hypothesis-driven regression modelling using the same data set from a cross-sectional observational study.

METHOD

A questionnaire was completed by 442 caregivers of children with confirmed intellectual disability and a diagnosis of autism spectrum disorder, cerebral palsy, Down syndrome, or Rett syndrome. The Quality of Life Inventory-Disability (QI-Disability) questionnaire was used to assess child QoL. Independent variables described the child's health, functional abilities, community participation, and sociodemographics. The R package rpart was used to build the regression trees.

RESULTS

The mean total QI-Disability score was 69.2 out of a maximum 100. The subgroup with the lowest QoL scores comprised children with a high degree of daytime sleepiness (n=74, mean 57.5) while the subgroup with the highest QoL scores (n=91, mean 80.3) comprised children with little daytime sleepiness who participated more frequently in community activities and displayed good eye contact while listening.

INTERPRETATION

Regression tree analysis provides insights into the relative importance of associated factors. Sleep problems and community participation were more important than functional abilities in accounting for differences in QoL.

WHAT THIS PAPER ADDS

A hypothesis-free regression tree analysis enables examination of multiple factors potentially influencing quality of life (QoL) in children with intellectual disability. Functional abilities were less strongly associated with QoL than sleep problems and community participation.

Caregiver assessment of quality of life in individuals with genetic developmental and epileptic encephalopathies

AIM

To summarize quality of life (QoL) and its determinants, including disease severity, in individuals with developmental and epileptic encephalopathies (DEEs) through a tailored questionnaire.

METHOD

A questionnaire containing 89 items addressing demographic characteristics, genetic diagnosis, clinical features, and QoL was distributed to primary caregivers of individuals with DEEs through patient advocacy organizations. Composite scores were generated from the mean values of QoL items, grouped into domain scores.

RESULTS

Out of 176 received responses, the most common genetic diagnoses reported were SCN2A (n=42/173, 24%), SLC6A1 (n=28/173, 16%), SCN1A (n=22/173, 13%), and KCNQ2 (n=21/173, 12%). Composite QoL scores centered around a mean score of 61.67 of 100 (SD 17.10). QoL scores were strongly associated with the number of days minimally disrupted by seizures, medication side effects, genetic diagnosis, and community type. The mean QoL scores for individuals with DEEs was significantly lower than for individuals with Rett syndrome, cerebral palsy, autism spectrum disorder, and Down syndrome.

INTERPRETATION

QoL in DEEs can be assessed through a standardized instrument. QoL only partially overlaps with objective measurements of disease severity and may represent an independent outcome measure in precision medicine trials.

Devising a Missing Data Rule for a Quality of Life Questionnaire-A Simulation Study

OBJECTIVE

The aim of this study was to devise an evidence-based missing data rule for the Quality of Life Inventory-Disability (QI-Disability) questionnaire specifying how many missing items are permissible for domain and total scores to be calculated using simple imputation. We sought a straightforward rule that can be used in both research and clinical monitoring settings.

METHOD

A simulation study was conducted involving random selection of missing items from a complete data set of questionnaire responses. This comprised 520 children with intellectual disability from 5 diagnostic groups. We applied a simple imputation scheme, and the simulated distribution of errors induced by imputation was compared with the previously estimated standard error of measurement (SEM) for each domain.

RESULTS

Using a stringent criterion, which requires that the 95th percentile of absolute error be less than the SEM, 1 missing item should be permitted for 2 of the 6 QI-Disability subdomain scores to be calculated and 1 missing item per domain for the total score to be calculated. Other, less stringent criteria would allow up to 2 missing items per domain.

CONCLUSION

Empirical evidence about the impact of imputing missing questionnaire responses can be gathered using simulation methods applied to a complete data set. We recommend that such evidence be used in devising a rule that specifies how many items can be imputed for a valid score to be calculated.

Improving clinical trial readiness to accelerate development of new therapeutics for Rett syndrome

Rett syndrome is associated with severe functional impairments and many comorbidities, each in urgent need of treatments. Mutations in the MECP2 gene were identified as causing Rett syndrome in 1999. Over the past 20 years there has been an abundance of preclinical research with some studies leading to human clinical trials. Despite this, few viable therapeutic options have emerged from this investment of effort. Reasons for this lack of success as they relate both to preclinical research and the clinical trial landscape are discussed. Considering what needs to be done to promote further success in the field, we take a positive and constructive approach and introduce the concept of clinical trial readiness and its necessary ingredients for Rett syndrome. These include: listening to the needs of families; support from advocacy groups; optimising use of existing clinic infrastructures and available natural history data; and, finally, the validation of existing outcome measures and/or the development and validation of new measures. We conclude by reiterating the need for a collaborative and coordinated approach amongst the many different stakeholder groups and the need to engage in new types of trial design which could be much more efficient, less costly and much less burdensome on families.

Influences on the trajectory and subsequent outcomes in CDKL5 deficiency disorder

OBJECTIVE

The study investigated the effect of seizure and medication burden at initial contact with the International CDKL5 Disorder Database on subsequent development and clinical severity and compared quality of life among those whose development progressed, remained stable, or regressed between baseline and follow-up.

METHODS

The effects of seizure and medication burden at baseline (high or low) on the CDKL5 Disorder Severity Scores and CDKL5 Developmental Score (CDS) at follow-up were assessed using linear and negative binomial regressions, respectively, with adjustment for age at baseline, gender, and follow-up duration with and without genotype. Seizure and medication burden were defined by average daily seizure count (high, ≥5/day; low, <5/day) and number of antiseizure medications (high, ≥3/day; low, <3/day), respectively. The effects of change in CDS over time (improved, stable, or deteriorated) on Quality of Life Inventory-Disability (QI-Disability) total and domain scores at follow-up were assessed in those aged at least 3 years at follow-up using linear regression models with adjustment for baseline CDS, gender, and follow-up duration.

RESULTS

The expected follow-up CDS was lower for individuals with high compared to low seizure burden at baseline (β = -.49, 95% confidence interval [CI] = -.84 to -.13). The average total QI-Disability score was 5.6 (95% CI = -.2 to 11.5) points higher among those with improved compared with stable or deteriorating CDS and 8.5 (95% CI = 3.1-13.8) points lower for those with deteriorating compared to stable or improved CDS.

SIGNIFICANCE

Our finding that later development showed slight improvement in those with better earlier seizure control even after adjustment for genotype suggests that the trajectory for an individual child is not necessarily predetermined and could possibly be influenced by optimal seizure management. This has implications for children's quality of life.

Comorbidities and quality of life in children with intellectual disability

BACKGROUND

Many children with intellectual disability live with medical comorbidities. This study examined the impacts of comorbidities on quality of life (QOL) of children with intellectual disabilities and whether impacts varied with caregiver perceptions that medical needs had been met.

METHODS

Primary caregivers of 447 children (aged 5-19 years) with an intellectual disability reported on their child's medical comorbidities and the extent to which they perceived their child's medical needs had been met in a cross-sectional observational study. The Quality of Life Inventory-Disability was used to measure QOL on a 100-point scale. Linear regression models including interaction terms were used to evaluate their associations.

RESULTS

Parent-reported recurrent child pain (-4.97, 95% CI -8.21, -1.72), night-time sleep disturbances (-4.98, 95% CI -7.23, -2.73), daytime somnolence (-8.71, 95% CI -11.30, -2.73), seizures that occurred at least weekly (-7.59, 95% CI -13.50, -1.68) and conservatively managed severe scoliosis (-7.39, 95% CI -12.97, -1.81) were negatively associated with child QOL. Despite the majority of parents (~70%) perceiving that their child's medical needs had been met to a great extent, this did not significantly moderate the association between any comorbidities and QOL.

CONCLUSIONS

Comorbidities were common and had marked associations with QOL. Evaluation and management of pain and sleep disturbance continue to be high priorities in improving QOL of young people with intellectual disabilities. Further research on the optimal methods of managing these comorbidities is warranted.

The effect of functioning on Quality of Life Inventory-Disability measured quality of life is not mediated or moderated by parental psychological distress

PURPOSE

The measurement of quality of life (QOL) in children with intellectual disability often relies upon proxy report via caregivers. The current study investigated whether caregiver psychological distress mediates or moderates the effects of impairment on their ratings of QOL in children with intellectual disability.

METHODS

Caregivers of 447 children with an intellectual disability reported their child's day-to-day functioning, their own psychological distress using the Kessler Psychological Distress Scale, and the Quality of Life Inventory-Disability (QI-Disability), a measure of QOL for proxy report of a child's observable behaviours that indicate quality of life. Linear regression was used to assess the effects of the child's functional abilities on their QI-Disability score and causal mediation analysis to estimate the extent to which these effects were mediated by caregivers' psychological distress.

RESULTS

A minority of caregivers (n = 121, 27.1%) reported no psychological distress. Lower day-to-day functional abilities, such as being fully dependent on others to manage their personal needs were associated with lower total QOL scores. There was no significant mediation effect of caregiver psychological distress on the association between child functioning and total QOL scores. Moderation analyses revealed small and largely nonsignificant interaction coefficients, indicating that caregiver psychological distress did not influence the strength of the relationship between child functioning and total QOL scores.

CONCLUSION

Caregiver psychological distress did not mediate or moderate the relationship between the level of functional abilities and QOL in children with intellectual disability. QI-Disability measured observable child behaviours which may reduce the influence of caregiver factors on the accurate measure of QOL for children with intellectual disability.

Functioning, participation, and quality of life in children with intellectual disability: an observational study

AIMS

To investigate associations between functioning, community participation, and quality of life (QoL) and identify whether participation mediates the effects of functioning on QoL.

METHOD

The caregivers of 435 children (211 females, 224 males; mean age 12y; SD 3y 11mo; age range 5-18y) with intellectual disability and autism spectrum disorder, cerebral palsy, Down syndrome, or Rett syndrome reported on their child's functioning (dependence for managing personal needs, mobility, communication, eye contact when speaking), frequency of participation, and QoL. Linear regression and mediation analyses were used to evaluate the relationships between child functioning, participation, and QoL.

RESULTS

Children with greater dependency for managing personal needs and limited eye contact when speaking experienced poorer QoL. Less impaired functioning was associated with more frequent participation, which, in turn, was associated with a 3-point gain in QoL for each additional point in frequency of participation (coefficient=2.67, 95% confidence interval 1.56-3.78). The effect of impaired functioning on QoL was partially mediated by participation in children with greater dependency in managing personal needs and those with mildly impaired communication.

INTERPRETATION

Greater levels of impairments with poorer functioning, notably a high level of dependence, were associated with poorer QoL. Poorer QoL can be partly explained by less frequent community participation.

Exploring quality of life in individuals with a severe developmental and epileptic encephalopathy, CDKL5 Deficiency Disorder

BACKGROUND

CDKL5 Deficiency Disorder (CDD) is a rare genetic disorder caused by a mutation in the cyclin-dependent kinase-like 5 (CDKL5) gene. It is now considered to be a developmental and epileptic encephalopathy because of the early onset of seizures in association with severe global delay. Other features include cortical visual impairment, sleep and gastro-intestinal problems. Progress in clinical understanding, especially regarding the spectrum of functional ability, seizure patterns, and other comorbidities was initially slow but accelerated in 2012 with the establishment of the International CDKL5 Database (ICDD). Our aim was to use this data source to investigate quality of life (QOL) and associated factors in this disorder.

METHOD

A follow-up questionnaire was administered in 2018 to parents of children registered with the ICDD who had a pathogenic CDKL5 variant. QOL was assessed using QI Disability, an instrument, specifically developed to measure total and specific domains of QOL (physical health, positive emotions, negative emotions, social interaction, leisure and the outdoors (leisure) and independence) in children with intellectual disability. Associations with functional abilities, physical health, mental health and family factors were investigated, initially using univariate analyses followed by multivariate analyses for each of these groups with a final composite model which included the important variables identified from previous models.

RESULTS

Questionnaires were returned by 129/160 families with a child aged >3 years. Functional impairment, including lack of ability to sit, use hands and communicate had the greatest adverse impact on QOL. There were also some relationships with major genotype groupings. Individuals using three or more anti-epileptic medications had poorer QOL than those on one or no medication, particularly in the physical health domain. There was also variation by geographical region with those living in North America typically having the best QOL and those living in middle or lower income countries poorer QOL.

CONCLUSION

Although lower functional abilities were associated with poorer quality of life further research is needed to understand how environmental supports might mitigate this deficit. Comprehensive care and support for both the child and family have important roles to play in helping families to thrive despite the severity of CDD.