Recruitment bias in a population-based study of children with cerebral palsy

Feasibility and performance of home sleep apnea testing in youth with Down syndrome

STUDY OBJECTIVES

In-laboratory polysomnography is recommended for the evaluation of obstructive sleep apnea (OSA) in youth with Down syndrome. However, insufficient sleep laboratories are available, particularly for youth with neurocognitive disabilities such as Down syndrome. We hypothesized that level II home sleep apnea testing (HSAT) would be feasible, acceptable, and accurate in detecting polysomnography-defined moderate-severe OSA in youth with Down syndrome.

METHODS

Youth 6 to 25 years old with Down syndrome were recruited to undergo in-home level II HSAT with electroencephalogram and in-lab polysomnography. Parents completed questionnaires assessing feasibility, acceptability, and test preference. HSAT, scored blinded to polysomnography result, were compared to reference polysomnography.

RESULTS

Forty-three youth (23 female) aged [median (range)] 15.5 (6.1, 25.1) years participated in the study. Forty-one participants were able to complete HSAT and 41 completed polysomnography, with 40 who underwent both tests. HSAT was preferred to polysomnography by 73.7% of parents. Total sleep time for HSAT was 437 ± 123 minutes vs 366 ± 90 minutes for polysomnography (P = .003). Obstructive apnea-hypopnea index by polysomnography was 12.7 events/h (0.2, 113.8), and 32 youth (80%) who completed all testing had OSA. Compared to polysomnography, sensitivity of HSAT was: 0.81, specificity was 0.75, accuracy was 0.8 including 2 youth whose HSAT demonstrated OSA when polysomnography did not.

CONCLUSIONS

In youth with Down syndrome, level II HSAT was well-tolerated, preferred compared to in-lab polysomnography, and had good accuracy for detecting moderate-severe OSA. Level II HSAT could provide a means for expanding the evaluation of OSA in youth with Down syndrome.

CITATION

Cielo CM, Kelly A, Xanthopoulos M, et al. Feasibility and performance of home sleep apnea testing in youth with Down syndrome J Clin Sleep Med. 2023;19(9):1605-1613.

Did previous involvement in research affect recruitment of young people with cerebral palsy to a longitudinal study of transitional health care?

OBJECTIVE

To assess whether being contacted about or participating in previous research and method of approaching potential participants affected recruitment to a transition study from child to adult healthcare services of young people with cerebral palsy (CP).

DESIGN AND METHODS

Young people with CP aged 14-18 years without severe intellectual impairment were identified from regional registers of CP in Northern Ireland and the North of England. χ² and Mann-Whitney U tests were used to assess differences in CP and sociodemographic characteristics between those recruited and those who refused. Logistic regression was used to assess contact about and recruitment to previous research and method of approach as predictors of recruitment, controlling for demographic and CP characteristics.

RESULTS

Of the 410 young people who were approached; 162 did not respond and of the 248 who responded, 96 (23%) were recruited. There were significant differences between those recruited and those who refused in age and number of previous studies they had participated in. Those who were older or who had previously been approached about research were more likely to be recruited to our study. However, those who had been recruited to previous studies were more likely to refuse to join our study.

CONCLUSIONS

The method of approach to potential participants did not affect recruitment. Older adolescents and those who had been approached about previous research were more likely to take part in our study, although there was evidence of research fatigue because if they had actually been recruited to the previous studies they were less likely to join our study. Recruitment of adolescents to studies remains challenging.

The use of functional electrical stimulation to improve upper limb function in children with hemiplegic cerebral palsy: A feasibility study

Background

Grasping and manipulating objects are common problems for children with hemiplegic cerebral palsy. Multichannel-functional electrical stimulation may help facilitate upper limb movements and improve function.

Objective

To evaluate the feasibility of multichannel-functional electrical stimulation to improve grasp and upper limb function in children with hemiplegic cerebral palsy to inform the development of a clinical trial.

Methods

A prospective pre-/post-test/follow-up (six months) design with three children, aged 6–13 years, was used. Multichannel-functional electrical stimulation (mFES) was applied to the hemiplegic upper limb for up to 48 sessions over 16 weeks. Feasibility indicators included recruitment of participants and adherence rates, safety, and discomfort/pain. Effectiveness was assessed using the grasp domain of the Quality of Upper Extremity Skills Test, and other secondary clinical outcome measures with “success” criteria set a priori.

Results

Participant recruitment target was not met but adherence was high, and multichannel-functional electrical stimulation was found to be safe and comfortable. Of the three participants, two improved in grasp at post-test, whereas one child’s ability deteriorated. Only one child met success criteria on most outcomes at post-test.

Conclusions

Feasibility indicators met success criteria, except for participant recruitment. Treatment effectiveness was mixed. A future case comparison investigation with a larger but more selected sample is suggested.

Success of University Student Volunteers in Obtaining Consent for Reviewing Private Health Information for Emergency Research

This study aimed to determine the success of university student volunteers in obtaining consent from parents to allow review of their child's personal health information (PHI) for emergency research screening. This study also aimed to examine the variables associated with successful consent. This was a prospective cross-sectional study conducted at a pediatric emergency department (ED). University students, who functioned as delegates of the health information custodian, approached parents for consent. Of 2,506 parents, 1,852 (73.9%) provided consent to allow review of their child's PHI for research screening. Variables associated with successful consent were high (≥12 months) versus low (<12 months) volunteer experience (OR = 2.0), research related (vs. unrelated) to the child's chief complaint (OR = 2.0), child treated regularly by specialists at the study institution (OR = 1.7), and ED presentation mid-week vs. weekend (OR = 1.7) and morning vs. evening presentation (OR = 1.4). When approached by a university student volunteer, about 25% of parents declined to have their child's PHI reviewed for research screening. This model of obtaining consent may put some emergency research at risk for selection bias. Variables that increase the odds of successful consent can be considered in program design to improve the effectiveness of this model.

Analysis of recruitment in a pragmatic observational study on C-reactive protein point-of-care testing in primary care

INTRODUCTION

Failure to recruit all eligible study patients can lead to biased results. Little is known on selective patient recruitment in studies on implementation of diagnostic devices.

OBJECTIVES

The aim of this observational study was to measure recruitment of patients in an implementation study in primary care on use of point-of-care (POC) C-reactive protein (CRP) and to evaluate recruitment bias and its impact on the study endpoint.

METHODS

In a cross-sectional observational study on POC CRP implementation and related antibiotics prescribing, we compared included patients with all eligible patients to assess the representativeness of the included subjects. Eligible patients were adults presenting with acute cough in primary care between March and September 2012. The frequency of POC CRP testing and the proportion of prescribed antibiotics were compared between recruited and non-recruited patients. As measure of bias, odds ratios (ORs) with accompanying 95% confidence intervals (CIs) for the association between CRP level (<20 mg/l or not) and antibiotic prescribing were computed.

RESULTS

Of all 1473 eligible patients 348 (24%) were recruited. In recruited patients, POC CRP tests were conducted and antibiotics prescribed more frequently as compared to non-recruited patients (81% versus 6% and 44% versus 29%, respectively). The ORs were 18.2 (95%CI: 9.6-34.3), 30.5 (95%CI: 13.2-70.3) and 3.8 (95%CI: 0.9-14.8) respectively in all eligible patients, the recruited and the non-recruited patients.

CONCLUSION

Selective recruitment resulted in an overestimation of POC CRP test use and antibiotic prescribing.

Passive range of motion in a population-based sample of children with spastic cerebral palsy who walk

While passive range of motion (PROM) is commonly used to inform decisions on therapeutic management, knowledge of PROM of children with spastic cerebral palsy (CP) is limited. A population-based sample of 178 children with spastic CP (110 male; unilateral, n = 94; bilateral, n = 84; age range 4-17 years) and 68 typically developing children (24 male; age range 4-17 years) were recruited to the study. All children were able to walk a minimum of 10 m over a straight flat course, with or without assistive devices. Gross Motor Function Classification System (GMFCS) levels of participants with CP were: Level I = 55, Level II = 88, Level III = 21, and Level IV = 14. Ankle dorsiflexion, knee extension, popliteal angle, hip abduction, hip internal rotation, and hip external rotation were measured using a goniometer. The results indicate that the children with CP had significantly reduced PROM compared to the children with typical development. Children with CP demonstrated reduced length in the hamstrings, hip adductor, iliopsoas and gastrocnemius-soleus musculature, and contracture at the knee joint. Among children with CP, there were significant reductions in range with increasing functional limitation (higher GMFCS level) and variations based on unilateral or bilateral involvement. This was particularly the case for the hamstrings and hip adductor musculature, where PROM varied considerably across GMFCS Levels I to IV.

Paternal age and psychiatric disorders: findings from a Dutch population registry

BACKGROUND

We measured the association between paternal age and schizophrenia (SCZ), autism spectrum disorders (ASD), major depressive disorder (MDD), and bipolar disorder (BPD) in the Dutch population.

METHODS

In total, 14231 patients and 56924 matched controls were collected and analyzed for an association with paternal age by logistic regression.

RESULTS

ASD is significantly associated with increased paternal age: Older fathers >40 years of age have a 3.3 times increased odds of having a child with ASD compared to young fathers <20 years of age. SCZ has significant associations for fathers aged >35 years (OR=1.27, 95% Confidence Interval: 1.05 and 1.53). For MDD, both younger and older fathers have increased odds. No association was found for BPD.

CONCLUSIONS

The effects of paternal age as a risk factor are different for ASD and SCZ on one hand, and the affective disorders on the other hand. Different types of association might indicate different biological or psychosocial mechanisms. Late paternity (associated with predispositions to psychiatric disorders) seems the most probable explanation for the association with paternal age.

Pelvic kinematics and their relationship to gait type in hemiplegic cerebral palsy

While there is general clinical consensus that children with Unilateral Spastic Cerebral Palsy (USCP) walk with an increased anterior pelvic tilt and the affected hemipelvis retracted, there is less agreement to observations in the coronal plane. Furthermore, the relationship of 3D pelvic kinematic parameters to the Winters, Gage and Hicks (WGH) hemiplegic gait classification has not been reported in the literature. Valid 3-D kinematic gait data were obtained in a representative population of 91 children with hemiplegia (56 M, mean age 10.8 yrs, age range 5-18 yrs; WGH classification Type I n=32, II n=5, III n=7, IV n=9, unclassified n=38). Deviations of symmetry and range of movement from our normative data set (n=48; 26F; mean age 9.9 yrs; age range 5-18 yrs) for mean tilt, tilt range, and difference between affected and unaffected sides for obliquity and rotation were defined as normal, mild, moderate or severe (<1 standard deviation (SD); >1<2 SD; >2<3 SD; >3 SD, respectively). Increased pelvic tilt range (>1 SD) was observed in 60.4% and pelvic retraction (>1 SD) was observed in 61.5% of USCP children in this study. Weak but significant correlations were found between WGH gait type and pelvic obliquity (ρ=0.29; p<0.01). No other correlations were found. Factors such as leg length discrepancy modify the functional leg length throughout the gait cycle contributing to the deviations observed. The evaluation of gait abnormalities in USCP should not be limited to the use of classifications based on sagittal plane kinematics but should seek to include 3D kinematics of the pelvis.

The health of children and young people with cerebral palsy: a longitudinal, population-based study

BACKGROUND

Cerebral palsy (CP) is a chronic condition about which little is known in relation to the long term stability of and factors influencing health.

OBJECTIVES

To describe the health status of 4-17 year olds with ambulant CP, compare with the general population and identify factors predicting change in health over time.

DESIGN

A longitudinal, clinical survey.

SETTING

A regional hospital-based Gait Analysis Laboratory.

PARTICIPANTS

Those aged 4-17 years and able to walk at least 10m independently were identified from a case register of people with CP. A total of 184 subjects took part (38% of all eligibles in the region); 154 (84%) returned for a second assessment on average 2.5 years later.

METHODS

The Child Health Questionnaire (Parent-form-50) was completed by 184 parents at time 1, and 156 at time 2.

RESULTS

Children and young people with CP have significantly poorer health across a number of domains when compared to children in the general child population. Over time improvements occurred in behaviour (p=0.01), family activities (p<0.001) and physical functioning (p=0.05). Linear regression showed that gross motor function (p<0.001) and cerebral palsy subtype (p<0.05) were associated with changes in physical functioning; age was associated with changes in behaviour (p=0.007) and family activities (p=0.01); and communication ability was significantly associated with changes in family activities (p=0.005).

CONCLUSIONS

Children and young people with CP have poorer health than their able bodied peers but relatively stable health over 2.5 years. Where change occurred, it was for the better.

Age-related changes in energy efficiency of gait, activity, and participation in children with cerebral palsy

AIM

The aim of this study was to use a prospective longitudinal study to describe age-related trends in energy efficiency during gait, activity, and participation in ambulatory children with cerebral palsy (CP).

METHOD

Gross Motor Function Measure (GMFM), Paediatric Evaluation of Disability Inventory (PEDI), and Lifestyle Assessment Questionnaire-Cerebral Palsy (LAQ-CP) scores, and energy efficiency (oxygen cost) during gait were assessed in representative sample of 184 children (112 male; 72 female; mean age 10y 9mo; range 4-16y) with CP. Ninety-four children had unilateral spastic CP, 84 bilateral spastic CP, and six had other forms of CP. Fifty-seven were classified as Gross Motor Function Classification System (GMFCS) level I, 91 as level II, 22 as level III, and 14 as level IV). Assessments were carried out on two occasions (visit 1 and visit 2) separated by an interval of 2 years and 7 months. A total of 157 participants returned for reassessment.

RESULTS

Significant improvements in mean raw scores for GMFM, PEDI, and LAQ-CP were recorded; however, mean raw oxygen cost deteriorated over time. Age-related trends revealed gait to be most inefficient at the age of 12 years, but GMFM scores continued to improve until the age of 13 years, and two PEDI subscales to age 14 years, before deteriorating (p<0.05). Baseline score was consistently the single greatest predictor of visit 2 score. Substantial agreement in GMFCS ratings over time was achieved (κ(lw) =0.74-0.76).

INTERPRETATION

These findings have implications in terms of optimal provision and delivery of services for young people with CP to maximize physical capabilities and maintain functional skills into adulthood.

Oromotor dysfunction and communication impairments in children with cerebral palsy: a register study

AIM

to report the prevalence, clinical associations, and trends over time of oromotor dysfunction and communication impairments in children with cerebral palsy (CP).

METHOD

multiple sources of ascertainment were used and children followed up with a standardized assessment including motor speech problems, swallowing/chewing difficulties, excessive drooling, and communication impairments at age 5 years.

RESULTS

a total of 1357 children born between 1980 and 2001 were studied (781 males, 576 females; median age 5y 11mo, interquartile range 3-9y; unilateral spastic CP, n=447; bilateral spastic CP, n=496; other, n=112; Gross Motor Function Classification System [GMFCS] level: I, 181; II, 563; III, 123; IV, 82; IV, 276). Of those with 'early-onset' CP (n=1268), 36% had motor speech problems, 21% had swallowing/chewing difficulties, 22% had excessive drooling, and 42% had communication impairments (excluding articulation defects). All impairments were significantly related to poorer gross motor function and intellectual impairment. In addition, motor speech problems were related to clinical subtype; swallowing/chewing problems and communication impairments to early mortality; and communication impairments to the presence of seizures. Of those with CP in GMFCS levels IV to V, a significant proportion showed a decline in the rate of motor speech impairment (p=0.008) and excessive drooling (p=0.009) over time.

INTERPRETATION

these impairments are common in children with CP and are associated with poorer gross motor function and intellectual impairment.

To what extent do children with cerebral palsy participate in everyday life situations?

The aims of the study are to describe participation of children with cerebral palsy in everyday life situations, to investigate the relationship between participation (primary outcome variable) with child and parent characteristics (independent variables) and to compare the frequency of participation (secondary outcome variable) of children with cerebral palsy with children without disabilities. A cross-sectional survey of parents of children with cerebral palsy in Northern Ireland was undertaken in families' homes using standard questionnaires. Children with cerebral palsy born between 31/8/1991 and 1/4/1997 were identified from a case register of people with the condition. A total of 102 parents opted in (51% response rate). Questionnaires included the Life Habits Questionnaire (Life-H) to measure difficulties in participation and The Frequency of Participation Questionnaire (FPQ), to measure frequency of participation with comparative data for children without disability. Overall, children with cerebral palsy participated less often than their non-disabled peers across a number of lifestyle and cultural pursuits. Among the 102 children with cerebral palsy, participation in 'relationships' was the least disrupted area of everyday life and aspects of 'school', 'personal care' and 'mobility' were the most disrupted. Children with cerebral palsy and severe co-impairments were significantly less likely to experience higher levels of participation in most areas of everyday life when compared to children with cerebral palsy and no severe co-impairments. Child physical and psychological well-being did not influence participation although higher parenting stress was significantly related to lower child participation in 'community activities'. Participation is an important health outcome for children with cerebral palsy and should be incorporated in routine clinical practice. Professionals have a role to play both at the level of addressing individual child and family needs as well as influencing legislation and policy to ensure improved access to services and local communities.

Further evidence of validity of the Gait Deviation Index

In this paper, the relationship of the Gait Deviation Index (GDI) to gross motor function and its ability to distinguish between different Gross Motor Function Classification System (GMFCS) levels was determined. A representative sample of 184 ambulant children with CP in GMFCS levels I (n=57), II (n=91), III (n=22) and IV (n=14) were recruited as part of a population-based study. Representative gait cycles were selected following a 3D gait analysis and gross motor function was assessed using the Gross Motor Function Measure (GMFM). GDI scores were calculated in Matlab. Valid 3D kinematic data were obtained for 173 participants and both kinematic and GMFM data were obtained for 150 participants. A substantial relationship between mean GDI and GMFM-66 scores was demonstrated (r=0.70; p<0.001) with significant differences in mean GDI scores between GMFCS levels (p<0.001) indicating increasing levels of gait deviation in subjects less functionally able. The relationship between the GDI, GMFM and GMFCS in a representative sample of ambulators, lends further weight to the validity of the GDI scoring system. Furthermore it suggests that the subtleties of gait may not be wholly accounted for by gross motor function evaluation alone. Gait specific tools such as the GDI more likely capture both the functional and aesthetic components of walking.

Hidden Empirical Research Ethics: A Review of Three Health Journals from 2005 through 2006

WE HYPOTHESIZED THAT A SIGNIFICANT amount of empirical data pertinent to research ethics is currently inaccessible to research ethics committee or Institutuional Review Board (IRB) members for at least three reasons: it is published in non-ethics journals; articles are not adequately indexed using ethics-related keywords; and articles do not discuss the ethical significance of their data. We reviewed all articles from three health journals from January 2005 to December 2006, and identified 26 articles that contained data pertinent to research ethics. Only 7 articles contained keywords clearly related to research ethics; 15 of the articles contained no discussion of the ethical significance of their findings. Overall the articles we found constituted 2.2% of the research articles published in the three journals during the two-year period. If the same average number of articles were extrapolated to the top 100 of the approximately 5,000 journals indexed in MEDLINE, then at least 433 hidden ethics articles would be published each year. We conclude that better indexing of articles is needed, that IRB members and researchers need training to identify relevant data in the literature, and that IRB composition should include members from diverse disciplines familiar with ethics-relevant empirical data in their respective disciplines.

The validity of an existing gait classification system when applied to a representative population of children with hemiplegia

This study describes sagittal plane gait patterns in a representative sample of children with hemiplegic cerebral palsy (CP). Ninety-four children were prospectively recruited to the study (age range 5-18 yrs, mean age 10 yrs 7 mo) and valid kinematic data was captured for 91 participants. Data was also captured for 49 children (age range 5-18 yrs, mean age 10 yrs) with no physical impairment. One representative gait cycle from each child was exported to an Excel template and run through an algorithm that facilitated the description of gait, using logical arguments derived from Winters' Classification. Children with hemiplegic CP, regardless of past surgery history, were allocated to the following gait types: Groups IV (n=9; 10%), III (n=7: 8%), II (n=5: 5%), I (n=32: 35%) and not classified (n=38: 42%). For children with no lower limb surgical history (n=61), gait types were: Groups IV (n=7: 12%), III (n=2: 3%), II (n=2: 3%), I (n=20: 33%) and not classified (n=30: 49%). The gait data taken from children with no physical impairment were not classified. The ability of the Winters' classification system to distinguish between children with higher levels of hemiplegic involvement and children with no physical impairment was demonstrated: the majority of children with hemiplegic CP present with relatively minor gait deviations. A more complete definition of sagittal plane ankle joint kinematics may account for those children that were not classified.

Psychological problems in children with cerebral palsy: a cross-sectional European study

OBJECTIVES

To describe psychological symptoms in 8-12-year-old children with cerebral palsy; to investigate predictors of these symptoms and their impact on the child and family.

DESIGN

A cross-sectional multi-centre survey.

PARTICIPANTS

Eight hundred and eighteen children with cerebral palsy, aged 8-12 years, identified from population-based registers of cerebral palsy in eight European regions and from multiple sources in one further region.

MAIN OUTCOME MEASURES

The Strengths and Difficulties Questionnaire (SDQ)(P4-16) and the Total Difficulties Score (TDS) dichotomised into normal/borderline (TDS < or = 16) versus abnormal (TDS > 16).

STATISTICAL ANALYSIS

Multilevel, multivariable logistic regression to relate the presence of psychological symptoms to child and family characteristics.

RESULTS

About a quarter of the children had TDS > 16 indicating significant psychological symptoms, most commonly in the domain Peer Problems. Better gross motor function, poorer intellect, more pain, having a disabled or ill sibling and living in a town were independently associated with TDS > 16. The risk of TDS > 16 was odds ratio (OR) = .2 (95% CI: .1 to .3) comparing children with the most and least severe functional limitations; OR = 3.2 (95%CI: 2.1 to 4.8) comparing children with IQ < 70 and others; OR = 2.7 (95% CI: 1.5 to 4.6) comparing children in severe pain and others; OR = 2.7 (95% CI:1.6 to 4.6) comparing children with another disabled sibling or OR = 1.8 (95%CI: 1.2 to 2.8) no siblings and others; OR = 1.8 (95% CI: 1.1 to 2.8) comparing children resident in a town and others. Among parents who reported their child to have psychological problems, 95% said they had lasted over a year, 37% said they distressed their child and 42% said they burdened the family at least 'quite a lot'.

CONCLUSIONS

A significant proportion of children with cerebral palsy have psychological symptoms or social impairment sufficiently severe to warrant referral to specialist services. Care must be taken in the assessment and management of children with cerebral palsy to ensure psychological problems are not overlooked and potentially preventable risk factors like pain are treated effectively. The validity of the SDQ for children with severe disability warrants further assessment.

Energy efficiency in gait, activity, participation, and health status in children with cerebral palsy

The aim of the study was to establish if a relationship exists between the energy efficiency of gait, and measures of activity limitation, participation restriction, and health status in a representative sample of children with cerebral palsy (CP). Secondary aims were to investigate potential differences between clinical subtypes and gross motor classification, and to explore other relationships between the measures under investigation. A longitudinal study of a representative sample of 184 children with ambulant CP was conducted (112 males, 72 females; 94 had unilateral spastic C P, 84 had bilateral spastic C P, and six had non-spastic forms; age range 4-17 y; Gross Motor Function Classification System Level I, n=57; Level II, n=91; Level III, n=22; and Level IV, n=14); energy efficiency (oxygen cost) during gait, activity limitation, participation restriction, and health status were recorded. Energy efficiency during gait was shown to correlate significantly with activity limitations; no relationship between energy efficiency during gait was found with either participation restriction or health status. With the exception of psychosocial health, all other measures showed significant differences by clinical subtype and gross motor classification. The energy efficiency of walking is not reflective of participation restriction or health status. Thus, therapies leading to improved energy efficiency may not necessarily lead to improved participation or general health.

Validity, trustworthiness and rigour: reasserting realism in qualitative research

AIM

This paper challenges recent sceptical approaches to the possibility of validating qualitative research and underlines the benefits of adopting a realist approach to validity.

BACKGROUND

In recent discussion about the methodological bases for qualitative research it has been argued that, because different methodologies take different approaches to validity, attempts to develop a common set of validation criteria are futile. On the basis of this sceptical view, a number of strategies for judging qualitative research have been proposed. These include suggestions that: it should be judged according to aesthetic or rhetorical criteria, rather than epistemological validity; responsibility for appraisal should move from researchers to readers; each methodology should be assessed individually according to its own merits.

DISCUSSION

None of these suggestions provide a viable alternative to validity, defined as the extent to which research reflects accurately that to which it refers. Because the form of research does not determine its content, replacement of epistemology by aesthetics is unsustainable. Because research reports mediate between writer and reader, a one-sided approach to this relationship constitutes a false dichotomy. If we accept the criterion of practitioner confidence as a means of judging methodological approaches, this involves rejection of judgement according to a methodology's own merits.

CONCLUSION

If qualitative research is actually about something, and if it is required to provide beneficial information, then a realist approach to validity holds out greatest promise.

Use of the Child Health Questionnaire in Children with Cerebral Palsy: A Systematic Review and Evaluation of the Psychometric Properties

OBJECTIVE

To review the psychometric performance of the Child Health Questionnaire (CHQ) in samples of children with cerebral palsy (CP).

METHOD

Four search terms were applied to five databases in a search for papers published between 1993 and January 2007.

RESULTS

A total of 13 papers were identified, providing data on 1229 unique children aged 2-18 years old. Three studies reported on the reliability of the CHQ (internal consistency), whilst six studies provided evidence on various dimensions of validity (concurrent; discriminant and item discriminant validity).

CONCLUSIONS

This review identified a number of psychometric issues that need to be addressed. These include the assessment of additional types of reliability; an examination of the factor structure of the CHQ within the CP population; and the development of normative data using substantial representative samples, particularly in Europe. Until these issues are addressed, researchers utilizing the CHQ in children with CP should be cautious about its interpretation.

Interobserver agreement of the Gross Motor Function Classification System in an ambulant population of children with cerebral palsy

Gross Motor Function Classification System (GMFCS) level was reported by three independent assessors in a population of children with cerebral palsy (CP) aged between 4 and 18 years (n=184; 112 males, 72 females; mean age 10y 10mo [SD 3y 7mo]). A software algorithm also provided a computed GMFCS level from a regional CP registry. Participants had clinical diagnoses of unilateral (n=94) and bilateral (n=84) spastic CP, ataxia (n=4), dyskinesia (n=1), and hypotonia (n=1), and could walk independently with or without the use of an aid (GMFCS Levels I-IV). Research physiotherapist (n=184) and parent/guardian data (n=178) were collected in a research environment. Data from the child's community physiotherapist (n=143) were obtained by postal questionnaire. Results, using the kappa statistic with linear weighting (kappa(1w)), showed good agreement between the parent/guardian and research physiotherapist (kappa(1w)=0.75) with more moderate levels of agreement between the clinical physiotherapist and researcher (kappa(1w)=0.64) and the clinical physiotherapist and parent/guardian (kappa(1w)=0.57). Agreement was consistently better for older children (>2y). This study has shown that agreement with parent report increases with therapists'experience of the GMFCS and knowledge of the child at the time of grading. Substantial agreement between a computed GMFCS and an experienced therapist (kappa(1w)=0.74) also demonstrates the potential for extrapolation of GMFCS rating from an existing CP registry, providing the latter has sufficient data on locomotor ability.

Oxygen cost versus a 1-minute walk test in a population of children with bilateral spastic cerebral palsy

Difficulties with direct measurement of oxygen (O2) consumption have led to the use of simpler proxy measures to estimate energy efficiency in children with cerebral palsy. This study aimed to investigate the relationship between a fast 1-minute walk test and O2 cost in children with bilateral spastic cerebral palsy. Eighty-four children (31 girls, 53 boys; mean age, 10 years 11 months; Gross Motor Function Classification System level I n = 8, level II n = 41, level III n = 21, level IV n = 14) were eligible to participate in the study. Seventy-seven children completed the walk test and 47 children completed the O2 consumption protocol. Results showed significant differences between Gross Motor Function Classification System levels for both tests (P < 0.001) and a significant moderate quadratic relationship between the distance covered during the 1-minute fast-walk test and the net O2 cost (adjusted r = 0.477; P < 0.001). The 1-minute fast-walk test may provide useful information on the efficiency of gait in children with bilateral spastic cerebral palsy in the absence of more sophisticated equipment; however, further work is required to address its reliability and responsiveness.

Assessment of data quality in a multi-centre cross-sectional study of participation and quality of life of children with cerebral palsy

BACKGROUND

SPARCLE is a cross-sectional survey in nine European regions, examining the relationship of the environment of children with cerebral palsy to their participation and quality of life. The objective of this report is to assess data quality, in particular heterogeneity between regions, family and item non-response and potential for bias.

METHODS

1,174 children aged 8-12 years were selected from eight population-based registers of children with cerebral palsy; one further centre recruited 75 children from multiple sources. Families were visited by trained researchers who administered psychometric questionnaires. Logistic regression was used to assess factors related to family non-response and self-completion of questionnaires by children.

RESULTS

431/1,174 (37%) families identified from registers did not respond: 146 (12%) were not traced; of the 1,028 traced families, 250 (24%) declined to participate and 35 (3%) were not approached. Families whose disabled children could walk unaided were more likely to decline to participate. 818 children entered the study of which 500 (61%) self-reported their quality of life; children with low IQ, seizures or inability to walk were less likely to self-report. There was substantial heterogeneity between regions in response rates and socio-demographic characteristics of families but not in age or gender of children. Item non-response was 2% for children and ranged from 0.4% to 5% for questionnaires completed by parents.

CONCLUSION

While the proportion of untraced families was higher than in similar surveys, the refusal rate was comparable. To reduce bias, all analyses should allow for region, walking ability, age and socio-demographic characteristics. The 75 children in the region without a population based register are unlikely to introduce bias.