Policy brief: adaptive cycling equipment for individuals with neurodevelopmental disabilities as durable medical equipment.

- Durable medical equipment (DME) policies require that the equipment be medically necessary; however, adaptive cycling equipment (bicycles and tricycles) are usually not deemed medically necessary. - Individuals with neurodevelopmental disabilities (NDD) are at high risk for secondary conditions, both physical and mental, that can be mitigated by increasing physical activity. - Significant financial costs are associated with the management of secondary conditions. - Adaptive cycling can provide improved physical health of individuals with NDD potentially reducing costs of comorbidities. - Expanding DME policies to include adaptive cycling equipment for qualifying individuals with NDD can increase access to equipment. - Regulations to ensure eligibility, proper fitting, prescription, and training can optimize health and wellbeing. - Programs for recycling or repurposing of equipment are warranted to optimize resources.

Clinical efficacy of instrumented gait analysis: Systematic review 2020 update.

BACKGROUND: This paper updates our 2011 systematic review on the clinical efficacy of three-dimensional instrumented gait analysis (3DGA). RESEARCH QUESTION: What is the current evidence base pertaining to the clinical efficacy of 3DGA? METHODS: We identified English language articles published from September 2009 to October 2019 reporting primary research that used typical motion analysis laboratory methods to study human walking. Five gait laboratory experts classified articles according to the highest type of efficacy they addressed: type 1 (technical), 2 (diagnostic accuracy), 2b (outcome prediction), 3-4 (diagnostic thinking and treatment), 5 (patient outcome), 6 (societal). Articles classified into type 3-4 and higher were rated for quality using LEGEND. RESULTS: Of 2712 articles related to the efficacy of 3DGA, over 99% addressed technical (n = 313), diagnostic (n = 1466), or outcome prediction (n = 927) efficacy. Six type 3-4 studies showed that 3DGA changes treatment plans, increases clinicians' confidence in their treatment decisions, and increases agreement among clinicians. Two type 5 articles based on a randomized controlled trial demonstrated that patient outcomes improved only when 3DGA data were available and its recommendations were followed. A population-based type 5 study found that the incidence of severe crouch gait dropped from 25% to 4% following practice changes including the addition of 3DGA. The strength of evidence was mainly 3b (lesser quality prospective cohort studies) but also included stronger studies (three level 2 controlled clinical trials). SIGNIFICANCE: Literature related to the clinical efficacy of 3DGA has grown substantially over the last decade. Thousands of articles contribute to continued improvement of data collection and interpretation, as well as understanding of gait pathology and treatment. A smaller number of studies clearly demonstrate the efficacy of 3DGA in changing and reinforcing treatment decisions, increasing clinicians' confidence in treatment planning, and increasing agreement among clinicians, as well as the potential to improve patient outcomes.

An Analysis of Relative Gait Impairment in Commonly Diagnosed Pediatric Conditions.

BACKGROUND: Gait indices were developed to represent the magnitude of impairment extracted from a gait analysis with a single value. The Gillette Gait Index (GGI), and the Gait Deviation Index (GDI) are 2 widely used indices that represent gait impairment differently based on their statistical properties. Our purpose was to (1) report on the results of gait analysis for a broad spectrum of pediatric conditions using the GGI and GDI, and (2) identify the parameters that dominate impairment. METHODS: A total of 1439 children with 13 different diagnoses with a complete, baseline gait analysis were identified. The GGI and its 16 parameters were calculated in all cases, and the GDI was calculated from a smaller subset. T tests, and z-scores were used to compare each of these values to typically developing children for each diagnosis. A separate linear regression controlling for age, sex, and use of an orthosis, or assistive device was performed for the GGI. RESULTS: In our series, there were 71 typically developing children with a GGI of 31. We qualify relative gait impairment as severe, mild, or moderate as based on the GGI, and propose that values <100 represent mild, 100 to 200 represent moderate, and >200 represents severe impairment. On the basis of strong correlation between the GGI and GDI, we suggest that GDI values >80 represent mild, and values <70 represent severe impairment. T tests and z-scores demonstrated that both the number and magnitude of abnormal parameters increase the GGI. These tests also identified the most clinically relevant parameters contributing to functional impairment for each diagnosis. Multivariate linear regression showed that all diagnoses except flatfoot and scoliosis demonstrated statistically significant differences in GGI scores. CONCLUSIONS: This is the first study to apply these gait indices to a large population of diverse pediatric conditions. We propose GGI and GDI values to qualify gait impairment among these conditions as severe, moderate, or mild. Furthermore, impairment in gait reflects both the number and magnitude of abnormal parameters within each condition. LEVEL OF EVIDENCE: Level III-retrospective comparative study.

Variation in kinematic and spatiotemporal gait parameters by Gross Motor Function Classification System level in children and adolescents with cerebral palsy.

AIM: The aim of this study was to examine differences in gait kinematics and spatiotemporal parameters in ambulatory children and adolescents with bilateral spastic cerebral palsy (BSCP) among Gross Motor Function Classification System (GMFCS) levels I-III. METHOD: A retrospective review was conducted of individuals with BSCP who had three-dimensional motion analysis (3DGA) at one of seven pediatric hospitals. Means and standard deviations of each gait parameter were stratified by GMFCS levels (I-III) and for a typically developing comparison group. RESULTS: Data from 292 children and adolescents with BSCP (189 males, 103 females; mean age 13 y) were compared to a typically developing comparison group (24 male, 26 female; mean age 10 y 6 mo). Gait patterns differed from typically developing in all GMFCS levels, with increasing deviation as GMFCS level increased in 21 out of 28 parameters. Despite significant differences in selected mean kinematic parameters among GMFCS levels such as knee angle at initial contact of 24°, 29°, and 41° in GMFCS levels I, II and III respectively, there was also substantial overlap among GMFCS levels. INTERPRETATION: GMFCS levels cannot be identified using specific gait kinematics. Treatment decisions should be guided by comprehensive 3DGA that allows measurement of gait impairments at the joint level for each individual.

Relationship of Strength, Weight, Age, and Function in Ambulatory Children With Cerebral Palsy.

BACKGROUND: The natural history of ambulatory function in individuals with cerebral palsy (CP) consists of deterioration over time. This is thought to be due, in part, to the relationship between strength and weight, which is postulated to become less favorable for ambulation with age. METHODS: The study design was prospective, case series of 255 subjects, aged 8 to 19 years, with diplegic type of CP. The data analyzed for the study were cross-sectional. Linear regression was used to predict the rate of change in lower extremity muscle strength, body weight, and strength normalized to weight (STR-N) with age. The cohort was analyzed as a whole and in groups based on functional impairment as reflected by Gross Motor Function Classification System (GMFCS) level. RESULTS: Strength increased significantly over time for the entire cohort at a rate of 20.83 N/y (P=0.01). Weight increased significantly over time for the entire cohort at a rate of 3.5 kg/y (P<0.0001). Lower extremity STR-N decreased significantly over time for the entire cohort at a rate of 0.84 N/kg/y (P<0.0001). The rate of decline in STR-N (N/kg/y) was comparable among age groups of the children in the study group. There were no significant differences in the rate of decline of STR-N (N/kg/y) among GMFCS levels. There was a 90% chance of independent ambulation (GMFCS levels I and II) when STR-N was 21 N/kg (49% predicted relative to typically developing children). DISCUSSION: The results of this study support the longstanding clinically based observation that STR-N decreases with age in children with CP. This decrease occurs throughout the growing years, and across GMFCS levels I to III. Independent ambulation becomes less likely as STR-N decreases. This information can be used to support the rationale, and provide guidelines, for a range of interventions designed to promote ambulation in children with CP.

Analysis of the relationships that body composition and muscular strength have with oxygen cost of walking in children with cerebral palsy.

OBJECTIVE: To investigate whether body composition and lower extremity strength relate to oxygen cost of walking in children with cerebral palsy (CP), and to evaluate the relative contributions of these measures to explain variation in oxygen cost seen in this population. METHODS: A total of 116 children with spastic diplegic CP, Gross Motor Function Classification System levels I-III, aged 8-18 participated. Strength, body composition (body mass index (BMI) and percent body fat) and oxygen cost were recorded. Pearson correlations assessed relationships between variables of body composition and strength to oxygen cost. Forward stepwise linear regression analyzed variance explained by strength and body composition measures. Oxygen data were analyzed by weight status classifications using one-way analysis of variance with significance set at p<0.05. RESULTS: Total strength (r=-0.27) and total extensor strength (r=-0.27) had fair inverse relationships with oxygen cost. Total extensor strength explained 7.5% (r(2)=0.075, beta=-0.274, p<0.01) of the variance in oxygen cost. Body composition did not explain significant variance in oxygen cost, however significant differences were found in oxygen consumption (p=0.003) and walking velocity (p=0.042) based on BMI weight classifications. CONCLUSIONS: For ambulatory children with CP, oxygen cost during walking can be partially explained by total extensor strength and not body composition. However, those categorized as obese may adjust to a slower walking speed to keep their oxygen cost sustainable, which may further affect their ability to keep up with typically developing peers and possibly lead to greater fatigue.

Variability explained by strength, body composition and gait impairment in activity and participation measures for children with cerebral palsy: a multicentre study.

OBJECTIVE: To determine the amount of variability in scores on activity and participation measures used to assess ambulatory individuals with cerebral palsy explained by strength, body composition, gait impairment and participant characteristics. DESIGN: Multicentre prospective cross-sectional study. SETTING: Seven paediatric-orthopaedic specialty hospitals. PARTICIPANTS: Three hundred and seventy-seven ambulatory individuals (241 males, 136 females) with cerebral palsy, Gross Motor Function Classification System (GMFCS) levels I-III (I = 148, II = 153, III = 76), ages 8-18 years (mean 12 years 9 months, SD 2 years 8 months). METHODS: Participants completed assessments of GMFCS level, patient history, lower extremity muscle strength, Gross Motor Function Measure (GMFM-66), Pediatric Outcomes Data Collection Instrument (PODCI), instrumented gait analysis, 1 minute walk test, Timed Up-and-Go and body composition. Multiple linear regression and bootstrap analyses were performed for each outcome measure, stratified by GMFCS level. RESULTS: The amount of variability in outcome measures explained by participant characteristics, strength, and gait impairment ranged from 11% to 50%. Gait impairment was the most common predictor variable and frequently explained the greatest variance across all outcome measures and GMFCS levels. As gait impairment increased, scores on outcome measures decreased. Strength findings were inconsistent and not a primary factor. Body composition contributed minimally (<4%) in explaining variability. Participant characteristics (cerebral palsy type, gestational age and age at walking onset), were significant predictor variables in several models. CONCLUSIONS: Variability in outcome measure scores is multifaceted and only partially explained by strength and gait impairment illustrating the challenges of attempting to explain variation within this heterogeneous population. Clinicians treating individuals with cerebral palsy should consider this when developing treatment paradigms.

Evaluation of the treatment of pectus carinatum with compressive orthotic bracing using three dimensional body scans.

PURPOSE: The purpose of this study is to measure the effectiveness of compressive orthotic brace therapy for the treatment of pectus carinatum using an adjusted Haller Index (HI) measurement calculated from 3D body scan (BS) images. METHODS: Pediatric patients with pectus carinatum were treated with either compressive orthotic bracing or observation. An adjusted BS Haller index (HI) was calculated from serial 3D BS images obtained on all patients. Medical records were evaluated to determine treatment with bracing and brace compliance more than 12hours daily. Compliant patient measurements were compared to non-compliant and non-brace groups. RESULTS: Forty patients underwent compressive orthotic bracing, while ten were observed. Twenty-three patients were compliant with bracing, and seventeen patients were non-compliant. Compliant patients exhibited an 8.2% increase, non-compliant patients had a 1.5% increase, and non-brace patients exhibited a 2.5% increase in BS HI. The change in BS HI of compliant patients was significantly different compared to non-brace patients (p=0.004) and non-compliant patients (p<0.001). CONCLUSIONS: Three dimensional BS is an effective, radiation free, and objective means to evaluate patients treated with compressive orthotic bracing.

One-Minute Walk and modified Timed Up and Go tests in children with cerebral palsy: performance and minimum clinically important differences.

AIM This prospective multicenter study assessed performance and changes over time, with and without surgical intervention, in the modified Timed Up and Go (mTUG) and One-Minute Walk tests (1MWT) in children with bilateral cerebral palsy (CP). Minimum clinically important differences (MCIDs) were established for these tools. METHOD Two hundred and nineteen participants with bilateral spastic CP (Gross Motor Function Classification System [GMFCS] levels I­III) were evaluated at baseline and 12 months follow-up. The non-surgical group (n=168; 54 females, 114 males; mean age 12y 11mo, [SD 2y 7mo], range 8y 1mo­19y) had no surgical interventions during the study. The surgical group (n=51; 19 females, 32 males; mean age 12y 10mo [SD 2y 8mo] range 8y 2mo­17y 5mo) underwent soft-tissue and/or bony procedures within 12 months from baseline. The mTUG and 1MWT were collected and MCIDs were established from the change scores of the non-surgical group. RESULTS Dependent walkers (GMFCS level III) required more time to complete the mTUG (p≤0.01) than independent walkers (GMFCS levels I and II). For the 1MWT, distance walked decreased with increasing impairment (p≤0.01). 1MWT and mTUG change scores were not significantly different at any GMFCS level for either the surgical or non-surgical groups (p≤0.01). INTERPRETATION Children with varying levels of function (GMFCS level) perform differently on the 1MWT and mTUG. The data and MCID values can assist clinicians in interpreting changes over time and in assessing interventions.

Gait and participation outcomes in adults with cerebral palsy: a series of case studies using mixed methods.

BACKGROUND: There is a paucity of information on long-term outcomes of adults with cerebral palsy (CP) who received orthopedic interventions in childhood. Clinical effectiveness research requires assessment of outcomes that account for personal and environmental factors that may mediate the effects of treatment, in addition to body structures & function, activity, and participation. OBJECTIVE/HYPOTHESIS: The purpose of this study is to provide a descriptive analysis of characteristics associated with gait and participation outcomes in a series of case studies of adults with CP. METHODS: Participants had follow up gait analysis and clinical evaluation in adulthood and assessment of outcomes with the FIM instrument, the SF-36 Health survey, the Canadian Occupational Performance Measure, and semi-structured questions. RESULTS: Twenty-two out of 26 participants (mean age = 25 years; GMFCS level I (n = 9); II (n = 3); III (n = 11); IV (n = 3)) maintained or improved childhood gait abilities, with levels of participation in society similar to age matched peers. Higher level of severity and personal choices impacted gait abilities in the four who declined. Majority of participants lost range of motion in hip flexion and knee extension, had pain, reported a fitness program, and increased in weight status. Personal factors and environmental factors played a role in both gait and participation outcomes. CONCLUSION: Promotion of fitness activities and social advocacy are warranted for adults with CP. Clinical effectiveness research of long-term impact of orthopedic interventions should account for treatment effects on body structures & function, activity, participation, and modifying effects of personal, and environmental factors.

Rasch analysis of items from two self-report measures of motor function: determination of item difficulty and relationships with children's ability levels.

AIM: The aim of this article was to determine item measurement properties of a set of items selected from the Gillette Functional Assessment Questionnaire (FAQ) and the Pediatric Outcome Data Collection Instrument (PODCI) using Rasch analysis, and to explore relationships between the FAQ/PODCI combined set of items, FAQ walking scale level, Gross Motor Function Classification System (GMFCS) levels, and the Gait Deviation Index on a common measurement scale. METHOD: Rasch analysis was performed on data from a retrospective chart review of parent-reported FAQ and PODCI data from 485 individuals (273 males; 212 females; mean age 9 y 10 mo, SD 3 y 10 mo) who underwent first-time three-dimensional gait analysis. Of the 485 individuals, 289 had a diagnosis of cerebral palsy (104 GMFCS level I, 97 GMFCS level II, 69 GMFCS level III, and 19 GMFCS level IV). Rasch-based person abilities and item difficulties based on subgroups defined by the FAQ walking scale level, Gait Deviation Index, and the GMFCS level were compared. RESULTS: The FAQ/PODCI item set demonstrated necessary Rasch characteristics to support its use as a combined measurement scale. Item groupings at similar difficulty levels were consistent with the mean person abilities of subgroups based on FAQ walking scale level, Gait Deviation Index, and GMFCS level. INTERPRETATION: Rasch-derived person ability scores from the FAQ/PODCI combined item set are consistent with clinical measures. Rasch analysis provides insights that may improve interpretation of the difficulty of motor functions for children with disabilities.

Accuracy, reliability, and validity of a 3-dimensional scanner for assessing torso shape in idiopathic scoliosis.

STUDY DESIGN: Prospective cohort with concurrent controls. OBJECTIVE: To establish accuracy, reliability, and validity of the Vitronic 3D Body Scanner for the evaluation of torso asymmetry in patients with idiopathic scoliosis. SUMMARY OF BACKGROUND DATA: Improved appearance is an important expectation of treatment for patients with scoliosis and their parents. Despite being the "gold standard" for quantifying outcomes, Cobb angles do not explain perception of appearance or quality of life. Surface topography is an attractive noninvasive alternative to radiography but has not been studied in the context of patient-centered outcomes. METHODS: Thirty-six adolescents with idiopathic scoliosis undergoing surgical correction had pre- and postoperative radiographs and evaluation of standing posture, torso surface shape, and responses to the Scoliosis Research Society-22 and Spinal Appearance Questionnaire. Twenty-one adolescents without scoliosis were evaluated for comparison. Scanner accuracy was assessed by scanning an object of known dimensions. Within-session reliability of body shape measures constructed from scan data was assessed. Discriminant validity was assessed by examining pre- to postoperative differences. Concurrent validity was examined through correlations of scan measures with radiographs, optoelectronic measures of posture, and self-report responses to the Scoliosis Research Society-22 and Spinal Appearance Questionnaire. RESULTS: Scan system measurement error was 1.74 ± 1.56 mm. Within-session reliability was excellent for the control (intraclass correlation coefficient = 0.83) and scoliosis (intraclass correlation coefficient = 0.94) groups. Medial/lateral torso shift, rotation, and right/left asymmetry differed significantly among the preoperative, postoperative, and control groups (analysis of variance, P < 0.05). Torso asymmetry measures correlated with radiographical measures (r = 0.43-0.51), optoelectronical measures of posture and symmetry (r = 0.33-0.75), and appearance and quality-of-life domains of the Scoliosis Research Society-22 (r = 0.35-0.64) and the Spinal Appearance Questionnaire (r = 0.48-0.67). CONCLUSION: The Vitronic 3D Body Scanner has sufficient accuracy, reliability, and validity to monitor torso asymmetry due to scoliosis. Scan-based measures differentiate between normal and pathological and between preoperative and postoperative body shape and show good correlation with measures of appearance and quality of life.

Determinants of intensity of participation in leisure and recreational activities by youth with cerebral palsy.

OBJECTIVE: To test a model of determinants of intensity of participation in leisure and recreational activities by youth with cerebral palsy (CP). DESIGN: Prospective cohort study. SETTING: Children's hospitals (N=7). PARTICIPANTS: Youth with CP (N=205; age, 13-21y) and their parents. The sample included 107 (57.2%) males and 26 (12.7%) to 57 (27.8%) youth in each of the 5 levels of the Gross Motor Function Classification System (GMFCS). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Youth completed the Children's Assessment of Participation and Enjoyment by means of an interview. Parents completed the Pediatric Outcomes Data Collection Instrument, Family Environment Scale, Coping Inventory, Measure of Processes of Care, a demographic questionnaire, and a services questionnaire. RESULTS: Structural equation modeling was used to test the model. Fit statistics indicate good model fit. The model explains 35% of the variance in intensity of participation. Path coefficients (P ≤ .05) indicate that higher physical ability, higher enjoyment, younger age, female sex, and higher family activity orientation are associated with higher intensity of participation. GMFCS level and caregiver education have indirect effects on intensity of participation. The path between services and intensity of participation was not significant. CONCLUSIONS: Participation by youth with CP is influenced by multiple factors. The influence of physical activity supports the importance of activity accommodations and assistive technology for youth who are not capable of improving physical ability. Knowledge of family activity orientation is important for identifying opportunities for participation. The unexplained variance suggests that the model should include other determinants, such as physical accessibility and availability of transportation and community leisure and recreational activities.

Efficacy of clinical gait analysis: A systematic review.

The aim of this systematic review was to evaluate and summarize the current evidence base related to the clinical efficacy of gait analysis. A literature review was conducted to identify references related to human gait analysis published between January 2000 and September 2009 plus relevant older references. The references were assessed independently by four reviewers using a hierarchical model of efficacy adapted for gait analysis, and final scores were agreed upon by at least three of the four reviewers. 1528 references were identified relating to human instrumented gait analysis. Of these, 116 original articles addressed technical accuracy efficacy, 89 addressed diagnostic accuracy efficacy, 11 addressed diagnostic thinking and treatment efficacy, seven addressed patient outcomes efficacy, and one addressed societal efficacy, with some of the articles addressing multiple levels of efficacy. This body of literature provides strong evidence for the technical, diagnostic accuracy, diagnostic thinking and treatment efficacy of gait analysis. The existing evidence also indicates efficacy at the higher levels of patient outcomes and societal cost-effectiveness, but this evidence is more sparse and does not include any randomized controlled trials. Thus, the current evidence supports the clinical efficacy of gait analysis, particularly at the lower levels of efficacy, but additional research is needed to strengthen the evidence base at the higher levels of efficacy.

Content range and precision of a computer adaptive test of upper extremity function for children with cerebral palsy.

This article reports on the content range and measurement precision of an upper extremity (UE) computer adaptive testing (CAT) platform of physical function in children with cerebral palsy. Upper extremity items representing skills of all abilities were administered to 305 parents. These responses were compared with two traditional standardized measures: Pediatric Outcomes Data Collection Instrument and Functional Independence Measure for Children. The UE CAT correlated strongly with the upper extremity component of these measures and had greater precision when describing individual functional ability. The UE item bank has wider range with items populating the lower end of the ability spectrum. This new UE item bank and CAT have the capability to quickly assess children of all ages and abilities with good precision and, most importantly, with items that are meaningful and appropriate for their age and level of physical function.

Factor- and item-level analyses of the 38-item activities scale for kids-performance.

AIM: Children and adolescents highly value their ability to participate in relevant daily life and recreational activities. The Activities Scale for Kids-performance (ASKp) instrument measures the frequency of performance of 30 common childhood activities, and has been shown to be valid and reliable. A revised and expanded 38-item ASKp (ASKp38) version has been reported in recent literature and is currently used in clinical research. The aim of this paper is to assess the factor structure and item-level statistics of the ASKp38. METHOD: Our study used factor analyses and Rasch analyses to determine the item-set dimensionality and to calculate item-level statistics respectively, for existing ASKp38 data from 200 children (104 males; 96 females; mean age 12y 7mo; SD 2y 8mo; range 6-20y) with physical disabilities. The children had a variety of physical impairments including cerebral palsy (n = 105; range 8-13 y), limb salvage (n = 18; range 11-20y), arthrogryposis (n = 13; 6-17y), and other, including individuals with spina bifida and spinal cord injury (n = 64; 8-19 y). RESULTS: A two-factor model, with components of activities of daily living and play, most optimally fit the data. Item-fit statistics based on this two-factor model demonstrated adequate fit and content coverage. INTERPRETATION: The ASKp38 appears to consist of two factors, defined as (1) activities of daily living and (2) play, and may be used to measure the frequency of activity performance on two corresponding subscales.

Determinants of intensity of participation in leisure and recreational activities by children with cerebral palsy.

AIM: To test a model of child, family, and service determinants of intensity of participation in leisure and recreational activities by children with cerebral palsy (CP). METHOD: Participants were 288 children with CP, age range 6 to 12 years (mean 9y 8mo, SD 2y), and their parents from seven children's hospitals. The sample comprised 166 (57.6%) males and 122 (42.4%) females, and between 40 (13.9%) and 74 (25.7%) children in each of the five levels of the Gross Motor Function Classification System. Children completed the Children's Assessment of Participation and Enjoyment by interview. Parents completed the Pediatric Outcomes Data Collection Instrument, Family Environment Scale, Coping Inventory, Measure of Processes of Care, and two questionnaires. Structural equation modeling was used to test the model. RESULTS: Fit statistics indicated a good model fit. The model explains 32% of the variance in intensity of participation. Path coefficients (p ≤ 0.05) indicate that higher gross motor function, higher enjoyment, more effective adaptive behavior, younger age, and higher family activity orientation are associated with higher intensity of participation. The path between services and participation was not significant. INTERPRETATION: Intensity of participation of children with CP is influenced by multiple child and family determinants. Children's gross motor function and behavior in life situations are important for participation; knowledge of activities the child and family enjoy has implications for opportunities for participation. Professionals are encouraged to address priorities for leisure and recreation identified by children with CP and their families.