Prevalence of cerebral palsy, co-occurring autism spectrum disorders, and motor functioning - Autism and Developmental Disabilities Monitoring Network, USA, 2008.

AIM: The aim of this study was to report the prevalence and characteristics of children with cerebral palsy (CP). METHOD: Children with CP (n=451) were ascertained by the Autism and Developmental Disabilities Monitoring (ADDM) Network, a population-based, record-review surveillance system monitoring CP in four areas of the USA. Prevalence was calculated as the number of children with CP among all 8-year-old children residing in these areas in 2008. Motor function was categorized by Gross Motor Function Classification System level and walking ability. Co-occurring autism spectrum disorders (ASD) and epilepsy were ascertained using ADDM Network surveillance methodology. RESULTS: The period prevalence of CP for 2008 was 3.1 per 1000 8-year-old children (95% confidence interval 2.8-3.4). Approximately 58% of children walked independently. Co-occurring ASD frequency was 6.9% and was higher (18.4%) among children with non-spastic CP, particularly hypotonic CP. Co-occurring epilepsy frequency was 41% overall, did not differ by ASD status or CP subtype, and was highest (67%) among children with limited or no walking ability. INTERPRETATION: The prevalence of CP in childhood from US surveillance data has remained relatively constant, in the range of 3.1 to 3.6 per 1000, since 1996. The higher frequency of ASD in non-spastic than in spastic subtypes of CP calls for closer examination.

The role of migration and choice of denominator on the prevalence of cerebral palsy.

AIM: Differential migration and choice of denominator have been hypothesized to contribute to differences between period prevalence and birth prevalence of cerebral palsy (CP). The purpose of this study was to evaluate the effects of migration and choice of denominator on the prevalence of CP. METHOD: Data from the Metropolitan Atlanta Developmental Disabilities Surveillance Program and census and birth certificate files were used to calculate various CP prevalence estimates for 2000. RESULTS: The overall CP period prevalence was 3.2 (95% confidence interval [CI] 2.7-3.8) per 1000 8-year-olds and was similar for those born in Atlanta who resided there at age 8 years (3.3; 95% CI 2.7-4.1) and those born outside Atlanta who moved into Atlanta by age 8 years (3.0; 95% CI 2.3-3.9). CP prevalence in these two migration strata was similar by sex and race/ethnicity. CP birth prevalence of 8-year-olds in Atlanta in 2000 was 2.0 (95% CI 1.6-2.5) per 1000 live births in 1992. INTERPRETATION: The authors found no evidence to support the hypothesis that differential in-migration explained higher period than birth prevalence of CP in Atlanta. Comparability of CP prevalence across geographic areas will be enhanced if future studies report both period and birth prevalence.

Feasibility and reliability of classifying gross motor function among children with cerebral palsy using population-based record surveillance.

For conditions with wide-ranging consequences, such as cerebral palsy (CP), population-based surveillance provides an estimate of the prevalence of case status but only the broadest understanding of the impact of the condition on children, families or society. Beyond case status, information regarding health, functional skills and participation is necessary to fully appreciate the consequences of the condition. The purpose of this study was to assess the feasibility and reliability of enhancing population-based surveillance by classifying gross motor function (GMF) from information available in medical records of children with CP. We assessed inter-rater reliability of two GMF classification methods, one the Gross Motor Function Classification System (GMFCS) and the other a 3-category classification of walking ability: (1) independently, (2) with handheld mobility device, or (3) limited or none. Two qualified clinicians independently reviewed abstracted evaluations from medical records of 8-year-old children residing in southeast Wisconsin, USA who were identified as having CP (n = 154) through the Centers for Disease Control and Prevention's Autism and Developmental Disabilities Monitoring Network. Ninety per cent (n = 138) of the children with CP had information in the record after age 4 years and 108 (70%) had adequate descriptions of gross motor skills to classify using the GMFCS. Agreement was achieved on 75.0% of the GMFCS ratings (simple kappa = 0.67, 95% confidence interval [95% CI 0.57, 0.78], weighted kappa = 0.83, [95% CI 0.77, 0.89]). Among case children for whom walking ability could be classified (n = 117), approximately half walked independently without devices and one-third had limited or no walking ability. Across walking ability categories, agreement was reached for 94% (simple kappa = 0.90, [95% CI 0.82, 0.96], weighted kappa = 0.94, [95% CI 0.89, 0.98]). Classifying GMF in the context of active records-based surveillance is feasible and reliable. Future surveillance efforts that include functional level among children with cerebral palsy may provide important information for monitoring the impact of the condition for programmatic and policy purposes.

Exclusion of progressive brain disorders of childhood for a cerebral palsy monitoring system: a public health perspective.

BACKGROUND: Cerebral palsy (CP) is defined by its nonprogressive features. Therefore, a standard definition and list of progressive disorders to exclude would be useful for CP monitoring and epidemiologic studies. METHODS: We reviewed the literature on this topic to 1) develop selection criteria for progressive brain disorders of childhood for public health surveillance purposes, 2) identify categories of disorders likely to include individual conditions that are progressive, and 3) ascertain information about the relative frequency and natural history of candidate disorders. RESULTS: Based on 19 criteria that we developed, we ascertained a total of 104 progressive brain disorders of childhood, almost all of which were Mendelian disorders. DISCUSSION: Our list is meant for CP surveillance programs and does not represent a complete catalog of progressive genetic conditions, nor is the list meant to comprehensively characterize disorders that might be mistaken for cerebral palsy. The criteria for progressive disorders that we developed could be applied by public health investigators in the future, as more children with very rare conditions are followed and new candidate disorders are identified.

Prevalence and functioning of children with cerebral palsy in four areas of the United States in 2006: a report from the Autism and Developmental Disabilities Monitoring Network.

AIM: To estimate the prevalence of cerebral palsy (CP) and the frequency of co-occurring developmental disabilities (DDs), gross motor function (GMF), and walking ability using the largest surveillance DD database in the US. METHODS: We conducted population-based surveillance of 8-year-old children in 2006 (N=142,338), in areas of Alabama, Georgia, Wisconsin, and Missouri. This multi-site collaboration involved retrospective record review at multiple sources. We reported CP subtype, co-occurring DDs, Gross Motor Function Classification System (GMFCS) level, and walking ability as well as CP period prevalence by race/ethnicity and sex. RESULTS: CP prevalence was 3.3 (95% confidence interval [CI]: 3.1-3.7) per 1000 and varied by site, ranging from 2.9 (Wisconsin) to 3.8 (Georgia) per 1000, 8-year olds (p<0.02). Approximately 81% had spastic CP. Among children with CP, 8% had an autism spectrum disorder and 35% had epilepsy. Using the GMFCS, 38.1% functioned at the highest level (I), with 17.1% at the lowest level (V). Fifty-six percent were able to walk independently and 33% had limited or no walking ability. INTERPRETATION: Surveillance data are enhanced when factors such as functioning and co-occurring conditions known to affect clinical service needs, quality of life, and health care are also considered.

Prevalence of cerebral palsy: Autism and Developmental Disabilities Monitoring Network, three sites, United States, 2004.

BACKGROUND: Cerebral palsy (CP) is the most common cause of motor disability in children and an important public health issue in the United States. The Autism and Developmental Disabilities Monitoring (ADDM) Network is a multisite program funded by the Centers for Disease Control and Prevention to determine trends in the prevalence of children with developmental disabilities, including CP, in the United States. This report describes population-based estimates of CP prevalence among 8-year-old children in three sites in the United States. METHODS: The ADDM Network conducted surveillance of CP among 8-year-old children living in north central Alabama, metropolitan Atlanta, and south central Wisconsin in 2004 (N = 68,272). This multisite collaboration involved the retrospective collection, linking, and analysis of data from multiple service providers and the population census estimates. RESULTS: The average prevalence of CP in 2004 across the three sites was 3.3 per 1,000 (95% confidence interval, 2.9-3.8). The prevalence was significantly higher in boys than in girls overall (male/female ratio, 1.4:1). The most common subtype across all three sites was spastic CP, ranging from 85% in Georgia to 89% in Alabama and Wisconsin. CONCLUSIONS: Ongoing, systematic, population-based surveillance in different areas of the United States is needed to describe and monitor CP prevalence. In addition, enhancing the surveillance system to include information about functional abilities is needed to better understand the public health impact of CP and strategies for improving quality of life and participation in activities at home and in the community.

Prevalence of cerebral palsy in 8-year-old children in three areas of the United States in 2002: a multisite collaboration.

OBJECTIVE: The goal was to estimate the prevalence of cerebral palsy and cerebral palsy subtypes among children in 3 areas of the United States by using a population-based surveillance system. METHODS: Using methods developed by the Centers for Disease Control and Prevention Metropolitan Atlanta Developmental Disabilities Surveillance Program, investigators from the Autism and Developmental Disabilities Monitoring Network conducted surveillance of cerebral palsy among 8-year-old children living in northern Alabama, metropolitan Atlanta, and southeastern Wisconsin in 2002 (N = 114,897). Cross-sectional data were collected through retrospective record review from multiple sources. Cases were linked to birth certificate and census files to obtain additional information. Period prevalence estimates were calculated per 1000 children 8 years of age. RESULTS: The average prevalence of cerebral palsy across the 3 sites was 3.6 cases per 1000, with notably similar site-specific prevalence estimates (3.3 cases per 1000 in Wisconsin, 3.7 cases per 1000 in Alabama, and 3.8 cases per 1000 in Georgia). At all sites, prevalence was higher in boys than girls (overall boy/girl ratio: 1.4:1). Also, at all sites, the prevalence of cerebral palsy was highest in black non-Hispanic children and lowest in Hispanic children. At all sites, the prevalence among children living in low- and middle-income neighborhoods was higher than that among children living in high-income neighborhoods. Spastic cerebral palsy was the most common subtype (77% of all cases), with bilateral spastic cerebral palsy dominating the spastic group (70%). CONCLUSION: These findings contribute new knowledge to the epidemiology of cerebral palsy in the United States. The similarities in prevalence rates and patterns of cerebral palsy reported for 8-year-old children at 3 geographically distinct sites provide evidence of the reliability of the surveillance methods used by the Autism and Developmental Disabilities Monitoring Network.