To describe cerebral palsy (CP) surveillance programmes and identify similarities and differences in governance and funding, aims and scope, definition, inclusion/exclusion criteria, ascertainment and data collection, to enhance the potential for research collaboration.
Representatives from 38 CP surveillance programmes were invited to participate in an online survey and submit their data collection forms. Descriptive statistics were used to summarize information submitted.
Twenty-seven surveillance programmes participated (25 functioning registers, two closed owing to lack of funding). Their aims spanned five domains: resource for CP research, surveillance, aetiology/prevention, service planning, and information provision (in descending order of frequency). Published definitions guided decision making for the definition of CP and case eligibility for most programmes. Consent, case identification, and data collection methods varied widely. Ten key data items were collected by all programmes and a further seven by at least 80% of programmes. All programmes reported an interest in research collaboration.
Despite variability in methodologies, similarities exist across programmes in terms of their aims, definitions, and data collected. These findings will facilitate harmonization of data and collaborative research efforts, which are so necessary on account of the heterogeneity and relatively low prevalence of CP.
Cerebral palsy (CP) is a heterogeneous neurological condition with many aetiologies. Population-based surveillance programmes are considered the criterion standard for describing its changing birth and childhood prevalence and characteristics.
Current collaborations between CP surveillance programmes that are geographically close allow not only comparisons between CP birth year cohorts but also pooling of data and greater statistical power for subgroup analyses. The first large network of CP surveillance programmes, the Surveillance of Cerebral Palsy in Europe (SCPE), was formed in 1998,
The purpose of this survey was to describe CP surveillance programmes and identify similarities and differences across topics of importance for the relevance and sustainability of, and collaboration between, surveillance programmes. It is anticipated that results will (1) encourage and inform those establishing new programmes about the methods and data items collected by existing programmes; (2) inform health professionals and researchers of the existence of national and international surveillance programmes and the potential for population-based research and data linkages; and (3) assist existing surveillance programmes to investigate the potential for future collaborations.
Representatives from 38 surveillance programmes were contacted by e-mail and invited to participate in the online survey. Surveillance programmes were identified by the study authors, and all participants were encouraged to forward the survey link to any other known surveillance programmes.
The survey, developed and constructed by the study authors, was available online via ‘Survey Monkey’ (
Given the negligible risk posed by the survey, exemption from ethical review was approved by the Cerebral Palsy Alliance Ethics Committee, a recognized National Health and Medical Research Council Human Research Ethics Committee (EC 00402). Informed consent of the participants was implied by survey completion. Participants were contacted by e-mail if clarification was required on specific responses.
Descriptive statistics were generated throughout. For questions with response rates of at least 80%, relative frequencies (percentages) are reported. Absolute frequencies (raw counts) are otherwise reported. Inductive content analysis was used to analyse the qualitative data from open-ended questions. For items where multiple responses were possible, percentages can exceed 100%.
Twenty-seven surveillance programmes participated (response rate 71%), including three collaborations between surveillance programmes (SCPE, ADDM, ACPR). Participants represented 11 countries and three geographical regions (Australia, Europe, and North America). Two surveillance programmes reported that they have ceased operation in recent years owing to lack of funding. Non-responders included 10 European programmes and one programme from Australasia. All further results refer to the 25 operating programmes. Programmes varied greatly in the birth years included. The earliest data available are from the birth year 1954 (
There was considerable common ground about the aims of surveillance programmes, and most reported multiple aims. Responses could be grouped in five key domains: (1) resource for CP research (100%), for example identifying potential subjects, identifying CP as a long term outcome, and gauging representativeness of study samples; (2) surveillance (92%), for example monitoring prevalence, time trends, or survival by key characteristics; (3) prevention (68%), for example identifying aetiological pathways and reporting prevalence over time with the introduction of preventive strategies; (4) planning (48%), for example assisting with the planning of services for people with CP; (5) provide information about CP (20%), for example raising community awareness.
Five definitions of CP were used, with 46% of surveillance programmes using more than one definition. The SCPE definition was most cited (63%),
There was significant variability in demographic criteria determining eligibility (where they were born, where they currently reside, where their family resided at time of birth), with many programmes using multiple criteria. Denominators reported included live births (78%), children living in area at a specified age (35%), neonatal survivors (26%), 1 year survivors (9%), with some programmes having access to more than one denominator.
Funding for surveillance programmes was received from the government (health/education/research) (72%), not for profit/charitable organizations (12%), and other external sources (12%). Some groups reported multiple funding sources and one programme received no specific funding for CP surveillance activities.
To help improve precision in identification of cases, 55% of programmes used either of the papers by Badawi et al.
Surveillance programmes were specifically asked about several eligibility issues that have historically varied between programmes. Variation was still seen, with 44% of programmes stipulating a minimum age of survival (
The consent requirements for collecting, recording, and maintaining the data set varied across surveillance programmes (
Many different methods were used to identify new cases, with 68% of surveillance programmes using four or more different methods and 84% using five or more different data sources (
Age at data collection varied greatly between the surveillance programmes, ranging from birth/first diagnosis to older adulthood, depending on the programme’s purpose and geographical region. Ascertainment was generally considered complete between 5 and 8 years of age. Forty-six per cent of surveillance programmes had a procedure for assessing the completeness of population ascertainment. Six programmes reported comparing rates with long-standing population surveillance programmes anticipated to have similar rates of CP, three compared with other surveillance programmes/health care sources, and two used capture–recapture techniques: however, short of house-to-house surveys,
Significant geographical variation existed in classification of CP based on the type/s and topographical pattern of the movement disorder, reflecting the different definitions used for CP. Within spastic CP subtypes, all European programmes used as a minimum ‘unilateral’ and ‘bilateral’ to classify topography. In Australia, monoplegia/hemiplegia/diplegia/triplegia/quadriplegia were used consistently, which can be grouped to match European categories when required. Most North American programmes used both systems.
Eighty-seven per cent of surveillance programmes collected information about aetiology of cases not postneonatally acquired, with many collecting this as free-text.
Seventy-five per cent of programmes collected data on congenital anomalies, most categorizing by International Statistical Classification of Diseases and Related Health Problems 10th Revision (ICD-10) codes and/or free text. The upper age limit for recognition of congenital anomalies varied from at birth to no restriction. Sixty-seven per cent of programmes reported that a congenital anomalies register existed serving the same population as their CP surveillance programme; seven programmes had performed linkages with these registers.
All programmes collected either (1) whether imaging had been performed (79%, of which 63% recorded where imaging was performed), and/or (2) clinical reports of imaging findings (54%), and/or (3) the original images (13%). Ninety-six per cent of all programmes collected data pertaining to cranial magnetic resonance imaging (MRI), 67% to cranial ultrasound, and 54% to cranial computed tomography.
Fourteen programmes reported the imaging classification system used by their surveillance programme to interpret and record images; seven programmes had not yet adopted a formal classification system. Seven programmes classified imaging based on clinical reports of neuroimaging findings, one programme classified scans by re-reading original images, and three used a combination of reports and rereading images. Imaging was classified by more than one person for seven programmes, and usually by a single person for three programmes. Classifications were made by a broad range of medical professionals (radiologist, neuropaediatrican, paediatric neurologist, neuroradiologist, paediatrician, paediatric neuroradiologist), other clinicians, and by surveillance programme staff.
Ninety-two per cent of programmes collected information on the plurality of the pregnancy, and 88% collected birth order. Only a few surveillance programmes systematically collected information on death of a co-multiple at <20 weeks’ gestation (17%), death of a co-multiple at >20 weeks’ gestation (17%), timing of death of a co-multiple (13%), health outcome of co-multiples (13%), zygosity (13%), or chorionicity/amnionicity (8%). Seventy-three per cent did not consider a survivor as a multiple if their comultiple(s) died before 20 weeks’ gestation.
Fifty-five per cent of programmes recorded some aspect of assisted conception, with most recording whether in vitro fertilization was used for the pregnancy.
Twenty-one per cent of programmes systematically completed follow-up of children after they had been verified as having CP. Age at follow-up and frequency varied widely, from annually, to 5 years, 10 years, and/or at 15 to 17 years of age.
Seventy-two per cent of programmes collected information on interventions received, including surgeries (56%), spasticity medications (48%), assistive devices (including orthotics and equipment) (48%), and therapies (36%). Four programmes had a longitudinal follow-up programme for secondary impairment prevention (CPUP Sweden, Danish National Cerebral Palsy Register, The Cerebral Palsy Register of Norway, NSW and ACT Cerebral Palsy Register Australia).
Data collection forms were available for 22 operating programmes. Overall, 38 items were collected by at least half of the programmes, with 10 collected by all programmes. Six of these items were collected in the same way across programmes. It was clear that there was some common ground for key data items but also considerable variation in additional data items and methods of collection (
All programmes reported an interest in collaborating with other surveillance programmes. Forty-eight per cent of programmes have had a linkage/collaborative relationship with other surveillance programmes serving the same denominator group for research purposes, for example perinatal data sets/newborn quality register, regional and national death indexes, intervention services/health databases, congenital anomalies registry, CP follow-up program. Sixty-seven per cent reported a linkage/collaborative relationship with similar CP surveillance programmes serving other denominator groups.
Eighty per cent of programmes were able to send ad hoc, de-identified individual data to be used in collaborative studies with appropriate ethics approval. Thirty-three per cent had access to controls through a variety of methods including national health care registers, sampling of birth certificates, and as invited study participants.
Current research themes being investigated by the surveillance programmes included aetiology (68%), participation (48%), evaluation of interventions (40%), and survival (32%). Fifty-two per cent of programmes reported trends that they would like to discuss with other programmes, such as the decrease in birth prevalence of CP in extremely preterm infants, increase in the proportion of unilateral CP, and the increase in the proportion of hypotonic CP, all of which were reported by more than one programme.
CP surveillance programmes, like the people with CP that they represent, are heterogeneous. Although differences in methodologies existed across various geographical regions, there was some consistency in aims, definitions, and data sets. Some differences in important areas such as inclusion/exclusion criteria have recently been reported in the paper by Smithers-Sheedy et al.
Although several data items were collected by the majority of programmes, the manner in which each was collected was not always comparable, particularly for items referring to aetiological risk factors, neonatal history, and associated impairments. For example, 34 different data items referring to vision were used across the data collection forms received. Professionals working with surveillance programmes need to decide if these common data elements are sufficiently important to warrant taking further steps to facilitate harmonization internationally. Himmelmann and colleagues recommended that the collection of CP register data be updated in line with emerging knowledge in the field,
The publication of the Gross Motor Function Classification System (GMFCS)
Where numbers of cases are small, collaborative research efforts are of paramount importance. All participating CP surveillance programmes reported an interest in collaborating with other programmes and, with ethics approval, most (80%) were able to provide ad hoc, de-identified individual data. Barriers to collaboration identified by survey respondents included funding difficulties, problems with harmonization and comparability of data (definition, inclusion/exclusion criteria), and with negotiating common ground and priorities for research. International collaborative research networks such as IMPACT for Cerebral Palsy (International Multidisciplinary Prevention and Cure Team) have been established to further encourage collaboration between groups.
Although systematic reviews and randomized controlled trials of interventions are considered the ‘criterion standard’ for evaluating effectiveness of interventions, surveillance programmes also have a role, particularly for heterogeneous conditions such as CP. Four surveillance programmes included an individual, longitudinal follow-up programme aiming to prevent secondary impairments. Such programmes have been shown to significantly decrease musculoskeletal complications such as hip dislocation,
It was not considered valid to report a combined prevalence of CP calculated across surveillance programmes because of the variability in methods of obtaining those estimates. Variations in estimated prevalence across surveillance programmes are considered to be at least partly accounted for by methodological differences (such as inclusion criteria, particularly whether postneonatally acquired cases are included, minimum age of survival, consent requirements, and type of denominator). The length of time a surveillance programme has been operating is also an important determinant. After commencement, it takes some years to build ascertainment as surveillance programme workers increase knowledge of locally appropriate ascertainment techniques and both medical and affected communities become aware of the existence of the surveillance programme. It is possible that variations in proportion reported with CP are due primarily to methodological differences and resulting variations in ascertainment proportion rather than to underlying differences in prevalence of the condition. Time trends should therefore only be assessed from proportions estimated by the same methods over time.
This survey had several limitations. Although attempts were made to identify and invite all known CP surveillance programmes, there are at least 11 currently operating programmes that did not participate, and a further three did not contribute their data collection forms. The programmes that did participate were mostly based in Europe and Australia, and developing countries are not represented. Although this may represent a true lack of surveillance programmes in developing countries,
Two surveillance programmes have closed in recent years owing to lack of funding, highlighting the continuing difficulties programmes face in a global climate of financial constraints. In this era of increased research into the possibilities for prevention of CP and achieving better outcomes for those with CP, surveillance programmes will play a vital role in the pragmatic evaluation of treatments that have been found to be efficacious or effective in a research setting. It is important that existing programmes are able to report not only trends in prevalence but also severity, and compare these across different geographical regions, particularly those that differ in their approaches to perinatal care and CP management.
We acknowledge and thank Kim Van Naarden Braun, Deborah Christensen, and Alyson Goodman for their comments on the draft version of this paper. The supplement was funded by the Cerebral Palsy Alliance.
A list of contributors is given in
Additional supporting information may be found in the online version of this article:
Australian Cerebral Palsy Register
Autism and Developmental Disabilities Monitoring
International Multidisciplinary Prevention and Cure Team
Manual Ability Classification System
Surveillance of Cerebral Palsy in Europe
Cerebral palsy surveillance programmes
| Name of register/surveillance group (city) | First birth | Approximate | Minimum | Postneonatal | Consent | |
|---|---|---|---|---|---|---|
| Australia | ||||||
| 1. Australian Cerebral Palsy Register | 1993 | 298 900 | No | 2 | N/A | |
| 2. NSW and ACT Cerebral Palsy Register (Sydney) | 1993 | 102 300 | No | 2 | C, O | |
| 3. Northern Territory Cerebral Palsy | 1993 | 3700 | No | 2 | C | |
| 4. Queensland Cerebral Palsy Register (Brisbane) | 1993 | 63 000 | No | 2 | C | |
| 5. Tasmanian Cerebral Palsy Register (Hobart) | 1993 | 6100 | No | 2 | C | |
| 6. The South Australian Cerebral Palsy | 1993 | 20 200 | No | 2 | M, L, C | |
| 7. Victorian Cerebral Palsy Register (Melbourne) | 1970 | 70 000 | No | 2 | L | |
| 8. Western Australian Register of Developmental | 1956 | 33 600 | No | 5 | M | |
| Europe | ||||||
| 9. C 28 RCP-HR Register of Cerebral Palsy | 2003 | 28 400 | Yes | 5 | 2 | C |
| 10. CPUP (Lund) | 1990 | 113 600 | Yes | 2 (for incidence) | 3 | C |
| 11. Danish National Cerebral Palsy | 1960 | 64 500 | Yes | 1 in case of | Not included | L |
| 12. Northern Ireland Cerebral Palsy | 1997 | 25 300 | Yes | 16 | 5 | L |
| 13. North of England Collaborative Cerebral | 1991 | 30 500 | No | 10 | C | |
| 14. Registre des Handicaps de l’Enfant en | 1986 | 16 000 | Yes | 4 | 5 | O |
| 15. RHEOP (Grenoble) | 1980 | 30 000 | No | 5 | O | |
| 16. Slovenian Register for Cerebral | 2001 | 19 800 | No | 2 | L | |
| 17. Surveillance of Cerebral Palsy in | 1976 | 350 000 | Yes | 2 | No limitation | N/A |
| 18. Surveillance program: Epidemiology | 1987 | 7000 | No | 5 | C | |
| 19. The Cerebral Palsy Register of | 1996 | 61 100 | Yes | 1 | 2 | C |
| 20. The CP Register of Western | 1954 | 24 600 | Yes | 2 | 2 | L |
| North America | ||||||
| 21. Metropolitan Atlanta Developmental | 1983 | 45 000–50 000 | Yes | 8 | 8 | L |
| 22. The Autism and Developmental Disabilities | 1994 | 130 000–150 000 | Yes | 8 | 8 | L |
| 23. The Canadian Cerebral Palsy Registry | 1999 | 194 400 Children | Yes | 2 | 2 | C |
| 24. The Cerebral Palsy Research Registry (Chicago) | N/A | 3 941 000 | No | 5 | C | |
| 25. Weinberg Family Cerebral Palsy Centre, | 1977 | 239 200 | No | No limitation | L, C | |
Two additional programmes that are no longer operational participated in the survey: 4 Child – Four Counties Database of Cerebral Palsy, Vision Loss and Hearing Loss in Children (Oxfordshire, Berkshire, Buckinghamshire, and Northamptonshire); and the Merseyside Cerebral Palsy Register. N/A, not applicable; C, require individual consent to collect data; O, other: (2) NSW and ACT Cerebral Palsy Register: opt-off consent model; (14) Registre des Handicaps de l’Enfant en Haute-Garonne: after gaining individual no objection to collect the data; (15) RHEOP: individuals are informed individually but do not have to confirm whether their data can be used; M, as part of a mandatory reporting process; L, in line with specific legislation or legal agreements that allow data collection without individual consent.
Data sources
| Data sources | Programmes |
|---|---|
| Medical professionals | 25 |
| Disability service providers | 19 |
| Hospital inpatient records | 19 |
| Hospital outpatient records | 17 |
| Allied health staff | 16 |
| Birth register/certificates | 12 |
| Parents | 12 |
| Death register/certificates | 10 |
| Self-reporting | 10 |
| Routine child health surveillance | 9 |
| Diagnostic registers | 7 |
| Midwives data system | 7 |
| Education records | 6 |
| Research partnerships | 4 |
| Morbidity data system | 3 |
| Health visitors | 1 |
| Tax register | 1 |
| Other: for example prospective registrations | 8 |
Data items common to most surveillance programmes
| Items collected | Items collected | Items collected |
|---|---|---|
| Date of birth | Vision | Number previous live |
| Sex | Hearing | Order of birth (multiple |
| Birthweight | Plurality | NICU/SCN admission |
| Gestational age | Intellectual | Neonatal seizures |
| GMFCS | Mother’s year of | Aetiology of main |
| Diagnosis/motor | Place of delivery | MACS |
| Postneonatal | Communication: | Age/date at diagnosis |
| Epilepsy/seizures | Education level of parents | |
| Syndromes/ | Date of death | |
| Magnetic | Apgar | |
| Strabismus | ||
| Cranial ultrasound in | ||
| Drug treatment for hypertonia | ||
| Paediatrician/health | ||
| Assistance with conception | ||
| Ventilation in neonatal | ||
| IQ | ||
| Feeding difficulties | ||
| Computed tomography scan | ||
| Orthopaedic surgery |
Data item collected in same way across all surveillance programmes.
If included in surveillance programme. NICU, neonatal intensive care unit; SCN, special care nursery; GMFCS, Gross Motor Function Classification System; MACS, Manual Ability Classification System.
CP surveillance programmes aim to be a resource for research and surveillance.
Methods vary significantly, however all surveillance programmes are committed to collaboration.
Seventeen core data items identified should be included in new surveillance programmes.