Epidemiological research provides insights into risk factors, prevalence and outcomes of cerebral palsy (CP), a lifelong motor disorder. It provides a foundation to monitor trends and evaluate the effectiveness of interventions and public health policy. There are different approaches to gathering these insights, including the use of population-based registries, administrative health databases and insurance claims data.

In this issue of Paediatric and Perinatal Epidemiology, Paget and colleagues¹ explored the differences between populations of children with CP identified through the New South Wales/Australian Capital Territory CP Register (gold standard) and New South Wales Admitted Patient Data Collection (hospital admission dataset). The authors compared socioeconomic, clinical characteristics and mortality of the children identified in these two data sources (supplemented with data from other registries/databases).¹

Population-based CP registries are considered the gold standard because they (i) aim to capture all children with CP within a specified region to ensure completeness, often utilising multiple data sources; (ii) confirm the diagnoses around age 5–8 years using standardised diagnostic criteria to rule out another neurodevelopment disorder and ensure accuracy; and (iii) collect a comprehensive set of common data elements (CDE) using harmonising definitions and terminology around this age that are relevant to understanding the epidemiology, clinical characteristics and outcomes of CP.^2-4 This is essential to promote comparability to other CP populations to conduct meaningful analyses and draw accurate conclusions.

In their study, Paget et al. found that hospital admission data, using one or more admissions with G80 International Classification of Disease-10 AM diagnostic codes, had a sensitivity of 70% and a positive predictive value of 62% for identifying children with CP compared with the CP register, indicating moderate accuracy.¹

Compared with population-based CP registries, children identified through the hospital admission data were more likely to have multiple chronic health conditions, reside in metropolitan areas and experience higher mortality rates.¹ These differences may represent the difficulties in making a clinical diagnosis, as CP is based on risk factors and signs of motor dysfunction, or the removal of the diagnosis at a later age.^{1, 5} Consequently, there remain some uncertainties in diagnosing CP. More recently, there has been a greater emphasis on early detection of CP, as early as less than 5 months of age (using specific guidelines), to improve outcomes.⁵ In addition, in some cases, a child may be dependent on a CP diagnosis to receive access to timely multi-disciplinary supportive healthcare services. Improvements in the type and quality of administrative health data collected could improve the usefulness of data for both service evaluation and research purposes.⁶ For example, the ability to record when a diagnosis is removed would prevent the inclusion of false positive cases, who in reality have another progressive condition, in CP populations created using administrative data as in the study by Paget et al.¹

There exists a pressing need for further exploration into CP across the lifespan, not just during childhood. Paget et al. raised an interesting point that because their study was limited to children with CP, the applicability of the results to adults with CP is uncertain.¹ They drew attention to the fact that there has been an increase in research on adults with CP, as evidenced by many epidemiological studies that have employed administrative health datasets to investigate various outcomes.¹ It is becoming increasingly common for CP registers to report on the epidemiology and outcomes of adults with CP through new data collection, given that the populations of individuals with CP have now reached adulthood. Some studies have reported that although adults with CP have high comorbidity rates, they lack access to the supportive healthcare services they had as children.⁷ A recent article from the Northern Ireland Cerebral Palsy Register sheds light on the prevalence and clinical characteristics of adults living with CP, showing the complex nature of their needs and aiming to enhance supportive healthcare services.⁸ Meanwhile, the Swedish CP Follow-up Programme and National Quality Registry (CPUP) have made significant advancements in their coverage, extending their registry in 2009 to include adults with CP residing in southern Sweden, followed by a nationwide expansion in 2019.⁹ Their findings indicate that more than 90% of individuals with CP reach adulthood, with 8 out of 10 experiencing spasticity, contractures, misalignments, as well as complications related to balance and walking impairments, an increased risk of falling, pain, fatigue and dysphagia.⁹ While the CPUP collects detailed information on adults with CP through the utilisation of the CPUP-adult assessment form, these valuable data remain absent from administrative health records. It would be highly beneficial to conduct research that compares administrative health data with CP registers, specifically focusing on adults with CP, as this would provide invaluable insights into this complex condition.

It should be noted that numerous studies examining CP primarily focus on populations residing in high-income countries. While there is limited data on CP registers in low- and middle-income countries, it is reported that the birth prevalence of CP is higher in these nations compared with high-income countries (3.4 versus 1.5 per 1000 live births).¹⁰ There are also disparities in the aetiology of CP between high-income countries and low- and middle-income countries. Given that the majority of births occur in these less developed regions, it is crucial to incorporate data from these areas whenever feasible to obtain an updated understanding of CP.¹⁰ However, a recent advancement in this field comes in the form of the Global Low- and Middle-Income Country CP Register (GLM-CPR), which was established as a collaborative effort between CP registers located in low- and middle-income countries across South Asia, South East Asia and Africa.¹¹ Epidemiological and clinical data were collected by these CP registers either by using the key informant method by local volunteers in the communities or when the children attended a health institution, using standardised data elements developed by the Surveillance of Cerebral Palsy in Europe and Australian CP Register.¹¹ The GLM-CPR has recently unveiled preliminary findings on risk factors for CP, such as elevated rates of home births and the scarcity of professional assistance during childbirth. Notably, post-neonatal CP was most often due to viral infections. The majority of children in these resource-limited settings had a severe type of CP (spastic bilateral) and level of gross motor dysfunction. Unfortunately, the CP registers were not able to identify all children within the respective regions needed to accurately determine prevalence estimates.¹¹

While there are certainly limitations to using administrative health data, this remains an important source of data in many regions without CP registers. In addition, data linkage between CP registers and other datasets can enhance research outcomes by providing a more complete picture of health outcomes, education levels, employment and service utilisation, among others. Nevertheless, researchers must acknowledge the potential effects on sensitivity and positive predictive value when interpreting data on CP populations that are not obtained through the standardised methods employed by CP registers.

流行病学研究提供了对脑瘫（CP）这种终生运动障碍的危险因素、患病率和结果的见解。它为监测趋势和评估干预措施和公共卫生政策的有效性提供了基础。收集这些见解有不同的方法，包括使用基于人口的登记、管理健康数据库和保险索赔数据。

在本期《儿科和围产期流行病学》中，Paget 及其同事¹探讨了通过新南威尔士州/澳大利亚首都地区 CP 登记册（黄金标准）和新南威尔士州入院患者数据收集（入院数据集）确定的 CP 儿童群体之间的差异）。作者比较了这两个数据源（辅以其他登记/数据库的数据）中确定的儿童的社会经济、临床特征和死亡率。¹

基于人口的 CP 登记被认为是黄金标准，因为它们 (i) 旨在捕获特定区域内所有患有 CP 的儿童以确保完整性，通常利用多个数据源；(ii) 使用标准化诊断标准确认 5-8 岁左右的诊断，以排除另一种神经发育障碍并确保准确性；(iii) 使用该年龄段的统一定义和术语收集一套全面的通用数据元素 (CDE)，这些定义和术语与了解 CP 的流行病学、临床特征和结果相关。^2-4这对于促进与其他 CP 人群的可比性以进行有意义的分析并得出准确的结论至关重要。

在他们的研究中，佩吉特等人。研究发现，与 CP 登记相比，使用 G80国际疾病分类-10 AM 诊断代码的一项或多项入院数据，识别 CP 儿童的敏感性为 70%，阳性预测值为 62%，表明中度准确性。¹

与基于人口的慢性病登记相比，通过入院数据确定的儿童更有可能患有多种慢性疾病、居住在大都市地区且死亡率更高。¹这些差异可能代表了临床诊断的困难，因为 CP 是基于危险因素和运动功能障碍的体征，或者在年龄较大时取消诊断。^{1, 5}因此，诊断 CP 仍存在一些不确定性。最近，人们更加重视 CP 的早期检测，最早可在 5 个月大时进行检测（使用特定指南），以改善预后。⁵此外，在某些情况下，儿童可能需要依赖 CP 诊断才能获得及时的多学科支持性医疗服务。收集的行政健康数据的类型和质量的改进可以提高数据对于服务评估和研究目的的有用性。⁶例如，在删除诊断时进行记录的能力将防止在使用管理数据创建的 CP 人群中纳入假阳性病例，这些病例实际上患有另一种进展性疾病，如 Paget 等人的研究中所示。¹

迫切需要在整个生命周期（而不仅仅是童年时期）进一步探索脑性瘫痪。佩吉特等人。提出了一个有趣的观点，因为他们的研究仅限于患有脑瘫的儿童，因此结果对患有脑瘫的成人的适用性尚不确定。¹他们提请注意这样一个事实，即针对成人脑瘫的研究有所增加，许多流行病学研究都采用了行政健康数据集来调查各种结果，这证明了这一点。¹鉴于脑瘫患者群体现已成年，脑瘫登记册通过新数据收集报告成人脑瘫患者的流行病学和结果变得越来越普遍。一些研究报告称，尽管成人脑瘫患者的合并症率很高，但他们无法获得儿童时期的支持性医疗服务。⁷北爱尔兰脑瘫登记处最近发表的一篇文章揭示了脑瘫成人患者的患病率和临床特征，显示了他们需求的复杂性，并旨在加强支持性医疗服务。⁸与此同时，瑞典 CP 随访计划和国家质量登记处 (CPUP) 在其覆盖范围方面取得了重大进展，于 2009 年扩大了登记范围，将居住在瑞典南部的 CP 成年人纳入其中，随后于 2019 年扩大到全国范围。⁹研究结果表明，超过 90% 的脑瘫患者到了成年，其中十分之八的人出现痉挛、挛缩、错位，以及与平衡和行走障碍相关的并发症，跌倒、疼痛、疲劳和吞咽困难的风险增加。⁹虽然 CPUP 通过利用 CPUP 成人评估表收集患有脑瘫的成人的详细信息，但行政健康记录中仍然缺乏这些有价值的数据。开展将行政健康数据与 CP 登记册进行比较的研究，特别是关注患有 CP 的成年人，将非常有益，因为这将为这种复杂的情况提供宝贵的见解。

应该指出的是，许多研究 CP 的研究主要关注居住在高收入国家的人群。虽然低收入和中等收入国家的脑瘫登记数据有限，但据报道，这些国家的脑瘫出生率高于高收入国家（每 1000 名活产儿 3.4 例和 1.5 例）。¹⁰高收入国家与低收入和中等收入国家之间的 CP 病因也存在差异。鉴于大多数出生发生在这些欠发达地区，只要可行，就必须纳入这些地区的数据，以获得对 CP 的最新了解。¹⁰然而，该领域的最新进展是以全球低收入和中等收入国家 CP 登记册 (GLM-CPR) 的形式出现，该登记册是低收入和中等收入国家 CP 登记册之间合作建立的横跨南亚、东南亚和非洲。¹¹这些 CP 登记册通过社区当地志愿者使用关键信息方法收集流行病学和临床数据，或者在儿童就诊时使用欧洲脑瘫监测和澳大利亚 CP 登记册开发的标准化数据元素收集流行病学和临床数据。¹¹ GLM-CPR 最近公布了关于 CP 风险因素的初步调查结果，例如家庭分娩率升高和分娩期间专业援助的缺乏。值得注意的是，新生儿后脑瘫最常见的原因是病毒感染。在这些资源有限的环境中，大多数儿童患有严重的 CP（双侧痉挛）和粗大运动功能障碍。不幸的是，CP 登记册无法识别各个地区内的所有儿童，以准确确定患病率估计值。¹¹

虽然使用行政健康数据肯定存在局限性，但这仍然是许多没有 CP 登记的​​地区的重要数据来源。此外，CP 登记册和其他数据集之间的数据链接可以通过提供更完整的健康结果、教育水平、就业和服务利用等信息来增强研究成果。然而，研究人员必须承认，在解释不是通过 CP 登记所采用的标准化方法获得的 CP 人群数据时，对敏感性和阳性预测值的潜在影响。