Skip to main content
Advertisement
Browse Subject Areas
?

Click through the PLOS taxonomy to find articles in your field.

For more information about PLOS Subject Areas, click here.

  • Loading metrics

Association between socioeconomic status and cerebral palsy

  • Sung-Hui Tseng,

    Roles Conceptualization, Data curation, Funding acquisition, Investigation, Methodology, Resources, Supervision, Validation, Writing – original draft, Writing – review & editing

    Affiliations Department of Physical Medicine and Rehabilitation, Taipei Medical University Hospital, Taipei, Taiwan, Department of Physical Medicine and Rehabilitation, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan

  • Jiun-Yih Lee,

    Roles Data curation, Formal analysis

    Affiliation Quality Manage Center, Shin Kong Wu Ho-Su Memorial Hospital, Taipei, Taiwan

  • Yi-Lin Chou,

    Roles Data curation, Formal analysis, Methodology

    Affiliation Department of Physical Medicine and Rehabilitation, Shin Kong Wu Ho-Su Memorial Hospital, Taipei, Taiwan

  • Mei-Ling Sheu,

    Roles Conceptualization, Data curation, Formal analysis, Funding acquisition, Investigation, Methodology, Resources, Software, Supervision, Writing – review & editing

    Affiliation School of Health Care Administration, Taipei Medical University, Taipei, Taiwan

  • Yuan-Wen Lee

    Roles Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Software, Supervision, Validation, Visualization, Writing – original draft, Writing – review & editing

    m102093020@tmu.edu.tw

    Affiliations Department of Anesthesiology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan, Department of Anesthesiology, Taipei Medical University Hospital, Taipei, Taiwan

Abstract

Background

The present study investigated the annual prevalence of cerebral palsy (CP) among children aged <7 years in Taiwan and the association between socioeconomic status and CP prevalence.

Methods

Data from the Taiwan National Health Insurance Research Database for the 2002−2008 period were used in this population-based study. Severe and total CP were defined according to catastrophic illness certificate and medical claim records, respectively. The annual CP prevalence was calculated as the number of children with CP among all children aged <7 years.

Results

From 2002 to 2008, the annual prevalence of total and severe CP ranged from 1.9 to 2.8 and from 1.1 to 1.4 per 1000 children, respectively. Boys were 30% more likely to have CP than girls [adjusted relative risk (RR) and 95% confidence interval (CI) ranged from 1.3 (1.2−1.4) to 1.4 (1.2−1.5)]. Low family income was associated with a higher CP prevalence [adjusted RR (95% CI) ranged from 5.1 (4.2−6.2) to 6.4 (5.4−7.6)]. The prevalence of CP in rural area was higher than that in urban or suburban areas. The mortality rate of severe CP ranged from 12.2−22.7 per 1000 children within the 7 years study period.

Conclusions

The prevalence of CP in Taiwan is similar to that in Western countries. A higher prevalence of CP is associated with male sex, low income, and rural residential location. Our findings provide insights into CP epidemiology among the Chinese population.

Introduction

Cerebral palsy (CP) is the most common cause of childhood physical disability. The disabling conditions associated with CP impose considerable demands on the health, education, and social services of society. Therefore, it is imperative to obtain accurate and up-to-date estimates of the prevalence and associated risk factors of CP to project the burden of this condition and provide appropriate health resource allocations and effective preventive measures.

The worldwide prevalence of CP has been reported to be 2.1 per 1000 live births [1]. However, CP appeared to be more prevalent in low- or middle-income countries than in high-income countries [19]. CP prevalence was about 1.8 to 2.3 cases per 1000 children in Europe, Australia, and the USA, but the prevalence was 2.9 and 3.6 per 1000 children in Uganda and Egypt respectively [8,9]. Most of the reported overall prevalence rates have indicated no substantial changes for the birth-year periods of 1985 to 2010; however, a report based on the Surveillance of Cerebral Palsy in Europe demonstrated a decline in the prevalence of CP among children with birth body weight <1500 g [10]. Studies conducted in the United States have reported that Asian children had a lower CP prevalence than Caucasian [11,12]. Furthermore, surveys in China and Hong Kong have reported that the prevalence of CP was 1.3 to 1.6 per 1000 children, which is lower than that in Western countries [1315]. However, it is unclear whether the lower prevalence of CP in Asian children can be attributed due to ethnic disparities.

Several nationwide, population-based CP registries from different continents have consistently reported a 6%−25% higher proportion of men with CP than women with CP [1,2,5]. Population-based and meta-analysis studies have also reported an association between low socioeconomic status (SES) and high CP prevalence [1618]. In these studies, sex, ethnicity, and residential-area-based and individual-level SES influenced CP prevalence.

In Taiwan, the government-run single-payer National Health Insurance affords equity and high quality medical care to more than 99% of its 23 million citizens and foreign residents [19]. CP treatment is covered under Taiwan’s National Health Insurance. Therefore, the Taiwan National Health Insurance Research Database is an excellent tool with which to investigate the prevalence of CP in Taiwan. The present study investigated the annual prevalence of CP among children in Taiwan aged <7 years and the association between CP prevalence and SES by evaluating the data from the Taiwan Health Insurance Research Database recorded from 2002 to 2008. Our findings could provide insights into CP epidemiology among the Chinese population.

Methods

Data source

The Taiwan National Health Insurance Research Database was used in this study. Taiwan’s National Health Insurance is a mandatory and single-payer program that covers 99.9% of the approximately 23 million people residing in Taiwan [19,20]. The program covers all medically necessary services, including inpatient and outpatient services, dental care, and prescription drugs. The Taiwan National Health Insurance Research Database contains de-identified registration files and original claims data for reimbursement under the national health insurance program, and these data are provided to scientists for research purposes [21]. The demographic variables of the study population, including sex, low income, and residential location, were obtained from the registry for beneficiaries files. The registry for beneficiaries files had records of low income households, however, it did not contain detailed information on family income. Therefore, children were classified into low income status according to the records of low income households. We categorized the residential locations into urban, suburban, and rural areas according to the urbanization stratification published by the Taiwan National Health Research Institute [22]. The present study used all registration files and claims data of beneficiaries younger than 7 years between 2002 and 2008 for analysis. This study was approved by the Joint Institutional Review Board of Taipei Medical University (TMU-JIRB No. 210206046).

Definition of severe CP

In the present study, children with CP were defined as those who aged 2 or older and had at least two claim records with ICD-9-CM codes 343.x within 1 year. Children with severe CP were those who had both definite CP diagnosis and moderate to severe physical or mental disability. In Taiwan, individuals diagnosed with severe and chronic diseases requiring extended treatment, such as CP, may apply for a catastrophic illness certificate. Patients with a catastrophic illness certificate are not required to make copayments for medical services. To obtain a catastrophic illness certificate, CP diagnosis must be confirmed by specialists [23]. In addition, the patient must be proven to have moderate to severe physical or mental disability by the designated hospitals [24]. Patients obtain this certificate after fulfilling the aforementioned provisions and verification by the National Health Insurance Administration. Therefore, we used the catastrophic illness registration file to define severe CP. Children having a catastrophic illness certificate with the International Classification of Disease, Ninth Revision, Clinical Modification (ICD-9-CM) diagnosis codes 343.x were defined as having severe CP. The number of total CP was defined as the number of children who fulfilled the above-mentioned criteria of CP or severe CP.

Statistical analysis

The annual prevalence of CP was calculated by dividing the number of cases by the total number of children aged less than 7 years in the research database annually. Confidence intervals (CIs) were calculated by using the Poisson approximation to the binomial distribution. We used Poisson regression to analyze trends in prevalence over time by treating calendar year as a continuous variable. Multivariable Poisson regression was use to analyze the prevalence of CP after controlling for sex, low income, and residential area. Pearson χ2 tests were used to compare the prevalence of CP by sex, family income, and residential location. The baseline characteristics of the children, including the data on low family income and residential location, were obtained from the registry for beneficiary files. The date of death is included in the registry of catastrophic illness files. Accordingly, these death records were used to calculate the mortality rate of children with severe CP. A P-value of <0.05 was condisered statistically significant. All data were analyzed using SAS for Windows (version 9.3, SAS Institute, Cary, NC, USA).

Results

The database covered nearly 99% of age-specific children in each specific year. The basic characteristic of study population are shown in Table 1. The number of children (age <7 y) in each year in the database indicated that Taiwan has a steadily declining fertility rate. The prevalence of total CP was 1.9 per 1000 children in 2002 (Table 2). Then the annual prevalence of total CP ranged from 2.5 to 2.8 per 1000 children and remained stable between 2003 and 2008 (P for trend = 0.843). For the period 2002 to 2008, the annual prevalence of severe CP ranged from 1.1 to 1.4 per 1000 children (Table 2). The prevalence rates of severe CP thus did not vary significantly throughout the 7-year study period (P for trend = 0.333). The proportion of boys with CP was consistently higher than that of girls with CP in both total and severe CP. Boys were 30% more likely to have CP than girls [relative risk and 95% confidence interval (CI) ranged from 1.3 (1.2−1.4) to 1.4 (1.2−1.5)] (Table 3).

thumbnail
Table 1. Basic characteristics of children aged 0−6 years in Taiwan between 2002 and 2008.

https://doi.org/10.1371/journal.pone.0191724.t001

thumbnail
Table 2. Annual prevalence of total and severe CP in Taiwan children aged 0−6 years.

https://doi.org/10.1371/journal.pone.0191724.t002

thumbnail
Table 3. Prevalence of total and severe CP according to sex.

https://doi.org/10.1371/journal.pone.0191724.t003

We also investigated the association of CP prevalence with family income and residential status. Compared with children from middle- or high-income families, the children from low-income families were associated with a fivefold higher prevalence of total and severe CP [relative risk (95% CI) ranged from 4.9 (4.3−5.6) to 6.6 (5.5−7.8)] (Table 4). With regard to residential-location based SES, the prevalence of total and severe CP in rural areas was higher than that in urban or suburban areas (Table 5). On the multivariable Poisson regression model controlling for confounders, the boys, low income, and rural residential location remained associated with higher prevalence of severe CP between 2002 and 2008 (Table 6). The mortality rate of severe CP ranged from 12.2 to 22.7 per 1000 children within the 7 years study period (Table 7).

thumbnail
Table 4. Prevalence of total and severe CP according to family income status.

https://doi.org/10.1371/journal.pone.0191724.t004

thumbnail
Table 5. Prevalence of total and severe CP according to residential location.

https://doi.org/10.1371/journal.pone.0191724.t005

thumbnail
Table 6. Multivariate Poisson regression analysis of the relative risk of severe CP.

https://doi.org/10.1371/journal.pone.0191724.t006

thumbnail
Table 7. Annual mortality rate of severe CP in Taiwan children aged 0−6 years.

https://doi.org/10.1371/journal.pone.0191724.t007

Discussion

This study was the first nationwide population-based analysis of the prevalence and associated socioeconomic risk factors of CP in children aged <7 years in Taiwan over a 7-year period. The prevalence of CP remained constant during the study period. The present results yielded a peak CP prevalence of 2.8 per 1000 children, which is similar to those reported in a previous meta-analysis for a specific age range [3] but higher than those of other surveys in the Chinese population. The prevalence of CP in China and Hong Kong was reported to be from 1.3 to 1.6 per 1000 children [1315], which is lower than that in other developed countries. However, our present findings based on the entire population of Taiwan provide new evidence that Chinese children do not have a lower CP risk.

Our results revealed that sex influences the prevalence of CP; a higher prevalence of CP was discovered in boys than girls, which is consistent with previous studies [25, 26]. In addition, CP prevalence was higher among the children of low-income families, which is in accordance with previous findings [11,27]. In the United States and United Kingdom, socioeconomic deprivation is associated with an increased risk of having a child with CP. A socioeconomic gradient has been observed in preterm birth, low birthweight, and postnatal injury, which are also risk factors for CP [18,28]. Some mediators have been suggested to explain the relationship between socioeconomic gradient and CP prevalence, including maternal illness, infection, inadequate prenatal care, poor nutrition, alcoholism, and smoking [11,2831]. Strategies to prevent these risk factors or mediators may interrupt the pathway to CP and reduce CP prevalence. The trend of higher CP prevalence in low-income families warrants further investigation to reduce the CP rate in this population. Furthermore, children lived in rural areas had a higher prevalence of CP, particularly severe CP. Because people living in rural areas are less likely to use medical services [32], it is important to facilitate the access to relevant health services for children with CP residing in rural areas to help them achieving optimal development and health.

Limited evidence is available on the life expectancy of children with CP [33,34]. According to the World Health Organization Global Health Observatory data, the mortality rate of children under 5 years significantly reduced from 91 deaths per 1000 live births in 1990 to 43 deaths per 1000 live births in 2015 [35]. The mortality rate of children with severe CP in our study was 12.2−22.7 per 1000 children. Although this mortality rate is lower than the overall global mortality rate for children less than 5 years, it is higher than that in developed countries. Therefore, further studies are warranted to investigate the causes of the high mortality rate and provide improved health care to these children with CP to improve their prognosis.

The present study had some limitations. First, we used a claims-based database to investigate the prevalence of CP. The definition of CP used to classify patients was never validated in any way. We might have included children who do not in fact have CP but incorrectly get the ICD-9 codes (e.g. patient with intellectual disability, neuromuscular disorders, or genetic disorders, etc.). We may also miss children with mild CP who do not use the medical services. However, to obtain a catastrophic illness certificate to be exempted from copayment, guardians must provide relevant medical information to the National Health Insurance Bureau. Therefore, the prevalence of severe CP in this study must be very close to the true value. Second, detailed clinical information was not available in the database. Therefore, we were unable to categorize the different types of CP in the affected children. Third, the database used in the present study did not contain detailed information on family income, educational level, and ethnicity. Accordingly, we used the low income status and residential area as proxies for socioeconomic status.

Conclusions

Our population-based study revealed that the annual prevalence of CP in children aged <7 years in Taiwan ranged from 1.9 to 2.8 per 1000 children. These CP prevalence are similar to those in Western countries. In addition, male sex, low family income, and rural residential location were associated with a higher CP prevalence. Developing a nationwide CP register system to thoroughly understand the prevalence and causes of CP and provide improved health care to children with CP is imperative.

Acknowledgments

This manuscript was edited by Wallace Academic Editing.

References

  1. 1. Oskoui M, Coutinho F, Dykeman J, Jetté N, Pringsheim T. An update on the prevalence of cerebral palsy: a systematic review and meta-analysis. Dev Med Child Neurol. 2013;55: 509–519. pmid:23346889
  2. 2. Himmelmann K, Uvebrant P. The panorama of cerebral palsy in Sweden. XI. Changing patterns in the birth-year period 2003–2006. Acta Paediatr. 2014;103: 618–624. pmid:24575788
  3. 3. Frøslev-Friis C, Dunkhase-Heinl U, Andersen JD, Stausbøl-Grøn B, Hansen AV, Garne E. Epidemiology of cerebral palsy in Southern Denmark. Dan Med J. 2015;62: A4990. pmid:25557331
  4. 4. Robertson CMT, Ricci MF, O'Grady K, Oskoui M, Goez H, Yager JY, et al. Prevalence Estimate of Cerebral Palsy in Northern Alberta: Births, 2008–2010. Can J Neurol Sci. 2017;44: 366–374. pmid:28322177
  5. 5. Smithers-Sheedy H, McIntyre S, Gibson C, Meehan E, Scott H, Goldsmith S, et al. A special supplement: findings from the Australian Cerebral Palsy Register, birth years 1993 to 2006. Dev Med Child Neurol. 2016;58 Suppl 2: 5–10.
  6. 6. Arneson CL, Durkin MS, Benedict RE, Kirby RS, Yeargin-Allsopp M, Van Naarden Braun K, et al. Prevalence of cerebral palsy: autism and developmental disabilities monitoring Network, three sites, United States, 2004. Disabil Health J. 2009;2: 45–48. pmid:21122742
  7. 7. Donald KA, Samia P, Kakooza-Mwesige A, Bearden D. Pediatric cerebral palsy in Africa: a systematic review. Semin Pediatr Neurol. 2014;21: 30–35. pmid:24655402
  8. 8. Kakooza-Mwesige A, Andrews C, Peterson S, Mangen FW, Eliasson AC, Forssberg H. Prevalence of cerebral palsy in Uganda: a population-based study. Lancet Glob Health. 2017;5: e1275–1282. pmid:29102350
  9. 9. EI-Tallawy HN, Farghaly WM, Shehata GA, Rageh TA, Metwally NA, Badry R, et al. Cerebral palsy in AI-Quseir City, Egypt: prevalence, subtypes, and risk factors. Neuropsychiatr Dis Treat. 2014;10: 1267–1272. pmid:25045270
  10. 10. Sellier E, Platt MJ, Andersen GL, Krägeloh-Mann I, De La Cruz J, Cans C, et al. Decreasing prevalence in cerebral palsy: a multi-site European population-based study, 1980 to 2003. Dev Med Child Neurol. 2016;58: 85–92. pmid:26330098
  11. 11. Wu YW, Xing G, Fuentes-Afflick E, Danielson B, Smith LH, Gilbert WM. Racial, ethnic, and socioeconomic disparities in the prevalence of cerebral palsy. Pediatrics 2011;127: e674–681. pmid:21339278
  12. 12. Lang TC, Fuentes-Afflick E, Gilbert WM, Newman TB, Xing G, Wu YW. Cerebral palsy among Asian ethnic subgroups. Pediatrics. 2012;129: e992–998. pmid:22430449
  13. 13. Liu JM, Li S, Lin Q, Li Z. Prevalence of cerebral palsy in China. Int J Epidemiol. 1999;28: 949–954. pmid:10597996
  14. 14. Yam WK, Chan HS, Tsui KW, Yiu BP, Fong SS, Cheng CY, et al. Prevalence study of cerebral palsy in Hong Kong children. Hong Kong Med J. 2006;12: 180–184. pmid:16760544
  15. 15. He P, Chen G, Wang Z, Guo C, Zheng X. Children with motor impairment related to cerebral palsy: Prevalence, severity and concurrent impairments in China. J Paediatr Child Health. 2017;53: 480–484. pmid:28094881
  16. 16. Hjern A, Thorngren-Jerneck K. Perinatal complications and socio-economic differences in cerebral palsy in Sweden—a national cohort study. BMC Pediatr. 2008;8: 49. pmid:18973666
  17. 17. Dolk H, Pattenden S, Bonellie S, Colver A, King A, Kurinczuk JJ, et al. Socio-economic inequalities in cerebral palsy prevalence in the United Kingdom: a register-based study. Paediatr Perinat Epidemiol 2010;24: 149–155. pmid:20415771
  18. 18. Oskoui M, Messerlian C, Blair A, Gamache P, Shevell M. Variation in cerebral palsy profile by socio-economic status. Dev Med Child Neurol. 2016;58: 160–166. pmid:26010819
  19. 19. National Health Insurance Administration, Ministry of Health and Welfare. Universal Health Coverage in Taiwan. Available from: https://www.nhi.gov.tw/English/Content_List.aspx?n=8FC0974BBFEFA56D&topn=ED4A30E51A609E49.
  20. 20. Lee YW, Chen TL, Shih YR, Tsai CL, Chang CC, Liang HH, et al. Adjunctive traditional Chinese medicine therapy improves survival in patients with advanced breast cancer: a population-based study. Cancer. 2014;120: 1338–1344. pmid:24496917
  21. 21. National Health Research Instututes. National Health Insurance Research Database. Available from: https://nhird.nhri.org.tw/en/index.html.
  22. 22. Liu CY, Hung YT, Chuang YL, Chen YJ, Weng WS, Liu JS, et al. Incorporating development stratification of Taiwan townships into sampling design of large scale health interview survey. J Health Manag. 2006;4: 1–22.
  23. 23. National Health Insurance Administration, Ministry of Health and Welfare. Patients with Catastrophic Illnesses or Rare Diseases. Available from: https://www.nhi.gov.tw/English/Content_List.aspx?n=F5B8E49CB4548C60&topn=1D1ECC54F86E9050.
  24. 24. Department of Social Welfare, Taipei City Government. Division of Welfare Services for the Disabled. Available from: http://english.dosw.gov.taipei/ct.asp?xItem=972119&ctNode=15822&mp=107002.
  25. 25. Chounti A, Hägglund G, Wagner P, Westbom L. Sex differences in cerebral palsy incidence and functional ability: a total population study. Acta Paediatr. 2013;102: 712–717. pmid:23551760
  26. 26. Christensen D, Van Naarden Braun K, Doernberg NS, Maenner MJ, Arneson CL, Durkin MS, et al. Prevalence of cerebral palsy, co-occurring autism spectrum disorders, and motor functioning—Autism and Developmental Disabilities Monitoring Network, USA, 2008. Dev Med Child Neurol. 2014;56: 59–65. pmid:24117446
  27. 27. Dolk H, Pattenden S, Johnson A. Cerebral palsy, low birthweight and socio-economic deprivation: inequalities in a major cause of childhood disability. Paediatr Perinat Epidemiol. 2001;15: 359–363. pmid:11703684
  28. 28. Solaski M, Majnemer A, Oskoui M. Contribution of socio-economic status on the prevalence of cerebral palsy: a systematic search and review. Dev Med Child Neurol. 2014;56: 1043–1051. pmid:24750064
  29. 29. Mclntyre S, Taitz D, Keogh J, Goldsmith S, Badawi N, Blair E. A systematic review of risk factors for cerebral palsy in children born at term in developed countries. Dev Med Child Neurol. 2013;55: 499–508. pmid:23181910
  30. 30. Clark SM, Ghulmiyyah LM, Hankins GD. Antenatal antecedents and the impact of obstetric care in the etiology of cerebral palsy. Clin Obstet Gynecol. 2008;51: 775–786. pmid:18981802
  31. 31. Abel EL. Cerebral palsy and alcohol consumption during pregnancy: is there a connection? Alcohol Alcohol. 2010;45: 592–594. pmid:20880958
  32. 32. Lin YJ, Tian WH, Chen CC. Urbanization and the utilization of outpatient services under National Health Insurance in Taiwan. Health Policy. 2011;103: 236–243. pmid:21920621
  33. 33. Hemming K, Hutton JL, Colver A, Platt MJ. Regional variation in survival of people with cerebral palsy in the United Kingdom. Pediatrics. 2005;116: 1383–1390. pmid:16322162
  34. 34. Strauss D, Cable W, Shavelle R. Causes of excess mortality in cerebral palsy. Dev Med Child Neurol. 1999;41: 580–585. pmid:10503915
  35. 35. World Health Organization. Global Health Observatory (GHO) data. Available from: http://www.who.int/gho/child_health/mortality/mortality_under_five_text/en/.