Evaluation of Cephalic Index Norms After the Back to Sleep Campaign: An Epidemiologic Study
Melissa J. McCarthy, M.P.H., Alannah Phelan, M.D., Garrick Gu, B.A., Danielle Stamer, B.S., Joyce K. McIntyre, M.D., Janice F. Lalikos, M.D..
University Of Massachusetts Medical School, Worcester, MA, USA.
In 1992, the Back to Sleep Campaign was instituted by the American Academy of Pediatrics. Although this dictum profoundly decreased infant mortality from sudden infant death syndrome (SIDS), positional plagiocephaly incidence has subsequently increased at least 5-fold.1
Plagiocephaly from back sleeping is most evident at 2-4 months of life but typically resolves as the infant gains head control and mobility.4,5 However, orthotic helmets are recommended for severe deformities. Insurers have criteria for helmet authorization based on deviations from norms, one indicator being cephalic index (CI = the ratio of head width to length). 2,3 This study seeks to evaluate whether CI values of infants and children have changed following the Back to Sleep campaign and aims to establish updated CI norms in a diverse sample of patients at multiple stages of development.
Children between the ages of 0-1 month, 4-6 months, 9-12 months, 2-3 years and 12- 14 years were recruited at their well child appointment. Exclusion criteria were diagnosis of premature birth, craniosynostosis, positional plagiocephaly, craniofacial abnormality, hydrocephalus, gross developmental delay or torticollis. Calipers were used to measure occipotofrontal and biparietal dimensions of the head. Parents were surveyed about demographic information, birth history, past medical history, and craniofacial history such as amount of daily tummy time in infancy, history of torticollis, and frequency of back sleeping in the first year. The mean and standard deviation for CI was calculated for each age group.
A total of 532 patients met inclusion criteria. In the 0-1-month group 81 patients had an average CI of 0.82 (SD ±0.042). There were 99 patients in the 4-6-month group, with a mean CI of 0.86 (SD ±0.053). Current helmeting norms in this 0-6-month age range are >0.837 for boys and >0.827 in girls.3 In this sample of children under 6 months, n= 51(57.3%) of the boys and n= 53(45.32%) of girls meet criteria for a helmet. (See Graphic) At 9-12 months, a sample of 81 patients had a CI of 0.84 (SD 0.061). This value was stable at 2-3 years, with mean CI of 0.83 and SD 0.077 (n=113), and at 12-14 years, CI 0.82, SD 0.062 (n=148).
The mean cephalic index of healthy children in this sample aged 0-1 month and 4-6 months was 0.83 and 0.86, respectively. These values are higher than previously established mean CI values for children under 6 months of .737(males) and .733(females) by Farkus et al demonstrating a global change in CI after the introduction of the Back to Sleep campaign.7 Our study also shows that up to 57% of children may inappropriately meet criteria for a helmet based on the prior norms. By updating data to reflect current norms, many children may be spared an unnecessary helmet orthosis.
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