Association of positional plagiocephaly and developmental delay within a primary care network

Abstract

Objective:

Prior research has suggested an association between plagiocephaly and developmental delay. However, study samples drawn from children seen in subspecialty clinics increase the potential for selection and referral bias. Our study evaluates the association between plagiocephaly and developmental delay and the timing of these diagnoses in a primary care setting, where plagiocephaly is commonly diagnosed and managed.

Method:

Our retrospective analysis used electronic medical record data from 45 primary care sites within a children’s health system from 1999–2017, including children aged 0–5 years with diagnoses determined by physician diagnosis codes at primary care visits. Children were classified in the plagiocephaly group if diagnosis occurred by 12 months of age. Primary outcome was any developmental delay. Pearson’s chi-square test, Fisher’s exact test, and logistic regression analyses were conducted, with multivariable models adjusted for sex, race, ethnicity, insurance, prematurity status (22–36 weeks’ gestation), primary care sites, birth year, and diagnoses of abnormal tone and torticollis.

Results:

Of 77,108 patients seen by 12 months, 2,315 (3.0%) were diagnosed with plagiocephaly, with an increase in diagnosis prevalence over the study time frame. Plagiocephaly was independently associated with an increased odds of any developmental delay diagnosis (aOR 1.50, 95% CI 1.32 – 1.70). The diagnosis of plagiocephaly was recorded before the diagnosis of developmental delay in the majority of cases when both diagnoses were present (374/404, 92.6%).

Conclusions:

Data from a large primary care cohort demonstrate an association between plagiocephaly and developmental delay, affirming findings in prior subspecialty literature.

INTRODUCTION

Corresponding with the American Academy of Pediatrics (AAP) “Back to Sleep” guidelines, which have been reaffirmed since 1992 because of decreased risk of sudden infant death syndrome (SIDS),^1,2 there has been an increase in plagiocephaly or positional skull deformity.³ Positional, or deformational, plagiocephaly and brachycephaly describe characteristic patterns of occipital skull flattening.^3–5 For purposes of brevity and clarity, positional plagiocephaly and positional brachycephaly will be referred to as plagiocephaly. To prevent progression of plagiocephaly, the AAP guidelines recommend preventive counseling about observed, awake “tummy time,” stretching, positioning, and close observation, with referral to a pediatric neurosurgeon or craniofacial specialist if there is no improvement by 4 to 6 months and to physical therapy if associated torticollis does not improve with stretching.³

While many providers have viewed plagiocephaly as minor and cosmetic,⁶ some recent studies suggest an association between plagiocephaly and developmental outcomes, including a systematic review that evaluated the association between plagiocephaly and developmental delay.⁷ Of the 19 studies included in the systematic review, 13 reported a positive association between plagiocephaly and developmental delay. Motor delay was the most commonly reported area of delay, with some studies also finding delays in language and cognition.⁷ However, the authors note that many of the reviewed studies were affected by selection bias, specifically referral bias as recruitment was from specialty clinics within tertiary care settings.⁷

Since the initial evaluation and some, if not all, of the management of plagiocephaly often occurs in the primary care setting, the selection bias noted in previous studies may prevent the generalizability of those findings to infants with plagiocephaly diagnosed and managed in the primary care setting. Therefore, the primary objective of this study was to evaluate for an association between plagiocephaly and developmental delay in a primary care cohort. The study hypothesis was that there would be an association between plagiocephaly and developmental delay diagnoses in the primary care setting. Given that plagiocephaly may be recognized clinically before signs of developmental delay, our second objective was related to the relative timing of these diagnoses to consider if plagiocephaly may be an early indicator of infants at risk for developmental delay. The aim was not to determine causation between plagiocephaly and developmental delay but rather to determine if plagiocephaly is clinically identified before developmental delay. The study hypothesis was that plagiocephaly diagnosis was likely to be recorded prior to any diagnosis of developmental delay.

PATIENTS AND METHODS

Study design

We conducted a retrospective cohort analysis of electronic medical record (EMR) data obtained through PEDSnet from 45 primary care sites within a single children’s health system spanning three states. PEDSnet is an electronic health record-derived database from eight children’s hospitals across the United States, for the purpose of observational research and clinical trials (https://pedsnet.org/about/, accessed 3/27/19). Our hospital’s institutional review board approved this study.

Data were retrieved for children from birth through 5 years who had a first primary care office visit by age 12 months between May 2000 and October 2017 (Fig. 1). Children with a plagiocephaly diagnosis by 12 months were classified in the plagiocephaly group (Fig. 1, Supplemental Table 1), as AAP guidelines recommend that children should be evaluated for plagiocephaly during routine well-child visits until 12 months of age.^3,6 Control patients were included if they did not have a diagnosis of plagiocephaly and were seen in primary care by 12 months of age (Fig. 1). Exclusion criteria included diagnoses of craniosynostosis, trisomy 21, cleft lip or cleft palate or both, or cerebral palsy. Individuals were also excluded if there was no sex documented (Fig. 1).

Figure 1.

Diagram depicting sample derivation for cases (children with plagiocephaly diagnosis) and controls (children without plagiocephaly diagnosis).

Primary outcome was any developmental delay diagnosis. Secondary outcomes were specific categories of delay—motor, language, social, cognitive, or general delays. Developmental delay diagnoses were determined by International Classification of Diseases (ICD) codes, 9th and 10th editions (Supplemental Table 1), which were assigned by primary care providers at the time of the visit for billing and coding purposes. Sociodemographic characteristics including sex, race, ethnicity, insurance, preterm status (22–36 weeks’ gestation), and primary language reported were obtained from the PEDSnet database based on information documented in the EMR. Clinical diagnoses of abnormal tone and torticollis diagnoses were ascertained by ICD codes (Supplemental Table 1). Abnormal tone and torticollis were included as covariates in multivariable analyses, as prior literature suggests that infants with plagiocephaly have more abnormal tone than infants without plagiocephaly⁸ and torticollis is a risk factor for plagiocephaly, although it was found to be significant in only about half of higher quality empiric studies included in a recent systematic review.⁹ Helmet therapy was identified by use of the order for “cranial remolding orthosis – procedure code S1040” in the EMR, which is the order clinically used according to our hospital’s neurosurgery team.

Analysis

Count and percentages were used to summarize sociodemographic characteristics (sex, race, ethnicity, insurance, preterm status, primary language reported) as well as clinical diagnoses of abnormal tone or torticollis across patients with and without plagiocephaly. Chi-square or Fisher’s exact tests examined the distribution of sociodemographic characteristics, clinical diagnoses of abnormal tone or torticollis, as well as specific developmental delay diagnoses across plagiocephaly groups. A univariate logistic regression model examined the crude association of plagiocephaly with each of the developmental delay outcome variables. A multivariable logistic regression model tested the association between plagiocephaly and outcome variables after adjustment for sex, race, ethnicity, insurance, primary language, prematurity status (22–36 weeks’ gestation), primary care sites, year of birth, diagnosis of abnormal tone, and diagnosis of torticollis. Logistic regression analyses were repeated including only infants with a documented gestational age of 37 weeks or greater with similar findings to the model including, but controlling for, prematurity status.

Age at time of diagnoses of both plagiocephaly and developmental delay was calculated (in months) to determine the relative timing of these diagnoses. Mann-Whitney U test was used to compare the ages at diagnosis for developmental delay between groups, as the data were not normally distributed. All tests were two-tailed with a level of significance of 0.05. Analyses were performed using SPSS Version 25 (IBM Corp. Released 2017. IBM SPSS Statistics for Windows, Version 25.0. Armonk, NY).

RESULTS

Of 77,108 patients seen by 12 months, 2,315 (3.0%) were diagnosed with plagiocephaly. As shown in Figure 2, the prevalence by birth year in our study increased from 0.1% in 2000 to a maximum of 6.2% in 2016 (chi-square test for linear trend p < 0.001). The median age of diagnosis of plagiocephaly was 3 months (range 0–12 months, IQR 2–4 months). Patients with plagiocephaly differed significantly from controls without plagiocephaly on all sociodemographic variables as well as diagnoses of abnormal tone and torticollis (Table 1). The patients with plagiocephaly were more likely to be male, white, have private insurance, and report English as the primary language (Table 1). From a clinical standpoint, patients with plagiocephaly were more likely to have a history of prematurity as well as diagnoses of abnormal tone and torticollis (Table 1).

Figure 2.

Prevalence of plagiocephaly diagnosis by birth year.

Table 1.

Patient characteristics by plagiocephaly category with N (%) based on Pearson’s chi-square test.

Total N = 77,108	Plagiocephaly N = 2,315 (3.0%)	No plagiocephaly N = 74,793 (97.0%)	p value
Sex			p < 0.001
Male	1,410 (60.9%)	37,969 (50.8%)
Race			p < 0.001
White	1,326 (57.3%)	30,031 (40.2%)
African American	297 (12.8%)	29,882 (40.0%)
Asian	188 (8.1%)	2,216 (3.0%)
Other/missing	504 (21.8%)	12,664 (16.9%)
Ethnicity			p < 0.001
Non-Hispanic	1,878 (81.1%)	61,950 (82.8%)
Hispanic	280 (12.1%)	9,290 (12.4%)
Other/missing	157 (6.8%)	3,553 (4.8%)
Insurance			p < 0.001
Medicaid	766 (33.1%)	38,257 (51.1%)
Private	1,516 (65.5%)	29,899 (40.0%)
Other/missing	33 (1.4%)	6,637 (8.9%)
Primary language			p < 0.001
English	2,084 (90.0%)	61,127 (81.7%)
Not recorded	118 (5.1%)	9,541 (12.8%)
Other	39 (1.7%)	931 (1.2%)
Spanish	74 (3.2%)	3,194 (4.3%)
Prematurity			p < 0.001
Term (37+ weeks)	1,686 (72.8%)	51,596 (69.0%)
Premature (22–36 weeks)	333 (14.4%)	7,518 (10.1%)
Missing gestational age	296 (12.8%)	15,679 (21.0%)
Abnormal tone diagnosis	41 (1.8%)	249 (0.3%)	p < 0.001
Torticollis diagnosis	465 (20.1%)	935 (1.3%)	p < 0.001

Association of plagiocephaly and any developmental delay

Of the 77,108 patients, 6,896 (8.9%) were diagnosed with any developmental delay (including motor, language, cognitive, social, and general delay categories). Developmental delay diagnosis was more likely in the plagiocephaly group, with 404 of 2,315 (17.5%) having a diagnosis of developmental delay compared with 6,492 of 74,793 (8.7%) in the group without plagiocephaly (OR 2.22, 95% CI 1.99 – 2.48, p < 0.001) (Table 2, Fig. 3). Controlling for other sociodemographic and clinical factors as well as primary care site, plagiocephaly was independently associated with an increased odds for any developmental delay diagnosis (aOR 1.50, 95% CI 1.32 – 1.70) (Table 3, Supplemental Table 2).

Table 2.

Associations between plagiocephaly and developmental delay diagnoses based on Pearson’s chi-square and Fisher’s exact tests.

Developmental delay diagnoses	Plagiocephaly N (%)	No plagiocephaly N (%)	p value
Any developmental delay (Total N = 6,896)			p < 0.001
Present	404 (17.5)	6,492 (8.7)
Absent	1,911 (82.5)	68,301 (91.3)
Motor delay (N= 812)			p < 0.001
Present	89 (3.8)	723 (1.0)
Absent	2,226 (96.2)	74,070 (99.0)
Language delay (N= 5,439)			p < 0.001
Present	282 (12.2)	5,157 (6.9)
Absent	2,033 (87.8)	69,636 (93.1)
Cognitive delay (N = 165)			p = 0.496
Present	3 (0.1)	162 (0.2)
Absent	2,312 (99.9)	74,631 (99.8)
Social delay ( N = 39)			p = 0.029
Present	4 (0.2)	35 (0.0)
Absent	2,311 (99.8)	74,758 (100.0)
General delay (N =1,321)			p < 0.001
Present	108 (4.7)	1,213 (1.6)
Absent	2,207 (95.3)	73,580 (98.4)

Figure 3.

Groups with plagiocephaly (dark gray bars) and without plagiocephaly (light gray bars) and concomitant developmental delay diagnoses. (%) * indicate p-value < 0.05

Table 3.

Multivariable logistic regression analysis for any developmental delay as well as specific developmental delay categories, adjusted for sociodemographic and clinical factors^a, with adjusted odds ratios (aOR) and 95% confidence intervals (CI).

	aOR (95% CI)
Any developmental delay (N = 6,896)	1.50 (1.32 – 1.70) b
Categories of delay:
Motor delay (N = 812)	1.67 (1.29 – 2.16)
Language delay (N = 5,439)	1.35 (1.17 – 1.56)
General delay (N = 1,321)	1.77 (1.39 – 2.24)
Social delay (N = 39)	2.72 (0.87 – 8.50)
Cognitive delay (N = 165)	0.36 (0.11 – 1.23)

^aSociodemographic and clinical factors controlled for in the model include sex, race, ethnicity, insurance, primary language, prematurity status (22–36 vs. 37 or greater weeks’ gestational age), primary care site, birth year, diagnosis of abnormal tone, and diagnosis of torticollis

^baOR and CI in bold are significant at an α level of 0.05

Association of plagiocephaly and categories of developmental delay diagnoses

Motor delay, language delay, social delay, and general delay diagnoses were significantly more likely in the plagiocephaly group, while cognitive delay was not (Table 2, Fig. 3). Plagiocephaly was associated with significantly increased odds of motor delay (OR 4.10, 95% CI 3.27 – 5.13, p <0.001), language delay (OR 1.87, 95% CI 1.65 – 2.13, p <0.001), social delay (OR 3.70, 95% CI 1.31 – 10.41, p = 0.013), and general delay (OR 2.97, 95% CI 2.43 – 3.63, p < 0.001). Plagiocephaly was not associated with significantly increased odds of cognitive delay (OR 0.60, 95% CI 0.19 – 1.87, p = 0.378).

Controlling for other sociodemographic and clinical factors and primary care site, plagiocephaly was independently associated with an increased odds for motor delay (aOR 1.67, 95% CI 1.29 – 2.16), language delay (aOR 1.35, 95% CI 1.17 – 1.56), and general delay (aOR 1.77, 95% CI 1.39 – 2.24) but not social delay (aOR 2.72, 95% CI 0.87 – 8.50) or cognitive delay (aOR 0.36, 95% CI 0.11 – 1.23) (Table 3, Supplemental Table 2).

Timing of diagnoses

Regarding the timing of plagiocephaly and developmental delay diagnoses, if a patient was diagnosed with both plagiocephaly and developmental delay, plagiocephaly was diagnosed before developmental delay in the majority of cases. Of the 404 patients with plagiocephaly and a developmental delay diagnosis, 374 (92.6%) were diagnosed with plagiocephaly before the developmental delay diagnosis compared with diagnosis occurring at the same time (21, 5.2%) and plagiocephaly diagnosis after the developmental delay diagnosis (9, 2.2%). If a patient had both plagiocephaly and developmental delay diagnoses, the median age of the first diagnosis of any developmental delay was earlier than the age of first developmental delay diagnosis if there was no diagnosis of plagiocephaly [15 months (range 0–71 months, IQR 6–24 months) vs. 24 months (range 0–71 months, IQR 16–36 months), p < 0.001] (Fig. 4).

Figure 4.

Median age at first developmental delay diagnosis by plagiocephaly diagnosis status with interquartile range (IQR).

DISCUSSION

Children with plagiocephaly comprised a small percentage of the primary care sample and of the children with developmental delay. However, there was a significant association between plagiocephaly and any developmental delay, as well as for specific delay categories of general, motor, and language delays, but not for social and cognitive delays. Our analysis demonstrates that plagiocephaly is independently associated with developmental delay despite adjustment for prematurity, a well-recognized risk factor for developmental delay. Further stratification of gestational age to compare degree of prematurity with odds of developmental delay when plagiocephaly is present would be an interesting future analysis. However, for the purpose of the general pediatrician or family physician, who often monitors the development of premature infants more closely regardless of plagiocephaly status, this study adds that even among those children born full term, plagiocephaly may suggest a higher risk of developmental delay.

The finding related to motor delays is consistent with known associations with musculoskeletal issues, such as torticollis² and abnormal tone.⁸ The increased odds of language delay with a diagnosis of plagiocephaly, which has also been shown in prior studies, may be related to the effect of motor development on the development of other developmental milestones, known as the developmental cascade.¹⁰ There can be similar effects of early motor development on social interactions, partially mediated by early communication skills¹¹ and cognitive development.¹² While prior research has shown associations between plagiocephaly and lower scores on cognitive measures,^5,13–15 our study did not find significant associations between plagiocephaly and social and cognitive delays, which may have been due to a limited analysis secondary to low frequencies of social and cognitive delays in this cohort of young children (n = 39 and n = 165, respectively), as some of these diagnoses may be more appropriate for school-aged children.

When a child had both plagiocephaly and a developmental delay diagnosis, plagiocephaly was diagnosed before the delay diagnosis the majority of the time, with the median age of plagiocephaly diagnosis (3 months) occurring earlier than the median age of the first developmental delay diagnosis (15 months). The median age of plagiocephaly diagnosis at 3 months is consistent with reported prevalence from a natural history study of plagiocephaly with the peak prevalence at 4 months of age.¹⁶ Additionally, the median age of first developmental delay diagnosis also occurred earlier when a child had a diagnosis of plagiocephaly (15 months, as noted above) compared with when a child did not have a diagnosis of plagiocephaly (24 months). As noted in the introduction, this is not meant to identify causation between plagiocephaly and developmental delay but rather intended to highlight that plagiocephaly may be an early indicator for children at risk for developmental delay.

These findings support previous findings from subspecialty clinics^5,15 that plagiocephaly may serve as an early indicator of children who may be at risk of developmental delay in the primary care setting. Accordingly, primary care providers should consider monitoring the development of infants with plagiocephaly with increased vigilance. While some providers may already be doing this increased monitoring as indicated by the earlier age of first developmental delay diagnosis in the plagiocephaly group, this was not included in the recommendations from the most recent AAP guidelines on diagnosis and management of infants with plagiocephaly.³ Developmental pediatricians may find themselves in roles to inform further research related to plagiocephaly and developmental delay as well as development of guidelines utilized widely by primary care providers and may help guide developmental screening best practices. Our finding of plagiocephaly being more common in males is consistent with prior literature review results.^6,9 Additionally, there is some evidence that lower maternal education status is associated with prone positioning of the infant,⁶ which in turn may decrease time on back and therefore mitigate some of the positional risk for plagiocephaly. Such a difference in positioning by education status may be reflected in the association found in our study of children with Medicaid insurance having a lower percentage with plagiocephaly compared to those with private insurance (Table 1).

There are several limitations to our study. One limitation is the reliance on administrative data from the EMR, such as diagnosis codes from office visits, which may lead to under-diagnosis of plagiocephaly, as well as other covariates such as torticollis or abnormal tone. Although administrative data may underestimate the true prevalence of plagiocephaly in this population, our overall rate of plagiocephaly diagnosis was 3%, with a significant increase over time, which is consistent with prior reports of prevalence of this condition.^3,4,17 Given the long time frame of data collection, we also adjusted the models for birth year of the patient, as provider and family knowledge of plagiocephaly may have changed over the data collection period. Additionally, the use of EMR data relies on provider judgment and documentation for diagnoses of developmental delay and plagiocephaly, often without standardization of evaluation approaches used in the primary care clinical setting. With respect to developmental delay diagnoses, a limitation is the lack of information about developmental screening tool use or outcomes. This imprecision in the exposure and outcome variables is a limitation with regard to reliability and predictive validity; however, it may reflect patterns present in primary care clinical practice. Furthermore, it is not possible to identify severity of plagiocephaly or treatment recommendations or effects among those diagnosed with plagiocephaly based on the administrative data. As an EMR-available proxy for severity, helmet data based on the order for a cranial remolding orthosis in the EMR were obtained, with 51 (2.2%) of the 2,315 patients with plagiocephaly noted to have an order for a helmet. Of the 404 patients with both plagiocephaly and developmental delay, only 11 (2.7%) patients had helmet orders, suggesting that helmet therapy was used in a small subset of children both with and without developmental delay. The use of EMR data also limits the ability to control for other proposed risk factors noted in the literature that are not available in an EMR. Although there is inconsistency in the literature regarding risk factors for plagiocephaly,⁹ we were unable to control for risk factors from the prenatal or perinatal period, such as maternal age, multiple gestation pregnancy, oligohydramnios, birth order, or assisted delivery, or in the postnatal period, such as hospitalization and amount of supine positioning.⁶ Another limitation is the risk of ascertainment bias, as there was a slightly higher median number of visits in the plagiocephaly group compared to the non-plagiocephaly group [18 (IQR 11–29) vs. 16 (8–26)].

Given the cross-sectional retrospective study design, future prospective study designs may better elucidate the connection between plagiocephaly and developmental delay outcomes, perhaps by helping to identify a shared risk factor that can serve as a point of intervention. One such factor may be abnormal muscle tone, which was more common in the plagiocephaly group and was associated with a nearly 15-times increased odds of any developmental delay diagnosis (Supplemental Table 2). Although our analysis demonstrated an association between developmental delay and plagiocephaly despite adjustment for abnormal tone, our findings and those of prior research suggest abnormal tone may play a mediating role.⁸

CONCLUSION

In a large, multistate primary care cohort of over 77,000 children spanning multiple years, we observed a significant association between plagiocephaly and developmental delay. Plagiocephaly diagnosis also usually occurred before a delay was diagnosed, suggesting that plagiocephaly may be an early marker of developmental risk. Although there are limitations related to use of administrative data for diagnoses of plagiocephaly and developmental delay, there is evidence for improved developmental outcomes with early intervention services,¹⁸ and, if further research supports such an association between plagiocephaly and developmental delay, there may be opportunity to reconsider current primary care practice patterns when caring for infants with plagiocephaly beyond recommendations of tummy time and referral to physical therapy only when improvement in plagiocephaly is not observed. Future studies may consider exploring a similar relationship prospectively in a primary care cohort with stricter definitions for plagiocephaly and delay diagnoses, as well as evaluating the effect of early physical therapy, early intervention, or other developmental interventions on developmental delay diagnoses in children with plagiocephaly.