Value and reliability of anthropometric measurements of cranial deformity in early childhood.

OBJECTIVES: Since the "back to sleep" campaign initiated by the American Pediatric Society in 1992, an increasing incidence of positional cranial deformity in early infancy has been widely observed. Anthropometric caliper measurements present the most practical tool for diagnosis and decision making although their value is being controversially discussed in literature. PATIENTS AND METHODS: Our study included 30 randomly chosen infants who had been diagnosed with plagiocephaly, brachycephaly, or a combination of both conditions. The 10 patients in each group were then measured anthropometrically by three examiners. The following parameters were measured six times in a standard manner and with a standard head position by each examiner: circumference, length, width, and oblique distance from the fronto-temporal area (ft) to the lambdoid suture on each side of the head (ld). Inter- and intra-observer variabilities for every value were statistically evaluated by a variance components estimation procedure.
RESULTS: Both inter- and intra-observer agreement had very low variability. Overall, mean inter-observer variability was lower than 0.182mm(2), and mean intra-observer variability was lower than 1.131mm(2). Altogether, interobserver variability as well as intraobserver variability had a maximum of about 2 mm measurement variance.
CONCLUSIONS: Standardized measurements are highly reproducible to quantify early childhood head deformity. Standard head position is indispensable for reliable measurement. Repeatability of anthropometric measurements is essential to define diagnoses and severity codes and to develop treatment concepts.