Introduction: Acquired cranial asymmetry is prevalent in infants today and largely attributed to the supine sleep position recommended for infant safety. There is a risk of permanent cranial asymmetry, so prevention and early detection are important. A prevention project was initiated in Sweden, and an intervention was planned. The aim of this study was to evaluate reliability of assessors judging infant cranial asymmetry in order to evaluate if they could be considered reliable interchangeable assessors in the planned intervention.
Materials and methodology: Five assessors were taught how to assess infant cranial asymmetry using illustrated severity assessments. They were intra-rater and inter-rater reliability tested by taking a photograph test-retest and an infant test. Agreement matrices were devised to illustrate assessor agreement based on both type and degree of cranial asymmetry. Agreement based on degree of asymmetry was analyzed by calculating AC2 using quadratic weights. Results were adjusted to arrive at the perceived genuine agreement and interpreted according to Landis and Koch's strength of agreement intervals.
Results: In the photograph test, mean percentage of perfect intra-rater agreement was 73. Adjusted mean intra-rater AC2 was 0.69 [0.63; 0.76], and adjusted inter-rater AC2s were 0.72 [0.64; 0.81] and 0.71 [0.63; 0.79]. In the infant test, the adjusted inter-rater AC2 was 0.73 [0.60; 0.87]. Results indicate substantial strength of assessor agreement.
Conclusion: Assessors were reliable and interchangeable. In a larger clinical context, results indicate that educating child health care nurses to assess infant cranial asymmetry can be used for early detection.
Keywords: Agreement measure; child health centers; infant cranial asymmetry; nonsynostotic plagiocephaly; nursing assessment; reliability.