DIAGNOSTIC PRACTICE AND THE ESTIMATED PREVALENCE OF CRANIOSYNOSTOSIS IN COLORADO

Background: In the late 1980s, evidence of an epidemic of craniosynost osis in Colorado included reports of clusters from selected high-altit ude communities and an investigation showing the high and rapidly risi ng rates of surgically corrected synostosis. Some evidence suggested t hat local diagnostic practice could account for the epidemic. Objectiv e: To determine the contributions of any excess rates of disease occur rence, surgery-based ascertainment, and diagnosis to the reported epid emic. Design: Population-based birth prevalence study with diagnostic evaluation. Setting: The Colorado Department of Health, April 15, 1986 , to July 14, 1989. Patients or Other Participants: Children in the Cr aniosynostosis Registry or state birth record files. Main Outcome Meas ures: Birth prevalence was estimated from registry and birth record da ta; case classification by suture type and malformation patterns were determined by review of radiographs and medical records. Results: The period birth prevalence of radiographically confirmed nonsyndromic syn ostosis was 14.1 per 10 000 live births. Of a total of 605 children, 3 07 (51%) had definite radiographic evidence of synostosis, for which t he intrarater reliability was good (except for the coronal suture on p lain films) and the interrater reliability was fair or good (except fo r the metopic suture on plain films). Between the first and third year s, case reports fell from 347 to 103. Conclusions: Diagnostic criteria strongly influenced the rate of synostosis. The rate of radiographica lly confirmed synostosis was within the range of published estimates. Low diagnostic thresholds, which changed over time, treated the sembla nce of a severe statewide epidemic and may have obscured excess rates of disease at high altitude.