Marked geographic patterns in the incidence of idiopathic central precocious puberty: a nationwide study in France.

Objectives: Precocious puberty seems to be increasing but epidemiological data are scarce. Our objective was to improve the epidemiologic knowledge on this disease. We analyzed the national incidence and spatial trends of idiopathic central precocious puberty in France in 2011-2013 in a cross-sectional descriptive study.

Design: We used an indicator based on treatment reimbursements recorded in the national insurance database, in girls under the age of nine years and in boys under the age of 10 years. We considered a time lag of up to one year from the onset of puberty to first drug delivery. We tested four different predictive spatial models at the scale, selecting the model best fitting the data. We carried out semi-structured interviews with qualified hospital teams in five selected regions to investigate spatial differences in medical practices.

Results: The national annual incidence was 2.68 (95% CI: 2.55, 2.81) per 10 000 girls under the age of 9 years and 0.24 (95% CI: 0.21, 0.27) per 10 000 boys under the age of 10 years. Incidence rates conformed to a purely spatial heterogeneity model in girls, consistent between age groups, with a large incidence range. A similar pattern was observed for boys, with peaks in the South West and Center East. Differences in medical practices may have slightly affected incidence locally, but could not entirely explain the marked geographic pattern.

Conclusions: The results suggest that the risk factors are similar for boys and girls and justify further investigations of the role of the environment.