To Örebro University

Introduction: Delayed puberty is defined as the absence of physical signs of puberty by the age of 14 years in boys and 13 years in girls. According to this definition, the prevalence of delayed puberty would be 2%, if the ages of pubertal onset were normally distributed in the population. However, the prevalence or incidence of delayed puberty has not been described before, as far as we know. Our aim was to study the incidence of delayed puberty in central Sweden.

Methods: In this population-based retrospective study all adolescents given the ICD-10 diagnosis “delayed puberty” in Örebro county during the period 2013-2015 were identified. Adolescents with other diagnoses potentially related to delayed puberty (e.g. short stature) were also identified to ensure that there were no additional cases. The medical records of these patients, except those not willing to participate, were systematically reviewed to ensure that the diagnosis was correct. The cases were then categorized into four groups depending on how accurate we found the diagnosis (certain, possible, wrong diagnosis, or unclear cases). Data on the total numbers of adolescents in Örebro county were obtained from the authority of statistics in Sweden.

Results: One hundred and twenty-eight of 180 eligible medical records were reviewed (response rate: 71 %). Nine boys and one girl were diagnosed with delayed puberty during the study time period and fulfilled our strict criteria for a certain diagnosis and 4 boys were classified as possible new cases. The total population in Örebro county for boys aged 14-18 years was on average 6,546 each year during the time period. The minimal annual incidence for boys was 46 per 100,000 (95% confidence interval (CI) 15-142 per 100,000). When possible cases were included, the annual incidence for boys increased to 66 (CI 26-170) per 100,000. Due to the low number of girls with delayed puberty no incidence for girls was calculated.

Discussion: This is, to our knowledge, the first study describing the incidence of delayed puberty in boys. We evaluated the accuracy of the diagnosis using strict criteria. The presented incidence should be regarded as the minimum incidence since some adolescents with delayed puberty may not seek medical advice or may be unrecognized by the health services in schools. Because of our small study population, larger studies are needed to confirm our findings and for calculation of the incidence in girls, where our data implies a much lower incidence.