Patterns and seasonality in pediatric referrals for functional somatic symptoms.

Functional somatic symptoms (FSS), or medically unexplained physical symptoms, are common in children and it has been suggested that the incidence is increasing. To determine the incidence and pattern of referrals for FSS to pediatricians, we performed a retrospective analysis including newly referred pediatric patients to our secondary pediatric practice in Zwolle, The Netherlands, ultimately diagnosed with FSS between 2013 and 2018. FSS was defined as functional abdominal pain, chronic fatigue, chronic musculoskeletal pain and chronic headache without an underlying medical diagnosis. In the 6-year period, 10.4% of elective referrals were related to FSS without a significant upward trend. We found clear seasonal variation with peaks in incidences in March (+31%) and November (+21%) and a nadir around August (-48%). In conclusion, FSS account for 1 in 10 non-acute pediatric referrals, without an increase in incidence in the past 6 years. The seasonal pattern is remarkable and warrants further analysis.