Cumulative incidence of chronic health conditions recorded in hospital inpatient admissions from birth to age 16 in England

Background: Monitoring the incidence of chronic health conditions (CHCs) in childhood in England, using administrative data to derive numerators and denominators, is challenged by unmeasured migration. We used open and closed birth cohort designs to estimate the cumulative incidence of CHCs to age 16 years.

Methods: In closed cohorts, we identified all births in Hospital Episode Statistics (HES) from 2002/3 to 2011/12, followed to 2018/19 (maximum age 8 to 16 years), censoring on death, first non-England residence record or 16th birthday. Children must have linked to later HES records and/or the National Pupil Database, which provides information on all state school enrolments, to address unmeasured emigration. The cumulative incidence of CHCs was estimated to age 16 using diagnostic codes in HES inpatient records. We also explored temporal variation. Sensitivity analyses varied eligibility criteria. In open cohorts, we used HES data on all children from 2002/3 to 2018/19 and national statistics population denominators.

Results: In open and closed approaches, the cumulative incidence of ever having a CHC recorded before age 16 among children born in 2003/4 was 25% (21% to 32% in closed cohort sensitivity analyses). There was little temporal variation. At least 28% of children with any CHC had more than one body system affected by age 16. Multimorbidity rates rose with later cohorts.

Conclusions: Approximately one-quarter of children are affected by CHCs, but estimates vary depending on how the denominator is defined. More accurate estimation of the incidence of CHCs requires a dynamic population estimate.