Co-Occurrence of Health Conditions during Childhood: Longitudinal Findings from the UK Millennium Cohort Study (MCS).
OBJECTIVE
To identify patterns of stability and change in co-occurrence in children between 5-11 years, and to assess if they vary by socio-demographic factors.


METHODS
Data from 9548 singleton children from the UK Millennium Cohort Study (MCS) were assessed for co-occurrence of five common adverse conditions: wheeze; longstanding illness; unfavorable weight; injury; and socio-emotional difficulties. We summed adverse conditions (0-5) for each child at ages 5, 7, and 11 and identified co-occurrence (≥2 conditions). Using multinomial regression, we explored associations between co-occurrence trajectories and child's sex and ethnicity, maternal education, and income quintile.


RESULTS
45.6% of children experienced co-occurrence between 5-11 years (7% experienced constant co-occurrence). More children moved into co-occurrence than moved out (16.9 vs. 11.9%). Mutually-adjusted relative risk ratios (aRRR) showed a gradient by maternal education: compared to children with no co-occurrence whose mothers had a higher/degree, children whose mothers had no qualifications were more likely to move into (aRRR = 1.32(95%CI:1.02,1.70)), out of (1.74(1.34,2.26)), have fluctuating (1.52(1.09,2.10)) or constant co-occurrence (2.58(1.76,3.80)). The same gradient (high vs. low) was evident for income quintiles. Girls were less likely to experience co-occurrence.


CONCLUSIONS
Co-occurrence of adverse conditions is common during childhood, and trajectories are socially patterned. Child-focused care for lower-income children and boys early in life may prevent and reduce co-occurrence in later childhood.
UCL Institute of Child Health, Guilford Street, London, United Kingdom.
Kathryn R
http://orcid.org/0000-0003-3963-9189
KR
Hesketh
UCL Institute of Child Health, Guilford Street, London, United Kingdom.
Catherine
C
Law
UCL Institute of Child Health, Guilford Street, London, United Kingdom.
Helen
H
Bedford
UCL Institute of Child Health, Guilford Street, London, United Kingdom.
Steven
S
Hope
D015992:Body Mass Index; D002648:Child; D002675:Child, Preschool; D015897:Comorbidity; D005260:Female; D006304:Health Status; D006801:Humans; D007182:Income; D007223:Infant; D008137:Longitudinal Studies; D008297:Male; D009035:Mothers / Q000523:psychology*; D011203:Poverty; D012307:Risk Factors; D012959:Socioeconomic Factors; D006113:United Kingdom