Prevalence and early-life determinants of mid-life multimorbidity: evidence from the 1970 British birth cohort
Authors: Gondek Dawid , Bann David , Brown Matt , Hamer Mark , Sullivan Alice , Ploubidis George B. 
Published: June 2020

AbstractObjectivesWe sought to: (1) estimate the prevalence of multimorbidity at age 46-48 in the 1970 British Cohort Study—a nationally representative sample in mid-life; and (2) examine the association between early-life characteristics and mid-life multimorbidity in the 1970 British Cohort Study.DesignProspective longitudinal birth cohort.SettingA community based sample from the 1970 British Cohort Study (BCS70).ParticipantsAll surviving children born in mainland Britain in a single week in April 1970; the analytical sample was those with valid data at age 46-48 (n=7,951; 2016-2018).Main outcome measureMultimorbidity was operationalised as a binary indicator of two or more long-term health conditions where at least one of these conditions was of physical health. It also included symptom complexes (e.g. chronic pain), sensory impairments, and alcohol problems.ResultsPrevalence of mid-life multimorbidity was 33.8% at age 46-48. Those with fathers from unskilled social occupational class (vs. professional) at birth had 43% higher risk of mid-life multimorbidity (risk ratio=1.43, 95% confidence interval 1.15 to 1.70). After accounting for a range of potential child and family confounders, an additional kilogram of birthweight was associated with 10% reduced risk of multimorbidity (risk ratio=0.90, 95% confidence interval 0.84 to 0.96); a decrease of one body mass index point at age 10 was associated with 3% lower risk (risk ratio=1.03, 95% confidence interval 1.01 to 1.05); one standard deviation higher cognitive ability score at age 10 corresponded to 4% lower risk (risk ratio=0.96, 95% confidence interval 0.91 to 1.00); an increase of one internalising problem at age 16 was equated with 4% higher risk (risk ratio=1.04, 95% confidence interval 1.00 to 1.08) and of one externalising problem at age 16 with 6% higher risk (risk ratio=1.06, 1.03 to 1.09).ConclusionPrevalence of multimorbidity was high in mid-life (33.8% at age 46-48) in Britain, with those in a more disadvantaged social class a birth being disproportionally affected. Potentially modifiable early-life exposures including early-life social circumstances, cognitive, physical and emotional development were associated with mid-life multimorbidity.What is already known on this topic?Due to differences in outcome definition, estimates of multimorbidity prevalence in mid-life (age 40-60) have varied extensively in high-income countries—from 15 to 80% between 1961 and 2013.There is a lack of contemporary national data in Great Britain describing the burden and nature of multimorbidity according to an agreed definition.The association between early-life risk factors and individual health conditions have been widely studied, however it is unknown if they are associated with multimorbidity.What this study addsPrevalence of multimorbidity in mid-life (age 46-48) was 33.8% in a nationally representative birth cohort in 2016-2018.Disadvantaged early-life parental social class, lower birthweight, lower cognitive ability, higher childhood body-mass index, and a higher number of internalising and externalising problems were found to be associated with a higher mid-life multimorbidity.