Low back pain (LBP) is a common, often long-term problem which occurs at all stages of life from childhood to old age. This thesis focuses on persistent LBP in ‘emerging adulthood’ (18-29 years), a developmental stage characterised by delayed subscription into adulthood in which formative behavioural transitions and unique cumulative exposure occur which could influence long-term health outcomes. LBP research within this period has relatively limited evidence on the frequency and specific causes. Emerging adults and adolescents experience sleep disturbance commonly, through increased social and educational demands. The aim of this thesis was to estimate prevalence of persistent LBP in emerging adulthood, its association with comorbidity, and the possible effect of sleep disturbance.
I conducted three analyses using data from the 1970 British Birth Cohort Study (BCS70): (i) cross-sectional prevalence study of persistent LBP at age 29 years (n=11,226); (ii) crosssectional analytic study of the associations of persistent LBP at 29 years with a range of physical and mental health co-morbidities ; (iii) nested case-control analysis investigating the association between sleep disturbance during childhood and emerging adulthood (ages 10, 16, 21, 26, 29 years) and persistent LBP at age 29 years.
The estimated lifetime, 12-month, and annual consultation prevalences for persistent LBP at age 29 years were 14.9% (95% CI 14.2, 15.5), 11.1% (10.5, 11.7) and 6.4% (6.0, 6.9) respectively. 81.1% reported their persistent LBP began in emerging adulthood. Compared to 29-year-olds without persistent LBP, those with persistent LBP were more likely to report a wide range of other health conditions (e.g. prevalence odds ratio (OR) for asthma = 1.35 (1.07, 1.70); for eating disorder = 2.62 (1.80, 3.82)), although they were generally not more likely to seek help for these co morbidities. Persistent LBP commencing in emerging adulthood was associated with sleep disturbance at age 26 and 29 years ((adjusted OR 1.32 (1.05, 1.65) and 1.46 (1.23, 1.73) respectively) but not at age 10, 16 and 21 years. Reporting sleep disturbance at multiple age points showed a dose-response relationship.
Persistent LBP by the end of ‘emerging adulthood’ is already common and associated with multiple physical and mental health co-morbidities Sleep disturbance in childhood does not appear to be a risk factor however the role of sleep disturbance in emerging adulthood itself, perhaps as a cause but also as an effect of persistent LBP, warrants further investigation.