Childhood socioeconomic position and objectively measured physical capability levels in adulthood: a systematic review and meta-analysis

Abstract

Background: Grip strength, walking speed, chair rising and standing balance time are objective measures of physical capability that characterise current health and predict survival in older populations. Socioeconomic position (SEP) in childhood may influence the peak level of physical capability achieved in early adulthood, thereby affecting levels in later adulthood. We have undertaken a systematic review with meta-analyses to test the hypothesis that adverse childhood SEP is associated with lower levels of objectively measured physical capability in adulthood.

Methods and findings: Relevant studies published by May 2010 were identified through literature searches using EMBASE and MEDLINE. Unpublished results were obtained from study investigators. Results were provided by all study investigators in a standard format and pooled using random-effects meta-analyses. 19 studies were included in the review. Total sample sizes in meta-analyses ranged from N = 17,215 for chair rise time to N = 1,061,855 for grip strength. Although heterogeneity was detected, there was consistent evidence in age adjusted models that lower childhood SEP was associated with modest reductions in physical capability levels in adulthood: comparing the lowest with the highest childhood SEP there was a reduction in grip strength of 0.13 standard deviations (95% CI: 0.06, 0.21), a reduction in mean walking speed of 0.07 m/s (0.05, 0.10), an increase in mean chair rise time of 6% (4%, 8%) and an odds ratio of an inability to balance for 5s of 1.26 (1.02, 1.55). Adjustment for the potential mediating factors, adult SEP and body size attenuated associations greatly. However, despite this attenuation, for walking speed and chair rise time, there was still evidence of moderate associations.

Conclusions: Policies targeting socioeconomic inequalities in childhood may have additional benefits in promoting the maintenance of independence in later life.

Figure 1. Flow diagram for identification of published studies.

Figure 2. Flow diagram showing contact with authors and ascertainment of results for inclusion in review.

* This included a review paper on longitudinal studies of ageing , relevant websites – and experts in the field of gerontology.

Figure 3. Age adjusted differences in mean standardised grip strength comparing lowest with highest childhood SEP.

Footnotes: Please note that in the study of middle aged Danish twins (MADTs) major wage earner's occupation and education rather than father's occupation and education were assessed. Swedish 1969/70 Conscription Cohort was a subset of the study on the Swedish Military Service Conscription Register so has not been included in the meta-analysis. The results were: Swedish 1969/70 Conscription Cohort; 100% male; mean age 18.3 years; N = 42,365; the standardised estimate for father's occupation and grip strength was an increase of 0.24 SDs (95% CI: 0.21, 0.28). The abbreviations of study names for figures 3– 6 are: ABC1921: Aberdeen Birth Cohort 1921; ABC1936: Aberdeen Birth Cohort 1936; Boyd Orr; CaPS: Caerphilly Prospective Study; ELSA: English Longitudinal Study of Ageing; HAS: Hertfordshire Aging Study; HCS: Hertfordshire Cohort Study; HRS: Health and Retirement Study; KLoSA: Korean Longitudinal Study of Ageing; LBC1921: Lothian Birth Cohort 1921; LBC1936: Lothian Birth Cohort 1936; Lc65+: Lausanne Cohort 65+; MADTs: The study of middle aged Danish twins; NSHD: MRC National Survey of Health and Development; PREHCO project: Puerto Rican Elderly Health Conditions project; SABE: Survey on Health and Wellbeing of Elders (conducted in: Bridgetown, Barbados; Havana, Cuba; Mexico City, Mexico; Santiago, Chile; Sao Paulo, Brazil); Swedish Military: Swedish Military Service Conscription Register; SWS: Southampton Women's Survey.

Figure 4. Age adjusted differences in mean walking speed (m/s) comparing lowest with highest childhood SEP.

Figure 5. Age adjusted differences in mean chair rise time (ln(s)) comparing lowest with highest childhood SEP.

Figure 6. Age adjusted odds ratios of inability to balance for 5 seconds comparing lowest with highest childhood SEP.