Association between socio-economic status and non-communicable disease risk in young adults from Kenya, South Africa, and the United Kingdom

Abstract

There is a pressing need for global health preventions to curb the escalating burden of non-communicable diseases (NCDs). Utilising multi-country study designs can improve our understanding of how socio-economic context shapes the aetiology of NCDs, and this has great potential to advance global health interventions. We examined the association between socio-economic status (SES) and NCD risk, and the potential moderating effects of smoking and alcohol intake in young adults (18-35-year-olds) from Kenya, South Africa (SA), and the United Kingdom (UK). Our study was a cross-sectional online survey that included 3000 respondents (n = 1000 per country, 50% women) conducted in April 2022. We utilised information on twelve NCDs to classify respondents as having “no condition”, “at least one condition”, and “multimorbidity” (having two or more conditions). A total household asset score was calculated and used as a proxy of SES, and subsequently categorised into quintiles (Q1-Q5; lowest-highest). Ordered logistic regression was used to test the associations between NCD risk and exposure variables. We found that a one-category increase in SES quintile was inversely associated with an increased NCD risk in the UK but was positively associated in SA and Kenya. In all countries, smoking and/or alcohol intake were positively associated with an increased NCD risk, and showed some moderating effects on the SES-NCD relationships. Specifically, in Kenya, the risk of developing NCD was more than two times higher in those in the middle (Q3) SES group (OR: 2.493; 95% CI: 1.519–4.091; p < 0.001) compared to their lowest (Q1) SES counterparts. After adjusting for smoking and alcohol, the ORs of middle (Q3) SES group changed from 2.493 to 2.241 (1.360–3.721; p = 0.002). Overall, we found that the strength and direction of SES-NCD associations differed within and between countries. This study highlights how different SES contexts shape the risk of NCDs among young adults residing in countries at different levels of economic development.