Common risk factors and edentulism in adults, aged 50 years and over, in China, Ghana, India and South Africa: results from the WHO Study on global AGEing and adult health (SAGE)

BACKGROUND Edentulism (loss of all teeth) is a final marker of disease burden for oral health common among older adults and poorer populations. Yet most evidence is from high-income countries. Oral health has many of the same social and behavioural risk factors as other non-communicable diseases (NCDs) which are increasing rapidly in low- and middle-income countries with ageing populations. The "common risk factor approach" (CRFA) for oral health addresses risk factors shared with NCDs within the broader social and economic environment. METHODS The aim is to improve understanding of edentulism prevalence, and association between common risk factors and edentulism in adults aged 50 years and above using nationally representative samples from China (N = 11,692), Ghana (N = 4093), India (N = 6409) and South Africa (N = 2985). The data source is the World Health Organization (WHO) Study on global AGEing and adult health (SAGE) Wave 1 (2007-2010). Multivariable logistic regression describes association between edentulism and common risk factors reported in the literature. RESULTS Prevalence of edentulism: in China 8.9 %, Ghana 2.9 %, India 15.3 %, and South Africa 8.7 %. Multivariable analysis: in China, rural residents were more likely to be edentulous (OR 1.36; 95 % CI 1.09-1.69) but less likely to be edentulous in Ghana (OR 0.53; 95 % CI 0.31-0.91) and South Africa (OR 0.52; 95 % CI 0.30-0.90). Respondents with university education (OR 0.31; 95 % CI 0.18-0.53) and in the highest wealth quintile (OR 0.68; 95 % CI 0.52-0.90) in China were less likely to be edentulous. In South Africa respondents with secondary education were more likely to be edentulous (OR 2.82; 95 % CI 1.52-5.21) as were those in the highest wealth quintile (OR 2.78; 95 % CI 1.16-6.70). Edentulism was associated with former smokers in China (OR 1.57; 95 % CI 1.10-2.25) non-drinkers in India (OR 1.65; 95 % CI 1.11-2.46), angina in Ghana (OR 2.86; 95 % CI 1.19-6.84) and hypertension in South Africa (OR 2.75; 95 % CI 1.72-4.38). Edentulism was less likely in respondents with adequate nutrition in China (OR 0.68; 95 % CI 0.53-0.87). Adjusting for all other factors, compared with China, respondents in India were 50 % more likely to be edentulous. CONCLUSIONS Strengthening the CRFA should include addressing common determinants of health to reduce health inequalities and improve both oral and overall health.