Socio-economic status by rapid appraisal is highly correlated with mortality risks in rural Africa

Socio-economic status is an important determinant of health and survival in rural Africa and necessitates a practical and valid instrument to implement in health studies. Our objective was to investigate the validity of the rapid appraisal method to assess socio-economic status and its ability to identify individuals at risk. Among 1573 households in rural northern Ghana, we calculated the Demographic Health Survey (DHS) wealth index and conducted two rapid appraisal methods: self-reported wealth and interviewer-reported wealth. In addition we followed the 25,184 participants from these households for survival with a mean follow-up of 3.9 years, during which 885 participants died. The DHS wealth index was moderately correlated to self-reported wealth (Spearman's rho 0.59, P<0.001) and interviewer-reported wealth (Spearman's rho 0.75, P<0.001). Mortality risks were significantly higher for people with lower than average self-reported wealth [hazard ratio (HR) 1.30 (95% CI 1.11-1.51)] and lower interviewer-reported wealth [HR 1.40 (95% CI 1.21-1.62)]. Mortality risks were lower for people with higher self-reported wealth [HR 0.81 (95% CI 0.32-2.03)] and higher interviewer-reported wealth [HR 0.84 (95% CI 0.58-1.21)]. Similar discriminative mortality risks were assessed when using tertiles of the DHS wealth index (Ptrend<0.001).