Mortality socio-economic inequalities for small-areas in Belgium: assessing concentration

Background: The reduction of socio-economic inequality in mortality is an i mportant public health goal. Previous ecological studies aimed at studying the relationship between mortality rate and socio-economic factors have pai d little attention to mortality causes avoidable by primary or secondary pr evention. Furthermore, these studies do not make the distinction between, o n the one hand, the strength of the relationship mortality/socio-economic d eprivation and, on the other hand the significance of the unequal distribut ion of mortality. The present work is aimed at measuring the strength of th is relationship and the concentration of mortality in relation to socio-eco nomic deprivation for both overall mortality and mortality avoidable by pri mary and secondary prevention. Method: Standardised mortality ratios were computed at the community level in Belgium (1985-93 period) for all causes and for 11 mortality causes avoi dable by primary and secondary prevention. A deprivation index was elaborat ed using a factorial principal component analysis on 11 socio-economic indi cators. The mortality/deprivation relationship was assessed by way of a sta ndardised regression coefficient (B) while socio-economic concentration of mortality was estimated using the Concentration Illness Index (Cii) and the P90/P10 ratio. Results: A strong positive relationship was found between mortality and dep rivation for under 65 years all-causes mortality (B = 0.71; CI [0.66; 0.76] ), mortality for cirrhosis of the liver (B = 0.56, CI [0.51; 0.62]), lung c ancer (B = 0.49, CI [0.42; 0.56]), suicide (B = 0.35; CI [0.29; 0.42]) and falls (B = 0.34; CI [0.28; 0,41]). However, the concentration of mortality was more limited: 14% (CI [11%-17%]) of cirrhosis of the liver mortality, 7 % of fall (CI [5%-10%]) and suicide mortality (CI [4%-9%]), 6% (CI [5%-7%]) of lung cancer mortality is unequally distributed. Conclusion: Socio-economic deprivation is positively associated with mortal ity. This association is more pronounced for tobacco, alcohol and mental he alth related mortality. However, the strength of the relationship between s ocio-economic deprivation and mortality is not a good indicator of unequal distribution.