Structural analysis of a set of socioeconomic indexes as an aid in defining the socioeconomic level of a family : results from an italian multicentric survey

The study of possible associations between social and health factors was one of the purposes of the multicentric Italian survey of perinatal preventive medicine. To get a concise and coherent social indicator, which could be useful to this study, we explored the socioeconomic information systematically collected on the parents of 12,058 babies born in 1973-1975 in four centres (Trieste, Milan, Parma and Bari), which reflect some of the heterogeneous aspects of Italy. The Correspondence analysis indicated that the seven considered indexes, concerning both parents' education levels and occupations, dwelling quality and the length of father's residence in the area in which the baby was born, were highly and similarly correlated in each centre. The Dynamic cluster analysis enabled us to bring together the socioeconomic profiles of the families into six classes, on the basis of their similarities, which depend only upon the multivariate distribution of the seven categorical variables under study. Therefore, the attained classification not only is independent of whatever score is assigned to the socioeconomic categories but also allows for the strong interactions between the variables and exploits all the available information. Our six classes were found to be rather similar to the six socioeconomic groups (S.E.G.) of the U.K. Registrar General and to show some resemblance to certain social groups defined by other classifications adopted in obstetric and pediatric field. The socioeconomic indicator constructed here should enable us to find out how much, in different areas of Italy, the social classes may account for inequalities in health conditions and care of the mother and her baby.