Missing data on retrospective recall of early-life socio-economic position in surveillance systems: an additional disadvantage?

Objectives: Inclusion of information on early-life socio-economic position (SEP) in population chronic disease and risk factor surveillance systems enables better monitoring of effects of policies and interventions on health inequities and intergenerational disadvantage. Examining data quality, in terms of item non-response, informs choices about which indicators of early-life SEP to include in surveillance questionnaires. This study examined differences in recall of indicators of early-life SEP between different socio-economic groups.

Study Design: Cross-sectional population survey.

Methods: A representative population of people aged 18 years and over living in South Australia (n=2999) was selected at random from the electronic white pages, and a computer-assisted telephone interview was administered.

Results: Respondents with missing data on early-life SEP indicators were disadvantaged in terms of current SEP compared with those who provided this information. Among all respondents, the highest proportions of missing data were observed for maternal grandfather's main occupation (27.2%), and mother's (20.1%) and father's (19.6%) highest level of education. Family structure, housing tenure and family financial situation when the respondent was 10 years old, and mother's and father's main occupation were the indicators of early-life SEP that performed best in terms of recall.

Conclusions: The differential response to early-life SEP questions according to current circumstances has implications for chronic disease surveillance examining the life-course impact of socio-economic disadvantage.