Loss in life expectancy after a colon cancer diagnosis by socioeconomic group: does the indicator of socioeconomic position matter?

Loss in life expectancy (LLE) by socioeconomic position (SEP) is obtained to explore cancer disparities. Often education or income are used to determine SEP. However, the low income of some older individuals or females within households with greater overall resources may not accurately reflect their SEP, potentially leading to biased estimates. Our study investigates how various conceptualizations of SEP influence the extent of these disparities. Data included all colon cancer diagnoses in Sweden between 2008 and 2016. We estimated LLE using different SEP indicators: education, individual income, part of household income. Household income accounts for individuals with low individual income but within high-income households. We allocated patients to income groups creating quartiles, overall or separately by sex, age-groups, or both, to account for SEP misclassification. We analysed data using flexible parametric survival models. Standardised LLE varied from 5.05 to 5.62 years for the lowest to the highest education, resulting in a 0.57-year difference. When income was used to determine SEP, LLE was similar with disparities ranging from 0.29 to 0.77 across definitions. Age and sex specific LLE disparities varied more across definitions. Disparities between 60-year-old females in the highest-lowest income groups were 0.94 when using household income and − 0.17 when using individual income. When studying LLE by SEP, thoughtful consideration must be given to selecting the most suitable indicator for conceptualizing SEP. The choice should align with the specific SEP pathway of interest and address potential misclassification concerns relevant to the study population.