Table 1.

Categorisation of socioeconomic variables.

Socioeconomic variable	Categorisation	Comparison
Social Class	Registrar General's Social Class coded 1–6 for classes I-V respectively. All other values considered missing in models of social class as only s/e variable (column 1 of Table 2) and as a separate "other" category in other models.	Rate ratio per unit change in 6-point scale (professional to unskilled).
Carstairs quintiles	Carstairs index for wards of E&W. All residents of ward assigned quintile based on ward ranking.	Rate ratio per unit change in 5-point scale (less to more disadvantage).
Car Access	Access to car or van by household.	No car access vs any access.
Housing Tenure	Owner-occupation or rented accommodation	Rent vs own/occ.