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Re: Confusion requiring clarification
The descriptions attached to each social class in Table 2 of our
paper are labels, not values, and were not intended to be interpreted as
the numbers used in analysis. Each of the four social class variables
used was scaled for analysis such that the highest numeric value was
attached to the highest social class, ie social class 1=6, 2=5, 3N=4,
3M=3, 4=2 and 5=1 where social class 3 was split, and 1=5,...,5=1
otherwise.
The negative regression coefficients obtained between social class at
birth and the outcome measure, combined with the positive associations
observed between poor housing conditions at birth and carotid intima-media
thickness, then become interpretable as lower socieconomic position
conferring higher risk, and vice versa.
We could have said "Lower socioeconomic position at birth and lower
birthweight were associated with higher values of carotid intima-media
thickness....", but felt that it was sufficiently clear that a negative
association between socioeconomic position and the outcome measure implied
low socioeconomic position, high intima-media thickness and vice versa.
Competing interests: No competing interests