Day 254 - 22 May 96 - Page 30


     
     1        this in the same order, it says underneath the chart that
     2        'relative risks are adjusted for the following variables.
     3        Age at menarche', then it goes through some other ones,
     4        'body mass index', more other adjustment, 'fibre intake,
     5        and energy intake'.  So, the risk adjustments were made on
     6        all of those, the relative risk adjustments were made on
     7        all those things, yes?
     8        A.  What they are trying to do by this, I am afraid ----
     9
    10   Q.   Could you just answer yes or no and then expand if you
    11        want?
    12        A.  Can you repeat the question?
    13
    14   Q.   It says 'the relative risks are adjusted for the following
    15        variables'; that means the risks in the chart above, yes?
    16        A.  Yes.
    17
    18   Q.   They have all been adjusted for all of those things, is
    19        that right?
    20        A.  The relative risks, yes.
    21
    22   Q.   Yes, and that includes age at menarche, body mass index,
    23        fibre intake, and energy intake?
    24        A.  Yes.
    25
    26   Q.   Which are all things which are influenced by diet?
    27        A.  What they are trying to do here is to take out factors
    28        which might confound the results, they are trying to look
    29        at a specific relationship, which is the relationship
    30        between fat and breast cancer, and, as we all know, all of
    31        these other factors which, at least a lot of them, we
    32        believe may be important.  I am not sure about education
    33        and so on, but they have looked at things like social
    34        status, mother having had breast cancer, a sister having
    35        breast cancer, things like hormones, oral contraception and
    36        so on.
    37
    38        They have tried to look at things which might possibly
    39        influence the risk of a patient having developed breast
    40        cancer, and what they do in this statistical analysis is
    41        adjust things so that you can look at comparable groups of
    42        patients who have this relative effect from, say, age at
    43        menarche at less than 11 or greater than 15 years, and they
    44        will then compare people with breast cancer and those
    45        without breast cancer to see if there is any difference
    46        related to the intake of fat.
    47
    48        So, they are trying to get rid of these confounding
    49        variables so they can look at the one thing which is the
    50        purpose behind this paper, which is, is there the 
    51        relationship between fat and breast cancer? 
    52 
    53   MR. JUSTICE BELL: Yes, but Ms. Steel's point she is putting to
    54        you is that some anyway of the confounding variables may
    55        have an element of fat involved in them, fat intake
    56        involved in them.  Do you see?  So, you may be taking away
    57        some of the effect of fat intake in allowing for those
    58        confounding variables.  What I cannot see is whether some
    59        statistical account of that is taken in the method of
    60        discounting for the confounding variables so that, for

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