According to the abstract of their paper, Heitmann et al. [1] found
that "a threshold effect for thigh circumference was evident, with greatly
increased risk of premature death below around 60 cm". Their Table 1 shows
the median thigh circumference was around 55 cm, so this implies that more
than half the population were at greatly increased risk. In contrast to
the misleading abstract and press release[2], the staff of BMJ Best
Treatments provided a more appropriate interpretation in the “best
treatments” section of Friday’s Guardian [3]: " Having thighs larger than
60cm made no difference to people's risk. People were most at risk if they
had a thigh measurement of less than 46.5 centimetres (18 inches). This
group had roughly double the chances of getting heart and circulation
problems or dying during the study. However, only 2.5 percent of the
people fell into this category."
Particularly in men, the reported effects were modest before analyses
were adjusted for anthropometric measures such as body mass index (BMI)
and waist circumference. These adjusted estimates are hard to interpret,
because they refer to the differences in risk that would apply if an
individual changed their thigh circumference while keeping these other
anthropometric measures constant.
The sources referred to above[1-3], as well as the accompanying
editorial[4], seemed to ignore these issues in interpretation.
[1] Heitmann BL, Frederiksen P. Thigh circumference and risk of
heart disease and premature death: prospective cohort study. BMJ
2009;339:b3292.
Rapid Response:
Thighs and thresholds
According to the abstract of their paper, Heitmann et al. [1] found
that "a threshold effect for thigh circumference was evident, with greatly
increased risk of premature death below around 60 cm". Their Table 1 shows
the median thigh circumference was around 55 cm, so this implies that more
than half the population were at greatly increased risk. In contrast to
the misleading abstract and press release[2], the staff of BMJ Best
Treatments provided a more appropriate interpretation in the “best
treatments” section of Friday’s Guardian [3]: " Having thighs larger than
60cm made no difference to people's risk. People were most at risk if they
had a thigh measurement of less than 46.5 centimetres (18 inches). This
group had roughly double the chances of getting heart and circulation
problems or dying during the study. However, only 2.5 percent of the
people fell into this category."
Particularly in men, the reported effects were modest before analyses
were adjusted for anthropometric measures such as body mass index (BMI)
and waist circumference. These adjusted estimates are hard to interpret,
because they refer to the differences in risk that would apply if an
individual changed their thigh circumference while keeping these other
anthropometric measures constant.
The sources referred to above[1-3], as well as the accompanying
editorial[4], seemed to ignore these issues in interpretation.
[1] Heitmann BL, Frederiksen P. Thigh circumference and risk of
heart disease and premature death: prospective cohort study. BMJ
2009;339:b3292.
[2] BMJ press releases Monday 31 August to Friday 4 September 2009.
<http://www.bmj.com/content/vol339/issue7720/press_release.dtl>
[3] BMJ Group. Could big thighs protect against heart disease? The
Guardian. 4 September 2009.
<http://www.guardian.co.uk/lifeandstyle/besttreatments/2009/sep/04/could
-big-thighs-protect-against-heart-disease>
[4] Scott IA. Thigh circumference and risk of heart disease and
premature death. BMJ 2009;339:b3302.
Competing interests:
None declared
Competing interests: No competing interests