Overdiagnosis of osteoporosis: fact or fallacy?
Overdiagnosis of osteoporosis: fact or fallacy?
J. Compston 0
0 Cambridge Biomedical Campus , Cambridge , UK
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In their paper in the British Medical Journal, BOverdiagnosis
of bone fragility in the quest to prevent hip fracture^, Järvinen
et al. claim that there is inadequate evidence to support current
pharmacological approaches to the prevention of hip fracture
[1]. They state, correctly, that the vast majority of hip fractures
follow a fall but fail to recognize the obvious connection
between the consequence of a fall and bone strength. With the
use of selective and misleading presentation of published
evidence, they provide a biased critique of current strategies for
risk assessment and prevention of hip fracture. Most
surprisingly, they fail even to mention Fracture Liaison Services, a
model of care that has been shown to be both effective and
cost-effective in the secondary prevention of fracture and has
been successfully adopted in many parts of the world [2–7].
No one would deny that, as in many fields of medicine,
there are gaps in the evidence or that current practice can be
improved. Indeed, we know that the majority of elderly people
who suffer a hip fracture are not assessed for osteoporosis or
offered treatment in the form of lifestyle advice, falls
counselling or bone protective therapy [8, 9]. These individuals are at
high risk of further fractures and the proven anti-fracture
efficacy of pharmacological interventions in this situation
provides a strong rationale for their use in secondary prevention.
Prevention of the first fracture is another important but more
difficult goal, and the efficacy of pharmacotherapy for the
primary prevention of fracture has been less well studied. In
much of their analysis, Järvinen et al. fail to make the critical
distinction between primary and secondary prevention and by
combining figures from studies of both in their meta-analysis,
they arrive at a NNT for hip fracture that is too high and
meaningless in the context of secondary prevention.
Järvinen et al. acknowledge the large body of published
literature demonstrating that the majority of older people
whose fracture do not have osteoporosis as defined by the
WHO, i.e. a bone mineral density (BMD) T-score ≤−2.5, but
appear to miss the point that this provides the rationale for
fracture risk algorithms which include clinical risk factors that
act independently of bone density. In particular, the strong
effect of age has been recognized for decades and its inclusion
in risk algorithms greatly improves prediction of fracture risk
when compared to BMD alone [10, 11]. Furthermore, both in
the title and body of their manuscript, the authors use the terms
bone fragility and osteoporosis interchangeably. This is
incorrect, since factors other than BMD contribute to bone strength
and there is not a single BMD T-score threshold that defines
bone fragility. The authors claim that estimations of absolute
fracture risk are Bfundamentally flawed^ because fewer than
one in three hip fractures is attributable to bone fragility; this
statement is based on BMD measurements in a single study in
postmenopausal women with a mean age of 71 years [12].
This is misleading, first, because BMD-defined osteoporosis,
not bone fragility, was assessed and secondly because (as
repeatedly emphasized in other contexts by the authors) over
75 % of hip fractures occur in people over the age of 75 years.
Another major inaccuracy in their analysis is the contention
that organisations supporting the development of FRAX have
advocated widespread screening for bone fragility (presumably
osteoporosis). In contrast to this assertion, both organisations
quoted, the National Osteoporosis Foundation and National
Osteoporosis Guideline Group, recommend a case finding
strategy based on the presence of risk factors, a position also
supported by, amongst others, the International Osteoporosis
Foundation and the National Institute of Health and Care Excellence
(NICE) in the UK [13–17]. These organisations have improved
awareness of osteoporosis in the general population and
amongst healthcare professionals and politicians, empowering
individuals who may be at risk of fracture to seek advice and
providing guidance on their assessment and management.
Rather than imposing an unnecessary Bpsychological burden^, this
strategy provides appropriate access for individuals to
information about their risk and the measures that may be taken to
reduce it.
The claim by Järvinen et al. that non-pharmacological
interventions are overlooked should also be challenged. All
guidelines include counselling about life style, including diet,
tobacco use and alcohol intake, and promote appropriate
levels of physical activity. Whilst adopting these measures
may have beneficial effects on bone health, evidence that they
prevent fractures is lacking. Guidelines also stress the
importance of taking measures to prevent falls. However, although
fall prevention programmes hav (...truncated)