158 VOLUME 4 • NUMBER 2 • JUNE 2012 JOURNAL OF PRIMARY HEALTH CARE
Mangin D. Adherence to
evidence-based guidelines is
the key to improved health
outcomes for general
practice patients—the ‘no’
case. J Prim Health Care.
Dee Mangin MBChB,
Department of Public
Health and General
Practice, University of
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Adherence to evidence-based guidelines is
the key to improved health outcomes for
general practice patients
‘Clinical Practice Guidelines’—a Google search
using this term netted 26 200 000 results in
0.43 seconds. Guidelines are as unmanageable as
the research they were designed to summarise.
Guidelines were intended to bring the best scien-
tific evidence to bear on primary care practice—
an upgrade from the Blue Book that we used to
carry in case of knowledge emergencies as a house
surgeon. Guidelines have now moved beyond
this—the quality of family practitioners’ care is
increasingly measured by guideline adherence.
Is adherence to guidelines the best way to im-
prove health outcomes? No—it may result in care
that seems measurably better, but is meaning-
fully worse for health outcomes. There are three
broad reasons for this—the quality of guidelines,
the quality of the available research data that
underpin them and their unfitness for purpose in
a primary care setting.
The quality of guidelines
If guidelines stuck to the data and critical as-
sessment of its gaps and uncertainties this might
be useful—but back-filling the gaps in data
with ‘consensus’ appears to be irresistible. In a
study of 2700 recommendations in the Ameri-
can Heart Association / American Cardiology
Association guidelines, only 10% were based on
high-quality RCT evidence.1 Half were simply
consensus. The widespread levels of conflict of
interest of group members with the manufactur-
ers amplifies the concern.
The label ‘level C evidence’ does not undo the air
of certainty of the written word on the page of a
guideline. One example is HbA1c target levels for
Type 2 diabetes, which are standards that increas-
ingly doctors are exhorted to adhere to, and in
some countries carry an income bonus. There is no
good evidence for treating to any particular target
HbA1c. Large well-designed studies have shown
the harm and increased mortality associated with
tight glucose control and the lack of meaningful
benefit of tight control on outcomes that matter
to patients. Yet guidelines continue to include
these targets, and do so inconsistently: targets in
recent Type 2 diabetes guidelines internationally
vary between <6.5% (<47.5 mmol/mol) and 8%
(<64 mmol/mol). Adhering to the targets speci-
fied in many guidelines for diabetes would kill
more patients than were helped. Forcing HbA1c
low also increases the risk of the patient suffering
hypoglycaemia, which does have an association