Table 1. Overview of the IHC Key Concepts.

1. Claims Claims about effects that are not supported by evidence from fair comparisons are not necessarily wrong, but there is an insufficient basis for believing them.	2. Comparisons Studies should make fair comparisons, designed to minimize the risk of systematic errors (biases) and random errors (the play of chance).	3. Choices What to do depends on judgements about a problem, the relevance of the evidence available, and the balance of expected benefits, harms, and costs.
1.1 It should not be assumed that treatments are safe or effective - or that they are not. a)    Treatments can cause harms as well as benefits. b)    Large, dramatic effects are rare. c)    It is rarely possible to be certain about the effects        of treatments. 1.2 Seemingly logical assumptions are not a sufficient basis for claims. a)    Treatment may not be needed. b)    Beliefs alone about how treatments work are        not reliable predictors of the presence or size of        effects. c)    Assumptions that fair comparisons of treatments        in research are not applicable in practice can be        misleading. d)    An outcome may be associated with a treatment        but not caused by it. e)    More data is not necessarily better data. f)     Identifying effects of treatments depends on        making comparisons. g)    The results of one study considered in isolation        can be misleading. h)    Widely used treatments or those that have been        used for decades are not necessarily beneficial        or safe. i)    Treatments that are new or technologically        impressive may not be better than available        alternatives. j)    Increasing the amount of a treatment does not        necessarily increase its benefits and may cause        harm. k)    Earlier detection of ‘disease’ is not necessarily        better. l)    It is rarely possible to know in advance who will        benefit, who will not, and who will be harmed by        using a treatment. 1.3 Trust in a source alone is not a sufficient basis for believing a claim. a)    Your existing beliefs may be wrong. b)    Competing interests may result in misleading        claims. c)    Personal experiences or anecdotes alone are an        unreliable basis for most claims. d)    Opinions alone are not a reliable basis for claims. e)    Peer review and publication by a journal do not        guarantee that comparisons have been fair.	2.1 Comparisons of treatments should be fair. a)    Comparison groups should be as similar as        possible. b)    Indirect comparisons of treatments across        different studies can be misleading. c)    The people being compared should be        cared for similarly apart from the treatments        being studied. d)    If possible, people should not know which        of the treatments being compared they are        receiving. e)    Outcomes should be assessed in the same        way in all the groups being compared. f)    Outcomes should be assessed using        methods that have been shown to be        reliable. g)    It is important to assess outcomes in all (or        nearly all) the people in a study.         h)    People’s outcomes should be counted in the        group to which they were allocated . 2.2 Syntheses of studies need to be reliable. a)    Reviews of studies comparing treatments        should use systematic methods. b)    Failure to consider unpublished results of        fair comparisons may result in estimates of        effects that are misleading. c)    Treatment claims based on models may be        sensitive to underlying assumptions. 2.3 Descriptions should clearly reflect the size of effects and the risk of being misled by the play of chance. a)    Verbal descriptions of the size of effects        alone can be misleading. b)    Relative effects of treatments alone can be        misleading. c)    Average differences between treatments can        be misleading. d)    Small studies may be misleading. e)    Results for a selected group of people within        a study can be misleading. f)    The use of p-values may be misleading;        confidence intervals are more informative. g)    Deeming results to be “statistically        significant” or “nonsignificant” can be        misleading. h)    Lack of evidence of a difference is not the        same as evidence of “no difference”.	3.1 Problems and options should be clear. a)    Be clear about what the problem        or goal is and what the options        are. 3.2 Evidence should be relevant. a)    Attention should focus on all        important effects of treatments,        and not surrogate outcomes. b)    Fair comparisons of treatments in        animals or highly selected groups        of people may not be relevant. c)    The treatments compared should        be similar to those of interest. d)    There should not be important        differences between the        circumstances in which the        treatments were compared and        those of interest. 3.3 Expected advantages should outweigh expected disadvantages. a)    Weigh the benefits and savings        against the harms and costs of        acting or not. b)    Consider the baseline risk or the        severity of the symptoms when        estimating the size of expected        effects. c)    Consider how important each        advantage and disadvantage is        when weighing the pros and cons. d)    Consider how certain you can        be about each advantage and        disadvantage. e)    Important uncertainties about        the effects of treatments should        be addressed in further fair        comparisons.