GRADEシステムの「エビデンスの質」と「推奨」の表現 (Wording)

EBM guidelineにおいては、GRADEによる「エビデンスの質」の定義と表現、および「推奨」に関して、臨床医にとって分かりやすくするために、以下のように解説されています(2011年10月)。
GRADE JCEシリーズにおいても、このエビデンスの質に関する新しい定義が使われています。

Last update: 12/12/2012

■エビデンスのレベルと定義・表現

エビデンスのレベル シンボル 定義 Wording *
レベル A
(高)

We are very confident that the true effect lies close to that of the estimate of the effect.

(真の効果が効果推定値に近いことに大きな確信がある)

…is effective / has some effect / is not effective / is harmful…
レベル B
(中)

We are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different.

(効果推定値に対し中等度の確信がある。つまり、真の効果は効果推定値に近いと考えられるが、大きく異なる可能性も否めない)

appears to be effective / appears to have some effect / appears not to be effective / appears to be harmful…
レベル C
(低)

Our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect.

(効果推定値に対する確信には限界がある。真の効果は効果推定値とは大きく異なるかもしれない)

may be effective / may have limited effect / may not be effective / may be harmful…
レベル D
(非常に低)

We have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect.

(効果推定値に対し、ほとんど確信が持てない。真の効果は、効果推定値とは大きく異なるものと考えられる)

might possibly/might possibly not ….be effective/have limited effect/be harmful… but the evidence is insufficient** There is insufficient evidence on the effect... ***
* A suitable verb can be used instead of the word “effective”, e.g. “...appears to improve survival”; “...may not prevent exacerbations”.
** “Might possibly be effective/have limited effect/be harmful” can be used when the point estimate suggests clinically meaningful/almost clinically meaningful beneficial or harmful effect.
*** This expression is used if no point estimate of the effect is available.

■推奨の種類と表現

推奨 表現
Strong recommendation for using an intervention (= beneficial) Use …
Weak recommendation for using an intervention (= likely to be beneficial) Consider using…
Weak recommendation against using an intervention (= unlikely to be beneficial) It may be better to avoid using…
Strong recommendation against using an intervention (= likely to be harmful) Do not use…
推奨の強さは、2種類です(1=strong, 2=weak)