Verbal communication of effect-sizes, possible comparators, and uncertainty of evidence in the Finnish clinical practice guidelines: Omitting effect-sizes and comparators without expressing much uncertainty.

RATIONALE, AIMS, AND OBJECTIVES: Our aim was to investigate verbal representations of intervention effect-size, uncertainty of evidence, and possible intervention comparators in statements concerning effects of interventions in Finnish clinical practice guidelines.

METHOD: We selected 10 clinical practice guidelines on common diseases and risk factors published by The Finnish Medical Society Duodecim. All the statements that considered beneficial effects of interventions and that were graded with a level of evidence (levels A, high, to D, very low) were included in analyses. We assessed whether the statements verbally represented intervention effect-size, uncertainty of evidence or a possible comparator, and the reported outcome.

RESULTS: Of 385 statements, verbal representation of beneficial effect-sizes occurred in 25 (6%) statements. Most (72%) statements indicated that intervention had a beneficial effect, but did not specify effect-size. Less than half (42%) of the statements represented uncertainty verbally. Comparisons to placebo or no-treatment were rare (3%) and 18% of the statements compared interventions to other treatments. Against instructions, a considerable part (35%) of statements with B-level evidence did not represent uncertainty.

CONCLUSION: Communicating beneficial intervention effects, effect-sizes, possible comparators, and uncertainty of evidence require much broader attention in the clinical practice guideline context.