Table 7.

Summary of findings for noise exposure and cardiac output

Outcomes	Relative or absolute effects (95% CI)	No. of participants (studies)	Certainty of the evidence (GRADE)
Cardiac output – Clinical trial assessed with: lab-simulated road traffic noise	[147]:90 dBA (steady) vs 80 dBA (steady): MD: 0.60 L/min, 95% CI: 0.37, 0.83 100 dBA (steady) vs 80 dBA (steady): MD: 0.20 L/min, 95% CI: 0.08, 0.32 90 dBA (intermittent) vs 80 dBA (intermittent): MD: –0.20 L/min, 95% CI: –0.41, 0.01 100 dBA (intermittent) vs 80 dBA (intermittent): MD: 0.30 L/min, 95% CI: –0.04, 0.64	22 (1 observational study)	⊕○○○VERY LOW *,†

CI: confidence interval; GRADE, Grading of Recommendations, Assessment, Development, and Evaluation; MD: mean difference. GRADE Working Group grades of evidence. High certainty: We are very confident that the true effect lies close to that of the estimate of the effect. Moderate certainty: 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. Low certainty: Our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect. Very low certainty: We have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of the effect. Explanations: ^*Serious concerns with confounding and missing data. Moderate concern with measurement of outcome. ^†Concerns with imprecision since the 95% CI for the intermittent comparisons cannot exclude the potential for no meaningful difference or the potential for harm. The small sample included does not meet the optimal information size and suggests fragility of the estimate.