Table 6.

Summary of findings for noise exposure and vascular resistance

Outcomes	Relative or absolute effects (95% CI)	No. of participants (studies)	Certainty of the evidence (GRADE)
Vascular resistance – clinical trial assessed with: exposure to lab-simulated noise	[147]:90 dBA (steady) vs 80 dBA (steady): MD: –160.0 dyne-sec/cm5, 95% CI: –210.53, –109.47 100 dBA (steady) vs 80 dBA (steady): MD: –67.0 dyne × sec/cm^5, 95% CI: –115.50, –18.50 90 dBA (intermittent) vs 80 dBA (intermittent): MD: 43.0 dyne × sec/cm^5, 95% CI: 8.33, 77.67 100 dBA (intermittent) vs 80 dBA (intermittent): MD: 20.0 dyne × sec/cm^5, 95% CI: –13.12, 53.12	22 (1 observational study)	⊕○○○VERY LOW *,†
Vascular resistance – cohort assessed with: exposure to lab-simulated noise	[151]:Railway (junior) noise vs control: MD: 30.31, 95% CI: 9.18, 51.44 Railway (senior) noise vs control: MD: 31.34, 95% CI: 15.31, 47.37 Quiet (junior) noise vs control: MD: 30.10, 95% CI: 15.92, 44.28 Quiet (senior) noise vs control: MD: 20.84, 95% CI: 0.33, 41.35	40 (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 concern with confounding and missing data. Moderate concern with measurement of outcome. ^†Concerns with imprecision since the 95% CI cannot exclude the potential for meaningful benefit or harm. The small sample included does not meet the optimal information size and suggests fragility of the estimate. ^‡Serious concern with confounding. ^$Junior refers to young subjects (26.2 years ± 3.6) and senior refers to middle-aged subjects (56.2 years ± 4.2).