Table A16.
Summary of findings table for the association between rail traffic noise exposure and the prevalence of hypertension.
| Question | Does Exposure to Rail Traffic Noise Increase the Risk Of Hypertension | |||
|---|---|---|---|---|
| People | Adult population (men and women) | |||
| Setting | Residential setting: people living in several cities in Europe | |||
| Outcome | The prevalence of hypertension | |||
| Summary of findings | RR per 10 dB increase in rail traffic noise level (LDEN) | 1.05 (95% CI: 0.88–1.26) per 10 dB | ||
| Number of participants (# evaluated studies) | 15,850 (5) | |||
| Number of cases | 2059 | |||
| Rating | Adjustment to rating | |||
| Quality assessment | Starting rating | 5 cross-sectional studies # | 2 (low) | |
| Factors decreasing confidence | Risk of bias | Serious a | Downgrading | |
| Inconsistency | Serious b | Downgrading | ||
| Indirectness | None c | No downgrading | ||
| Imprecision | None d | No downgrading | ||
| Publication bias | NA e | No downgrading | ||
| Factors increasing confidence | Strength of association | Small f | No upgrading | |
| Exposure-response gradient | Evidence of a non-significant exposure-response gradient f | No upgrading | ||
| Possible confounding | No conclusions can be drawn g | No upgrading | ||
| Overall judgement of quality of evidence | 0 (Very low) | |||
# Since only cross-sectional studies were available, we started with a grading of “low”(2); a In three studies, the participants were randomly selected taking into account road- and/or rail traffic noise exposure; although the participants of these studies were randomly selected, two other studies were originally not designed to investigate the impact of (rail) traffic noise exposure; In one study there is a chance that the participants were aware that they took part in a study investigating the impact of noise; in two other studies it is not very likely that participants were aware that they took part in a study investigating the impact of noise, since they were not originally set up to investigate the impact of noise. For one study, it was unclear whether participants were aware of taking part in a noise study. In two studies, response rates were below 60%; b Results across studies differed in the magnitude and direction of effect estimates (see Figure 4.5 of the complete review). This was confirmed by the results of the heterogeneity analyses, demonstrating “moderate” heterogeneity (I2residual = 57.6%); c The evaluated studies assessed population, exposure, and outcome of interest; d We considered the results to be precise: the number of cases was large enough, and the 95% CI was sufficiently narrow; e Due to the low number of available effect estimates it was not possible to test for publication bias or small study bias; f Most studies found that the risk of hypertension increased when rail traffic noise level increased (RR per 10 dB > 1). There was evidence of a non-significant exposure-response gradient: After aggregating the results of the evaluated studies, we found a non-significant effect size of 1.05 per 10 dB. The noise range of the studies under evaluation was 30–80 dB (LDEN). This means that if rail traffic noise level increases from 30 to 80 dB, the RR = 1.28; g We were not able to draw any conclusions whether possible residual confounders or biases would reduce our effect estimate.