Correlations of blood lead with heart rate variability measured by Fourier transform
| Variable | Unadjusted | Adjusted | ||
| Estimate (95% CI) | P value | Estimate (95% CI) | P value | |
| Supine position | ||||
| Total power (%) | 23.3 (–9.6 to 68.7) | 0.19 | 3.0 (–20.4 to 33.0) | 0.82 |
| Low-frequency power (nu) | –3.00 (–7.83 to 1.83) | 0.22 | –2.26 (–7.09 to 2.57) | 0.36 |
| High-frequency power (nu) | –1.59 (–5.24 to 2.06) | 0.39 | –2.60 (–6.01 to 0.81) | 0.13 |
| Low to high frequency ratio (%) | –1.8 (–20.8 to 21.6) | 0.87 | 6.2(–12.9 to 29.1) | 0.56 |
| Standing position | ||||
| Total power (%) | 11.7 (–17.0 to 50.3) | 0.46 | –6.0 (–26.2 to 19.7) | 0.61 |
| Low-frequency power (nu) | –1.037 (–6.22 to 4.14) | 0.69 | –1.36 (–6.48 to 3.76) | 0.60 |
| High-frequency power (nu) | –1.61 (–3.78 to 0.55) | 0.14 | –1.66 (–3.79 to 0.47) | 0.13 |
| Low to high frequency ratio (%) | 14.0 (–7.3 to 40.3) | 0.21 | –14.0 (–4.9 to 42.2) | 0.14 |
| Orthostatic change | ||||
| Total power (%) | –8.8 (–31.8 to 17.5) | 0.47 | –8.8 (–31.8 to 17.5) | 0.47 |
| Low-frequency power (%) | 4.7 (–6.7 to 20.2) | 0.42 | –2.3 (–8.8 to 17.4) | 0.74 |
| High-frequency power (%) | –8.8 (–27.6 to 14.8) | 0.40 | –6.7 (–24.2 to 14.8) | 0.61 |
| Low to high frequency ratio (%) | 14.8 (–8.8 to 47.9) | 0.22 | 7.2 (–14.9 to 34.9) | 0.52 |
Covariables in adjusted models included age, heart rate (or heart rate change for orthostatic changes), mean arterial pressure and serum insulin. Association sizes, given with 95% CI, are the difference in the outcome variable associated with a 10-fold increase in the blood lead concentration. For logarithmically transformed outcomes, differences are given as a percentage or as a percentage change on assuming the standing from the supine position.