Table 4.
Effect of PM2.5 Exposure on HRV at Different Mean TLR2 Methylation Levels, Normative Aging Study, 2000–2011 (N=500)
| Mean TLR2 Methylation | % Change* | 95% CI | P Value |
|---|---|---|---|
| HR | |||
| Midpoint of Q1 (1.5 5mc%) | −0.56 | −2.88 to 1.82 | 0.64 |
| Midpoint of Q2 (2.2 5mc%) | −0.10 | −1.99 to 1.81 | 0.92 |
| Midpoint of Q3 (3.0 5mc%) | 0.42 | −1.25 to 2.11 | 0.62 |
| Midpoint of Q4 (4.4 5mc%) | 1.34 | −0.92 to 3.66 | 0.25 |
| Pglobal for interaction* | 0.62 | ||
| rMSSD | |||
| Midpoint of Q1 (1.5 5mc%) | 8.77 | −7.55 to 27.95 | 0.31 |
| Midpoint of Q2 (2.2 5mc%) | −1.01 | −13.14 to 12.81 | 0.88 |
| Midpoint of Q3 (3.0 5mc%) | −11.11 | −20.87 to −0.16 | 0.05 |
| Midpoint of Q4 (4.4 5mc%) | −26.38 | −37.20 to −13.69 | 0.0002 |
| Pglobal for interaction* | 0.006 | ||
| SDNN | |||
| Midpoint of Q1 (1.5 5mc%) | −0.39 | −11.76 to 12.45 | 0.95 |
| Midpoint of Q2 (2.2 5mc%) | −3.85 | −12.78 to 6.00 | 0.43 |
| Midpoint of Q3 (3.0 5mc%) | −7.65 | −15.31 to 0.71 | 0.07 |
| Midpoint of Q4 (4.4 5mc%) | −13.94 | −23.55 to −3.12 | 0.01 |
| Pglobal for interaction* | 0.03 | ||
| LF | |||
| Midpoint of Q1 (1.5 5mc%) | −7.25 | −27.74 to 19.06 | 0.56 |
| Midpoint of Q2 (2.2 5mc%) | −10.88 | −27.11 to 8.96 | 0.26 |
| Midpoint of Q3 (3.0 5mc%) | −14.86 | −28.80 to 1.81 | 0.08 |
| Midpoint of Q4 (4.4 5mc%) | −21.40 | −38.47 to 0.39 | 0.05 |
| Pglobal for interaction* | 0.05 | ||
| HF | |||
| Midpoint of Q1 (1.5 5mc%) | 10.06 | −16.25 to 44.64 | 0.49 |
| Midpoint of Q2 (2.2 5mc%) | −2.82 | −22.02 to 21.10 | 0.80 |
| Midpoint of Q3 (3.0 5mc%) | −15.71 | −30.75 to 2.60 | 0.09 |
| Midpoint of Q4 (4.4 5mc%) | −34.28 | −49.87 to −13.84 | 0.003 |
| Pglobal for interaction* | 0.04 | ||
Results were adjusted for age; body mass index; fasting glucose level; hypertension; smoking status; alcohol consumption; physical exercise; household income; the use of calcium channel blocker, β‐blocker, and angiotensin‐converting enzyme inhibitor; room temperature; outdoor apparent temperature; season; weekday; and visit date. Q1, Q2, Q3, and Q4 indicate the first, second, third, and fourth quartile. HF indicates high‐frequency power (0.15 to 0.4 Hz); HR, heart rate; HRV, heart rate variability; LF, low‐frequency power (0.04 to 0.15 Hz); PM2.5, particulate matter with aerodynamic diameter <2.5 μm; rMSSD, root mean square of successive differences; SDNN, standard deviation of normal‐to‐normal intervals; TLR2, Toll‐like receptor 2.
The percent change in HRV per 10 μg/m3 increase in PM2.5 concentration.
Based on a global test for effect modification by position‐specific methylation. Interaction terms between each of the 5 TLR2 positions and PM2.5 were included in the model, and these 5 interaction terms were tested jointly for effect modification using a Wald test (global test).