Table 5.
Effect of wearing vs. not wearing an N95 respirator during near-roadway exposures (visits 2–5) on cardiovascular outcomes
| Blood pressuresa | Aortic blood pressuresa | Heart rate variabilitya | RHI outcomesb | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Outcomes Covariates |
Systolic BP (mm Hg) |
Diastolic BP (mm Hg) |
Heart rate (beats/minute) |
AorticSBP (mm Hg) |
AorticPP (mm Hg) |
AorticAP (mm Hg) |
AIx@75 (%) |
SDNN (ms) |
LF (ms2) |
HF (ms2) |
LF/HF | RHI (%) |
RHI90–120 (%) |
| N95 respiratorc | 0.04 (−1.00, 1.08) P = 0.94 |
−0.33 (−1.16, 0.50) P = 0.43 |
0.15 (−0.87, 1.17) P = 0.77 |
−0.39 (−1.52, 0.73) P = 0.49 |
0.14 (−0.58, 0.87) P = 0.70 |
−0.47
(−1.10, 0.16) P = 0.14 |
−1.28
(−2.93, 0.37) P = 0.13 |
2.3 (−1.4, 5.9) P = 0.22 |
−170 (−1,135, 796) P = 0.73 |
343
(−91, 778) P = 0.12 |
−0.2 (−0.5, 0.1) P = 0.16 |
0.1 (−0.1, 0.2) P = 0.44 |
0.4 (−0.3, 1.1) P = 0.26 |
| Age (per year) | 0.06 (−0.12, 0.24) P = 0.50 |
0.02 (−0.14, 0.17) P = 0.85 |
−0.05 (−0.26, 0.15) P = 0.61 |
0.14 (−0.03, 0.30) P = 0.11 |
0.12∗∗∗ (0.03, 0.21) P = 0.008 |
0.15∗∗∗ (0.072, 0.22) P<0.001 | 0.30∗∗∗ (0.09, 0.52) P = 0.006 |
−1.1∗∗∗ (−2.0, −0.4) P = 0.005 |
−92∗∗ (−165, −19) P = 0.014 |
−57∗∗∗ (−94, −19) P = 0.004 |
0.02 (−0.01, 0.04) P = 0.15 |
0.01∗∗ (0.00, 0.01) P = 0.030 |
0.02 (−0.01, 0.04) P = 0.19 |
| Female | −4.94∗ (−10.6, 0.72) P = 0.09 |
−3.34 (−7.99, 1.30) P = 0.16 |
0.70 (−5.60, 6.99) P = 0.83 |
−3.21 (−8.37, 1.94) P = 0.22 |
0.31 (−2.42, 3.04) P = 0.82 |
1.94∗ (−0.33, 4.21) P = 0.10 |
5.62 (−1.09, 12.33) P = 0.10 |
0.4 (−24.3, 25.2) P = 0.97 |
23 (−2,265, 2,311) P = 0.98 |
185 (−1,000, 1,369) P = 0.76 |
−1.2∗∗∗ (−2.0, −0.5) P = 0.002 |
−0.01 (−0.2, 0.2) P = 0.93 |
0.3 (−0.5, 1.1) P = 0.49 |
| BMI (per 1 kg/m2) | 1.22∗∗∗ (0.72, 1.73) P<0.001 | 0.66∗∗∗ (0.24, 1.08) P = 0.002 |
0.24 (−0.33, 0.80) P = 0.41 |
1.16∗∗∗ (0.69, 1.62) P < 0.001 | 0.46∗∗∗ (0.21, 0.70) P < 0.001 | 0.24∗∗ (0.03, 0.44) P = 0.024 |
0.38 (−0.22, 0.99) P = 0.21 |
−0.8 (−3.1, 1.4) P = 0.46 |
−7 (−211, 196) P = 0.94 |
45 (−60, 151) P = 0.40 |
−0.02 (−0.08, 0.05) P = 0.66 |
−0.01 (−0.02, 0.01) P = 0.50 |
−0.04 (−0.1, 0.03) P = 0.30 |
| Temperature (per 1 °C) |
−0.51∗∗∗ (−0.64, −0.37) P<0.001 |
−0.33∗∗∗ (−0.44, −0.22) P<0.001 | 0.53∗∗∗ (0.40, 0.66) P<0.001 | −0.37∗∗∗ (−0.51, −0.22) P < 0.001 | −0.09∗ (−0.18, 0.01) P = 0.06 |
0.21∗∗∗ (0.13, 0.28) P<0.001 | 0.76∗∗∗ (0.56, 0.97) P<0.001 | −1.5∗∗∗ (−2.0, −1.1) P<0.001 | 17 (−99, 133) P = 0.77 |
−31 (−84, 23) P = 0.26 |
0.1∗∗∗ (0.06, 0.1) P<0.001 | 0.00 (−0.02, 0.02) P = 0.91 |
−0.04 (−0.1, 0.05) P = 0.40 |
Data presented as effect estimate, (95% confidence interval), P value. Main effect of use of N95 respirator on cardiovascular outcomes trending toward significant changes (P values <0.15) during near-roadway exposures in bold. Abbreviations: AIx@75, augmentation index at a heart rate of 75 beats/minute; AP, augmentation pressure; BMI, body mass index; BP, blood pressure; HF, high frequency power; LF, low frequency power; PP, pulse pressure; RHI, reactive hyperemia index; RHI90–120, reactive hyperemia index from 90 to 120 seconds after cuff release; SBP, systolic blood pressure; SDNN, standard deviation of normal-to-normal intervals.
aResults represent main effect estimates (i.e., β-coefficients) of association of respirator use on cardiac outcomes, controlling for demographics and temperature, evaluated using linear mixed models with patient-level random intercept to account for within-patient correlation of outcomes; with exception of the constant term, effect estimates for all covariates included in the models are provided. We did not include visit and the visit × N95 respirator interaction in models because no visit-effect was observed—and we expect the environmental exposure(s) to capture variation of interest. We did not include a variable for the “Visit 1, N95 respirator placebo vs. nocebo effect” in the models as we found no associations with any outcome across any model (all P’s > 0.10) and any variation due to the N95 respirator should be captured in the N95 respirator main effect.
bResults represent main effect estimates (i.e., β-coefficients) of association of respirator use on cardiac outcomes, controlling for demographics and temperature, evaluated using linear model as RHI outcomes were collected only at visit 4.
cMain outcome in Table 4. Effect estimates represent the change in cardiac outcomes associated with use of the N95 respirator during roadway exposures (visits 2–5).
*P < 0.1, **P < 0.05, ***P < 0.01.