Table 4.
Stratum-specific combined estimates of the association of PM10 exposure with change in PEF (L/min) and with cough episodes in children symptomatic for or diagnosed with asthma.
| PEF |
Cough |
|||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| All studies |
PEACE studies excluded |
All studies |
PEACE studies excluded |
|||||||||
| Stratum | n | βR (95% CI) | pStrataphet (I2) | n | βR (95% CI) | pStrataphet (I2) | n | ORR (95% CI) | pStrataphet (I2) | n | ORR (95% CI) | pStrataphet (I2) |
| Continent | 0.041 | 0.750 | 0.001 | 0.047 | ||||||||
| Europe | 33 | 0.002 (−0.182 to 0.186) | < 0.001 (72%) | 5 | −0.235 (−0.600 to 0.131) | 0.006 (73%) | 34 | 0.998 (0.983 to 1.014) | < 0.001 (62%) | 8 | 1.020 (1.006 to 1.034) | 0.026 (56%) |
| Other | 7 | −0.305 (−0.534 to −0.076) | 0.003 (69%) | 7 | −0.305 (−0.534 to −0.076) | 0.003 (69%) | 6 | 1.053 (1.024 to 1.082) | 0.004 (71%) | 6 | 1.053 (1.024 to 1.082) | 0.004 (71%) |
| Season | 0.260 | 0.905 | ||||||||||
| Summer only | 2 | 1.039 (0.992 to 1.088) | 0.602 (0%) | 2 | 1.039 (0.992 to 1.088) | 0.602 (0%) | ||||||
| Other | 40 | −0.082 (−0.214 to 0.050) | < 0.001 (72%) | 12 | −0.272 (−0.449 to −0.095) | < 0.001 (69%) | 38 | 1.010 (0.996 to 1.025) | < 0.001 (70%) | 12 | 1.035 (1.019 to 1.051) | < 0.001 (76%) |
| Population | 0.007 | 0.086 | 0.001 | 0.217 | ||||||||
| Asthmatics | 7 | −0.549 (−0.920 to −0.177) | 0.006 (67%) | 7 | −0.549 (−0.920 to −0.177) | 0.006 (67%) | 8 | 1.046 (1.022 to 1.071) | 0.001 (70%) | 8 | 1.046 (1.022 to 1.071) | 0.001 (70%) |
| Symptomatics | 33 | 0.010 (−0.159 to 0.180) | < 0.001 (73%) | 5 | −0.148 (−0.415 to 0.119) | 0.002 (76%) | 32 | 0.995 (0.978 to 1.013) | < 0.001 (63%) | 6 | 1.026 (1.006 to 1.046) | 0.005 (70%) |
| Duration | 0.402 | 0.416 | 0.422 | 0.762 | ||||||||
| ≤ 2 months | 12 | −0.161 (−0.394 to 0.071) | < 0.001 (67%) | 4 | −0.440 (−0.843 to −0.037) | 0.010 (73%) | 13 | 1.019 (0.995 to 1.043) | 0.003 (59%) | 5 | 1.034 (1.017 to 1.051) | 0.188 (35%) |
| > 2 months | 28 | −0.032 (−0.225 to 0.160) | < 0.001 (74%) | 8 | −0.241 (−0.500 to 0.018) | 0.079 (69%) | 27 | 1.007 (0.990 to 1.026) | < 0.001 (70%) | 9 | 1.038 (1.017 to 1.059) | < 0.001 (77%) |
| Lag | 0.325 | 0.189 | 0.018 | 0.030 | ||||||||
| ≤ 2 days | 14 | −0.167 (−0.354 to 0.021) | < 0.001 (70%) | 8 | −0.203 (−0.426 to 0.020) | 0.001 (71%) | 19 | 0.997 (0.979 to 1.014) | < 0.001 (74%) | 6 | 1.022 (1.006 to 1.038) | 0.004 (71%) |
| > 2 days | 26 | −0.025 (−0.237 to 0.187) | < 0.001 (73%) | 4 | −0.396 (−0.578 to −0.214) | 0.392 (0%) | 21 | 1.036 (1.009 to 1.065) | 0.001 (56%) | 8 | 1.067 (1.030 to 1.106) | 0.001 (71%) |
| PM10 level | 0.774 | 0.344 | 0.706 | 0.173 | ||||||||
| < 40 μg/m3 | 14 | −0.021 (−0.441 to 0.398) | < 0.001 (68%) | 4 | −0.116 (−0.613 to 0.381) | 0.006 (76%) | 17 | 1.006 (0.983 to 1.029) | 0.002 (57%) | 7 | 1.022 (1.004 to 1.041) | 0.047 (53%) |
| ≥ 40 μg/m3 | 25 | −0.086 (−0.233 to 0.061) | < 0.001 (74%) | 7 | −0.380 (−0.607 to −0.152) | 0.005 (68%) | 22 | 1.012 (0.991 to 1.033) | < 0.001 (74%) | 6 | 1.045 (1.018 to 1.073) | < 0.001 (79%) |
| NO2 level | 0.722 | 0.028 | 0.012 | 0.031 | ||||||||
| < 40 μg/m3 | 21 | −0.018 (−0.278 to 0.242) | 68%* | 3 | 0.144 (−0.224 to 0.512) | 0.155 (46%) | 20 | 0.980 (0.954 to 1.007) | < 0.001 (60%) | 3 | 1.013 (1.001 to 1.025) | 0.342 (7%) |
| ≥ 40 μg/m3 | 11 | −0.091 (−0.399 to 0.216) | 80%* | 3 | −1.085 (−2.120 to −0.051) | 0.028 (72%) | 13 | 1.032 (1.001 to 1.064) | < 0.001 (72%) | 6 | 1.065 (1.019 to 1.113) | < 0.001 (82%) |
| Rural/urban | 0.911 | 0.433 | 0.116 | 0.604 | ||||||||
| Rural | 18 | −0.125 (−0.286 to 0.036) | < 0.001 (65%) | 4 | −0.301 (−0.507 to −0.096) | 0.020 (70%) | 17 | 0.994 (0.968 to 1.021) | < 0.001 (65%) | 4 | 1.050 (0.995 to 1.109) | 0.003 (79%) |
| Urban | 21 | −0.108 (−0.360 to 0.144) | < 0.001 (75%) | 7 | −0.473 (−0.851 to −0.095) | 0.008 (66%) | 23 | 1.020 (1.002 to 1.039) | < 0.001 (69%) | 10 | 1.035 (1.017 to 1.052) | < 0.001 (70%) |
Abbreviations: ORR/βR, combined estimate of the OR (or regression coefficient β for PEF in L/min) from the random effects model for a 10-μg/m increase in pollutant; pStrataphet (I ), p-value for differences between strata and p-value for test of heterogeneity based on Cochrane’s Q, with I2 of Higgins and Thompson reflecting the proportion of total variation in the estimate that is due to heterogeneity between studies.
*
p < 0.001.