Table 3.
Sensitivity analysis for association of stroke incidence with 10 μg/m3 increase in fine particulate matter (PM2.5)*
| Sensitivity analysis | No of cases | Hazard ratio (95% CI) | P value |
|---|---|---|---|
| Further adjusting for county level averaged years of education | |||
| Total stroke | 3509 | 1.15 (1.11 to 1.19) | <0.001 |
| Ischemic stroke | 2262 | 1.24 (1.18 to 1.30) | <0.001 |
| Hemorrhagic stroke | 1004 | 1.13 (1.06 to 1.21) | <0.001 |
| Annual mean PM2.5 as a time varying exposure during follow-up | |||
| Total stroke | 3511 | 1.17 (1.13 to 1.21) | <0.001 |
| Ischemic stroke | 2262 | 1.23 (1.18 to 1.29) | <0.001 |
| Hemorrhagic stroke | 1006 | 1.14 (1.07 to 1.21) | <0.001 |
| Baseline two year average PM2.5 exposure | |||
| Total stroke | 3509 | 1.15 (1.11 to 1.20) | <0.001 |
| Ischemic stroke | 2262 | 1.23 (1.17 to 1.29) | <0.001 |
| Hemorrhagic stroke | 1004 | 1.13 (1.05 to 1.21) | <0.001 |
| Further adjusting for smoking pack year† | |||
| Total stroke | 2769 | 1.18 (1.13 to 1.23) | <0.001 |
| Ischemic stroke | 1758 | 1.28 (1.21 to 1.34) | <0.001 |
| Hemorrhagic stroke | 798 | 1.16 (1.07 to 1.24) | <0.001 |
| Exclusion of China MUCA (1992-94) study | |||
| Total stroke | 2977 | 1.17 (1.13 to 1.22) | <0.001 |
| Ischemic stroke | 1876 | 1.28 (1.22 to 1.35) | <0.001 |
| Hemorrhagic stroke | 868 | 1.14 (1.06 to 1.22) | <0.001 |
| Further adjusting for baseline diabetes and total cholesterol level | |||
| Total stroke | 3326 | 1.12 (1.08 to 1.17) | <0.001 |
| Ischemic stroke | 2155 | 1.19 (1.14 to 1.25) | <0.001 |
| Hemorrhagic stroke | 940 | 1.10 (1.03 to 1.18) | 0.005 |
| Excluding those with coronary heart disease at baseline‡ | |||
| Total stroke | 3459 | 1.14 (1.10 to 1.18) | <0.001 |
| Ischemic stroke | 2224 | 1.20 (1.15 to 1.26) | <0.001 |
| Hemorrhagic stroke | 996 | 1.12 (1.05 to 1.20) | <0.001 |
| Excluding incident stroke occurring within first year of follow-up§ | |||
| Total stroke | 3290 | 1.12 (1.08 to 1.16) | <0.001 |
| Ischemic stroke | 2128 | 1.17 (1.12 to 1.23) | <0.001 |
| Hemorrhagic stroke | 924 | 1.13 (1.06 to 1.21) | <0.001 |
MUCA=Multi-Center Collaborative Study of Cardiovascular Epidemiology.
Particles of diameter ≤2.5 μm.
Data on smoking pack year history were collected in three of four subcohorts: China MUCA (1998), InterASIA (International Collaborative Study of Cardiovascular Disease in Asia), and CIMIC (Community Intervention of Metabolic Syndrome in China and Chinese Family Health Study).
Coronary heart disease before baseline interview or 1 January 2000 (if date of baseline examination was earlier than 2000) was excluded.
Incident stroke events within first year after baseline interview or 1 January 2000 (if date of baseline examination was earlier than 2000) was excluded.