Cox proportional hazards estimates for the development of asthma by age 10 years, stratified by era
| Birth (fiscal) year and LHIN subregion | HR (95% CI) | ||
|---|---|---|---|
| Unadjusted | Adjusted* | Adjusted† | |
| 1993–1996 | |||
| Lambton | 1.00 (Ref.) | 1.00 (Ref.) | NA |
| Windsor | 0.68 (0.64–0.73) | 0.60 (0.56–0.65) | |
| London–Middlesex | 0.57 (0.54–0.61) | 0.54 (0.51–0.58) | |
| 1997–2000 | |||
| Lambton | 1.00 (Ref.) | 1.00 (Ref.) | |
| Windsor | 0.84 (0.77–0.90) | 0.77 (0.71–0.84) | NA |
| London–Middlesex | 0.63 (0.59–0.68) | 0.61 (0.56–0.66) | |
| 2001–2004 | |||
| Lambton | 1.00 (Ref.) | 1.00 (Ref.) | 1.00 (Ref.) |
| Windsor | 0.90 (0.83–0.97) | 0.80 (0.73–0.88) | 0.81 (0.72–0.91) |
| London–Middlesex | 0.69 (0.64–0.75) | 0.65 (0.60–0.71) | 0.65 (0.58–0.72) (Jan. 1, 2003–Mar 31, 2005; n = 15 558) |
| 2005–2008 | |||
| Lambton | 1.00 (Ref.) | 1.00 (Ref.) | 1.00 (Ref.) |
| Windsor | 0.85 (0.78–0.92) | 0.67 (0.61–0.74) | 0.67 (0.61–0.74) |
| London–Middlesex | 0.77 (0.71–0.83) | 0.65 (0.60–0.71) | 0.65 (0.60–0.71) (n = 29 179) |
| 1993–2008 (all years) | |||
| Lambton | 1.00 (Ref.) | 1.00 (Ref.) | 1.00 (Ref.) |
| Windsor | 0.81 (0.78–0.84) | 0.70 (0.67–0.73) | 0.72 (0.67–0.77) |
| London–Middlesex | 0.66 (0.63–0.68) | 0.61 (0.58–0.63) (n = 114 427) | 0.65 (0.61–0.69) (n = 44 737) |
Note: CI = confidence interval, HR = hazard ratio, LHIN = Local Health Integration Network, NA = not available, Ref. = reference category.
↵* Adjusted for maternal age, maternal asthma, sex, rural geography, neighbourhood material deprivation, neighbourhood ethnic concentration, cesarean delivery and fiscal year. The number of individuals per model is variable because the cohorts were restricted to children with no missing data for exposures to pollutants.
↵† Adjusted for all variables listed above and restricted to children with data available for exposures to all pollutants.