Table 2.
Hazard ratios (95% CIs) for chronic blue day exposure with all-cause mortality and cardiovascular events.
| Per 10-day increment | Tertiles of blue days | P trend | |||
|---|---|---|---|---|---|
| Worst tertile | Middle tertile | Best tertile | |||
| All-cause mortality | |||||
| No. of cases | 1,096 | 320 | 347 | 429 | / |
| Incidence rate† | 10.49 | 10.25 | 10.73 | 10.50 | / |
| Adjusted Model 1a | 1.00 (0.98–1.02) | 1.00 (ref) | 0.89 (0.74–1.06) | 0.93 (0.80–1.08) | 0.421 |
| Adjusted Model 2b | 1.00 (0.98–1.02) | 1.00 (ref) | 0.86 (0.72–1.03) | 0.93 (0.80–1.08) | 0.455 |
| Adjusted Model 3c | 1.00 (0.97–1.02) | 1.00 (ref) | 0.80 (0.66–0.96) | 0.85 (0.72–1.00) | 0.131 |
| Adjusted Model 4d | 1.00 (0.98–1.02) | 1.00 (ref) | 0.84 (0.70–1.00) | 0.88 (0.75–1.04) | 0.241 |
| CVD (fatal + nonfatal) | |||||
| No. of cases | 993 | 305 | 347 | 341 | / |
| Incidence rate† | 9.45 | 9.73 | 10.69 | 8.27 | / |
| Adjusted Model 1a | 0.98 (0.96–1.00) | 1.00 (ref) | 1.13 (0.95–1.34) | 0.80 (0.68–0.93) | 0.002 |
| Adjusted Model 2b | 0.98 (0.96–1.00) | 1.00 (ref) | 1.06 (0.90–1.26) | 0.78 (0.67–0.92) | 0.001 |
| Adjusted Model 3c | 0.96 (0.94–0.98) | 1.00 (ref) | 0.91 (0.76–1.10) | 0.63 (0.53–0.76) | <.001 |
| Adjusted Model 4d | 0.97 (0.94–0.99) | 1.00 (ref) | 0.86 (0.72–1.03) | 0.68 (0.57–0.81) | <.001 |
| Stroke (fatal + nonfatal) | |||||
| No. of cases | 597 | 192 | 209 | 196 | / |
| Incidence rate† | 5.64 | 6.09 | 6.39 | 4.72 | / |
| Adjusted Model 1a | 0.95 (0.92–0.97) | 1.00 (ref) | 1.19 (0.95–1.49) | 0.70 (0.57–0.86) | <.001 |
| Adjusted Model 2b | 0.94 (0.92–0.97) | 1.00 (ref) | 1.11 (0.89–1.40) | 0.69 (0.56–0.84) | <.001 |
| Adjusted Model 3c | 0.91 (0.88–0.94) | 1.00 (ref) | 0.93 (0.74–1.17) | 0.50 (0.39–0.64) | <.001 |
| Adjusted Model 4d | 0.93 (0.90–0.95) | 1.00 (ref) | 0.80 (0.64–1.00) | 0.57 (0.45–0.71) | <.001 |
†Incident rate per 1,000 person-years.
CVD, cardiovascular disease.
aModel 1: adjusted for age, sex, urbanity, ethnicity, geographic region, educational level, smoking status, alcohol consumption, and BMI.
bModel 2: Model 1 + hypertension, hypercholesterolemia, diabetes mellitus, family history of CVD, and CVD medication history.
cModel 3: Model 2 + outdoor PM2.5 concentrations, and ambient temperature.
dModel 4: Model 3 + county-level average years of education, per capita GDP, population density, and altitude.