Table 2.
Summary of findings, with 95% confidence intervals based on uncertainty in relative risk parameters.
| Built environment variables |
BRRC | Winterville | Sparta | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Before | After | Change | Before | After | Change | Before | After | Change | |
| Walkability score | −3.61 | 0.96 | +4.57 | — | — | — | — | — | — |
| Sidewalk density (km/km2) | — | — | — | 0.8 | 3.8 | +3.0 | — | — | — |
| PEF (categorical) | — | — | — | — | — | — | Low | Medium | +1 |
|
| |||||||||
| Walking outcomesa | Before | After | Change | Before | After | Change | Before | After | Change |
|
| |||||||||
| No walking (percent) | 40.7% | 40.7% | 0% | 84.3% | 83.4% | −0.9% | 85.4% | 82.4% | −3.0% |
| 1–149 min/week (percent) | 41.5% | 21.2% | −20.3% | 12.3% | 12.9% | +0.6% | 12.1% | 14.6% | +2.5% |
| 150+ min/week (percent) | 17.8% | 38.1% | +20.3% | 3.4% | 3.6% | +0.2% | 2.5% | 3.0% | +0.5% |
| Ave. walk time (min/week) | 13.1 | 30.4 | +17 | 12.5 | 13.2 | +0.7 | 10.4 | 12.6 | +2.2 |
|
| |||||||||
| Health outcomesa | Years after construction | Years after construction | Years after construction | ||||||
| 10 | 20 | 40 | 10 | 20 | 40 | 10 | 20 | 40 | |
|
| |||||||||
| Avoided premature mortality | 4.9 (1.8–7.7) |
8.5 (3.1–13.3) |
14.3 (5.2–22.6) |
0.3 (0.1–0.5) |
0.5 (0.2–0.9) |
0.9 (0.3–1.4) |
0.3 (0.1–0.4) |
0.4 (0.2–0.7) |
0.5 (0.2–0.8) |
| Avoided cases of CHD | 1.9 (1.6–2.1) |
3.7 (3.1–4.1) |
6.1 (5.1–6.7) |
0.0 (−0.1–0.1) |
0.0 (−0.1–0.2) |
0.0 (−0.2–0.3) |
0.0 (−0.1–0.2) |
0.0 (−0.2–0.3) |
0.0 (−0.2–0.3) |
| Avoided cases of type 2 diabetes | 4.9 (2.6–7.6) |
9.4 (5.1–14.5) |
15.6 (8.3–24.1) |
0.5 (0.0–1.0) |
1.0 (−0.1–1.9) |
1.5 (−0.2–2.9) |
0.4 (0.0–0.7) |
0.6 (−0.1–1.2) |
0.8 (−0.1–1.6) |
| Avoided cases of hypertension | 11.8 (4.5–16.7) |
21.4 (8.4–30.1) |
32.1 (12.3–45.1) |
1.5 (0.4–2.5) |
2.7 (0.6–4.5) |
4.0 (0.9–6.9) |
0.9 (0.2–1.5) |
1.4 (0.3–2.4) |
1.8 (0.4–3.2) |
| Avoided cases of stroke | 1.1 (0.0–1.6) |
1.8 (−0.1–2.9) |
2.1 (−1.1–4.0) |
0.1 (−0.1–0.3) |
0.2 (−0.2–0.6) |
0.3 (−0.3–0.8) |
0.1 (−0.1–0.3) |
0.2 (−0.1–0.4) |
0.2 (−0.2–0.5) |
|
| |||||||||
| Economic outcomesb,c | Years after construction | Years after construction | Years after construction | ||||||
| 10 | 20 | 40 | 10 | 20 | 40 | 10 | 20 | 40 | |
|
| |||||||||
| Net present value (2012 USD) | 33.4M (10.8–53.7) |
50.4M (18.4–79.0) |
66.8M (26.8–103) |
−5.1M (−6.5–−3.9) |
−3.9M (−5.9–−2.1) |
−2.9M (−5.3–−0.6) |
1.4M (0.1–2.5) |
2.2M (0.5–3.7) |
2.6M (0.7–4.2) |
| Benefit-cost ratio | 10.6 (4.1–16.5) |
15.5 (6.3–23.7) |
20.2 (8.7–30.6) |
0.3 (0.1–0.5) |
0.5 (0.2–0.7) |
0.6 (0.3–0.9) |
3.0 (1.1–4.6) |
4.1 (1.7–6.3) |
4.7 (2.1–7.1) |
|
| |||||||||
| Time for B : C to exceed 1 | 1 year (1-2 years) | Benefits do not exceed costs | 3 years (2–9 years) | ||||||
aEstimates of walking for transportation after construction in Winterville do not add to 100% due to rounding.
bFor all health and economic outcomes, 95% confidence intervals are estimated using the lower and upper bounds of the relative risk parameters as noted in Table 1.
c5% discount rate assumed.