Table 2.
Pooled relative risks (95% confidence intervals) for cardiovascular disease, coronary heart disease and stroke in relation to water arsenic concentrations
| CVD incidence | CVD mortality | CHD incidence | CHD mortality | Stroke incidence | Stroke mortality | |||
|---|---|---|---|---|---|---|---|---|
| # Studies (# relative risks)a | 2 (5) | 6 (18) | 4 (10) | 6 (16) | 2 (5) | 6 (16) | ||
| Log-linear or constant dose-response association model (log-transformed arsenic) | ||||||||
| 10 µg/l arsenic | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) | ||
| 20 µg/l arsenic | 1.09 (1.03, 1.14) | 1.07 (1.01, 1.14) | 1.11 (1.05, 1.17) | 1.16 (1.07, 1.26) | 1.08 (1.00, 1.17) | 1.06 (0.93, 1.20) | ||
| 50 µg/l arsenic | 1.21 (1.08, 1.36) | 1.17 (1.02, 1.34) | 1.27 (1.12, 1.43) | 1.41 (1.17, 1.71) | 1.20 (0.99, 1.45) | 1.14 (0.85, 1.53) | ||
| 100 µg/l arsenic | 1.32 (1.12, 1.56) | 1.25 (1.02, 1.53) | 1.40 (1.18, 1.66) | 1.64 (1.25, 2.15) | 1.29 (0.98, 1.69) | 1.21 (0.80, 1.83) | ||
| 200 µg/l arsenic | 1.43 (1.16, 1.78) | 1.34 (1.03, 1.74) | 1.55 (1.24, 1.94) | 1.90 (1.34, 2.70) | 1.40 (0.98, 1.99) | 1.28 (0.75, 2.20) | ||
| P-linear trendb | 0.001 | 0.029 | <0.001 | <0.001 | 0.065 | 0.37 | ||
| I2 (95% CI)c | 0 (0, 0) | 64 (0, 91) | (0, 0) | 51 (0, 83) | 0 (0, 0) | 87 (0, 96) | ||
| P-heterogeneityd | 0.66 | 0.041 | 0.33 | 0.087 | 0.35 | <0.001 | ||
| Non-linear or flexible dose-response association model (restricted cubic splines of log-transformed arsenic) | ||||||||
| 10 µg/l arsenic | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) | ||
| 20 µg/l arsenic | 1.05 (0.90, 1.21) | 1.07 (1.00, 1.14) | 1.14 (1.01, 1.29) | 1.16 (1.05, 1.27) | 1.04 (0.81, 1.33) | 1.07 (0.97, 1.18) | ||
| 50 µg/l arsenic | 1.25 (0.92, 1.72) | 1.17 (1.02, 1.33) | 1.83 (1.05, 3.19) | 1.40 (1.13, 1.73) | 1.24 (0.73, 2.12) | 1.11 (0.98, 1.26) | ||
| 100 µg/l arsenic | 1.53 (0.90, 2.60) | 1.25 (1.00, 1.57) | 2.81 (1.05, 7.52) | 1.62 (1.15, 2.28) | 1.53 (0.61, 3.80) | 1.11 (0.89, 1.38) | ||
| 200 µg/l arsenic | 1.92 (0.86, 4.31) | 1.35 (0.96, 1.90) | 4.33 (1.05, 17.80) | 1.87 (1.13, 3.10) | 1.92 (0.47, 7.83) | 1.10 (0.76, 1.59) | ||
| P-non-linear trende | 0.30 | 0.91 | 0.091 | 0.99 | 0.52 | 0.51 | ||
aSum of the non-reference exposure categories across studies; the total number of relative risks in each model.
bP-value for linear trend from a Wald test of the coefficient for log-transformed water arsenic concentrations.
cProportion of total variance due to between-study heterogeneity.
dP-value for heterogeneity is chi-square P-value of the Q-statistic.
eNon-linear trend P-value for the non-linear spline coefficient in a model with arsenic concentrations entered as a restricted cubic spline with knots at 10th, 50th and 90th percentiles of log-transformed water arsenic.