a decreasing trendP<0.01
Nevertheless, the mean of rural-to-urban RR in mild, moderate and severe CHI was 1.15, 1.10 and 0.96, respectively, indicating a decreasing trend (P<0.01).
Nevertheless, the mean of rural-to-urban RR in mild, moderate and severe CHI was 1.15, 1.10 and 0.96, respectively, indicating a decreasing trend (P<0.01).