Fig. 1.

OR of kidney stone formation (determined by water and fluid intake measurements). Solid lines represent adjusted OR based on restricted quadratic splines for daily water and fluid intake measurements with knots at the 10th, 50th and 90th percentiles (corresponding to 39·5, 807·2 and 2281·1 g/d, respectively, for daily water intake; and 1627·6, 2761·6 and 4613·6 g/d, respectively, for daily fluid intake). Dotted lines represent 95 % CI. The reference was set at the 10th percentile of the distribution. Adjustment factors were identical to those used in Model 3 (Table 2). Bars represent a histogram of distribution of daily water and fluid measurements among participants (extreme tails of the histogram were truncated)