Fig. 2.

OR of kidney stone formation (determined by common urine concentration indicators). Solid lines represent adjusted OR based on restricted quadratic splines for common urine concentration indicators (including urine creatinine, osmolality and flow rate) with knots at the 10th, 50th and 90th percentiles (corresponding to 33, 105 and 220 mg/dl, respectively, for urine creatinine; 233, 634 and 820 mOsm/kg, respectively, for urine osmolality; and 0·25, 0·62 and 1·75 ml/kg/h, respectively, for urine flow rate). Dotted lines represent 95 % CI. 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 the distribution of analysed urine concentration indicators among participants (extreme tails of the histogram were truncated)