Table 2.

Changes in dietary factors after an incident kidney stone

Dietary Factor	Absolute Change Stone Formers	Absolute Change Nonstone Formers	Difference in Differences (95% Confidence Interval)	P Value
Dietary calcium, mg/d
1–4 yr	7.1	13.7	−6.6 (−15.2 to 2.0)	0.13
5–8 yr	45.4	42.8	2.6 (−7.8 to 13.0)	0.62
Animal protein, g/d
1–4 yr	−2.5	−2.5	−0.1 (−0.6 to 0.4)	0.76
5–8 yr	−5.1	−5.4	0.3 (−0.2 to 0.9)	0.23
Caffeine, mg/d
1–4 yr	−14.7	−13.4	−1.4 (−5.5 to 2.7)	0.50
5–8 yr	−29.1	−37.9	8.8 (3.4 to 14.1)	≤0.001
Fructose, mg/d
1–4 yr	−0.4	−0.4	−0.1 (−0.4 to 0.2)	0.57
5–8 yr	−0.6	−0.4	−0.2 (−0.6 to 0.1)	0.18
Potassium, mg/d
1–4 yr	−0.3	8.3	−8.6 (−24.7 to 7.5)	0.29
5–8 yr	74.2	50.8	23.4 (4.6 to 42.3)	0.02
Sodium, mg/d
1–4 yr	−180.5	−209.8	29.4 (11.0 to 47.8)	0.002
5–8 yr	−124.4	−167.5	43.1 (19.8 to 66.5)	≤0.001
Oxalate, mg/d
1–4 yr	8.8	16.4	−7.5 (−10.8 to −4.3)	≤0.001
5–8 yr	21.0	28.3	−7.3 (−11.4 to −3.2)	≤0.001
Phytate, mg/d
1–4 yr	42.5	35.8	6.7 (−1.3 to 14.6)	0.10
5–8 yr	88.3	76.2	12.1 (2.5 to 21.7)	0.01
Vitamin C, mg/d
1–4 yr	−28.2	0.5	−28.7 (−40.0 to −17.3)	≤0.001
5–8 yr	−24.6	9.6	−34.2 (−48.8 to −19.6)	≤0.001
Vitamin D, IU/d
1–4 yr	37.4	55.4	−18.0 (−27.9 to −8.0)	≤0.001
5–8 yr	107.1	109.7	−2.6 (−15.2 to 9.9)	0.68
Total fluid, ml/d
1–4 yr	−40.9	−98.4	57.5 (36.3 to 78.7)	≤0.001
5–8 yr	−144.0	−191.1	47.1 (22.7 to 71.5)	≤0.001
DASH score, points per day
1–4 yr	−0.2	−0.2	0 (−0.1 to 0.1)	0.90
5–8 yr	−0.4	−0.4	0 (−0.1 to 0.1)	0.99
NEAP, mEq/d
1–4 yr	−2.0	−2.0	0 (−0.4 to 0.4)	0.96
5–8 yr	−5.4	−5.0	−0.4 (−0.9 to 0.1)	0.11

Linear regression models are stratified by time period and adjusted for age, body mass index, history of high BP, history of diabetes, and use of thiazides. Those dietary factors for which the interaction by cohort was significant in both time periods are reported separately by cohort in Table 3. DASH, Dietary Approaches to Stop Hypertension; NEAP, net endogenous acid production.