Table 2.

Relative risk of symptomatic kidney stones, according to category of energy-adjusted vitamin B6 intake among 85,574 women (the Nurses' Health Study)

ParameterVitamin B6 Category (mg/d)χ (P for trend)
<33 to 45 to 910 to 3940+
aCI, confidence interval.
bThe multivariate model included age (in 5-yr age categories), body mass index (seven categories), alcohol (six categories), vitamin C (five categories), supplemental calcium (four categories), and dietary intake of calcium, animal protein, sodium, potassium, sucrose, caffeine, and total fluid (quintile groups).
No. of cases836781003628
No. of person-years760,91367,76591,41126,39033,829
Age-adjusted relative risk1.001.040.991.230.75-0.44 (0.66)
95% CIReferent0.83 to 1.320.80 to 1.220.89 to 1.730.52 to 1.09
Multivariate relative riskb1.001.051.001.140.66-2.08 (0.04)
95% CIaReferent0.88 to 1.240.79 to 1.260.79 to 1.640.44 to 0.98