Table 3.

RR for incident kidney stones in men (HPFS), older women (NHS I), and younger women (NHS II) by quintile of oxalate intakea

ParameterQuintileP for Trend
12345
HPFS
    quintile median (mg/d)106149191236328
    cases363317325313309
    person-years105,806106,298107,393108,200107,788
    age-adjusted RR (95% CI)1.00.89 (0.76 to 1.03)0.89 (0.77 to 1.04)0.85 (0.73 to 0.99)0.85 (0.73 to 0.99)0.04
    multivariate RR (95% CI)b1.01.01 (0.86 to 1.17)1.07 (0.92 to 1.25)1.10 (0.94 to 1.29)1.22 (1.03 to 1.45)0.01
NHS I
    quintile median (mg/d)87127164205287
    cases312279304250269
    person-years254,953257,271259,528259,712258,882
    age-adjusted RR (95% CI)1.00.89 (0.76 to 1.05)0.96 (0.82 to 1.12)0.79 (0.67 to 0.93)0.85 (0.72 to 1.00)0.03
    multivariate RR (95% CI)b1.01.02 (0.86 to 1.20)1.16 (0.99 to 1.36)1.03 (0.87 to 1.23)1.21 (1.01 to 1.44)0.05
NHS II
    quintile median (mg/d)85117157202293
    cases365340296286277
    person-years169,306168,806169,837169,964169,674
    age-adjusted RR (95% CI)1.00.95 (0.82 to 1.10)0.83 (0.71 to 0.96)0.80 (0.69 to 0.94)0.79 (0.67 to 0.92)0.001
    multivariate RR (95% CI)b1.01.03 (0.88 to 1.20)0.96 (0.82 to 1.13)1.00 (0.85 to 1.18)1.06 (0.89 to 1.27)0.57
  • a CI, confidence interval; RR, relative risk.

  • b Results are adjusted for age; body mass index (BMI; six categories); use of thiazide diuretics (yes or no); fluid intake (in quintiles); alcohol use (seven categories); calcium supplement use (four categories); and dietary intake of animal protein, calcium, potassium, sodium, phytate, vitamin C, and magnesium (all in quintiles).