Table 3.

Quintiles of nondairy animal protein intake and risk of kidney stones

CohortQuintile 1Quintile 2Quintile 3Quintile 4Quintile 5P Value for Trend
HPFS
 Median, g/d31.442.650.358.672.50.004
 Range<38.938.9–47.247.3–55.455.5–66.2>66.20.04
 Patients351364379424445
 Person-time133,204133,448134,142134,288134,406
 Age-adjusted HR (95% CI)1.00 (reference)1.04 (0.90 to 1.20)1.05 (0.91 to 1.22)1.17 (1.01 to 1.35)1.19 (1.04 to 1.37)
 Multivariate-adjusted HR (95% CI)1.00 (reference)0.98 (0.84 to 1.14)0.99 (0.85 to 1.15)1.09 (0.93 to 1.28)1.15 (0.97 to 1.36)
NHS I
 Median, g/d30.939.645.952.864.40.001
 Range<36.236.2–42.943.0–49.549.6–58.1>58.10.06
 Patients229253259268322
 Person-time202,112203,103203,627202,284199,316
 Age-adjusted HR (95% CI)1.00 (reference)1.10 (0.92 to 1.31)1.09 (0.91 to 1.30)1.12 (0.94 to 1.34)1.34 (1.13 to 1.59)
 Multivariate-adjusted HR (95% CI)1.00 (reference)1.04 (0.87 to 1.25)1.02 (0.84 to 1.22)1.03 (0.85 to 1.25)1.20 (0.99 to 1.46)
NHS II
 Median, g/d30.941.348.355.868.50.01
 Range<37.337.3–45.145.2–52.752.8–62.7>62.70.64
 Patients560645566576667
 Person-time286,109286,994286,767285,358282,807
 Age-adjusted HR (95% CI)1.00 (reference)1.14 (1.02 to 1.28)1.01 (0.90 to 1.13)1.03 (0.92 to 1.16)1.21 (1.09 to 1.36)
 Multivariate-adjusted HR (95% CI)1.00 (reference)1.07 (0.95 to 1.20)0.91 (0.80 to 1.03)0.91 (0.80 to 1.03)1.02 (0.90 to 1.17)
Pooled cohorts
 Age-adjusted HR (95% CI)1.00 (reference)1.10 (1.02 to 1.19)1.04 (0.96 to 1.12)1.09 (1.00 to 1.18)1.23 (1.14 to 1.33)<0.001
 Multivariate-adjusted HR (95% CI)1.00 (reference)1.04 (0.95 to 1.12)0.95 (0.88 to 1.04)1.00 (0.89 to 1.12)1.10 (1.00 to 1.21)0.20
  • Multivariate models were adjusted for age, body mass index, history of diabetes, history of hypertension, use of thiazides, supplemental calcium, and intakes of fluid, sodium, potassium, fructose, oxalate, phytate, alcohol, and all other types of protein. Medians refer to the first time period; however, dietary variables were updated over the course of the study. HPFS, Health Professionals Follow-Up Study; HR, hazard ratio; 95% CI, 95% confidence interval; NHS I, Nurses’ Health Study I; NHS II, Nurses’ Health Study II.