Table 4.

Quintiles of dietary potassium intake and risk of kidney stones

CohortQuintile 1Quintile 2Quintile 3Quintile 4Quintile 5P Value for Trend
HPFS
 Median, g/d26013016332736674224<0.001
 Range<28352835–31753176–34883489–3888>3888<0.001
 Patients567459368332237
 Person-time128,870134,246135,483135,420135,469
 Age-adjusted HR (95% CI)1.00 (reference)0.78 (0.69 to 0.88)0.64 (0.56 to 0.73)0.60 (0.52 to 0.68)0.44 (0.38 to 0.51)
 Multivariate-adjusted HR (95% CI)1.00 (reference)0.78 (0.68 to 0.89)0.64 (0.55 to 0.74)0.60 (0.51 to 0.70)0.44 (0.36 to 0.53)
NHS I
 Median, g/d23232694297132613722<0.001
 Range<25352535–28352836–31083109–3448>3448<0.001
 Patients393287245211195
 Person-time196,777203,677204,510204,711200,767
 Age-adjusted HR (95% CI)1.00 (reference)0.71 (0.61 to 0.82)0.61 (0.52 to 0.72)0.53 (0.45 to 0.63)0.50 (0.42 to 0.60)
 Multivariate-adjusted HR (95% CI)1.00 (reference)0.74 (0.63 to 0.87)0.66 (0.55 to 0.79)0.58 (0.48 to 0.72)0.57 (0.45 to 0.72)
NHS II
 Median, g/d22752649291031803612<0.001
 Range<24912491–27842785–30383039–3354>3354<0.001
 Patients815662595533409
 Person-time282,413285,735287,785286,885285,518
 Age-adjusted HR (95% CI)1.00 (reference)0.81 (0.73 to 0.90)0.72 (0.65 to 0.80)0.65 (0.58 to 0.73)0.50 (0.45 to 0.57)
 Multivariate-adjusted HR (95% CI)1.00 (reference)0.91 (0.82 to 1.02)0.87 (0.77 to 0.98)0.83 (0.73 to 0.94)0.67 (0.57 to 0.78)
  • Multivariate models were adjusted for age, body mass index, history of diabetes, history of hypertension, use of thiazides, supplemental calcium, and intakes of fluid, calcium, sodium, 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. Cohort-specific results were not pooled because of statistically significant test for heterogeneity. 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.