Table 1.

Overall and Age-Specific Incidence Rates of Kidney Stones Among Urban Chinese Men and Women

	Women Cases/noncases	Men Cases/noncases
Incident cases (n)	1451/67,804	1202/56,895
PY of follow-up	691,836.17	316,122.06
Incidence rate/1000PY (95% CI)
Crude	2.10 (1.99, 2.21)	3.80 (3.59, 4.02)
Age specific
40–49.9	2.23 (2.08, 2.40)	3.94 (3.60, 4.32)
50–59.9	2.36 (2.14, 2.61)	4.01 (3.63, 4.43)
60–69.9	1.61 (1.43, 1.81)	3.85 (3.39, 4.37)
≥70	0.97 (0.37, 2.60)	2.66 (2.18, 3.26)

CI = confidence interval; PY = person-years.