Table 1.

NHAMCS ED 1996–2007 adult, non-pregnant visits, with primary reason for visit of flank pain/kidney pain

	1996–1998	1999–2001	2002–2004	2005–2007	p-values
Number of visits	1,629	868	1,176	1,145	-
Estimated visits^ϕ	2,876,566 [2,418,161 – 3,334,971]	3,635,441 [2,964,892 – 4,305,990]	3,556,561 [3,110,189 – 4,002,933]	4,273,515 [3,490,287 – 5,056,743]	0.07
Imaging utilization^ϕϕ
None	2,601,160 (90.4) [2,173,276 – 3,029,044]	2,780,014 (76.5) [2,238,107 – 3,321,921]	2,253,311 (63.4) [1,942,812 – 2,563,810]	2,298,538 (53.8) [1,840,508 – 2,756,568]	<0.001
Ultrasound	153,236 (5.3) [94,291 – 212,181]	160,052 (4.4) [86,901 – 233,203]	163,426 (4.6) [106,929 – 219,923]	103,750 (2.4) [54,088 – 153,412]	0.01
CT	116,177 (4.0) [52,951 – 179,403]	665,344 (18.3) [474,001 – 856,687]	1,096,462 (30.8) [900,650 – 1,292,274]	1,814,727 (42.5) [1,411,353 – 2,218,101]	<0.001
Dx of urolithiasis	513,383 (17.8) [376,393 – 650,373]	657,236 (18.1) [472,228 – 842,244]	694,740 (19.5) [556,505 – 832,975]	812,213 (19.0) [598,736 – 1,025,690]	0.55
Admissions, any Dx	336,328 (11.7) [244,088 – 428,568]	409,503 (11.3) [274,259 – 544,747]	356,796 (10.0) [271,583 – 442,009]	451624 (10.6) [313,787 – 589,461]	0.49

Numbers in parentheses are percentages, numbers in brackets are 95% confidence intervals

^ϕ

Trend test performed on visits with weighted linear regression

^ϕϕ

Trend test based on percentages

CT = computed tomography; Dx = diagnosis; NHAMCS = National Ambulatory Medical Care Survey