Table 3.

Procedures: comparison of nationwide inpatient sample (NIS) and health facts® (HF) EHR population

		Total number of discharges					Percentage of total discharges
	CCS Principal Procedure Category and Name	HCUP	Std. error	HF	Rel Diff (%)	t-value	HCUP	HF
							%	%
1	Operations on the nervous system	768496	42694	831098	8.15	1.47	3.12	2.80
2	Operations on the endocrine system	101141	7645	57033	43.61	5.77*	0.41	0.19
3	Operations on the eye	26432	2121	25783	2.46	0.31	0.11	0.09
4	Operations on the ear	15706	1335	25066	59.60	7.01*	0.06	0.08
5	Operations on the nose; mouth; and pharynx	133650	8828	127031	4.95	0.75	0.54	0.43
6	Operations on the respiratory system	659275	26693	749931	13.75	3.40*	2.68	2.52
7	Operations on the cardiovascular system	3459861	151346	4361495	26.06	5.96*	14.05	14.68
8	Operations on the hemic and lymphatic system	162493	11793	218612	34.54	4.76*	0.66	0.74
9	Operations on the digestive system	3316780	112496	3144045	5.21	1.54	13.47	10.58
10	Operations on the urinary system	540236	35296	599543	10.98	1.68	2.19	2.02
11	Operations on the male genital organs	1147705	51821	705496	38.53	8.53*	4.66	2.37
12	Operations on the female genital organs	700797	27975	793889	13.28	3.33*	2.85	2.67
13	Obstetrical procedures	3850461	173578	3986028	3.52	0.78	15.63	13.41
14	Operations on the musculoskeletal system	2958608	126795	2229428	24.65	5.75*	12.01	7.5
15	Procedures on the breast	760317	32677	717334	5.65	1.32	3.09	2.41
	Miscellaneous diagnostic and therapeutic procedures	6025241	556092	9597019	59.28	6.42*	24.47	32.3
	All Procedures	24627198	1369184	18837298

*Indicates t-values over 1.960. These are procedures that are significantly different between the data sets at 95 % confidence