Table 1 Demographic characteristics

Age (years), mean ± SD

5.50 ± 3.32

1.36 ± 0.34

3.92 ± 0.80

8.66 ± 2.35

Sex, n (%)

 Male

1575 (63.82%)

300 (68.34%)

594 (61.43%)

681 (64.12%)

.04

 Female

893 (36.18%)

139 (31.66%)

373 (38.57%)

381 (35.88%)

Clinical visits, n (%)

 Outpatient

70,570 (98.58%)

14,419 (98.11%)

32,722 (98.76%)

23,429 (98.63%)

 < .01

 Inpatient

1014 (1.42%)

278 (1.89%)

411 (1.24%)

325 (1.37%)

Hospital grade, n (%)

 Tertiary

44,440 (62.08%)

9304 (63.31%)

20,325 (61.34%)

14,811 (62.35%)

 < .01

 Secondary

13,686 (19.12%)

2582 (17.57%)

6808 (20.55%)

4296 (18.09%)

 Primary

13,433 (18.77%)

2811 (19.13%)

5994 (18.09%)

4628 (19.48%)

Hospital type, n (%)

 General

51,731 (72.27%)

8554 (58.20%)

24,147 (72.88%)

19,030 (80.11%)

 < .01

 Specialized

19,828 (27.70%)

6143 (41.80%)

8980 (27.10%)

4705 (19.81%)

Regions, n (%)

 East China

1900(76.99%)

352(80.18%)

756(78.18%)

792(74.58%)

 < .01

 Central China

223(9.04%)

44(10.02%)

97(10.03%)

82(7.72%)

 West China

345(13.98%)

43(9.79%)

114(11.79%)

188(17.70%)

City Levels, n(%)

 1^st-tier

601(24.35%)

74(16.86%)

246(25.44%)

281(26.46%)

 < .01

 2^nd-tier

1268(51.38%)

289(65.83%)

522(53.98%)

457(43.03%)

 3^rd-tier

195(7.90%)

29(6.61%)

77(7.96%)

89(8.38%)

 4^th and 5^th tier

314(12.72%)

47(10.71%)

122(12.62%)

145(13.65%)