Demographic information of enrolled individuals and Helicobacter pylori infection risk factors
| Categories | Total no. of individual (31098), n (%) | H. pylori-infected, n | H. pylori uninfected, n | Infection rate (%) | Crude OR (95% CI) | P value* | Adjusted OR (95% CI) | P value |
| Demographic information | ||||||||
| Geographical areas | ||||||||
| Southwest | 6046 (19.44) | 2145 | 3901 | 35.48 | Reference | Reference | ||
| North | 4975 (16.00) | 1903 | 3072 | 38.25 | 1.13 (1.04 to 1.23) | 0.003 | 1.17 (1.06 to 1.29) | <0.001† |
| Central | 2171 (6.98) | 823 | 1348 | 37.91 | 1.08 (0.97 to 1.20) | 0.154 | 1.13 (1.00 to 1.28) | 0.057 |
| East | 8168 (26.27) | 3447 | 4721 | 42.20 | 1.37 (1.27 to 1.47) | <0.001 | 1.29 (1.19 to 1.42) | <0.001† |
| South | 3265 (10.50) | 1386 | 1879 | 42.45 | 1.34 (1.22 to 1.47) | <0.001 | 1.37 (1.23 to 1.53) | <0.001† |
| Northeast | 2576 (8.28) | 1077 | 1499 | 41.81 | 1.42 (1.29 to 1.57) | <0.001 | 1.26 (1.12 to 1.41) | <0.001† |
| Northwest | 3897 (12.53) | 1865 | 2032 | 47.86 | 1.76 (1.61 to 1.91) | <0.001 | 1.64 (1.48 to 1.82) | <0.001† |
| Gender | ||||||||
| Female | 17 620 (56.66) | 6983 | 10 637 | 39.63 | Reference | Reference | ||
| Male | 13 478 (43.34) | 5663 | 7815 | 42.02 | 1.11 (1.06 to 1.16) | <0.001 | 1.14 (1.08 to 1.21) | <0.001† |
| Age | ||||||||
| Adult (≥18 years) | 27 317 (87.84) | 11 869 | 15 448 | 43.45 | Reference | Reference | ||
| Children and adolescents (<18 years) | 3781 (12.16) | 777 | 3004 | 20.55 | 0.39 (0.35 to 0.42) | <0.001 | 0.57 (0.46 to 0.70) | <0.001† |
| Marital status | ||||||||
| Single | 6350 (20.42) | 1702 | 4648 | 26.80 | Reference | Reference | ||
| Married | 24 092 (77.47) | 10 678 | 13 414 | 44.32 | 1.98 (1.86 to 2.11) | <0.001 | 1.31 (1.18 to 1.45) | <0.001 † |
| Other | 656 (2.11) | 266 | 390 | 40.55 | 1.76 (1.48 to 2.09) | <0.001 | 1.34 (1.07 to 1.69) | 0.010 † |
| Resident location | ||||||||
| City | 23 203 (74.61) | 9326 | 13 877 | 40.19 | Reference | Reference | ||
| Rural | 7895 (25.39) | 3320 | 4575 | 42.05 | 1.16 (1.10 to 1.23) | <0.001 | 1.06 (0.98 to 1.14) | 0.133 |
| Education level | ||||||||
| Middle/high school | 9861 (40.45) | 4287 | 5574 | 43.47 | Reference | <0.001 | Reference | |
| College and above | 14 518 (59.55) | 6131 | 8387 | 42.23 | 0.90 (0.85 to 0.95) | <0.001 | 0.85 (0.79 to 0.91) | <0.001 † |
| Occupation | ||||||||
| Farmer | 3723 (11.97) | 1579 | 2144 | 42.41 | Reference | Reference | ||
| Worker | 3763 (12.10) | 1702 | 2061 | 45.23 | 1.05 (0.95 to 1.15) | 0.365 | 1.11 (0.97 to 1.27) | 0.127 |
| Teacher | 1341 (4.31) | 593 | 748 | 44.22 | 0.94 (0.83 to 1.08) | 0.396 | 1.05 (0.89 to 1.25) | 0.551 |
| Investigator | 2423 (7.79) | 1040 | 1383 | 42.92 | 0.88 (0.79 to 0.98) | 0.025 | 1.04 (0.89 to 1.22) | 0.592 |
| Doctor | 4090 (13.15) | 1729 | 2361 | 42.27 | 0.90 (0.82 to 0.99) | 0.022 | 1.09 (0.95 to 1.26) | 0.225 |
| Soldier | 91 (0.29) | 44 | 47 | 48.35 | 1.21 (0.79 to 1.87) | 0.377 | 1.37 (0.84 to 2.24) | 0.213 |
| Merchant | 1778 (5.72) | 796 | 982 | 44.77 | 1.04 (0.93 to 1.17) | 0.488 | 1.07 (0.91 to 1.24) | 0.422 |
| Others | 9752 (31.36) | 4224 | 5528 | 43.31 | 0.95 (0.88 to 1.03) | 0.229 | 1.10 (0.97 to 1.25) | 0.131 |
| Student | 4137 (13.30) | 939 | 3198 | 22.70 | 0.41 (0.37 to 0.46) | 0.000 | 0.85 (0.69 to 1.05) | 0.132 |
| Lifestyle-related factors | ||||||||
| Drinking tap water | ||||||||
| No | 28 900 (92.93) | 11 759 | 17 141 | 40.69 | Reference | |||
| Yes | 2198 (7.07) | 887 | 1311 | 40.35 | 1.02 (0.93 to 1.12) | 0.698 | ||
| Washing hands before meal and after defecation | ||||||||
| No | 2430 (7.81) | 970 | 1460 | 39.92 | Reference | |||
| Yes | 28 668 (92.19) | 11 676 | 16 992 | 40.73 | 0.97 (0.89 to 1.05) | 0.421 | ||
| Cafeteria dining | ||||||||
| Rare | 27 700 (89.07) | 11 316 | 16 384 | 40.85 | Reference | Reference | ||
| Frequent | 3398 (10.93) | 1330 | 2068 | 39.14 | 0.90 (0.83 to 0.97) | 0.006 | 0.93 (0.85 to 1.02) | 0.143 |
| Dining at road side restaurant | ||||||||
| Rare | 26 318 (84.63) | 10 539 | 15 779 | 40.04 | Reference | Reference | ||
| Frequent | 4780 (15.37) | 2107 | 2673 | 44.08 | 1.15 (1.08 to 1.23) | <0.001 | 0.99 (0.91 to 1.07) | 0.789 |
| Dining at hotel restaurant | ||||||||
| Rare | 28 578 (91.90) | 11 534 | 17 044 | 40.36 | Reference | Reference | ||
| Frequent | 2520 (8.10) | 1112 | 1408 | 44.13 | 1.12 (1.02 to 1.22) | 0.013 | 1.09 (0.98 to 1.21) | 0.124 |
| No. of infected family members exposed‡ | ||||||||
| 0 | 13 804 (44.39) | 4849 | 8955 | 35.13 | Reference | Reference | ||
| 1 | 11 358 (36.52) | 4947 | 6411 | 43.56 | 1.56 (1.48 to 1.65) | <0.001 | 1.52 (1.43 to 1.62) | <0.001† |
| 2 | 4121 (13.25) | 1882 | 2239 | 45.67 | 1.67 (1.56 to 1.80) | <0.001 | 1.69 (1.55 to 1.85) | <0.001† |
| 3 | 1260 (4.05) | 637 | 623 | 50.56 | 2.12 (1.88 to 2.38) | <0.001 | 2.12 (1.84 to 2.45) | <0.001† |
| 4 | 382 (1.23) | 225 | 157 | 58.90 | 3.02 (2.45 to 3.73) | <0.001 | 2.86 (2.22 to 3.68) | <0.001† |
| Five and above | 173 (0.56) | 106 | 67 | 61.27 | 3.34 (2.44 to 4.56) | <0.001 | 2.72 (1.86 to 4.00) | <0.001† |
| Medical history | ||||||||
| Gastrointestinal symptoms within last 1 year | ||||||||
| No | 22 519 (72.41) | 8863 | 13 656 | 39.36 | Reference | |||
| Yes | 8579 (27.59) | 3783 | 4796 | 44.10 | 1.01 (0.96 to 1.07) | 0.609 | ||
| Previous H. pylori diagnosis | ||||||||
| Did not test H. pylori | 24 742 (79.56) | 9261 | 15 481 | 37.43 | Reference | Reference | ||
| Tested as negative | 3398 (10.93) | 687 | 2711 | 20.22 | 0.42 (0.38 to 0.46) | <0.001 | 0.44 (0.39 to 0.48) | <0.001† |
| Tested as positive | 2958 (9.51) | 2698 | 260 | 91.21 | 6.56 (5.71 to 7.54) | <0.001 | 6.28 (5.41 to 7.28) | <0.001† |
| History of gastroduodenal surgery | ||||||||
| No | 30 782 (98.98) | 12 496 | 18 286 | 40.60 | Reference | |||
| Yes | 316 (1.02) | 150 | 166 | 47.47 | 1.10 (0.86 to 1.40) | 0.453 | ||
*P value was calculated by univariate logistic regression, p<0.05 indicates that infection risk increase/decrease significantly compared with the reference groups.
†These are independent risk (protective) factors for H. pylori infection compared with the reference group. P value was calculated by multivariate logistic regression and was adjusted with items of p<0.1 in univariate logistic regression.
‡Number of infected family members exposed is defined as the number of H. pylori-infected persons in a household that the participant is exposed.