Table 1.
Characteristics of the study population and air pollution factors, overall and by periodontal status.
| CPI ≥ 3 | CPI = 4 | ||||
|---|---|---|---|---|---|
| Variables | Overall a | No Periodontitis b | Periodontitis b | No Severe Periodontitis c | Severe Periodontitis c |
| Age (years), mean (RSD) | 44.91 (0.003) | 41.71 (0.004) | 52.97 (0.004) | 44.16 (0.003) | 54.88 (0.006) |
| Gender, N (%) | |||||
| Men | 17,876 (49.6) | 11,055 (46.1) | 6821 (58.3) | 16,023 (48.6) | 1853 (62.7) |
| Women | 24,144 (50.4) | 17,719 (53.9) | 6425 (41.7) | 22,742 (51.4) | 1402 (37.3) |
| Smoking status, N (%) | |||||
| Non-smokers | 29,532 (68.4) | 21,193 (71.5) | 8339 (60.3) | 27,539 (69.1) | 1993 (58.8) |
| Current smokers | 11,336 (31.6) | 6835 (28.5) | 4501 (39.7) | 10,187 (30.9) | 1149 (41.2) |
| Educational level, N (%) | |||||
| Primary school | 9974 (17.3) | 5442 (13.1) | 4532 (28.1) | 8881 (16.5) | 1093 (29.1) |
| Middle school | 4425 (9.7) | 2542 (7.8) | 1883 (14.4) | 3917 (9.2) | 508 (16.1) |
| High school | 13,999 (39.5) | 10,221 (41.7) | 3778 (34.0) | 13,083 (40.0) | 916 (33.5) |
| University/College | 12,061 (33.5) | 9548 (37.4) | 2513 (23.5) | 11,473 (34.4) | 588 (21.3) |
| Monthly household income, N (%) | |||||
| Low | 7945 (15.3) | 4623 (13.1) | 3322 (20.8) | 7126 (14.8) | 819 (21.6) |
| Middle-low | 10,449 (25.3) | 6957 (24.7) | 3492 (26.8) | 9592 (25.2) | 857 (26.4) |
| Middle-high | 11,330 (29.4) | 8079 (30.1) | 3251 (27.4) | 10,527 (29.6) | 803 (26.5) |
| High | 11,658 (30.1) | 8716 (32.0) | 2942 (25.1) | 10,934 (30.4) | 724 (25.4) |
| Area of residence, N (%) | |||||
| Urban | 32,902 (82.0) | 23,302 (84.2) | 9600 (76.3) | 30,597 (82.6) | 2305 (73.1) |
| Rural | 9118 (18.0) | 5472 (15.8) | 3646 (23.7) | 8168 (17.4) | 950 (26.9) |
| Marital status, N (%) | |||||
| Never married | 6196 (22.2) | 5578 (28.0) | 618 (7.5) | 6107 (23.5) | 89 (4.2) |
| Married and living with a spouse | 30,180 (67.6) | 19,854 (63.5) | 10,326 (78.0) | 27,588 (66.6) | 2592 (81.0) |
| Married but living alone | 5504 (10.2) | 3252 (8.5) | 2252 (14.5) | 4947 (9.9) | 557 (14.8) |
| BMI (kg/m²), mean (RSD) | 23.71 (0.001) | 23.49 (0.001) | 24.25 (0.002) | 23.65 (0.001) | 24.42 (0.003) |
| Alcoholism (AUDIT score), mean (RSD) | 6.95 (0.007) | 6.72 (0.009) | 7.55 (0.013) | 6.87 (0.008) | 8.04 (0.025) |
| Hypertension status, N (%) | |||||
| Normal | 18,560 (49.9) | 14,342 (55.4) | 4218 (36.0) | 17,644 (51.2) | 916 (32.3) |
| Pre-hypertension | 9709 (24.7) | 6513 (24.3) | 3196 (26.0) | 8897 (10872) | 812 (26.5) |
| Hypertension | 12,255 (25.4) | 6934 (20.3) | 5321 (38.0) | 10,872 (24.2) | 1383 (41.2) |
| Tooth-brushing frequency, N (%) | |||||
| 0–1 per day | 6120 (13.9) | 3612 (12.2) | 2508 (18.2) | 5458 (13.4) | 662 (19.7) |
| 2 per day | 16,760 (39.0) | 11,051 (37.6) | 5709 (42.5) | 15,379 (38.8) | 1381 (41.7) |
| ≥3 per day | 19,063 (47.1) | 14,066 (50.2) | 4997 (39.2) | 17,856 (47.7) | 1207 (38.5) |
| Use of interproximal toothbrush, N (%) | |||||
| No | 30,383 (82.4) | 20,544 (81.7) | 9839 (84.0) | 28,000 (82.3) | 2383 (84.2) |
| Yes | 6216 (17.6) | 4517 (18.3) | 1699 (16.0) | 5791 (17.7) | 425 (15.8) |
| Stress, N (%) | |||||
| Not/slightly stressed | 29,920 (72.1) | 20,185 (71.0) | 9735 (75.1) | 27,483 (71.8) | 2437 (77.0) |
| Moderately/highly stressed | 10,914 (27.9) | 7827 (29.0) | 3087 (24.9) | 10,214 (28.2) | 700 (23.0) |
| Air pollution factors | |||||
| Humidity (%), mean (RSD) | 65.940 (0.001) | 65.861 (0.001) | 66.136 (0.001) | 65.910 (0.001) | 66.335 (0.002) |
| PM10 (μg/m3), mean (RSD) | 50.011 (0.002) | 49.917 (0.002) | 50.248 (0.003) | 50.032 (0.002) | 49.736 (0.004) |
| Ozone (ppm), mean (RSD) | 0.024 (0.002) | 0.024 (0.003) | 0.025 (0.003) | 0.024 (0.002) | 0.025 (0.005) |
| Nitrogen dioxide (ppm), mean (RSD) | 0.025 (0.003) | 0.026 (0.004) | 0.025 (0.005) | 0.026 (0.003) | 0.024 (0.008) |
| Sulfur dioxide (ppm), mean (RSD) | 0.005 (0.004) | 0.005 (0.005) | 0.005 (0.005) | 0.005 (0.004) | 0.005 (0.007) |
CPI: Community Periodontal Index; RSD: relative standard deviation; BMI: body mass index; AUDIT: Alcohol Use Disorders Identification Test score; PM10: particulate matter. Data are presented as unweighted N (weighted %) for binary and categorical variables and as weighted mean (weighted RSD) for continuous variables. N is the unweighted population size for each group; the sum of N varied according to missing data for each variable. a Overall: N(unweighted) = 42,020; n(weighted) = 35,224,590. b CPI ≥ 3 case definition. No periodontitis: N(unweighted) = 28,774; n(weighted) = 25,199,934 (71.5%). Periodontitis: N(unweighted) = 13,246; n(weighted) = 10,024,655 (18.5%). c CPI = 4 case definition. No Severe Periodontitis: N(unweighted) = 38,765; n(weighted) = 32,742,134 (93.0%). Severe Periodontitis: N(unweighted) = 3255; n(weighted) = 2,482,456 (7.0%).