Table 1.
Characteristics of the study participants according to cooking fuel used at baseline.
| Cooking fuels | Clean fuels | Solid fuels | Total | P |
|---|---|---|---|---|
| N = 2,667 | N = 3,065 | N = 5,732 | ||
| Age | 84.5 (10.8) | 85.0 (11.3) | 84.8 (11.1) | 0.13 |
| Sex | 0.89 | |||
| Male | 1,234 (46.3%) | 1,424 (46.5%) | 2,658 (46.4%) | |
| Female | 1,433 (53.7%) | 1,641 (53.5%) | 3,074 (53.6%) | |
| Residence | <0.001 | |||
| Rural | 1,010 (37.9%) | 2,177 (71.0%) | 3,187 (55.6%) | |
| City | 1,657 (62.1%) | 888 (29.0%) | 2,545 (44.4%) | |
| Education level | <0.001 | |||
| Illiterate (0 year) | 1,374 (51.6%) | 1,929 (63.1%) | 3,303 (57.7%) | |
| Primary school (1–6 years) | 900 (33.8%) | 917 (30.0%) | 1,817 (31.8%) | |
| High school or higher (>6 years) | 388 (14.6%) | 213 (7.0%) | 601 (10.5%) | |
| Current marital status | 0.29 | |||
| Never married | 1,641 (61.8%) | 1,846 (60.4%) | 3,487 (61.0%) | |
| Married | 1,016 (38.2%) | 1,211 (39.6%) | 2,227 (39.0%) | |
| Family annual income (Yuan) | <0.001 | |||
| <30,000 | 506 (19.3%) | 1,371 (45.6%) | 1,877 (33.4%) | |
| 30,000–50,000 | 958 (36.6%) | 1,112 (37.0%) | 2,070 (36.8%) | |
| >50,000 | 1,151 (44.0%) | 523 (17.4%) | 1,674 (29.8%) | |
| Smoking status | <0.001 | |||
| Never | 1,715 (64.6%) | 2,000 (65.6%) | 3,715 (65.1%) | |
| Former | 468 (17.6%) | 432 (14.2%) | 900 (15.8%) | |
| Current | 473 (17.8%) | 618 (20.3%) | 1,091 (19.1%) | |
| Drinking status | <0.001 | |||
| Never | 1,719 (65.0%) | 2,118 (69.6%) | 3,837 (67.5%) | |
| Former | 434 (16.4%) | 376 (12.4%) | 810 (14.2%) | |
| Current | 491 (18.6%) | 550 (18.1%) | 1,041 (18.3%) | |
| Dietary diversity scoresb | <0.001 | |||
| Low | 1,369 (51.3%) | 957 (31.2%) | 2,327 (40.6%) | |
| Medium | 816 (30.6%) | 1,112 (36.3%) | 1,928 (33.6%) | |
| High | 482 (18.1%) | 996 (32.5%) | 1,478 (25.8%) | |
| BMI | <0.001 | |||
| Underweight | 543 (21.6%) | 782 (26.7%) | 1,325 (24.3%) | |
| Normal | 1,323 (52.6%) | 1,630 (55.7%) | 2,953 (54.2%) | |
| Overweight/Obese | 651 (25.9%) | 516 (17.6%) | 1,167 (21.4%) | |
| Social activityc | <0.001 | |||
| Low | 1,169 (43.8%) | 1,534 (50.0%) | 2,704 (47.2%) | |
| Medium | 560 (21.0%) | 656 (21.4%) | 1,216 (21.2%) | |
| High | 938 (35.2%) | 875 (28.5%) | 1,813 (31.6%) | |
| Population-weighted PM2.5 [ug/m3] | <0.001 | |||
| ≤ 50 | 1,059 (39.7%) | 925 (30.2%) | 1,985 (34.6%) | |
| >50 | 1,608 (60.3%) | 2,140 (69.8%) | 3,748 (65.4%) | |
| IADLd | 0.65 | |||
| Normal/partial dependence | 1,527 (57.3%) | 1,773 (57.8%) | 3,301 (57.6%) | |
| Complete dependence | 1,140 (42.7%) | 1,292 (42.2%) | 2,432 (42.4%) | |
| ADLd | 0.002 | |||
| Normal/partial dependence | 2,253 (84.5%) | 2,677 (87.3%) | 4,931 (86.0%) | |
| Complete dependence | 414 (15.5%) | 388 (12.7%) | 802 (14.0%) | |
| City population | 0.009 | |||
| ≤ 8 million | 2,105 (81.3%) | 2,304 (78.4%) | 4,409 (79.8%) | |
| >8 million | 485 (18.7%) | 633 (21.6%) | 1,118 (20.2%) | |
| Cognitive functiona | <0.001 | |||
| Normal | 2,026 (76.0%) | 2,125 (69.3%) | 4,152 (72.4%) | |
| Cognitive impairment | 641 (24.0%) | 940 (30.7%) | 1,581 (27.6%) | |
| Chronic diseasee | <0.001 | |||
| No | 1,531 (57.41%) | 2,051 (66.92%) | 3,583 (62.5%) | |
| Yes | 1,136 (42.59%) | 1,014 (33.08%) | 2,150 (37.5%) |
Cognitive impairment was validated according to MMSE scores and education level: Illiterate (0 year) and MMSE <18; Primary school (1–6 years) and MMSE <21; High school or higher (>6 years) and MMSE <25.
Dietary diversity scores were divided by tertiles.
Social activity score was calculated by eight kind of activities (taking in homework, growing vegetable, cleaning the garden, reading newspaper, raising pets, participating in Mahjong, listening to video and interacting with others) and each item was score at 1 “never,” 2 “sometimes,” 3 “always.” The scores range from 8 to 24 with the higher score indicated more social function, and the total score was divided into three-class by tertiles.
Complete dependence of IADL and ADL was defined as last one item need always others to provide assistant.
Four kinds of chronic diseases were included (hypertension, diabetes, stroke and heart disease).