Table 1 Baseline characteristics, n (%).

From: Long-term exposure to particulate matter was associated with increased dementia risk using both traditional approaches and novel machine learning methods

 

All participants

Dementia events over the 13-year follow-up

P value

Nonevents

Events

(n = 457,064)

(n = 400,032)

(n = 57,032)

Age at baseline, years

 Mean (SD)

63 (9.9)

61.8 (9.4)

71.4 (8.7)

 < 0.0001

Sex

 Men

227,448 (49.8)

201,437 (50.4)

26,011 (45.6)

 < 0.0001

 Women

229,616 (50.2)

198,595 (49.6)

31,021 (54.4)

 

Duration of follow-up, years

 Mean (SD)

10.8 (3.7)

11.4 (3.4)

7.1 (3.7)

 < 0.0001

Baseline comorbidity

 Hypertension

207,256 (45.3)

170,740 (42.7)

36,516 (64.0)

 < 0.0001

 Diabetes

95,129 (20.8)

78,329 (19.6)

16,800 (29.5)

 

 Hyperlipidemia

121,988 (26.7)

103,123 (25.8)

18,865 (33.1)

 

Modified CCI*

 0

372,606 (81.5)

331,622 (82.9)

40,984 (71.9)

 < 0.0001

 1

25,143 (5.5)

20,650 (5.2)

4493 (7.9)

 

 2

13,475 (2.9)

11,217 (2.8)

2258 (4.0)

 

 3

4882 (1.1)

4019 (1.0)

863 (1.5)

 

 ≥ 4

40,958 (9.0)

32,524 (8.1)

8434 (14.8)

 

Number of townships

338

   
  1. *Modified CCI, which excluded dementia.