Table 2

Dementia syndromes in participants with and without environmental tobacco smoke (ETS) exposure by exposure sources and duration in the five-province study, China

Dementia syndrome level
0 (n=4426)1–2 (n=869)3–5 (n=626)
Source of ETS exposuren%n%n%p Value
Exposure level
 At home
  None290365.653161.133453.4<0.001
  No4329.8546.2335.3
  Yes*109124.628432.725941.4
 At work
  None290365.653161.133453.4<0.001
  No84019.022025.317528.0
  Yes*68315.411813.611718.7
 In other locations
  None290365.653161.133453.4<0.001
  No73516.619122.013721.9
  Yes*78817.814716.915524.8
 Above 3 combined
  None290365.653161.133453.4<0.001
  Some (1–2)†121227.428733.023036.7
  A lot (3–6)†3117.0515.9629.9
Exposure duration (years)
 At home
  None290365.653161.133453.4<0.001
  No4329.8546.2335.3
  >0–192465.6647.4375.9
  20–3953512.111212.910116.1
  ≥403107.010812.412119.3
 At work
  None290365.653161.133453.4<0.001
  No84019.022025.317528.0
  >0–191182.7283.2223.5
  20–393828.6515.9497.8
  ≥401834.1394.5467.3
 In other locations
  None290365.653161.133453.4<0.001
  No73516.619122.013721.9
  >0–192746.2404.6355.6
  20–393738.4627.16610.5
  ≥401413.2455.2548.6
 Above 3 combined score‡
  None290365.653161.133453.4<0.001
  11964.4485.5325.1
  248010.89611.0568.9
  3–446510.510512.110016.0
  5–93828.68910.210416.6
Cumulative dose score (level×duration)§
 None290365.653161.133453.4<0.001
 0–243307.5637.2416.5
 25–494039.110612.26810.9
 50–743507.9637.2599.4
 75–992235.0546.2447.0
 ≥1002174.9526.08012.8
  • *Including any participants indicating ‘yes, some’ or ‘yes, a lot’ of ETS exposure.

  • †Each participant had an overall score for total exposure from all three ETS sources. Exposure levels of ‘no, none at all’, ‘yes, some’ and ‘yes, a lot’ were scored as 0, 1 and 2, respectively. Therefore, a participant exposed to ETS ‘no, none at all’ at home, ‘yes, a lot’ at work and ‘yes, some’ in other locations would have a total score of 3 (0+2+1).

  • ‡Participants with ETS exposure durations of 0, >0–19, 20–39 or ≥40 years were scored as 0, 1, 2 or 3 for each exposure source. Overall scores were the sum of the individual scores for the three sources of exposure.

  • §Cumulative dose score calculated by multiplying exposure level by exposure duration (years) for each ETS source, and then combining the results for the three sources of exposure. Therefore, a participant exposed to ETS ‘yes, some’ at home for 20 years, ‘yes, a lot’ at work for 15 years, and ‘yes, some’ in other locations for 10 years, would have total score of 60 years (1×20+2×15+1×10).

  • “None” means “no ETS at all”. “No” means “not ETS exposure at either home, work or other places”