Table 4

Meta-analyses of circulatory risks for smokeless tobacco users

CountryConditionSmokeless tobacco statusCigarette smoking status*Number of study estimates (estimate numbers†)Relative risk (95% CI)Measures of heterogeneity
SwedenIschaemic heart diseaseCurrentNevern=3 (15, 17, 37)1.04 (0.93 to 1.16)p=0.494 I2=0.0%
CurrentAnyn=4 (15, 17, 18, 37)0.99 (0.85 to 1.16)p=0.345 I2=9.7%
FormerNevern=5 (1, 16, 22, 23, 28)0.85 (0.66 to 1.08)p=0.609 I2=0.0%
StrokeCurrentNevern=1 (39)1.04 (0.92 to 1.17)
CurrentAnyn=2 (19, 39)1.04 (0.93 to 1.17)p=0.914 I2=0.0%
FormerNevern=2 (24, 29)0.91 (0.50 to 1.64)p=0.131 I2=56.2%
Other circulatory disease
 Heart failureCurrentAnyn=2 (34, 35)1.43 (0.91 to 2.24)p=0.190 I2=41.9%
FormerNevern=1 (36)0.99 (0.44 to 2.22)
 HypertensionCurrentNevern=1 (25)1.43 (1.12 to 1.83)
FormerNevern=1 (26)0.85 (0.40 to 1.79)
All circulatory diseaseEverNevern=1 (27)1.15 (0.97 to 1.37)
Among users with previous myocardial infarction (‘quitters’ vs ‘continuers’)
 Cardiovascular eventsCurrentAnyn=1 (38)0.38 (0.11 to 1.32)
USIschaemic heart diseaseCurrentNevern=3 (6, 9, 40)1.17 (1.09 to 1.27)p=0.292 I2=18.7%
Current/everNevern=5 (2, 3, 6, 9, 40)1.18 (1.06 to 1.31)p=0.167 I2=38.2%
FormerNevern=2 (12, 42)0.80 (0.61 to 1.05)p=0.220 I2=33.7%
StrokeCurrentNevern=3 (7, 10, 41)1.28 (1.01 to 1.62)p=0.028 I2=72.0%
Current/everNevern=5 (4, 5, 7, 10, 41)1.25 (1.00 to 1.55)p=0.066 I2=54.6%
FormerNevern=2 (13, 43)1.25 (0.93 to 1.69)p=0.766 I2=0.0%
Other circulatory disease
 Circulatory disease excluding ischaemic heart disease and strokeCurrentNevern=2 (8, 11)1.06 (0.93 to 1.20)p=0.902 I2=0.0%
All circulatory disease
 Ischaemic heart disease and strokeCurrentNevern=1 (30)1.14 (0.55 to 2.39)
FormerNevern=1 (31)1.25 (0.77 to 2.03)
 Ischaemic heart disease and strokeCurrentNon-current (adjusted)n=1 (32)1.31 (1.06 to 1.61)
FormerNon-current (adjusted)n=1 (33)0.90 (0.73 to 1.11)
Among former cigarette smokers (‘switchers’)
 Ischaemic heart diseaseCurrentFormern=1 (20)1.13 (1.00 to 1.29)
 StrokeCurrentFormern=1 (21)1.24 (1.01 to 1.53)
  • *Meta-analyses of studies with any smoking status include all study estimates for that condition and smokeless tobacco use status regardless of cigarette smoking status in individual studies. Meta-analyses of studies with non-current smoking status include estimates from studies that excluded current but not former smokers.

  • †Study estimate numbers are from table 3.