Systematic Reviews
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©The Author(s) 2020. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Meta-Anal. Jun 28, 2020; 8(3): 245-264
Published online Jun 28, 2020. doi: 10.13105/wjma.v8.i3.245
Table 1 Studies in meta-analysis of lung cancer and exclusive cigar smoking1
Study name2 Data source Study type Years of follow-up3 Sex Age group Study size4 BOUCOT Boucot et al [20 ], 1972 P 10 M 45+ 6027 CPS I Hammond[21 ], 1966 P 4 M 35-84 4405585 Hammond[22 ], 1972 P 6 M 35-84 Shanks et al [23 ], 1998 P 13 M 35+ CPS II Jacobs et al [24 ], 1999 P 12 M 30+ 5085766 Shapiro et al [25 ], 2000 P 12 M 30+ DORN (US veterans study) Dorn[26 ], 1959 P 2 M 30+ 2480467 Kahn[27 ], 1966 P 8 M 35-84 Rogot et al [28 ], 1980 P 16 M 31-84 HAMMON Hammond et al [18 ,19 ], 1958 P 3 M 50-69 187783 KAISER Iribarren et al [13 ], 1999 P 25 M 30-85 17774 LEVIN Levin[29 ], 1954 C - M 35+ 2855 MALHOT Malhotra et al [14 ], 2017 P 15 M 55-62 5244408 NLMS Christensen et al [17 ], 2018 P 26 C 35-80 146529 SADOWS Sadowsky et al [30 ], 1953 C - M All 2605 WYNDE7 Higgins et al [31 ], 1988 C - M 20-80 60339
Table 2 Studies in meta-analysis of chronic obstructive pulmonary disease and exclusive cigar smoking1
Study name2 Data source Study type Years of follow-up Sex Age group Study size3 CPS I Shanks et al [23 ], 1998 P 13 M 35+ 442455 DORN (US veterans study) Kahn[27 ], 1966 P 8 M 35-84 2480464 KAISER Iribarren et al [13 ], 1999 P 25 M 30-85 17774 NLMS Christensen et al [17 ], 2018 P 26 C 35-80 146529
Table 3 Studies on ischaemic heart disease, stroke and circulatory disease and exclusive cigar smoking1
Study name2 Data source Study type Years of follow-up3 Sex Age group Study size4 Disease data available and notes5 CPS I Hammond[21 ], 1966 P 4 M 35-84 4405586 IHD: CHD (ICD-6 420); Stroke: -; Circ: - Shanks et al [23 ], 1998 P 13 M 35+ IHD: CHD; Stroke: CVD; Circ: - CPS II Jacobs et al [32 ], 1999 P 9 M 30+ 508576 IHD: CHD; Stroke: -; Circ: - DORN (US veterans study) Dorn[26 ], 1959 P 2 M 30+ 2480466 IHD: -; Stroke: -; Circ: Cardiovascular diseases (ICD-6 330-334, 400-468) Kahn[27 ], 1966 P 8 M 35-84 IHD: Arteriosclerotic (coronary) heart disease (ICD-6 420); Stroke: Cerebral vascular lesions (ICD-6 330-334); Circ: Total cardiovascular disease (ICD-6 330-334, 400-468) Rogot et al [28 ], 1980 P 16 M 31-84 IHD: CHD (ICD-6 420); Stroke: Stroke (ICD-6 330-334); Circ: Cardiovascular (ICD-6 330-334, 400-468) HAMMON Hammond et al [19 ], 1958 P 3 M 50-69 187783 IHD: Coronary artery disease; Stroke: Cerebral vascular diseases; Circ: Heart and circulatory diseases (ICD-6 330-334, 400-468) KAISER Iribarren et al [13 ], 1999 P 25 M 30-85 17774 IHD: CHD; Stroke: Ischaemic stroke and haemorrhagic stroke combined; Circ: - KAUFMA Kaufman et al [33 ], 1987 C - M 40-54 15067 IHD: Non-fatal myocardial infarction; Stroke: -; Circ: - NHIS Inoue-Choi et al [16 ], 2019 P 17 C 18-95 71314 IHD: - (“Coronary heart disease” used too broad a definition); Stroke: Cardiovascular disease (ICD-10 I60-I69); Circ: Combined “Coronary heart disease” and Stroke; this excludes some hypertensive disease, diseases of arteries and diseases of veins and other circulatory disease – included in sensitivity analysis only Rostron et al [15 ], 20198 X - C 35+ Not specified IHD: Heart conditions; this includes angina, CHD, heart attack and other heart disease – included in sensitivity analysis only; Stroke: Stroke; Circ: - NLMS Christensen et al [17 ], 2018 P 26 C 35-80 146529 IHD: - (“Cardiovascular diseases” used too broad a definition); Stroke: Cerebrovascular disease (ICD-10 I60-I69); Circ: Circulatory disease (ICD-10 I00-I09, I20-I25, I26-I28, I29-I51, I60-I69, I70, I71, I72-I78); this definition excludes “Diseases of veins” and “Other circulatory diseases” (ICD-10 I80-I89) – included in sensitivity analysis only
Table 4 Individual estimates used in the meta-analyses1
Disease Study name2 Source Exposure Relative risk (95%CI) Lung cancer BOUCOT [20 ] Ever 8.81 (0.45 to 170.58) CPSI [23 ] Current 3.30 (2.68 to 4.06) [22 ] Ever 2.11 (1.45 to 3.07) CPSII [25 ] Current 5.10 (4.00 to 6.60) [25 ] Former 1.60 (1.20 to 2.40) [25 ] Ever 3.01 (2.42 to 3.74) DORN [28 ] Current 1.66 (1.18 to 2.34) [27 ] Former 1.02 (0.41 to 2.54) [27 ] Ever 1.49 (0.97 to 2.27) HAMMON [19 ] Ever 1.02 (0.42 to 2.51) KAISER [13 ] Current3 2.14 (1.12 to 4.11) LEVIN [29 ] Ever 1.41 (0.76 to 2.60) MALHOT [14 ] Ever3 2.73 (2.06 to 3.60) NLMS [17 ] Current 3.26 (1.86 to 5.71) [17 ] Former 1.35 (0.70 to 2.61) [17 ] Ever 2.04 (1.33 to 3.15) SADOWS [30 ] Ever 2.98 (1.06 to 8.33) WYNDE7 [31 ] Current 3.15 (1.78 to 5.57) [31 ] Former 2.46 (1.27 to 4.77) [31 ] Ever 2.83 (1.78 to 4.51) COPD CPSI [23 ] Current 1.42 (0.96 to 2.03) DORN [27 ] Current 0.79 (0.31 to 2.03) [27 ] Former 1.38 (0.42 to 4.51) [27 ] Ever 0.94 (0.43 to 2.04) KAISER [13 ] Current3 1.45 (1.10 to 1.91) NLMS [17 ] Current 2.44 (0.98 to 6.05) [17 ] Former 0.05 (0.00 to 3.19) [17 ] Ever 0.77 (0.32 to 1.87) IHD CPSI [23 ] Current 1.05 (1.00 to 1.11) CPSII [32 ] Current 1.13 (0.96 to 1.34) [32 ] Former 1.07 (0.93 to 1.24) [32 ] Ever 1.09 (0.98 to 1.22) DORN [28 ] Current 1.12 (1.05 to 1.18) [27 ] Former 1.41 (1.25 to 1.60) [27 ] Ever 1.13 (1.05 to 1.22) HAMMON [19 ] Ever 1.28 (1.13 to 1.44) KAISER [13 ] Current3 1.27 (1.12 to 1.45) KAUFMA [33 ] Current 1.25 (0.58 to 2.67) NHIS [15 ] Current3 0.88 (0.61 to 1.27) [15 ] Former3 1.33 (1.03 to 1.72) [15 ] Ever3 1.15 (0.93 to 1.41) Stroke CPSI [23 ] Current 0.96 (0.87 to 1.06) DORN [28 ] Current 1.07 (0.95 to 1.21) [27 ] Former 1.14 (0.85 to 1.53) [27 ] Ever 1.09 (0.93 to 1.29) HAMMON [19 ] Ever 1.33 (1.04 to 1.70) KAISER [13 ] Current3 1.08 (0.88 to 1.33) NHIS [16 ] Current 1.60 (0.72 to 3.57) [16 ] Former 0.56 (0.20 to 1.57) [16 ] Ever 0.94 (0.50 to 1.77) NLMS [17 ] Current 0.50 (0.21 to 1.22) [17 ] Former 1.08 (0.66 to 1.75) [17 ] Ever 0.85 (0.55 to 1.30) Circulatory disease DORN [28 ] Current 1.10 (1.05 to 1.16) [27 ] Former 1.37 (1.24 to 1.52) [27 ] Ever 1.13 (1.06 to 1.20) HAMMON [19 ] Ever 1.27 (1.15 to 1.40) NHIS [16 ] Current3 1.34 (0.88 to 2.06) [16 ] Former3 0.75 (0.52 to 1.10) [16 ] Ever3 0.93 (0.70 to 1.24) NLMS [17 ] Current3 1.11 (0.87 to 1.42) [17 ] Former3 1.13 (0.93 to 1.38) [17 ] Ever3 1.12 (0.96 to 1.31)
Table 5 Meta-analysis results for lung cancer, chronic obstructive pulmonary disease, ischaemic heart disease, stroke and circulatory disease for cigar smoking1
Disease Exposure Number of studies Relative risk (95%CI) fixed effect Relative risk (95%CI) random effects Heterogeneity I 2 (2 ) Lung cancer Current cigar smokers, excluding KAISER 5 3.36 (2.93 to 3.84) 3.12 (2.11 to 4.62) 85.22 (P < 0.001) Current cigar smokers, including KAISER 6 3.29 (2.88 to 3.76) 2.98 (2.08 to 4.26) 82.65 (P < 0.001) Former cigar smokers 4 1.61 (1.23 to 2.09) 1.61 (1.23 to 2.09) 0.00 (NS) Ever cigar smokers, excluding MALHOT 9 2.35 (2.04 to 2.71) 2.11 (1.64 to 2.72) 54.77 (P < 0.05) Ever cigar smokers, including MALHOT 10 2.43 (2.13 to 2.75) 2.22 (1.79 to 2.74) 51.51 (P < 0.05) COPD Current cigar smokers, excluding KAISER 3 1.42 (1.02 to 1.96) 1.42 (0.89 to 2.26) 29.95 (NS) Current cigar smokers, including KAISER 4 1.44 (1.16 to 1.77) 1.44 (1.16 to 1.77) 0.00 (NS) Former cigar smokers 2 1.06 (0.34 to 3.31) 0.47 (0.02 to 9.88) 58.19 (NS) Ever cigar smokers 2 0.86 (0.48 to 1.54) 0.86 (0.48 to 1.54) 0.00 (NS) IHD Current cigar smokers, excluding NHIS and KAISER 4 1.08 (1.04 to 1.13) 1.08 (1.04 to 1.13) 0.28 (NS) Current cigar smokers, including NHIS and KAISER 6 1.09 (1.06 to 1.14) 1.11 (1.04 to 1.19) 48.68 (P < 0.1) Former cigar smokers, excluding NHIS 2 1.25 (1.14 to 1.38) 1.23 (0.94 to 1.61) 87.72 (P < 0.01) Former cigar smokers, including NHIS 3 1.26 (1.16 to 1.38) 1.26 (1.03 to 1.53) 75.96 (P < 0.05) Ever cigar smokers, excluding NHIS 3 1.15 (1.09 to 1.21) 1.16 (1.06 to 1.26) 51.96 (NS) Ever cigar smokers, including NHIS 4 1.15 (1.09 to 1.21) 1.15 (1.08 to 1.23) 27.95 (NS) Stroke Current cigar smokers, excluding KAISER 4 1.00 (0.93 to 1.08) 1.01 (0.87 to 1.16) 46.09 (NS) Current cigar smokers, including KAISER 5 1.01 (0.94 to 1.09) 1.02 (0.92 to 1.13) 33.51 (NS) Former cigar smokers 3 1.08 (0.85 to 1.38) 1.08 (0.85 to 1.38) 0.00 (NS) Ever cigar smokers 4 1.12 (0.98 to 1.27) 1.11 (0.95 to 1.31) 21.80 (NS) Circulatory disease Current cigar smokers, excluding NHIS and NLMS 1 1.10 (1.05 to 1.16) - - Current cigar smokers, including NHIS and NLMS 3 1.10 (1.05 to 1.16) 1.10 (1.05 to 1.16) 0.00 (NS) Former cigar smokers, excluding NHIS and NLMS 1 1.37 (1.24 to 1.52) - - Former cigar smokers, including NHIS and NLMS 3 1.28 (1.17 to 1.39) 1.11 (0.84 to 1.46) 81.92 (P < 0.01) Ever cigar smokers, excluding NHIS and NLMS 2 1.17 (1.11 to 1.23) 1.19 (1.06 to 1.33) 72.63 (P < 0.1) Ever cigar smokers, including NHIS and NLMS 4 1.15 (1.10 to 1.21) 1.15 (1.06 to 1.26) 51.29 (NS)
Table 6 Relative risks and 95%CIs by current amount smoked
1
Study Cigars per day RR (95%CI) lung cancer RR (95% CI) COPD RR (95%CI) IHD Adjustment factors CPS I[23 ] 1-2 0.90 (0.54 to 1.66) 1.39 (0.74 to 2.38) 0.98 (0.91 to 1.07) Age 3-4 2.36 (1.49 to 3.54) 1.78 (0.89 to 3.18) 1.06 (0.96 to 1.16) 5+ 3.40 (2.34 to 4.77) 1.03 (0.37 to 2.23) 1.14 (1.03 to 1.24) CPS II[32 ] Age 30-74 years 1 1.18 (0.76 to 1.82) Age+2 2-3 1.43 (1.03 to 1.99) 4+ 1.33 (0.95 to 1.86) Age 75+ years 1 1.07 (0.64 to 1.78) 2-3 0.72 (0.45 to 1.16) 4+ 1.03 (0.70 to 1.51) DORN[27 ]3 Age 55-64 < 5 0.64 (0.15 to 2.69) 0.84 (0.70 to 1.01) None 5+ 3.74 (1.53 to 9.10) 0.98 (0.78 to 1.24) Age 65-74 < 5 1.32 (0.65 to 2.69) 1.07 (0.94 to 1.23) 5+ 1.83 (0.78 to 4.27) 1.21 (1.02 to 1.45) KAISER[13 ] < 5 1.57 (0.67 to 3.66) 1.30 (0.93 to 1.81) 1.20 (1.03 to 1.40) Age+4 5+ 3.24 (1.01 to 10.40) 2.25 (1.39 to 3.65) 1.56 (1.21 to 2.01) KAUFMAN[33 ] 1-4 0.90 (0.30 to 2.70) Age+5 5+ 1.70 (0.60 to 4.80) NLMS[17 ] < 1 0.74 (0.08 to 7.26) Age+6 1+ 4.18 (2.34 to 7.46) SADOW[30 ]7 1 1.62 None 2 4.51 3 4.38 4+ 2.54