Table 1.
Subgroup analyses for the association between BMI and lung cancer risk in never smokers
| Categories | Subgroups | Number of studies | RR (95% CI) | P value | Heterogeneity | P-interaction | ||
|---|---|---|---|---|---|---|---|---|
| chi-squared | I 2 | P-heterogeneity | ||||||
| Obesity | 18 | 0.78(0.65–0.94) | 0.01 | 37.23 | 54.30% | < 0.01 | ||
| Design | Cohort | 14 | 0.74(0.60–0.91) | < 0.01 | 27.83 | 53.30% | 0.01 | 0.32 |
| Case-control | 4 | 0.97(0.58–1.62) | 0.90 | 8.75 | 65.70% | 0.03 | ||
| Outcome | Incidence | 15 | 0.79(0.63–0.99) | 0.04 | 30.83 | 54.60% | < 0.01 | 0.74 |
| Mortality | 3 | 0.71(0.45–1.12) | 0.14 | 6.40 | 68.70% | 0.04 | ||
| Gender | Male | 5 | 0.69(0.41–1.15) | 0.16 | 16.58 | 69.80% | < 0.01 | 0.81 |
| Female | 8 | 0.86(0.72–1.02) | 0.08 | 7.49 | 19.90% | 0.28 | ||
| Ethnicity | Non-Asian | 13 | 0.82(0.64–1.04) | 0.10 | 27.92 | 57.00% | < 0.01 | 0.51 |
| Asian | 5 | 0.70(0.54–0.91) | < 0.01 | 5.56 | 28.00% | 0.24 | ||
| Quality | High | 12 | 0.76(0.61–0.94) | 0.01 | 27.5 | 60.00% | 0.004 | 0.72 |
| Low | 6 | 0.84(0.55–1.29) | 0.43 | 9.72 | 48.60% | 0.08 | ||
| Diagnosis | Registry | 10 | 0.77(0.59–1.00) | 0.05 | 22.28 | 59.60% | < 0.01 | 0.89 |
| Pathology | 8 | 0.79(0.59–1.06) | 0.11 | 14.16 | 50.60% | 0.05 | ||
| Adjustment for confounders | ||||||||
| Alcohol intake | Yes | 11 | 0.83(0.68–1.02) | 0.07 | 18.98 | 47.30% | 0.04 | 0.49 |
| No | 7 | 0.68(0.45–1.04) | 0.07 | 16.25 | 63.10% | 0.01 | ||
| Vegetable/fruit intake | Yes | 6 | 0.81(0.58–1.13) | 0.22 | 12.80 | 60.90% | 0.02 | 0.80 |
| No | 12 | 0.76(0.59–0.97) | 0.03 | 23.41 | 53.00% | 0.02 | ||
| Physical activity | Yes | 9 | 0.91(0.75–1.11) | 0.34 | 12.18 | 34.30% | 0.14 | 0.19 |
| No | 9 | 0.67(0.49–0.93) | 0.02 | 18.15 | 55.90% | 0.02 | ||
| Medical historya | Yes | 3 | 0.78(0.58–0.95) | 0.24 | 35.80 | 60.90% | < 0.01 | 0.61 |
| No | 15 | 0.90(0.76–1.07) | 0.02 | 0.78 | 0.00% | 0.68 | ||
| Overweight | 15 | 0.76(0.65–0.87) | < 0.01 | 28.37 | 50.60% | 0.01 | ||
| Design | Cohort | 12 | 0.74(0.62–0.88) | < 0.01 | 27.30 | 59.70% | < 0.01 | 0.78 |
| Case-control | 3 | 0.80(0.63–1.02) | 0.08 | 1.03 | 0.00% | 0.60 | ||
| Outcome | Incidence | 12 | 0.76(0.64–0.90) | < 0.01 | 16.92 | 35.00% | 0.11 | 0.93 |
| Mortality | 3 | 0.73(0.53–1.01) | 0.06 | 10.51 | 81.00% | < 0.01 | ||
| Gender | Male | 5 | 0.92(0.62–1.36) | 0.68 | 14.38 | 72.20% | < 0.01 | 0.44 |
| Female | 8 | 0.82(0.72–0.93) | < 0.01 | 6.52 | 0.00% | 0.48 | ||
| Ethnicity | Non-Asian | 11 | 0.87(0.78–0.97) | < 0.01 | 10.34 | 3.30% | 0.41 | 0.09 |
| Asian | 4 | 0.61(0.44–0.86) | < 0.01 | 10.87 | 72.40% | 0.01 | ||
| Quality | High | 10 | 0.85(0.77–0.94) | < 0.01 | 9.47 | 4.90% | 0.40 | 0.32 |
| Low | 5 | 0.70(0.46–1.06) | 0.09 | 13.76 | 70.90% | < 0.01 | ||
| Diagnosis | Registry | 8 | 0.82(0.68–0.98) | 0.03 | 14.38 | 51.30% | 0.04 | 0.25 |
| Pathology | 7 | 0.68(0.55–0.84) | < 0.01 | 8.74 | 31.40% | 0.19 | ||
| Adjustment for confounders | ||||||||
| Alcohol intake | Yes | 11 | 0.79(0.68–0.92) | < 0.01 | 18.32 | 45.40% | 0.05 | 0.37 |
| No | 4 | 0.67(0.46–0.97) | 0.03 | 6.36 | 52.80% | 0.10 | ||
| Vegetable/fruit intake | Yes | 5 | 0.89(0.79–0.99) | 0.03 | 1.46 | 0.00% | 0.83 | 0.15 |
| No | 10 | 0.68(0.54–0.85) | < 0.01 | 22.26 | 50.60% | < 0.01 | ||
| Physical activity | Yes | 9 | 0.87(0.77–0.97) | 0.02 | 8.86 | 9.70% | 0.35 | 0.14 |
| No | 6 | 0.66(0.49–0.88) | < 0.01 | 12.85 | 61.10% | 0.02 | ||
| Medical historya | Yes | 3 | 0.89(0.79–1.00) | 0.05 | 24.35 | 0.00% | 0.66 | 0.42 |
| No | 12 | 0.72(0.60–0.87) | < 0.01 | 0.84 | 50.60% | 0.01 | ||
| Excess weight | 23 | 0.77(0.68–0.88) | < 0.01 | 58.46 | 62.40% | < 0.01 | ||
| Design | Cohort | 16 | 0.80(0.69–0.94) | < 0.01 | 40.07 | 62.60% | < 0.01 | 0.47 |
| Case-control | 7 | 0.71(0.56–0.91) | < 0.01 | 13.78 | 56.50% | 0.03 | ||
| Outcome | Incidence | 19 | 0.75(0.64–0.88) | < 0.01 | 38.12 | 52.80% | < 0.01 | 0.60 |
| Mortality | 4 | 0.83(0.63–1.10) | 0.19 | 16.73 | 82.10% | < 0.01 | ||
| Gender | Male | 8 | 0.88(0.70–1.11) | 0.29 | 17.94 | 55.40% | 0.02 | 0.85 |
| Female | 12 | 0.75(0.62–0.91) | < 0.01 | 28.89 | 61.90% | < 0.01 | ||
| Ethnicity | Non-Asian | 14 | 0.80(0.68–0.95) | < 0.01 | 28.25 | 54.00% | < 0.01 | 0.66 |
| Asian | 9 | 0.74(0.59–0.94) | 0.01 | 26.05 | 69.30% | < 0.01 | ||
| Quality | High | 16 | 0.83(0.73–0.95) | < 0.01 | 30.06 | 50.10% | 0.01 | 0.18 |
| Low | 7 | 0.68(0.50–0.90) | < 0.01 | 17.7 | 66.10% | < 0.01 | ||
| Diagnosis | Registry | 11 | 0.88(0.75–1.05) | 0.15 | 24.27 | 58.80% | < 0.01 | 0.06 |
| Pathology | 12 | 0.68(0.57–0.81) | < 0.01 | 19.97 | 44.90% | 0.05 | ||
| Adjustment for confounders | ||||||||
| Alcohol intake | Yes | 12 | 0.83(0.71–0.97) | 0.02 | 26.74 | 58.90% | 0.01 | 0.31 |
| No | 11 | 0.71(0.57–0.89) | < 0.01 | 22.73 | 56.00% | < 0.01 | ||
| Vegetable/fruit intake | Yes | 7 | 0.85(0.69–1.05) | 0.13 | 17.29 | 57.10% | < 0.01 | 0.37 |
| No | 16 | 0.73(0.62–0.87) | < 0.01 | 34.93 | 65.30% | < 0.01 | ||
| Physical activity | Yes | 9 | 0.87(0.77–0.99) | 0.04 | 10.14 | 21.10% | 0.26 | 0.52 |
| No | 14 | 0.75(0.61–0.92) | < 0.01 | 41.15 | 68.40% | < 0.01 | ||
| Medical historya | Yes | 7 | 0.84(0.68–1.04) | 0.11 | 13.32 | 55.00% | 0.04 | 0.52 |
| No | 16 | 0.75(0.63–0.89) | < 0.01 | 40.57 | 63.00% | < 0.01 | ||
| BMI increase per 5 Kg/m2 | 28 | 0.89(0.84–0.95) | < 0.01 | 86.44 | 68.80% | < 0.01 | ||
| Design | Cohort | 20 | 0.89(0.82–0.96) | < 0.01 | 58.12 | 67.30% | < 0.01 | 0.88 |
| Case-control | 8 | 0.90(0.79–1.03) | 0.13 | 24.77 | 71.70% | 0.01 | ||
| Outcome | Incidence | 23 | 0.89(0.83–0.96) | < 0.01 | 65.3 | 66.30% | < 0.01 | 0.98 |
| Mortality | 5 | 0.89(0.76–1.04) | 0.16 | 20.98 | 80.90% | < 0.01 | ||
| Gender | Male | 12 | 0.96(0.83–1.11) | 0.60 | 28.43 | 61.30% | < 0.01 | 0.42 |
| Female | 13 | 0.89(0.81–0.97) | < 0.01 | 34.74 | 65.50% | < 0.01 | ||
| Ethnicity | Non-Asian | 18 | 0.91(0.84–0.98) | 0.01 | 47.23 | 64.00% | < 0.01 | 0.66 |
| Asian | 10 | 0.88(0.78–0.98) | 0.03 | 33.12 | 72.80% | < 0.01 | ||
| Quality | High | 20 | 0.91(0.86–0.98) | < 0.01 | 51.74 | 63.30% | < 0.01 | 0.39 |
| Low | 8 | 0.85(0.72–1.00) | 0.05 | 26.41 | 73.50% | < 0.01 | ||
| Diagnosis | Registry | 15 | 0.93(0.86–1.00) | 0.06 | 42.41 | 67.00% | < 0.01 | 0.35 |
| Pathology | 13 | 0.86(0.78–0.95) | < 0.01 | 32.26 | 62.80% | < 0.01 | ||
| Adjustment for confounders | ||||||||
| Alcohol intake | Yes | 15 | 0.89(0.83–0.95) | < 0.01 | 36.97 | 62.10% | < 0.01 | 0.60 |
| No | 13 | 0.92(0.79–1.07) | 0.28 | 48.42 | 75.20% | < 0.01 | ||
| Vegetable/fruit intake | Yes | 7 | 0.93(0.84–1.02) | 0.13 | 12.57 | 52.3% | 0.05 | 0.77 |
| No | 21 | 0.89(0.82–0.96) | < 0.01 | 72.90 | 72.6% | < 0.01 | ||
| Physical activity | Yes | 10 | 0.92(0.86–0.98) | < 0.01 | 11.33 | 20.60% | 0.25 | 0.96 |
| No | 18 | 0.90(0.81–0.99) | < 0.01 | 86.44 | 77.3% | < 0.01 | ||
| Medical historya | Yes | 11 | 0.90(0.83–0.97) | < 0.01 | 29.05 | 65.60% | < 0.01 | 0.84 |
| No | 17 | 0.88(0.80–0.98) | 0.02 | 56.45 | 71.70% | < 0.01 | ||
Note: In the subgroup analyses, amedical history included history of chronic lung disease, history of family lung cancer, diabetes status, and hormone treatment. Other confounders such as total energy intake, environmental status and concomitant medication (use of aspirin and metformin) were not common in original studies; thus, subgroup analyses stratified by them were not performed