Table 1.
Characteristics of cohort studies included in the meta-analysis
| References | Study period | Study population | Exposure | Relative riska (95% CI) | Adjustment | ||||
|---|---|---|---|---|---|---|---|---|---|
| Setting | Number of nonsmoking subjects | Event | Number of incident cases or deaths | Place/Source | Category | ||||
| Hirayama (25) | 1966–81 | Population-based, 29 public health center areas in 6 prefectures | 91 540 women | Death | 200 | Husband's smoking habit | Current, overall | 1.45 (0.98–2.15) | Husband's age |
| 1–14/day | 1.42 (0.94–2.14) | ||||||||
| 20+/day | 1.91 (1.29–2.91) | ||||||||
| Nishino (31) | 1984–92 | Population-based, a city and two towns in Miyagi Prefecture | 9675 women | Incidence | 24 | Household members’ smoking habit | Husband (+) | 1.80 (0.69–4.72) | Age, study area, alcohol, green and yellow vegetable intake, fruit intake, meat intake, past history of lung diseases |
| Ozasa (32) | 1988–90 | Population-based, 45 cities, towns, or villages in 18 prefectures | 420 201; women (person year) | Death | 109 | Home | Almost everyday | 1.06 (0.68–1.65) | Age, study area |
| Sometimes, 1–4/week | 0.84 (0.49–1.45) | ||||||||
| 3 hours or longer day | 1.12 (0.55–2.28) | ||||||||
| 67 997; men (person year) | Death | 24 | Home | Almost everyday | 0.45 (0.09–2.23) | Age, study area | |||
| Sometimes, 1–4/week | 1.48 (0.57–3.84) | ||||||||
| 3 hours or longer day | 5.29(1.03–27.18) | ||||||||
| Kurahashi (30) | 1990–2004 | Population-based, 5 public health center areas (Cohort I), and 6 public health center areas (Cohort II) | 28 414 women | Incidence | 109 | Husband's smoking habit | Current | 1.34 (0.81–2.21) | Age, study area, menopause, alcohol, family history of lung cancer |
CI, confidence interval.
aThe standard error and 95% CI were re-calculated from the reported relative risk and CI. Therefore, 95% CIs in this table do not always correspond to the CIs reported in each study.