BioMed Research International / 2017 / Article / Tab 2

Review Article

Long-Term Sleep Duration as a Risk Factor for Breast Cancer: Evidence from a Systematic Review and Dose-Response Meta-Analysis

Table 2

The outcome and related information included in this meta-analysis.

AuthorYearData collectionBreast cancer ascertainmentSleep duration (h/d) and risk (95% CI)Adjusted variableQuality assessment

Xiao et al. [9]2016QuestionnaireState cancer registries; pathology reports;
medical records
<6: 1.09 (0.83–1.44)
6: 1.01 (0.78–1.30)
7: 1.19 (0.92–1.53)
8: reference
≥9: 1.07 (0.80–1.43)
Age, enrollment year, enrollment state, race, education, income, marital status, BMI, physical activity, overall sitting, smoking, pack-year, number of live birth, age at first birth, length of breastfeeding, age at menarche, menopause status, hormone therapy, multivitamin, aspirin, diabetes, family history of cancer, alcohol consumption, and dietary intakes of total fat, fiber, folate and total calories8

Hurley et al. [10]2015QuestionnaireCalifornia cancer registry3–6: 0.97 (0.91–1.04)
7–9: reference
≥10: 1.13 (0.86–1.50)
Race/ethnicity, alcohol consumption, menopausal status, hormone therapy use6

Wang et al. [11]2014Face-to-face interviewMedical records≤6: 1.62 (1.18–2.21)
6.1–8.9: reference
≥9: 1.58 (1.18–2.12)
Age, education, BMI, age at menarche, menopausal status, parity, physical activity, breastfeeding, family history of breast cancer, other sleep factors7

Vogtmann et al. [12]2013InterviewPathology reports; medical records≤5: 0.89 (0.80–1.00)
6: 0.92 (0.85–0.98)
7: reference
8: 1.00 (0.93–1.07)
≥9: 1.05 (0.92–1.20)
Age, clinical trial arm assignment, number of live births, age at menarche, age at menopause, BMI, energy expenditure, education, income, race/ethnicity, marital status, age at first birth, use of hormone therapy, history of benign breast disease, family history of breast cancer, alcohol consumption, smoking status8

Wu et al. [13]2012In-person interviewNational cancer registry≤6: reference
7: 1.00 (0.84–1.19)
8: 1.00 (0.84–1.21)
≥9: 0.89 (0.64–1.22)
Age, year, dialect group, education, parity, BMI, menopausal status8

Girschik et al. [14]2012Self-administered postal questionnaireWestern Australian cancer registry<6: 1.04 (0.83–1.32)
6-7: 0.95 (0.79–1.14)
7-8: reference
>8: 1.05 (0.83–1.33)
Age, number of children, age at first birth, breastfeeding, menopausal status, use and duration of hormone therapy, alcohol consumption, comparative weight at the age of 30 years, melatonin, physical activity8

Kakizaki et al. [15]2008QuestionnaireMiyagi prefectural cancer registry≤6: 1.67 (1.002–2.78)
7: reference
8: 0.99 (0.59–1.65)
≥9: 0.29 (0.09–0.98)
Age, BMI, history of disease, family history of cancer, marital status, education, alcohol consumption, time spent walking, caloric intake, menopausal status, age at menarche, age at first delivery, number of deliveries, oral contraceptive drugs, hormone drug8

Pinheiro et al. [16]2006Mailed questionnaireBlinded medical chart review≤5: 0.93 (0.79–1.09)
6: 0.98 (0.91–1.06)
7: reference
8: 1.05 (0.97–1.13)
≥9: 0.95 (0.82–1.11)
Age, BMI, height, history of benign breast disease, family history of breast cancer, parity and age at first birth, age at menarche, postmenopausal hormone use, physical activity, alcohol, caloric intake, smoking7

McElroy et al. [17]2005Telephone interviewsState cancer registries<5: 0.94 (0.62–1.44)
5–5.9: 0.82 (0.65–1.05)
6–6.9: 0.89 (0.79–1.01)
7–7.9: reference
8–8.9: 1.01 (0.91–1.11)
≥9: 1.01 (0.84–1.23)
Age, state, parity, age at first full-term pregnancy, family history of breast cancer, alcohol consumption, BMI, menopause status, age at menopause, postmenopausal hormone use, marital status8

Verkasalo et al. [18]2005QuestionnairesFinnish cancer registries≤4: 0.88 (0.11–6.91)
5: 0.91 (0.36–2.32)
6: 0.74 (0.44–1.27)
7: 0.81 (0.60–1.10)
8: reference
9: 0.64 (0.40–1.02)
≥10: 0.65 (0.24–1.75)
Age, zygosity, social class, number of children, use of oral contraceptives, BMI, alcohol use, smoking, physical activity8

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