Introduction
Methods
Study selection
Data extraction
Calculation of interaction
Statistical interaction
Biological interaction
Results
Study | Participants | Follow-up (years) | Physical activity | Obesity | Type of stratification | Confounders | Statistical model | Interaction analysis presented | Interaction calculation possible |
---|---|---|---|---|---|---|---|---|---|
Hu 1999 [11]a
| 70,102 Female nurses aged 30–55 years, no diabetes, cardiovascular disease or cancer at baseline | 8 | Self-report five quintiles (MET h−1 week−1) | Two BMI categories | The presentation of individual effects of both exposures and their joint effect, each relative to no exposure | Age, study year, smoking status, alcohol drinking, menopausal status, family history of diabetes, history of high cholesterol, history of hypertension | Pooled logistic regression model | No | Yes |
Hu 2001 [12] | 37,918 Male aged 40–75 years, no diabetes, cardiovascular disease or cancer at baseline | 10 | Self-report five quintiles (MET h−1 week−1) | Three BMI categories | The presentation of individual effects of both exposures and their joint effect, each relative to no exposure | Age, smoking status, family history of diabetes, alcohol intake, vitamin E supplement use | Pooled logistic regression model | No | Yes |
Hu 2001 [17] | 84,941 Female aged 30–55 years, no diabetes, cardiovascular disease and cancer at baseline | 16 | Self-report five quintiles (h week−1) | Three BMI categories | The presentation of effect estimates of exposure and outcome in strata of the suspected effect-modifying exposure | Age, time, family history of diabetes, menopausal status, postmenopausal hormone use | Pooled logistic regression model | No | No |
Hu 2004 [13]b
| 2,017 Finnish men and 2,352 women aged 45–64 years, no diabetes history at baseline | 9.4 | Self-report three categories (low, moderate, high) | Two BMI categories | The presentation of individual effects of both exposures and their joint effect, each relative to no exposure | Age, sex, study year, blood pressure, BMI, smoking status, education | Cox proportional hazard model | No | Yes |
Kriska 2003 [14] | 1,728 Nondiabetic Pima individuals aged 15–59 years at baseline | 6 | Self-report two categories (MET h−1 week−1) | Three BMI categories | The presentation of individual effects of both exposures and their joint effect, each relative to no exposure | Age | Cox proportional hazard model | Yes | No |
Meisinger 2005 [18] | 4,069 Men and 4,034 women aged 25–74 years, no diabetes at base line | 7.4 | Self-report three categories (moderate to high activity, low activity, inactivity | Two BMI categories | The presentation of effect estimates of exposure and outcome in strata of the suspected effect-modifying exposure | Age, study year, hypertension, deslipdaemia, parental history of diabetes, smoking, alcohol drinking, education | Cox proportional hazard model | No | No |
Weinstein 2004 [16]c
| 37,878 US female health care professional aged ≥45 years, free of cardiovascular disease, cancer and diabetes at baseline | 6.9 | Self-report two categories (active, inactive) | Three BMI categories | The presentation of individual effects of both exposures and their joint effect, each relative to no exposure | Age | Cox proportional hazard model | Yes | Yes |
Rana 2007 [15] | 68, 907 America female nurses aged 30–55 years, no diabetes, cardiovascular disease and cancer at baseline | 16 | Self-report five quintiles (MET h−1 week−1) | Three BMI categories | The presentation of individual effects of both exposures and their joint effect, each relative to no exposure | Age, smoking status, alcohol drinking, menopausal status, postmenopausal hormone use, family history of diabetes | Cox proportional hazard model | Yes | Yes |
Study | Relative risk joint effect | Relative risk individual effect obesity | Relative risk individual effect physical inactivity | INT
M
b
| RERIc
| AP (%) |
---|---|---|---|---|---|---|
1. Hu et al. [13]a
| 9.86 | 4.10 | 2.18 | 1.10 | 4.58 | 46.4 |
2. Hu et al. [12]a
| 9.87 | 5.62 | 1.12 | 1.56 | 4.12 | 41.7 |
3. Rana et al. [15] | 16.75 (13.99–20.04) | 10.74 (8.74–13.18) | 2.08 (1.66–2.61) | 0.75 | 4.93 | 29.4 |
4. Hu et al. [11]a
| 12.50 | 8.75 | 2.00 | 0.71 | 2.75 | 22.0 |
5. Weinstein et al. [16] | 18.6 (13.9–24.8) | 17.5 (12.9–23.9) | 1.25 (0.91–1.72) | 0.85 | 0.85 | 4.6 |