Table 1.

PA and all-cause dementia: main results, main sensitivity analyses with meta-regressions and subgroup analyses, and dose–response analysis

	Pooled RR	95% CI	I2 (%)	Studies combined (n)	Beta estimate*	95% CI
All physical activity	0.80	0.77 to 0.84	68.7	49
Baseline age (continuous)					1.00	0.98 to 1.02
Baseline age (categorical)
Age group 30–55 years9 33 35 36 39 40 42 55 61 62 66 73 77 80	0.79	0.71 to 0.87	42.9	14
Age group 55–69 years44 45 57 58 81 83	0.82	0.74 to 0.90	70.8	6
Age group ≥70 years11 32 34 37 38 41 43 46–54 56 59 60 63–65 72 74–76 79 82	0.80	0.75 to 0.85	70.4	29
Follow-up length (continuous)					1.00	0.97 to 1.03
Follow-up length (categorical)
Follow-up length <5 years38 43 46 51 52 54 63 75 78 79	0.61	0.50 to 0.74	64.8	10
Follow-up length 5–20 years9 11 32 34 37 41 44 45 47–50 56–59 64 65 72 74 76 81–83	0.86	0.82 to 0.90	64.2	24
Follow-up length ≥20 years9 33 35 36 39 40 42 53 55 60–62 66 73 77 80	0.79	0.71 to 0.87	44.8	16
Study quality (high vs moderate vs low)†					0.99	0.64 to 1.53
Low quality9 11 32 34 35 38 41 43–47 49–51 56–58 60 62–66 72 74–76 78 79 81 83	0.81	0.77 to 0.85	75.5	32
Moderate quality9 33 36 37 39 42 48 52–54 59 73 77 80 82	0.79	0.72 to 0.86	28.4	15
High quality9 40 55 61	0.82	0.67 to 0.99	58.9	4
Meeting PA guidelines‡ 11 33 36 38 43 44 48 53–55 59–61 63 65 72 73 76 80 83	0.82	0.76 to 0.87	22.0	20
Not meeting PA guidelines‡ 9 11 32 33 36 38 44 45 47–49 51 57 58 61 62 65 66 72–75 77–79 83	0.76	0.69 to 0.83	60.8	25
Highest quality studies only: age group 30–55 years, follow-up length >20 years and high quality40 55 61	0.79	0.62 to 1.01	67.4	3

*Beta estimate is the regression coefficient from the meta-regression examining the relationship of modifier or continuous PA on the log risk ratio of dementia.

†Study quality was assessed with a quality assessment tool we developed (see online supplemental material part 1 for details).

‡The test for heterogeneity between groups was non-significant (p=0.202).

I², heterogeneity; PA, physical activity; RR, relative risk.