9 The evidence
The evidence statements from 3 reviews are provided by Cambridge Institute of Public Health. The summary points are from review 4 that was done in‑house by NICE.
This section lists how the evidence statements and expert papers link to the recommendations and sets out a brief summary of findings from the economic analysis.
The evidence statements are short summaries of evidence, in a review, report or paper (provided by an expert in the topic area). Each statement has a short code indicating which document the evidence has come from.
Evidence statement number 1.3.1PA indicates that the linked statement is numbered 3.1 in review 1; the letters refer to the risk factors: PA for physical activity; DI for diet; SM for smoking, AL for alcohol; EC for Eye Care; H for health prevention interventions (in general). SP5 indicates that summary point 5 in review 4 is linked to a recommendation. EP7 indicates that expert paper 7 is linked to a recommendation.
Where a recommendation is not directly taken from the evidence statements, but is inferred from the evidence, this is indicated by IDE (inference derived from the evidence).
Recommendation 1: EP1, 2, 3, 5, 6; IDE
Recommendation 2: evidence statements EP1, 5, 9; IDE
Recommendation 3: evidence statements 1.2.2PA, 1.2.3PA, 1.2.4PA, 1.2.5PA, 1.2.10PA, 3.3.5PA; EP 1, 2, 3, 5, 9; SP12: IDE
Recommendation 4: evidence statements 1.2.2PA, 1.2.3PA, 1.2.4PA, 1.2.5PA, 1.2.10PA, 2.3.3PA, 2.3.2PA, 2.3.3PA, 2.3.4PA, 2.3.5PA, 2.5.1DI, 2.6.1SM, 2.6.3SM, 2.6.4SM, 2.6.5SM, 2.6.6SM, 2.6.7SM, 2.7.2AL, 2.9.3LC, 3.3.1PA, 3.3.3PA, 3.3.5PA,3.3.7PA, 3.3.8PA, 3.5.1SM, 3.5.2SM, 3.9.1DM, 3.9.2DM; SP12; EP2, 3, 5, 9
Recommendation 5: evidence statements 1.2.1SM, 1.3.1SM, 1.4.1SM, 1.5.1SM, 1.5.2SM, 1.5.3SM, 2.6.1SM, 2.6.3SM, 2.6.4SM, 2.6.5SM, 2.6.6SM, 2.6.7SM; EP 1, 3, 5
Recommendation 6: evidence statements 1.4.1PA, 1.4.3PA, 1.7.8PA, 1.7.15PA, 2.3.2PA, 2.3.3PA, 2.3.4PA, 2.3.5PA, 2.3.6PA, 3.3.2PA; EP9
Recommendation 7: evidence statements 1.3.1AL, 1.3.2AL, ; EP2; IDE
Recommendation 8: evidence statements 1.3.1DI, 1.3.5DI, 1.3.9DI 1.5.1DI, 1.5.2DI, 1.5.4DI, 1.7.1DI, 18.104.22.168DI; EP5, 9
Recommendation 9: SP1; EP8; IDE
Recommendation 10: evidence statements 1.5.4PA, 1.5.5PA, 3.3.3PA, 3.6.1AL, 3.9.1DM, 3.9.2DM, 3.9.3DM, 3.9.4DM: SP1, 2, 3, 4, 5, 6, 7, 8, 9
Recommendation 11: evidence statements SP3, 4, 5, 6, 7, 8, 9, 10, 11
Recommendation 12: evidence statements 3.3.1PA, 3.3.3PA, 3.3.7PA, 3.3.8PA, 3.9.1DM, 3.9.2DM; SP1, 10, 11
Recommendation 13: SP1
Recommendation 14: evidence statements EP5; IDE
Recommendation 15: evidence statements 1.2.10PA, 1.3.1PA, 3.3.2PA; SP10; IDE
Expert papers 1–10. See what evidence is the guideline based on?
The model was exploratory in nature and as such did not report a single estimate of cost‑effectiveness but presented a series of threshold analyses to see the conditions under which cost‑effectiveness can be achieved.
Overall, the model found that population‑level and individual-level interventions that aim to increase the physical activity of people in mid‑life have the potential to be highly cost‑effective. Population‑level interventions were found to have a slightly greater potential of being cost‑effective at lower thresholds of willingness to pay than individual‑level interventions when aimed at the general population. However, individual‑level interventions were found to be cost‑effective at acceptable willingness to pay thresholds (below £20,000) when targeted at inactive people under certain assumptions.
The results for both types of intervention were varied extensively in a number of sensitivity and scenario analyses. The most crucial determinant for interventions to be cost‑effective is whether people succeed in maintaining increased levels of physical activity over their lives. The dose‑response relationship between physical activity in mid‑life and risk of developing dementia in later life also influences the cost‑effectiveness.
The specific scenarios considered and the full results can be found in cost-effectiveness of interventions aimed at increasing physical activity to prevent the onset of dementia.