Microlife

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Graphic representation of microlives Microlife effort.png
Graphic representation of microlives

A microlife is a unit of risk representing half an hour change of life expectancy. [1]

Contents

Discussed by David Spiegelhalter and Alejandro Leiva, and also used by Lin et al. [2] for decision analysis, microlives are intended as a simple way of communicating the impact of a lifestyle or environmental risk factor, based on the associated daily proportional effect on expected length of life. Similar to the micromort (one in a million probability of death) the microlife is intended for "rough but fair comparisons between the sizes of chronic risks". [1] This is to avoid the biasing effects of describing risks in relative hazard ratios, converting them into somewhat tangible units. Similarly they bring long-term future risks into the here-and-now as a gain or loss of time.

"A daily loss or gain of 30 minutes can be termed a microlife, because 1 000 000 half hours (57 years) roughly corresponds to a lifetime of adult exposure." [1]

The microlife exploits the fact that for small hazard ratios the change in life expectancy is roughly linear. [3] They are by necessity rough estimates, based on averages over population and lifetime. Effects of individual variability, short-term or changing habits, and causal factors are not taken into account.[ citation needed ]

Examples

Microlives gained/lost per day of exposure, based on estimated life expectancy effects of long term lifestyle and demographic risk factors, for men and women aged 35 years. [1]
Risk factorMenWomen
Smoking
Smoking 15–24 cigarettes−10−9
Alcohol intake
First drink (of 10 g alcohol)11
Each subsequent drink (up to 6)−½−1
Obesity
Per 5 units above body mass index of 22.5 each day−3−3
Per 5 kg above optimum weight for average height each day−1−1
Sedentary behaviour
2 hours watching television−1−1
Diet
Red meat, 1 portion (85 g, 3 oz)−1−1
Fruit and vegetable intake, =5 servings (blood vitamin C >50 nmol/L)43
Coffee intake
2-3 cups11
Physical activity
First 20 minutes of moderate exercise 22
Subsequent 40 minutes of moderate exercise1½
Statins
Taking a statin 11
Air pollution
Per day living in Mexico City v London −½−½
Geography
Per day being a resident of Russia v Sweden−21−9
Era
Per day living in 2010 v 19101515
Per day living in 2010 v 198085

See also

References

  1. 1 2 3 4 Spiegelhalter, D. (2012-12-14). "Using speed of ageing and "microlives" to communicate the effects of lifetime habits and environment" (PDF). BMJ. 345 (dec14 14): e8223. doi:10.1136/bmj.e8223. ISSN   1756-1833. PMID   23247978. S2CID   27745393.
  2. ↑ Lin, Chia-Yu, Gelman, Andrew, Price, Phillip N., and Krantz, David H. (1999). "Analysis of Local Decisions Using Hierarchical Modeling, Applied to Home Radon Measurement and Remediation" (PDF). Statistical Science. 14: 305–337.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  3. ↑ Haybittle, J. (1998-10-01). "The use of the Gompertz function to relate changes in life expectancy to the standardized mortality ratio". International Journal of Epidemiology. 27 (5). Oxford University Press (OUP): 885–889. doi: 10.1093/ije/27.5.885 . ISSN   1464-3685. PMID   9839748.

Further reading

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