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Understanding variation in disease risk: the elusive concept of frailty.

Aalen OO, Valberg M, Grotmol T, Tretli S - Int J Epidemiol (2014)

Bottom Line: Heterogeneity often manifests itself as clustering of cases in families more than would be expected by chance.We emphasize that apparently moderate familial relative risks can only be explained by strong underlying variation in disease risk between families and individuals.Finally, we highlight the potential impact of frailty variation in the interpretation of standard epidemiological measures such as hazard and incidence rates.

View Article: PubMed Central - PubMed

Affiliation: Oslo Centre for Biostatistics and Epidemiology, Department of Biostatistics, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway and Cancer Registry of Norway, Institute of Population-Based Cancer Research, Oslo, Norway o.o.aalen@medisin.uio.no.

No MeSH data available.


Various types of possible distributions of the frailty (unexplained risk), , at an early age. The panels illustrate: (1) small variation in frailty between individuals, (2) large group have moderate frailty, and a smaller group of individuals have a high frailty, (3) very skewed: many individuals have a low frailty and a small group have a high frailty, (4) most individuals have close to zero frailty and a few individuals have a high frailty.
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dyu192-F2: Various types of possible distributions of the frailty (unexplained risk), , at an early age. The panels illustrate: (1) small variation in frailty between individuals, (2) large group have moderate frailty, and a smaller group of individuals have a high frailty, (3) very skewed: many individuals have a low frailty and a small group have a high frailty, (4) most individuals have close to zero frailty and a few individuals have a high frailty.

Mentions: Figure 2 illustrates various ways in which frailty, , can be distributed between individuals. Panel 1 indicates a frailty that is quite similar across individuals, with some variation. Panel 2 shows a situation where most individuals have a relatively similar frailty, but there are some individuals who deviate quite a lot (the upper tail). This is expressed even more clearly in panel 3, where many individuals have a frailty close to zero whereas there are a number of individuals with high frailty. An even stronger variation is illustrated in panel 4, where most individuals have frailty close to zero but some individuals have a very high frailty. All these types of variation could actually occur. The examples given in this paper show that even the types of variation shown in panels 3 and 4 could be common. However, another issue is how frailty develops over time. One view is that there is a rather small variation in frailty at an early age, which increases over time as the result of the varying stresses of life. An alternative view argues that much of the variation in frailty between individuals is determined very early in life, maybe even prior to birth.Figure 2.


Understanding variation in disease risk: the elusive concept of frailty.

Aalen OO, Valberg M, Grotmol T, Tretli S - Int J Epidemiol (2014)

Various types of possible distributions of the frailty (unexplained risk), , at an early age. The panels illustrate: (1) small variation in frailty between individuals, (2) large group have moderate frailty, and a smaller group of individuals have a high frailty, (3) very skewed: many individuals have a low frailty and a small group have a high frailty, (4) most individuals have close to zero frailty and a few individuals have a high frailty.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License
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getmorefigures.php?uid=PMC4588855&req=5

dyu192-F2: Various types of possible distributions of the frailty (unexplained risk), , at an early age. The panels illustrate: (1) small variation in frailty between individuals, (2) large group have moderate frailty, and a smaller group of individuals have a high frailty, (3) very skewed: many individuals have a low frailty and a small group have a high frailty, (4) most individuals have close to zero frailty and a few individuals have a high frailty.
Mentions: Figure 2 illustrates various ways in which frailty, , can be distributed between individuals. Panel 1 indicates a frailty that is quite similar across individuals, with some variation. Panel 2 shows a situation where most individuals have a relatively similar frailty, but there are some individuals who deviate quite a lot (the upper tail). This is expressed even more clearly in panel 3, where many individuals have a frailty close to zero whereas there are a number of individuals with high frailty. An even stronger variation is illustrated in panel 4, where most individuals have frailty close to zero but some individuals have a very high frailty. All these types of variation could actually occur. The examples given in this paper show that even the types of variation shown in panels 3 and 4 could be common. However, another issue is how frailty develops over time. One view is that there is a rather small variation in frailty at an early age, which increases over time as the result of the varying stresses of life. An alternative view argues that much of the variation in frailty between individuals is determined very early in life, maybe even prior to birth.Figure 2.

Bottom Line: Heterogeneity often manifests itself as clustering of cases in families more than would be expected by chance.We emphasize that apparently moderate familial relative risks can only be explained by strong underlying variation in disease risk between families and individuals.Finally, we highlight the potential impact of frailty variation in the interpretation of standard epidemiological measures such as hazard and incidence rates.

View Article: PubMed Central - PubMed

Affiliation: Oslo Centre for Biostatistics and Epidemiology, Department of Biostatistics, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway and Cancer Registry of Norway, Institute of Population-Based Cancer Research, Oslo, Norway o.o.aalen@medisin.uio.no.

No MeSH data available.