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I am somewhat confused about lifetime risk. The National Kidney Federation released data saying that the lifetime risk of a white American male needing dialysis was around 3%. However, considerably less than 1% of the population actually are on dialysis... why the discrepancy? Why aren't 3% of American males on dialysis if the lifetime risk is 3%?

Nick Cox
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arif khwaja
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    It's unclear what you are seeking here. If you have a specific question about facts on dialysis, this isn't the forum. If you have a conceptual question about "lifetime risk", please spell it out. Meanwhile consider that people's lifetime risk of contracting a fatal condition is 100%, but that doesn't mean that everyone is just about to die. Similarly, you or I may be in the 3% who need dialysis in their lifetimes, but that doesn't necessarily mean right now. In this particular case, there may also be limits on the availability of dialysis facilities. – Nick Cox Aug 04 '13 at 10:44
  • Thanks... The question I'm asking is does the lifetime risk of a disease have any bearing on the cross sectional prevalence of a disease or the annual incidence of the disease? Nothing to do with kidneys just a general question – arif khwaja Aug 04 '13 at 19:06

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You cannot expect the actual prevalence of dialysis to be 3% now based on the lifetime risk of dialysis being 3% unless the lifetime risk of needing dialysis were consistently at 3% for a time period covering the lives to date of everyone alive now. If lifetime risk level was lower in the past (a reasonable guess if the risk is related to age and life expectancy has been going up), that would be reflected in a lower proportion of people on dialysis now.

It would also only follow if dialysis or conditions surrounding it were not linked to lifespan (since otherwise membership of the group needing dialysis would fall away from the population more quickly or more slowly and be underrepresented or overrepresented). Even if the first condition (3% lifetime risk level for decades and decades) were true, if this second condition were not true, and instead dialysis were linked with lower lifespan, this would also result in a lower proportion of people on dialysis now.

A.M.
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