Daily Variations in CD4 Counts
Feb 13, 2005
In your experience do most patients get lab tests at the same time of day each quarter? Do most research subjects get lab tests at the same time of day?
This is important because CD4 counts can vary normally by 200 each day.
Studies don't say what time of day samples were taken. This is potentially a big problem in drawing conclusions.Two studies that that describes patients with a CD4 count averaging 500 may be dealing with very different groups if one study took the majority of samples in the morning (patients might have a range of 500-700)and one took the majority of samples in the afternoon (patients might have a range of 300-500). With a slightly lower average especially this could lead to misleading conclusions, and daily differences could also throw off the results of small studies intended to show a decrease or increase over time.
Shouldn't this information be included in all studies?
Response from Dr. Holodniy
Hard to say what all clinics and trials do. In my experience, people in our clinic and on our clinical trials get their blood work done at pretty much the same time of day over time.
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