Lay summary by Frank Yeung
Edited by Rona Herzog, Crystal Han
This is a summary of a research study conducted by Lukas Grassner, Jan Schwab, Gale Whiteneck, Fred Geisler, and ICORD researchers Dr. John Kramer, Anh Vo, and Catherine Jutzeler. Read the original article here.
What is albumin?
Albumin is the most abundant protein in blood plasma. The function of albumin is to help transport things found in blood, such as hormones, vitamins and drugs. The other major function of albumin is keeping blood from leaking out of blood vessels. There are some situations where we may have low albumin levels: this is called hypoalbuminemia.
Hypoalbuminemia refers to abnormally low levels of albumin. This can be caused by reduced production of albumin due to liver dysfunction, increased breakdown of albumin following an infection, or leakage of albumin from the blood vessels. It is also a risk factor associated with faster disease progression and worse outcomes in ALS, Guillain-Barré syndrome, and stroke.
How does albumin relate to spinal cord injury?
Spinal cord injury (SCI) results in a lot of trauma and is associated with a high rate of infection. As hypoalbuminemia can occur as a result of increased breakdown after infection, it is common to see hypoalbuminemia following an SCI.
A previous study has demonstrated that hypoalbuminemia predicted poor neurological recovery. This suggests that serum albumin has the potential to act as a predictive molecule, specifically helping us to predict neurological recovery after SCI. Since this finding was based on older data, the current study was done to confirm the results by using newer data that reflects updated medical practices.
What was the purpose of this study?
There were two goals in this study:
- The primary goal: to see if serum albumin levels can help predict neurological recovery after SCI.
- To use contemporary data that reflects more modern methods of SCI management.
How was the research conducted?
The researchers used data from the Spinal Cord Injury Rehabilitation study in 2007 to 2009, which enrolled participants aged ≥12 years, whom all have an SCI and were undergoing rehabilitation at six participating rehabilitation centres in the United States. They had collected data about albumin and neurological outcomes from these participants. By using this more recent data, they addressed their second goal of utilizing contemporary data that reflects how an SCI is managed currently.
The primary analysis looked at the relationship between serum albumin, injury severity, and long-term outcomes. Injury severity of participants were represented numerically: the lower extremity motor scores (LEMS) and the American Spinal Injury Association Impairment Scale (AIS) grades. Both of these represent how much the SCI has impaired the subject’s ability to function.
First, they looked at the relationship between the LEMS and AIS grade and serum albumin concentrations during the subject’s admission into rehabilitation. This helped make sure that injury severity at admission to rehabilitation was associated with serum albumin. For example: if the injury severity is high, low serum albumin levels were expected.
To study neurological recovery, they re-evaluated the LEMS and AIS grade at 1-year post-injury to check for changes in the grades. This analysis helped determine if serum albumin can be used to predict neurological recovery after SCI. Given that serum albumin levels were intended to act as a predictive marker of neurological recovery, it was expected that low serum albumin levels upon admission into rehabilitation predicted poor neurological recovery a year later. Thus, it was expected that there would be little changes to the LEMS and AIS scores one year following injury if participants were admitted into rehabilitation with low serum albumin levels.
What were the results of the study?
The researchers found that lower serum albumin concentrations were associated with more severe injuries at admission to rehabilitation, which matched with previous studies. As a result of an SCI, there would be a high degree of trauma and rates of complications, like infections, in the initial days to weeks. If there is a prolonged infection or severe trauma, hypoalbuminemia could occur, and it would be associated with poor health, which limits the extent of neurological recovery.
The researchers’ primary analysis found that serum albumin concentrations were able to predict neurological recovery. However, its predictive ability regarding neurological recovery did not improve beyond what was already predicted from using the baseline LEMS and AIS grades. Thus, although it was found that low serum albumin concentrations are predictive of poor neurological recovery, it does not prove to be a better predictive tool than the LEMS and AIS grades.
Why are the findings important?
This replicative study has helped confirm the results in previous studies, which have found that albumin concentration is associated with baseline injury characteristics (LEMS and AIS) and long-term neurological recovery after SCI. Since more contemporary data was used, the findings of this paper reflect more modern practices as well.
The researchers believe that serum albumin concentrations provide a rough estimate of injury severity and possible future neurological recovery. Thus, it may only be useful for cases where the injury severity can not be assessed by the LEMS and AIS grades. Along these lines, they believe that there is potential for serum albumin to be applied in the clinic as a predictive molecule, and it could lead to more studies.