Detecting inflammation
In micronutr: Determining Vitamin and Mineral Status of Populations

knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>"
)

library(micronutr)

Inflammation, and its different stages, can be assessed based on the the levels of acute-phase proteins - one of either c-reactive protein (CRP) or α1-acid-glycoprotein (AGP), or both.

Classifying inflammation based on CRP or AGP only

The classification of inflammation status based on either CRP or AGP only is shown in the table below.

Acute-phase Protein | Cut-off Points :--- | :--- CRP | > 5 microgram/L AGP | > 1 g/L

The function detect_inflammation_crp() classifies c-reactive protein levels based on the cut-off point shown above to detect inflammation. For example, if CRP is at 2 microgram/L,

detect_inflammation_crp(crp = 2)

the individual is classified as not having inflammation.

We can also set the function to provide simple integer codes to classify inflammation by setting the label argument to FALSE.

detect_inflammation_crp(crp = 2, label = FALSE)

In this case, an integer code of 0 is provided to indicate a no inflammation status. This would be useful in workflows that require/prefer integer codes for binary classification.

The function detect_inflammation_agp() classifies α1-acid-glycoprotein (AGP) levels based on the cut-off point shown above to detect inflammation. For example, if AGP is at 1.5 g/L,

detect_inflammation_agp(agp = 1.5)

the individual is classified as having inflammation.

We can also set the function to provide simple integer codes to classify inflammation by setting the label argument to FALSE.

detect_inflammation_agp(agp = 1.5, label = FALSE)

In this case, an integer code of 1 is provided to indicate inflammation status. This would be useful in workflows that require/prefer integer codes for binary classification.

These functions are useful for classifying inflammation when data for only one of active-phase proteins is available.

Classifying inflammation based on both CRP and AGP

The detailed classification of inflammation status based on the combination of CRP and AGP is shown in the table below.

The function detect_inflammation() accepts values for both CRP and AGP to classify inflammation status. For example, an individual with CRP of 2 microgram/L and AGP of 1.5 g/L,

detect_inflammation(crp = 2, agp = 1.5)

the individual is classified as being in late convalescence.

We can also set the function to provide simple integer codes to classify inflammation by setting the label argument to FALSE.

detect_inflammation(crp = 2, agp = 1.5, label = FALSE)

In this case, an integer code of 3 is provided to indicate late convalescence status. This would be useful in workflows that require/prefer integer codes for classification.

The detect_inflammation() function can also be used for assessing inflammation status using only one of the active-phase proteins. Using the earlier example of an individual with a CRP of 2 µg/L,

detect_inflammation(crp = 2)

we get the same result as using the detect_inflammation_crp().

References

C-reactive protein concentrations as a marker of inflammation or infection for interpreting biomarkers of micronutrient status. Vitamin and Mineral Nutrition Information System. Geneva: World Health Organization; 2014.