The International Contact Dermatitis Research Group patch test scoring system (ICDRG score) is a method used to evaluate the severity of dermatitis based on visible skin changes. This assessment hinges on the morphology of the skin reaction and translates into an interpretative result explaining the type of dermatological reaction.

Here's how the interpretation works:

- No reaction: This indicates a "Negative reaction," meaning there is no visible response on the skin.
- Faint erythema only: Leads to a "Doubtful reaction," where the skin shows very light redness which might not be clinically significant.
- Erythema, infiltration, possibly papules: This morphology is identified as a "Weak positive reaction," highlighting moderate skin changes including slight papule formation.
- Erythema, infiltration, papules, vesicles: Corresponds to a "Strong positive reaction," reflecting clear, noticeable skin alterations with vesicles present.
- Intense erythema, infiltrate, coalescing vesicles: This represents an "Extreme positive reaction," showcasing severe irritation with coalescing vesicles on the skin.
- Various morphologies (such as soap effect, bulla, necrosis): Classified as an "Irritant reaction," this describes severe skin changes that could include bullae or necrosis.

The ICDRG system efficiently correlates the specific morphological attributes of the skin to a descriptive outcome, aiding in the evaluation and management of contact dermatitis. The summarization below captures this morphology-to-result relationship concisely:

| Morphology                                         | Result                   |
|----------------------------------------------------|--------------------------|
| No reaction                                        | Negative reaction        |
| Faint erythema only                                | Doubtful reaction        |
| Erythema, infiltration, possibly papules           | Weak positive reaction   |
| Erythema, infiltration, papules, vesicles          | Strong positive reaction |
| Intense erythema, infiltrate, coalescing vesicles  | Extreme positive reaction|
| Various morphologies (such as soap effect, bulla, necrosis) | Irritant reaction |

This streamlined methodology ensures that healthcare professionals can accurately interpret and act upon dermatitis indicators seen during patch testing.

The International Contact Dermatitis Research Group (ICDRG) patch test scoring system is a clinical calculator used in the field of dermatology. It is specifically designed for patients suspected of having allergic contact dermatitis, a type of skin inflammation caused by direct contact with an allergen. 

The ICDRG scoring system is used to interpret the results of patch testing, a diagnostic method used to identify the specific allergens that trigger a patient's symptoms. The score categorizes the skin reaction to each tested allergen into different grades, ranging from negative reactions to extreme positive reactions. 

The clinical utility of this calculator lies in its ability to standardize the interpretation of patch test results, thereby aiding in the accurate diagnosis of allergic contact dermatitis. It also helps in guiding the management and treatment plan by identifying the allergens that need to be avoided.

There are no specific exclusion criteria for the use of the ICDRG scoring system. However, it should be noted that the patch test and the scoring system are not suitable for patients with active dermatitis or those who have recently used systemic or topical corticosteroids, as these conditions can interfere with the test results.