Most impairments are based on the Diagnosis-based Impairments (DBI) where Impairment Class is determined by the diagnosis and/or other specific criteria; this is then adjusted by "non-key" factors (grade modifiers) that may include Functional History/Assessment, Physical Examination Findings, and Clinical Studies/Objective Test Results. Over-simplified, a condition's impairment can be determined using the following three steps:
- Identify the condition, or diagnosis. This is referred to as the "key factor".
- Identify the severity of the condition. This is referred to as the "class". The class provides the range for the condition's impairment.
- Identify non-key factors and adjust the impairment either up or down depending on the non-key factor's class.
This topic focuses on non-key factors, also referred to as grade modifiers, what they are, how they are applied, and cases when they should be omitted from the impairment calculation.
Physical Examination, or Findings identify pertinent findings on physical examination that corroborate or refute the diagnosis itself, or that serve as indicative measures of severity of the particular condition. These should also be as disease-specific as possible. When assigning a class to the physical examination findings, class 0 will be for those patients who may have had findings in the past but are now healthy (with no expectation that they will have recurrent findings), while class 4 is for those patients with severe continuous findings that persist despite treatment (ie, are not controlled by treatment) or with extreme intermittent findings.
Objective Test Results or Clinical Studies identify objective tests – for example, X rays, computed tomography (CT), magnetic imaging (MRI), laboratory tests, electrocardiography (ECG), electromyography (EMG), and ultrasonography – with specific findings that confirm or validate the diagnosis and/or indicate severity of the particular condition.
Functional Assessment or History, considers the functional impact of the condition, disorder, or disease. Grade assignment for functional symptoms is based on subjective reports that are attributable to the impairment. These reports may include a self-report tool that is administered, scored, and assessed for consistency with the clinical presentation, and for credibility.
Note: Functional History Grade Modifier should be applied only to the single, highest diagnosis-based Impairment. Specific jurisdictions may modify this process such that Functional History Adjustment is considered for each Diagnosis-based Impairment or not considered at all as a Grade Modifier. By default, ImpairMaster will select the highest diagnosis-based impairment, however this can be changed in a report's settings.
Diagnosis-related Non-key Factors
If a non-key factor was used for primary selection of the diagnosis, it may not be used again in the impairment calculation. For example, if a diagnostic class was determined using range of motion as a factor, then range of motion is not considered again when determining the physical examination adjustment factor. Another way to look at it is that range of motion cannot be both the key factor and a non-key factor – that would result in duplication.