Before making any impairment or disability determination, the physician is obligated to understand how an organ system (or body part under study) normally functions in the absence of disease. This is then coupled with a thorough understanding of the mechanism of the disease process under investigation. Causality is possible--ie, biologically plausible--if the nature of the adverse effects produced by a given physical, chemical, biologic, or psychological stressor is sufficient to alter the anatomy or physiology of the system or body part involved in a fashion that results in the disease under investigation. There also must be an appropriate temporal relationship between the alleged causal event and the disease manifestations. Furthermore, in situations where there is trauma, the mechanical forces involved must be sufficient to cause the alleged physiologic or anatomic stress.
One should then look for studies supporting the causal relationship between the type of exposure or injury the claimant sustained and the disease process or injury under investigation in the medical literature. If they exist, the next step is to assess whether the epidemiologic and statistical principles used in these studies suggest that the causal association is real, or whether these studies are merely anecdotal or otherwise without scientific basis or validity. If the association between an exposure or injury and the postulated “effect” meets epidemiologic, physiological, and mechanistic criteria for imputing causality, or the injury is a clear sequela of direct trauma, it is then reasonable to assume that a causal relationship between an alleged exposure or injury and the disease process actually exists.
These types of determinations must not be made solely on the basis of the claimant’s history. The medical records provide a more accurate and defensible history and must support the occurrence of the injury and the appearance of symptoms orsigns of pathology within a time frame that is consistent with the disease process under investigation. Those records from immediately after the injury are best for this purpose, as they are regarding the claimant’s status both before and after a trauma, and often provide the most accurate description of what actually occurred. Emergency room records, police and accident reports, and the employer’s report of occupational injury or disease (for workers’ compensation claims) are examples of documents that are particularly useful in this regard. If these records are not available or are ambiguous, it is best to describe the assessment of causality as provisional rather than definitive, even if the mechanism of injury, the physical examination, and the literature review indicate that a causal relationship may indeed be present.
Combinations of direct trauma and a preexisting disease process are more difficult to assess for causality and apportionment. One must determine, again, if the requirements of temporal relationship, biologic plausibility, literature support, and sufficient injury have been met. This includes an assessment of whether the trauma would have caused the disease in the absence of the preexisting process or whether the injuries caused by the trauma or whether the injuries caused by the trauma or exposure would ordinarily decrease over time, because these answers provide grounds for apportionment. It is equally important to assess whether the trauma would have progressed on its own accord to a point where the claimant would have has the same clinical presentation; if so, one can argue that the accident only caused an acceleration of an inevitable process.
When dealing with preexisting conditions, it is mandatory to examine all the records carefully, paying particular attention to the records of those providers who treated the claimant immediately after the accident. These are often the most accurate rendition of the incident and treatment that can be found. Records prior to the accident are even more critical, as they may be the only source of information regarding preexisting conditions. When there are no medical records from before and immediately after an accident, one cannot definitely establish that a causal relationship between current complaints and the accident exists--only that the claimant’s history supports the causal relationship. If the examiner believes that additional information, records, or tests are needed to support conclusions regarding relatedness, then it is necessary to state this and to describe exactly what information or testing is required.
In conclusion, the examiner can only provide an accurate determination of causality if he or she applies accurate determination of causality assessment, within an objective framework, in which the claimant’s statements have validity only to the extent that they are supported by the medical records. In those instances where the medical records in inadequate, the examiner can make preliminary conclusions regarding causality, especially if the elements of temporal relationship and biologic plausibility have been met, but should reserve final judgment until the entire relevant medical record is available for review.