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California: When to Add Impairments: The Synergistic Effect Explained

August 18, 2021 (5 min read)

Although the 2005 Permanent Disability Rating Schedule (2005 PDRS) indicates that impairments are generally combined by using a reduction formula, the AMA Guides, upon which the 2005 PDRS is based, describe several different methods that may be used to combine multiple impairments. One method of combining impairments is by simple addition. Appellate Court decisions have accepted that method when expert medical opinion confirms that simple addition provides a more accurate reflection of overall impairment because of the synergistic effect among the impairments. (Athens Administrators v. Workers’ Comp. Appeals Bd. (Kite) (2013) 78 Cal. Comp. Cases 213 [2013 Cal. Wrk. Comp. LEXIS 34] (writ den.); Barret Business Services, Inc. v. Workers’ Comp. Appeals Bd. (Chavez) (2019) 84 Cal. Comp. Cases 991 [2019 Cal. Wrk. Comp. LEXIS 89] (writ den.).) Which method to use to combine multiple impairments seems straightforward enough. The Combined Values Chart (CVC) is the preferred approach, but other factors may warrant a different method. Just exactly what those factors might be continues to befuddle many a practitioner. Both Kite and Chavez endorse combination of impairments by addition because of the synergistic effect of the injured employee’s impairments, but neither defines the meaning of that term. (Likely a definition seemed unnecessary in Kite because the injured employee sustained industrial injury to both of his hips.) In contrast, a recent Appeals Board Panel decision provides a helpful definition of “synergy” and an example of the circumstances that warrant use of simple addition to achieve the best reflection of the injured employee’s overall impairment. That case is Hodson v. Vacasa, LLC, 2021 Cal. Wrk. Comp. P.D. LEXIS 170 (Appeals Board noteworthy panel decision).

In Hodson, the employee was cleaning snow off a stairway when he slipped on ice and fell, striking his head. He sustained injured to multiple body parts and required surgical treatment of his hand and knee injuries. He had recurring cognitive and psychiatric complaints that were treated by Dr. Stephen McCormack. Hodson’s treatment included two separate one-month stays in a rehabilitation facility.

A Panel Qualified Medical Evaluator (PQME) evaluated Hodson’s orthopedic complaints and found residual impairment to the neck, back, knee, hand, elbow and in the form of headaches. When these impairments were adjusted for age and occupation and apportionment was considered, the PQME combined them on the CVC and the result was 51%. The PQME opined that the orthopedic disability of 51% should be added to cognitive and psychiatric disabilities because those impairments caused flaring up of orthopedic impairments. As regards Hodson’s cognitive and psychiatric impairments, Dr. McCormack described cognitive disability of 14% whole person Impairment (WPI) and psychiatric disability of 8% WPI.

Following the PQME’s recommendation, the WCJ determined that the combined value of the orthopedic impairments should be added to the combined value of the cognitive and psychiatric impairments, to produce permanent disability of 95%. Hodson sought reconsideration, contending that the WCJ failed to properly combine cognitive and psychiatric impairments. He argued that Dr. McCormack had recommended that those two impairments be added together because of their synergistic effect. In response, the WCJ rescinded the decision and issued an amended decision that added the combined orthopedic impairments with the cognitive impairments and psychiatric impairments to produce 100% permanent disability.

Defendant then sought reconsideration, challenging the WCJ’s use of addition to combine the orthopedic, cognitive and psychiatric impairments. In his Report on Petition for Reconsideration (Report), the WCJ pointed out that Dr. McCormack did in fact state that Hodson’s cognitive and psychiatric impairments resulted in a synergistic effect that, when combined, causes more impairment than each standing alone.

The Appeals Board panel affirmed the WCJ’s decision and incorporated the reasoning set forth in his Report. In addition, the decision includes quoted portions of Dr McCormack’s report that defines and explains the synergistic effect of cognitive and psychiatric disabilities based on the specific facts in the case. Specifically, the panel notes that, “[s]ynergy is the interaction or cooperation of two or more systems that produce a combined effect greater than the sum of their separate effects.” Next, in discussing how Hodson’s cognitive and psychiatric disabilities interact to produce impairments, the panel again quotes Dr. McCormack, stating: “…cognitive and psychological symptoms interact whereby the cognitive symptoms cause the emotional symptoms (worry, fear, helplessness and sadness) to become more intense and the emotional symptoms cause greater difficulty in accessing and using cognitive functional abilities (attention, concentration and memory). The two combined together in this way cause more disability than each by themselves.” Next, the panel Includes Dr. McCormack’s explanation of the lack of overlap between Hodson’s cognitive and psychiatric impairments. Dr. McCormack explains: “The cognitive disability is due to an organic injury to the brain and the psychological (which for purposes of discussion I will refer to as the injury causing emotional distress) is due to the reaction to that brain injury. Thus, there is no overlap in disability caused by the organic brain injury and the disability caused by the emotional reaction to the impairment caused by that brain injury. By analogue the disability caused by the loss of a hand function would not overlap with the impairment due to the emotional reaction to that loss of hand function.” Finally, the panel concludes its decision with the recognition that because Hodson’s cognitive/psychiatric and orthopedic disabilities are totally different systems, the most accurate reflection of overall disability is achieved through the addition method of combining those impairments.

It is true that the panel decision in Hodson is only three pages in length, but don’t let that factor dissuade you from its import. In fact, Hodson is a gem. Not only does it provide a clear definition of synergistic effect, it also illustrates that effect by explaining the interaction between cognitive and psychiatric impairments, which results in more disability than each by themselves. Last but not least, it shows why there is no overlap in Hodson’s cognitive disability and his psychiatric disability.

Reminder: Board panel decisions are not binding precedent.

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