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Complexities in Understanding the Role of Compensation-Related Factors on Recovery From Whiplash-Associated Disorders: Discussion Paper 2

Carroll, Linda J., PhD*; Connelly, Luke B., PhD; Spearing, Natalie M., MBA; Côté, Pierre, DC, PhD§; Buitenhuis, Jan, MD, PhD; Kenardy, Justin, PhD

doi: 10.1097/BRS.0b013e3182388739
Focus Papers: Roundtable
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Study DesignFocused discussion.

Objective. To present some of the complexities in conducting research on the role of compensation and compensation-related factors in recovery from whiplash-associated disorders (WAD) and to suggest directions for future research.

Summary of Background Data. There is divergence of opinion, primary research findings, and systematic reviews on the role of compensation and/or compensation-related factors in WAD recovery.

Methods. The topic of research of compensation/compensation-related factors was discussed at an international summit meeting of 21 researchers from diverse fields of scientific enquiry. This article summarizes the main points raised in that discussion.

Results. Traffic injury compensation is a complex sociopolitical construct, which varies widely across jurisdictions. This leads to conceptual and methodological challenges in conducting and interpreting research in this area. It is important that researchers and their audiences be clear about what aspect of the compensation system is being addressed, what compensation-related variables are being studied, and what social/economic environment the compensation system exists in. In addition, summit participants also recommended that nontraditional, sophisticated study designs and analysis strategies be employed to clarify the complex causal pathways and mechanisms of effects.

Conclusion. Care must be taken by both researchers and their audiences not to overgeneralize or confuse different aspects of WAD compensation. In considering the role of compensation/compensation-related factors on WAD and WAD recovery, it is important to retain a broad-based conceptualization of the range of biological, psychological, social, and economic factors that combine and interact to define and determine how people recover from WAD.

The role of compensation and specific compensation factors in recovery of whiplash-associated disorders continues to be a widely debated issue. This article outlines some of the reasons for this, including a discussion of some of the methodological challenges in conducting research and synthesizing the evidence in this field.

*Department of Public Health Sciences and Alberta Centre for Injury Control and Research, School of Public Health, University of Alberta, Edmonton, Alberta, Canada

Australian Centre for Economic Research on Health (ACERH); and Centre of National Research on Disability and Rehabilitation Medicine (CONRAD)

Australian Centre for Economic Research on Health, The University of Queensland, Brisbane, Queensland, Australia

§Dalla Lana School of Public Health, University of Toronto and Toronto Western Research Institute, Toronto Western Hospital, Toronto, Ontario, Canada

Medical Department Univé Insurance and Department of Health Sciences, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands

Centre of National Research on Disability and Rehabilitation Medicine, School of Medicine, The University of Queensland, Brisbane, Queensland, Australia

Address correspondence and reprint requests to Linda J. Carroll, PhD, Department of Public Health Sciences, University of Alberta, 4075 Research Transition Facility, 8308–114 St, Edmonton, Alberta, Canada T6G 2E1; E-mail: lcarroll@ualberta.ca

Acknowledgment: June 22, 2011; First Revision: July 20, 2011; Accept: September 19, 2011.

The manuscript submitted does not contain information about medical device(s)/drug(s).

No funds were received in support of this work. Although one or more of the author(s) has/have received or will receive benefits for personal or professional use from a commercial party related directly or indirectly to the subject of this manuscript, benefits will be directed solely to a research fund, foundation, educational institution, or other nonprofit organization which the author(s) has/have been associated.

One of the most hotly debated issues in whiplash research is the role of compensation in recovery of those with whiplash-associated disorders (WAD). There are many reasons why this question has not been settled. The goal of this article is to outline some of these reasons and to suggest directions for future research into this important issue.

In considering compensation for WAD, a key factor is that traffic injury compensation itself is a very complex sociopolitical issue. The attributes of compensation systems vary widely across jurisdictions, as do their administrative structures. Small differences in the structure, administrative processes, or service provision practices of personal injury compensation systems could conceivably lead to large differences in the impacts (both positive and negative) of compensation systems; and their implications for the health and well-being of a person seeking compensation for WAD could also vary considerably. It is not enough to identify an insurance scheme as either a tort-based (“fault-based”) system or a no-fault system (Table 1). Even tort-based systems may have basic benefits available to all injured individuals (regardless of fault), although the extent of these benefits varies greatly across jurisdictions. No-fault systems may be “pure” no fault or have a monetary threshold or a verbal threshold. Each of these latter two types of systems has numerous variations, such as the eligibility threshold, and each of these provisions may have different consequences. For example, in no-fault systems with monetary thresholds, it is not uncommon for medical tests and procedures to be overutilized in order to meet that threshold.1 To add to the complexity of the various systems providing compensation for WAD, some jurisdictions (e.g., Saskatchewan in Canada and several states in the United States) offer drivers a choice of purchasing tort or no-fault insurance (Table 1).

TABLE 1

TABLE 1

In addition to the complexity and variety of compensation systems themselves, compensation systems do not operate in a social vacuum. Rather, they exist within a larger sociopolitical context. Thus, any role played by insurance compensation in the course and prognosis of WAD may be affected by other aspects of society. These societal aspects include (but are not limited to) variations in the health care and other social benefits available to individuals (outside of the compensation system); the ambient attitudes toward injury, pain, WAD, and compensation in the jurisdiction or cultural context in which the injured individual lives; and the ambient attitudes toward personal versus social rights and responsibilities; and so on.

At first glance, there appears to be a wide divergence of opinion on what role, if any, compensation factors have on WAD outcome. For example, in a recent editorial, Cameron and Gabbe2 conclude that there is convincing evidence that long-term outcomes are worse when an injured person receives compensation (in the editorial, they focused on injuries such as surgical orthopedic injuries, not WAD), and they discuss the possibility of this being a causal relationship. Other writers have described chronic whiplash as a culture-driven disorder.3 There have also been a number of primary studies examining compensation factors and WAD. For example, lawyer involvement has been reported to be associated with greater neck disability in those with WAD,4 and to predict longer recovery in some studies,5 although in another study, the investigator concluded that there was no statistically significant association.6 Two studies have reported better WAD recovery after a jurisdiction changed from a tort-based to a no-fault compensation system (in which WAD compensation does not include payment for pain and suffering),5,7 whereas another investigator concluded that WAD patients claiming under the worker's compensation system (a no-fault system) had more work loss than those claiming under other systems.8 A comparison of two countries with similar socioeconomic characteristics, road traffic, and medical care systems revealed greater WAD incidence and longer recovery times in the jurisdiction with greater economic compensation for WAD.9 A recent study in Australia found that lodging a compensation claim for WAD has an adverse effect on recovery only when pain and disability are mild or moderate but not when pain and disability are severe.10 In narrative reviews of the literature, two noted that WAD researchers have offered the opinion that litigation/compensation is not prognostic of WAD recovery.11,12 Still, conclusions from systematic reviews are mixed. A 2001 systematic review of the literature concluded that compensation factors are prognostic in WAD recovery13; another (published in 2003) concluded that compensation (which was equated with litigation in that review) is not prognostic in WAD recovery14; and a 2008 systematic review concluded that there is preliminary evidence that compensation factors are prognostic in WAD recovery.15 Finally, a systematic metareview (which included but was not limited to WAD) has concluded that the hypothesis that compensation is bad for health has not been supported by the evidence.16

The purpose of this article is to open a dialogue among scientists who have diametrically different views on the role of compensation on the prognosis of WAD. Our goal is not to critique the opinions, primary studies, systematic reviews, or metareview in this field. Neither do we attempt to arrive at a consensus statement about the role of compensation/compensation factors in WAD recovery nor attempt to explain some of the discrepancies in study conclusions. Instead, our aim in this article is to identify some fundamental conceptual and methodological issues that should be considered when conducting and synthesizing these studies and when considering and interpreting the WAD compensation literature. Therefore, this article represents an open dialogue on this complex issue.

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METHODS

A multidisciplinary summit meeting of 21 international researchers, hosted by the NHMRC Centre of Clinical Research Excellence–Spinal Pain, Injury and Health and the Centre of National Research on Disability and Rehabilitation Medicine, was held in February 2011 at the University of Queensland in Australia. The purpose of this meeting was to gather experts from diverse fields of scientific enquiry, including basic sciences, clinical sciences, and epidemiology, to engage in a broad-based discussion of the problem of WAD's transition to chronicity. As part of this process, five key areas for future research were identified and debated at the meeting, with emphasis on identifying the areas of convergent and divergent thoughts on these topics from these various scientific disciplines. One identified area was the issue of research into compensation-related factors and WAD recovery, and the authors of this article took the responsibility of reporting the key elements of this discussion. This is reported as areas of general agreement within this discussion, and areas of disagreement, where opinions of the group members varied.

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RESULTS

Areas of Agreement

First and foremost, it is important to raise the question of what is meant by “compensation.” It is by no means a single or simple construct. At its most basic level, Western societies consider the availability of compensation to be a basic and important social benefit for covering injury-related wage loss and health care costs, thus providing a financial safety net for those who sustain injuries, whether these injuries are work- or traffic-related. In fact, many jurisdictions have legislation making both third party liability insurance (to cover traffic injuries) and workers’ compensation insurance (to cover work-related injuries) mandatory.17 Yet compensation laws and the characteristics of compensation systems for road traffic and work injuries (worker's compensation system) are distinct.18,19 For example, worker's compensation schemes are usually no-fault, with the employer (rather than the employee) paying premiums, whereas compensation plans for people injured in road traffic crashes are a mix of designs (Table 1), with drivers responsible for buying third party liability insurance.17 Because of these and other distinctions, it is likely that there are differences between these two systems in the role that compensation and compensation factors play on recovery from injury.

The crux of the matter may be in identifying and investigating the specific components of WAD compensation that may individually or in some aggregate fashion be beneficial, harmful, or neutral with respect to WAD recovery. This means that we need to clearly define the question we are asking before we can answer it and before we can understand the answers we find. The question “does compensation affect WAD recovery?” is quite different from the question “do specific, clearly identified compensation factors (e.g., compensation for pain and suffering) affect WAD recovery?” Many of the studies currently in the WAD literature have studied specific aspects of the compensation system, rather than addressing the presence or absence of compensation. Unfortunately, the distinction in the research question and in the findings has not always been made'sometimes it is unclear in the published article, and sometimes it is the reader who misinterprets the research question being addressed or the study findings. Thus, WAD studies reporting an association between a particular aspect of a compensation scheme and adverse outcomes may be misinterpreted as evidence that compensation itself has an adverse outcome. Conversely, studies that show a particular compensation factor has no effect may be similarly misinterpreted as evidence that neither compensation as a whole nor any other compensation factor is important in WAD health outcomes. This adds to the confusion in understanding the current literature on compensation issues and WAD. For example, in the literature, “litigation” is frequently equated with “compensation,” whereas litigation is only one aspect of only some types of compensation systems.

Even when an individual component, such as the effect of litigation on health outcomes, is studied, findings need to be understood within the context of other aspects of the overall environment in which the study takes place. For example, WAD litigation may not have the same effect in a given jurisdiction in the United States as it has in a given jurisdiction in Canada, Australia, or Europe. This is not only because the injury compensation schemes differ but also because of institutional and social differences across jurisdictions. As well, the effect of seeking compensation may be different from the effect of receiving compensation, and any effects of either are likely to be influenced both by the specific characteristics of the relevant system (e.g., how compensation decisions are made and/or how compensation is delivered) and by its context within the broader society in which the injured individual lives. This presents a challenge because compensation systems and processes (and the broader social systems they occur in) are invariably quite complex and, often, poorly understood.

There was general agreement in the group that research to examine the effects (both harmful and beneficial) of compensation-related factors on WAD recovery is important. Potentially relevant components of injury compensation that deserve investigation include—but are not limited to—questions such as the type of compensation system in place (e.g., tort-based vs. no-fault, characteristics of the tort/no fault system in place, whether or not the system is adversarial in nature; what is and is not covered; other system-related questions); the breath of insurance coverage and the extent and scope of benefits; choices within the system as a whole (e.g., what choices does the injured individual have with respect to making a claim and is injury-related health care available in the absence of making a claim and/or in the absence of litigation); issues concerned with lawyer involvement, litigation, and/or court system involvement in a case; the beneficial and adverse incentives for lawyers, health care providers, claimants, and other stakeholders within the system; and the way the insurance process is administered (e.g., what discretionary powers do claims adjusters have and what are the attitudes of claims adjusters and medical assessors to claimants). In studying particular aspects of compensation, the hypothesis (for hypothesis-driven research paradigms) or the research question (for non–hypothesis-driven research paradigms, such as qualitative approaches) should be well formulated and clearly stated, grounded in theory, and informed by existing biological, clinical, psychological, sociological, and/or economic evidence. Moreover, the study design selected should be that which is optimal to test these specific hypotheses or answer the specific research questions.

When interpreting, generalizing, and synthesizing findings from research studies, attention also needs to be paid to the population that was studied. In WAD and WAD-compensation studies, participants are typically insurance claimants, drawn from clinical populations (i.e., recruited from emergency departments, primary care settings, and specialty care settings), or, less frequently, drawn from the general population. There will be systematic differences in the characteristics of participants drawn from each of these sampling frames. For example, depending on the jurisdiction, some individuals with WAD are unable to or choose not to make an insurance claim and would thus be excluded from studies drawing their participants from insurance claimants. On the contrary, many of those making an insurance claim do not go to the emergency department after the crash20 and thus would have been excluded from any study drawing on the emergency department for participants. Thus, depending on the sampling frame used in the study, different groups of individuals with WAD will be systematically excluded. These systematic differences in study participants across types of sampling frames may also lead to differences in what role compensation factors play in recovery. Furthermore, it cannot be assumed that the role of compensation factors is the same for those with acute versus chronic WAD. For example, the effect of litigating in insurance claimants with acute WAD5 may be different from the effect of litigating in chronic WAD patients seeking specialty care,21 which may be similar to or different from the effect of litigating in chronic WAD patients in a primary care setting.22 Therefore, findings generated from research of one particular target population cannot necessarily be generalized to other target populations.13

Study designers and those reading/interpreting these studies not only have to clearly understand what the research question is (e.g., what component of the WAD insurance compensation system is being studied) and what target population has been sampled in the study but also to understand precisely what outcome is being assessed. For example, claim closure may be an important administrative and policy outcome but can serve as a suitable proxy for health recovery only if it has been validated against health outcomes in a particular jurisdiction.5,23 Complete cessation of neck pain and other symptoms may not be the best marker of recovery because of the prevalence and course of these symptoms in the general (uninjured) population.24,25 This makes it a challenge to distinguish WAD specific from endemic neck symptoms. Especially within a compensation context, claimants’ judgments and reporting of recovery may be affected by compensation incentives. In addition, we need to consider that whiplash injuries can lead to a variety of consequences, not just neck pain and neck symptoms,2629 although neck symptoms and neck disability are frequently the only outcomes considered.

There was also agreement that this research is challenging to conduct. Most studies in this area are longitudinal, because it is difficult to tease apart the issues of cause and effect with other types of data. However, even in longitudinal studies where temporality can be established (i.e., where the exposure to the compensation factor in question clearly precedes the health outcome), close attention must be paid in observational studies to minimize systematic bias and control confounding. For example, there is strong evidence that high initial pain intensity is an important predictor of poorer outcome.13,15,30,31 Thus, when studying the effect of a particular compensation factor on WAD recovery, it is important to ensure by design or by analysis that an observed effect of that compensation factor is not, in reality, due to group differences in initial pain intensity or other baseline differences. Another challenge in conducting this research is the difficulty in establishing comparison groups. For example, in jurisdictions where receipt of health care for WAD is dependent upon making a claim for compensation, a comparison group of those not making a claim would likely consist primarily of those whose symptoms were so mild that they did not seek health care, although there may be other reasons for not seeking health care, such as fear of what could be causing the symptoms or lack of access. Because compensation factors may not vary within a particular jurisdiction (e.g., the policies, structure, and administration of compensation in a particular jurisdiction may not differ among claimants), comparisons of compensation factors in two different jurisdictions become appealing. However, such studies are fraught with difficulties, in part because aspects other than the compensation factor in question (e.g., cultural/societal differences) may have an important role, yet are difficult to measure and control.

Other methodological and conceptual challenges include identifying and analyzing feedback loops in the causal chain; for example, symptom status may influence certain aspects of claiming behavior, which may in turn influence health outcomes. In addition, the prognostic importance of compensation factors may be time dependent; for example, a particular compensation-related factor may affect outcome at a particular time point during the recovery phase but not at other time points, and this may differ among various compensation factors studied. There may also be interactions between claimant or injury characteristics and compensation factors, such that a particular compensation factor affects outcome for some claimants and not others. There is, in fact, some evidence that this is the case.10 These and other challenges in this field call for greater usage of nontraditional study designs and analysis strategies, for example, structural equation modeling and multilevel multivariable modeling. Not only do we need to understand whether there are aspects of the WAD compensation system that have an adverse impact on recovery, it is of great importance to also understand the mechanism through which those aspects affect recovery.

Other methodological factors also need to be attended to by both the researcher conducting the study and the study's reader. One important issue is the size of the study, which affects the study's power or ability to detect a difference when one exists. Statistically nonsignificant findings may arise because of small sample sizes, and even in a relatively large study, there may be insufficient numbers of participants in a particular subgroup of interest. This can be a particular problem in compensation studies where the majority of claims follow a particular path; for example, in a jurisdiction where only a small minority of claimants settle their insurance claim through litigation, it may be difficult to determine the effect of litigation simply because of insufficient power in the analysis.

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Areas of Disagreement

The main area of divergent thoughts among the summit group was disagreement about the strength of the evidence from primary studies and from the systematic reviews that are currently available in this area. This is to be expected. As outlined earlier, primary research is challenging to conduct, the available studies are highly variable in methodological quality, and address a variety of research questions. Systematic reviews and metareviews come to divergent conclusions, in part, because they often start out with different research questions; include different studies because they are published in different years (thus earlier reviews have fewer studies available) and use different criteria to decide on inclusion of studies for consideration; begin with different philosophies and methods for their critique of studies/reviews; and engage different philosophies, perspectives, and methods to synthesize findings and develop conclusions.32 It has been demonstrated that even when including the same studies, systematic reviews using different methodologies for critical appraisal and synthesis yield different results and conclusions.33

Pooling findings through quantitative methods (meta-analysis) requires a degree of homogeneity across studies (e.g., similar aspects of compensation studied, similar compensation systems in place, similar environments in which these compensation schemes function, and similar outcomes used) that does not yet seem to have been achieved. In fact, given the crucial differences across jurisdictions in both the characteristics of the compensation systems in place and the societal context of that compensation system, the requisite homogeneity required for data pooling seems unlikely to be met. When studies are pooled using qualitative methods, the results tend to be sensitive to the differing scientific philosophies and methods that are brought to the endeavor, for example, judgments about study quality and methods of synthesizing evidence.32,34,35 Thus, it is not surprising that there was a lack of consensus in both those participating in the summit and in the published systematic reviews’ conclusions about whether compensation/compensation factors play a role in WAD recovery.

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CONCLUSION

Clarifying the effect that WAD compensation/compensation components have on health outcomes is important, because WAD compensation is ubiquitous and many compensation components are potentially modifiable. These endeavors are fraught with conceptual and methodological challenges, some of which have been outlined in this article. Further strong, methodologically sound primary studies need to be conducted on the wide range of research questions enveloped within the “compensation question,” and these studies need to be clear about what aspect of the compensation system is being addressed, what compensation-related variables are being studied, and what the societal context is. When studying specific aspects of the compensation system, randomized controlled trials or quasi-experimental techniques should be utilized where possible. Clearly, it is not feasible to randomize persons with WAD to (for example) make a compensation claim or not; receive compensation or not; or claim within a tort versus no-fault system. However, certain compensation-related procedures may be amenable to random assignment; for example, there may be some aspects of how claimants are managed within the compensation system that can be studied in this way. In fact, there has recently been registration of a study protocol for a randomized controlled trial to evaluate the effectiveness of an Internet intervention aimed at empowering insurance claimants with traffic-related injuries.36

Most studies on this topic, though, will continue to be observational and adherence to the STROBE (strengthening of the reporting of observational studies in epidemiology) statement for reporting of observational studies will improve the quality of the evidence.37 Nontraditional, sophisticated study designs (e.g., consideration of structural equation modeling approaches or mixed-methods designs), and analysis strategies (e.g., the use of propensity scores, instrumental variables, and sophisticated multivariable analyses to try to adjust for differences between study groups) can help in studying such aspects as causal pathways and feedback loops, identifying time-dependent prognostic effects, and understanding the mechanism of effects. There also needs to be work toward a consensus of what health-related and compensation-related outcomes should be measured to enhance comparisons and syntheses across studies.

Crucially, researchers and their audiences must also take care not to overgeneralize or confuse different aspects of WAD compensation. A study of one aspect of the compensation system cannot be used to draw conclusions about compensation as a whole, and because of the complexity of the compensation system and its intrinsic nature within a greater societal context, findings from one jurisdiction cannot necessarily be generalized to other jurisdictions. Finally, as in other investigations exploring the complex question of how to prevent the transition to chronic WAD, in studying the role of compensation and compensation-related factors, it is important to retain a broad-based conceptualization of WAD and WAD recovery that includes recognition of the broad range of biological, psychological, societal, and economic factors that combine and interact to define and determine how people recover from WAD.

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Key Points

  • Clarifying the effect that WAD compensation/compensation components have on health outcomes is important.
  • Research in this area is conceptually and methodologically challenging because of the complexity of compensation systems.
  • There needs to be clarity on what aspect of the compensation system is being studied and what the larger socioenvironmental context is within which the compensation system is operating.
  • Novel study designs and sophisticated data analyses strategies may help in clarifying the complex causal pathways and mechanisms of effects.
  • Care must be taken by both researchers and their audiences not to overgeneralize or confuse different aspects of WAD compensation, and to retain a broad-based conceptualization of WAD and WAD recovery.
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Keywords:

compensation; design; research; whiplash

© 2011 Lippincott Williams & Wilkins, Inc.