Natalie M. Spearing, Luke B. Connelly, Susan Gargett, Michele SterlingFrom the University of Queensland, Australia BACKGROUND FROM DAN MURPHY: CLAIMAINT ONLY STUDY: One that only looks at injured people that are suing. This type of study isconsidered to be of poor quality. These authors excluded these studies. PROXY MEASURES FOR HEALTH STUDIES: This is when determining the health status of an individual is done not by looking attheir health but by looking at something like their ability to return to work or howlong their claim remained open. This type of study is considered bogus. Examples ofthis type of study includes: J. David Cassidy, D.C., Ph.D., Linda J. Carroll, Ph.D., Pierre Côté, D.C., MarkLemstra, M.Sc., Anita Berglund, B.Sc., and Åke Nygren, M.D., Ph.D.; Effect ofEliminating Compensation for Pain and Suffering on the Outcome of InsuranceClaims for Whiplash Injury; New England Journal of Medicine; April 20, 2000; Vol.342; No. 16; pp. 1179-1186. REVERSE CAUSALITY BIAS: This occurs when the results of a study are interpreted to mean that (Whiplash-Injured)people who hire lawyers to obtain compensation have worse healthrecovery outcomes; when in fact it may actually mean that [whiplash-injured]people with greater injuries, more pain and more disability are the ones who seeklawyers to help them obtain the benefits they need. KEY POINTS FROM THIS STUDY: 1) Many believe that compensation [after whiplash injury] does more harm thangood. There is a view that injury compensation leads to worse health; this is calledthe compensation hypothesis. 2) This view that compensation is harmful has been used to argue forreductions to compensation benefits and changes to scheme design, influencejudicial decisions, and advise people that compensation payments will impede theirrecovery. 3) The compensation hypothesis has important implications for injured people,insurers, governments, and health and legal professionals, among others. 4) This systematic review focuses on whiplash, which is a contentious injurybecause there is no gold standard diagnostic test, and its most common symptom,pain, is subjective. These issues have led some to question whether the lure ofcompensation prompts symptom exaggeration. 5) This study systematically reviewed the evidence on the compensationhypothesis using PubMed, CINAHL, EMBASE, PEDro, PsycInfo, CCTR, Lexis, andEconLit. 6) These authors excluded studies using claimants only, or using proxymeasures of health outcome, noting that they were of poor quality and not reliable. 7) 9 of 16 studies used in this review [56%] indicated that compensationadversely influenced health outcomes. However, none evaluated or considered thepotential for reverse causality bias in making their conclusions. Consequently,there is no clear evidence to support the idea that compensation and its relatedprocesses lead to worse health. [Key Point] 8) It is not possible to tell if statistically significant negative associations reflecta compensation effect, or if they simply reflect the pursuit of compensation bythose with comparatively worse health and/or a worse prognosis (a selectioneffect); however, the former is often assumed. 9) Our overall conclusion, that it is currently not possible to determine whetheror not compensation leads to worse health after whiplash because reverse causalitybias has not been addressed, varies from that of earlier systematic reviews onwhiplash as they did not consider this source of bias.[Consequently, these earlier reviews concluding that compensation leadsto worse outcomes may be biased and flawed.] 10) Claiming lawyer involvement leads to worse pain, could also be interpretedas worse pain increases the likelihood of lawyer involvement. [REVERSE CAUSALITY BIAS] 11) The potential for reverse causality bias is largely unacknowledged in thewhiplash literature, and lies similarly unaddressed in studies on other types ofcompensable injuries. [Key Point] 12) It is important to ascertain whether statistically significant negativeassociations between compensation-related factors and health do indeed indicatethat exposure to these factors leads to worse health, or whether they simply reflectthe likelihood that people in comparatively worse health (eg, pain) are more likelyto pursue compensation. Unless the latter possibility is considered, decisions toreduce compensation benefits, for example, may inadvertently disadvantage thosewho are in most need of assistance, which would be an undesirable (andunintended) policy consequence. [Key Point] 13) Statistically significant negative associations between compensation-relatedvariables and health are reported in some studies on whiplash. However, ouranalysis suggests it is inappropriate to interpret these associations as evidence thatcompensation factors lead to worse health because the problem of reverse causalityhas not been addressed. As a result, the magnitude and direction of any observedeffect is unclear and potentially biased. 14) Only when reverse causality is addressed will it be possible to make.