Reaffirmed Limitations of Meta-Analytic Methods in the Study of Mild Traumatic Brain Injury: A Response to Rohling et al.

Abstract

In 2009 Pertab, James, and Bigler published a critique of two prior meta-analyses by Binder, Rohling, and Larrabee (1997) and Frencham, Fox, and Maybery (2005) that showed small effect size difference at least 3 months post-injury in individuals who had sustained a mild traumatic brain injury (mTBI). The Binder et al. and Frencham et al. meta-analyses have been widely cited as showing no lasting effect of mTBI. In their critique Pertab et al. (2009) point out many limitations of these two prior meta-analyses, demonstrating that depending on how inclusion/exclusion criteria were defined different meta-analytic findings occur, some supporting the persistence of neuropsychological impairments beyond 3 months. Rohling et al. (2011) have now critiqued Pertab et al. (2009). Herein we respond to the Rolling et al. (2011) critique reaffirming the original findings of Pertab et al. (2009), providing additional details concerning the flaws in prior meta-analytic mTBI studies and the effects on neuropsychological performance.

The neuropsychological outcomes of concussion: A systematic review of meta-analyses on the cognitive sequelae of mild traumatic brain injury.

“…Others have posited more rapid recovery windows, specifically among athletes (i.e., 7 days, ; however, many meta-analyses on sports-related concussion have been constrained by limited research exploring cognitive outcomes past 7-10 days (e.g., Broglio & Puetz, 2008;Dougan et al, 2013), with more research required to predict delayed recovery trajectories among head-injured athletes. Although the average prognosis appears positive, a subgroup of patients with mTBI may remain chronically impaired into the postacute phase (Bigler et al, 2013;Frencham et al, 2005;Pertab et al, 2009), but the size and existence (Larrabee et al, 2013;Rohling et al, 2011;Rohling, Larrabee, & Millis, 2012) of this symptomatic subgroup remains debatable. Focusing on mean performances, meta-analytic methods may hide the few participants presenting persistent symptoms post-mTBI (Iverson, 2010).…”

“…Focusing on mean performances, meta-analytic methods may hide the few participants presenting persistent symptoms post-mTBI (Iverson, 2010). Further, multiple biomarkers (e.g., DTI, eye tracking) have detected nontransient neurological changes following mTBI (Bigler et al, 2013), evidencing the potential for long-term impairment. However, these persistent symptoms could also derive from preexisting psychological factors (e.g., psychosocial stressors, lower cognitive ability) rather than representing outcomes attributable to the mild head injury itself (Larrabee et al, 2013).…”

“…Presenting an ominous trajectory, the prevalence of head trauma has increased among U. S. military personnel throughout the previous decade, with 77% of military-related brain injuries qualifying as mild (Coronado et al, 2012). Despite the prevalence and public concern surrounding mTBI, past researchers have dismissed its long-term neuropsychological impact as clinically insignificant Frencham, Fox, & Maybery, 2005;Larrabee, Binder, Rohling, & Ploetz, 2013;Rohling et al, 2011;Shretlen & Shapiro, 2003); however, some individuals may remain symptomatic long after the concussive event (Bigler et al, 2013;Pertab, James, & Bigler, 2009), potentially explained by acute neurological impairment that can persists after injury (e.g., Cohen et al, 2007;Holli et al, 2010). Alternatively, some researchers have identified more psychogenic predictors of persistent symptoms (Silverberg & Iverson, 2011).…”

“…Despite the prevalence and public concern surrounding mTBI, past researchers have dismissed its long-term neuropsychological impact as clinically insignificant Frencham, Fox, & Maybery, 2005;Larrabee, Binder, Rohling, & Ploetz, 2013;Rohling et al, 2011; Shretlen & Shapiro, 2003); however, some individuals may remain symptomatic long after the concussive event (Bigler et al, 2013;Pertab, James, & Bigler, 2009), potentially explained by acute neurological impairment that can persists after injury (e.g., Cohen et al, 2007;Holli et al, 2010). Alternatively, some researchers have identified more psychogenic predictors of persistent symptoms (Silverberg & Iverson, 2011).Persistent symptoms of mTBI remain a contentious issue, with a recent scholarly dialogue closely examining the evidence both for and against their existence (Bigler et al, 2013;Larrabee et al, 2013;Pertab et al, 2009;Rohling et al, 2011). Dating back to the 19th century, scholars have argued between the psychological and physiological etiologies of post-mTBI symptoms (see Binder et al, 1997).…”

“…Persistent symptoms of mTBI remain a contentious issue, with a recent scholarly dialogue closely examining the evidence both for and against their existence (Bigler et al, 2013;Larrabee et al, 2013;Pertab et al, 2009;Rohling et al, 2011). Dating back to the 19th century, scholars have argued between the psychological and physiological etiologies of post-mTBI symptoms (see Binder et al, 1997).…”