We investigated seventeen-year trends of possible and confirmed SBS diagnoses among young children admitted to the hospital for abuse. In our study, SBS represented a small subset of overall abuse, which aligns with literature on SBS.10,20,21 Consistent with children hospitalized for abuse, our findings indicate that total SBS was more frequent among infants (< 1-year-old), boys, or low-income children compared to non-SBS abuse. 10,23 It is unsurprising that SBS was more frequent among infants than non-SBS abuse, given infants’ vulnerability to shaking.3–5,17
Our results indicating that girls more frequently received confirmed SBS diagnoses than possible SBS diagnoses approached significance. In contrast, boys more frequently received possible SBS than confirmed SBS diagnoses. Our findings provide context for studies on the relationship between gender and physical abuse diagnoses. When toddlers present with repeat abusive fractures, Ravichandiran and colleagues24 reported that physicians initially missed the abuse of boys more often than girls. These findings suggest that physicians may perceive injuries differently among boys and girls, possibly because boys are socialized for rough-and-tumble play and are more prone to accidental injury.25
For every subgroup in our study, confirmed SBS diagnoses have declined since 2002, while possible SBS diagnoses have increased. In 2011, possible SBS diagnoses surpassed confirmed SBS and remained higher, i.e., ‘the crossover effect.’ SBS diagnoses varied by hospital size and type in our study, suggesting a discrepancy in diagnostic processes. Possible SBS diagnoses were more common among urban teaching hospitals and small to medium hospitals than for other hospital types, with the crossover effect occurring as early as 2010.
Public opinion and controversy among researchers about SBS may have contributed to demographic variations and the crossover effect of SBS. First, public opinion about SBS appears to have shifted. Both the CDC and AAP, which issue best practices for pediatric care, have promoted the use of broad terms like AHT instead of SBS since the mid-2000s.9 Mainstream news coverage also has impacted public opinion by focusing on legal cases related to SBS, rather than medical or scientific evidence, and framing SBS as a questionable diagnosis.26 Together, media emphasis on legal issues and the AAP’s stance on SBS may make physicians more reluctant to diagnose SBS.27 Second, the quality and value of SBS research has recently been under scrutiny by some researchers and legal experts, citing inadequate scientific evidence that the injuries typically associated with SBS are caused solely by shaking.28−30 Many researchers, however, refute the claim that SBS is diagnosed purely by the presence of retinal hemorrhaging, brain hemorrhaging, and brain swelling, a combination sometimes referred to as the “triad”.31−33 Narang and Greeley,34 for example, emphasized that diagnosing SBS is a complex, context-driven process without reputable diagnosis guidelines.
In all, we contribute to the literature by examining seventeen-year trends of SBS among young children hospitalized for abuse, yet there are limitations. First, our possible SBS measure may not account for all SBS victims who are hospitalized. Physicians use a variety of tools, including available diagnosis codes and a child’s history, to diagnose SBS. We chose a combination of codes highly indicative of acceleration/deceleration injury to avoid false-positive diagnoses, but these codes are not exhaustive. Second, our analysis includes no correction for confounders in the estimation of time trends. The lack of research on these trends, however, warranted our approach of estimating simple time trends by subgroup. Finally, we may underestimate actual rates of SBS by excluding SBS victims who were not hospitalized. This surveillance issue is a common problem for all studies on child maltreatment.
4.1 Implications
Our findings highlight the difficulty of defining and diagnosing SBS. Many physicians find SBS diagnoses useful, yet the lack of standardized definitions and practice guidelines contribute to the complexity of diagnostic processes. Findley and colleagues25 recommend the development of a national registry on SBS and protocols for diagnosing SBS along with alternative explanations for SBS-like injuries. Likewise, we propose that researchers and pediatric medical providers agree to a standardized definition and diagnostic guidelines for SBS, much like the AHT guidelines proposed by CDC, which may help reduce discrepancies in diagnosis and treatment and improve options for surveillance.35,36
The distinct biomechanics and etiology of SBS have implications for pediatric education, research, and prevention. Biomechanics research is a main source of evidence about the mechanisms by which shaking injures the pediatric brain. However, biomechanics is not a regular feature of pediatric education. Inclusion of a module on the biomechanics of brain injury could help physicians better understand the underlying mechanical pathways for injury and related symptoms and outcomes for infant-shaking injuries, as well as injuries like sports concussions. Investment in biomechanical research, which has not been prominent in injury prevention research for two decades, would also advance knowledge of causal mechanisms.
Finally, our finding that total SBS has increased over time suggests that prevention efforts have not been far-reaching enough to address the scope of the problem. Most prevention programs focus on raising awareness about normal infant crying and the dangers of shaking a baby, as well as improving caregivers’ response to crying.37 Results from these programs are promising, suggesting that prevention programs can improve parental knowledge about crying behaviors and may help reduce emergency department visits for prolonged crying.38 The Period of PURPLE Crying, for example, is a prevention campaign designed by the National Center on Shaken Baby Syndrome and well known for its empirical support.34,35 Given our findings and the evidence on prevention programs, prevention programs should be expanded to more locations and offered to more expecting parents.