AHT is a serious form of child physical abuse that happens when caregivers violently shake young children (Lopes et al. 2013). These abusive head injuries were classified as SBS until 2009, when the AAP and CDC recommended AHT diagnosis codes instead of SBS (Christian and Block 2010). Though non-fatal AHT diagnosis codes have stabilized or declined over time (Shanahan et al. 2013; Parks et al. 2012), little is known about SBS diagnosis trends. This knowledge gap is problematic considering that 40% of AHT hospitalizations with an SBS diagnosis would not be classified as AHT without an SBS diagnosis (Parks et al. 2012). Without knowing trends in SBS diagnosis codes, we cannot determine the extent to which medical professionals follow the diagnosis recommendations of CDC and AAP. Further, the patient and hospital characteristics associated with SBS diagnosis codes remain unknown. Having this data could help researchers and policymakers identify the factors associated with SBS diagnosis. In response, we investigated seventeen-year trends in possible SBS, confirmed SBS, total SBS, and non-SBS abuse diagnosis codes among young children. We also examined the patient and hospital characteristics associated with these diagnosis codes.
SBS and AHT remain difficult social phenomena to surveil due to several factors, including the lack of mechanisms to detect mild cases in the general population, the reluctance of caregivers to come forward when AHT occurs, and discretion of professionals diagnosing SBS and AHT (including training, attitudes and controversy). Though diagnosis codes are an approximation of SBS, it is likely that the use of diagnosis codes is an imprecise measure of the actual incidence of SBS. Despite this limitation, these codes and setting are the best epidemiological data available for surveilling non-fatal SBS to our knowledge. In our study, we found support for the following: 1) Non-SBS abuse is the most common form of abuse in our study; 2) Confirmed SBS diagnosis trends have declined while possible SBS diagnosis trends have increased and total SBS trends remained stable; 3) All abuse diagnosis codes were more common among infant, male, or low-income children and urban teaching hospitals. Taken together, our findings contribute to literature on AHT and SBS along with non-SBS abuse diagnosis codes within hospitals, including diagnosis trends and characteristics associated with each abuse category. Policymakers can use our findings to develop plans for aligning current diagnostic practices with CDC and AAP guidelines.
According to our estimates, possible and confirmed SBS diagnosis codes represent a fraction of the overall abuse codes young children receive, with total SBS diagnosis codes comprising about 21% of abuse hospitalizations. Though diagnosis codes on possible and confirmed SBS in no way indicate the presence of abuse, diagnosis codes provide a rough estimate of SBS among young children hospitalized for abuse. A majority of hospitalizations were related to non-SBS abuse. Among children age 1 or younger, there was an overall increase in the probability of non-SBS abuse, whereas the probability of non-SBS abuse among children older than 1 year remained fairly stable. Hospitalizations often represent the most severe incidences of non-fatal child abuse, which are disproportionately experienced by young children (Farst et al. 2013). Similar to our results, researchers have reported stable overall trends in child maltreatment hospitalizations among children ages 0 to 3 from 1997 to 2009 (Wojciak et al. 2020). Farst and colleagues reported unchanging rates of child abuse hospitalizations among children ages 0 to 18, with young children facing the largest share of hospitalizations between 1998 and 2016 (Farst et al. 2013). Along with these study findings, our results provide evidence that child abuse hospitalizations remain a significant problem in the US, and may be a growing problem among young children.
Of our four abuse diagnosis categories, only confirmed SBS diagnosis codes declined between 2002 to 2014. This finding aligns with AHT literature indicating that AHT diagnosis codes decreased during overlapping time periods (2003–2008 (Parks et al. 2012); 2000–2009 (Shanahan et al. 2013)). There may be various explanations for reductions to confirmed SBS diagnosis codes over time, including declines in the actual incidence of SBS. Unfortunately, our findings on the decreasing use of SBS code 995.55 most likely does not reflect shifts in abusive caregiver practices. Given that possible SBS diagnose codes increased steadily over the study period and total SBS remained stable, a likelier explanation relates to changing diagnostic practices of medical professionals. Though AAP and CDC recommendations likely impacted the decline in confirmed SBS diagnosis codes, confirmed SBS diagnosis codes began decreasing in 2002, seven years before AAP’s recommendation in 2009. It is possible that medical and legal controversy surrounding the credibility of SBS diagnosis codes also contributed to declining use of SBS code 995.55. A few papers, for example, have questioned SBS as a reputable diagnosis, citing inadequate scientific evidence that the injuries typically associated with SBS are caused solely by shaking (Findley et al. 2019; Choudhary et al. 2019; Lyons 2003). The presence of these papers in medical research may have influenced physicians’ use of confirmed SBS diagnosis codes.
Whereas confirmed SBS diagnosis codes have decreased, possible SBS diagnosis codes have increased. By 2011, the rate of possible SBS diagnosis codes exceeded the rate of confirmed SBS diagnosis codes. This finding suggests that medical professionals are not diagnosing retinal hemorrhage and/or convulsions not associated with a seizure disorder, as confirmed SBS, even in the presence of physical abuse and Type 1 internal traumatic brain injury. If these diagnosis codes represent SBS yet are not coded as SBS, there are implications for diagnostic norms for AHT. At present, CDC-recommended AHT codes do not include retinal hemorrhage and/or convulsions without seizure disorder (i.e. possible SBS). The implication is that the diagnosis codes used to measure possible SBS may capture some cases, albeit a small amount, that would not meet the CDC’s definition of AHT (Center for Disease Control and Prevention 2012), perhaps leading to misclassification of AHT abuse, as previously indicated by Parks and colleagues (Parks et al. 2012).
Additionally, our findings suggest that the SBS diagnostic code 995.55 alone is not adequate to surveil for AHT, suggesting support for the use of the CDC’s AHT survelience codes. Although beyond the scope of this study, future researchers should investigate the overlap between AHT diagnoses codes and codes for retinal hemorrhages and convulsions without a seizure disorder, and compare trends in SBS diagnosis codes and AHT diagnosis codes over time. Future research should also examine whether current definitions of AHT neglect some diagnosis codes associated with abusive head injuries in young children (e.g., retinal hemorrhage and/or convulsions without seizure disorder in the presence of physical abuse and Type 1 internal traumatic brain injury). If current AHT definitions exclude some instances of abusive head injuries, policymakers could consider adding diagnosis codes to those recommended for AHT.
Our finding on increasing possible SBS diagnosis codes may also provide context to the overall process for diagnosing SBS, which Narang and Greeley describe as a complex, context-driven process without reputable diagnosis guidelines (Narang et al. 2020). Through our findings, there are a few directions researchers, policymakers, and medical professionals could take. If medical professionals find utility in diagnosing SBS, it appears that clearer diagnostic guidelines are needed, especially in light of the hospital characteristics associated with possible versus confirmed SBS diagnosis. According to our study, possible SBS diagnosis codes were more frequent in urban teaching hospitals and large hospitals, suggesting different diagnostic protocols in these institutions. Findley and colleagues recommend the development of a national registry on SBS and protocols for diagnosing SBS along with alternative explanations for SBS-like injuries (Findley et al. 2011). Likewise, we propose that researchers and pediatric medical providers agree to a standardized definition and diagnostic guidelines for possible and confirmed SBS, much like the AHT guidelines proposed by CDC, which may help reduce discrepancies in diagnosis and treatment and improve options for surveillance (Kim et al. 2017b; Paine et al. 2016).
Finally, our findings on the patient and hospital characteristics associated with SBS diagnosis codes align with what is known about AHT in the literature. Like AHT, our findings indicate that all abuse types were diagnosed more frequently among infants (< 1-year-old), boys, and children from low-income households than toddlers, girls, and children from higher-income households (Shanahan et al. 2013; Parks et al. 2012; Leventhal et al. 2012). The prevalence of SBS and AHT among infants under the age of 1 may be related to infant crying and subsequent parental or caregiver stress. Explanations for the prevalence of SBS among male infants may include the acoustic characteristics of male cries, societal norms related to crying in boys, gender stereotypes and biological differences. One recent study found that adult male caregivers were more aggravated by the cries of male infants than females (Richey et al. 2020). Future research may benefit from examining differences in SBS and AHT hospitalizations by child and perpetrator sex, given that the NIS data set includes codes for perpetrator’s gender and relationship to victim (e.g., abuse by father/step-father and abuse by mother/step-mother). Societal norms and gender stereotypes around crying may influence physicians and medical professionals diagnosis codes of abuse related injuries. For example, Ravichandiran and colleagues reported that physicians initially miss the abuse of boys more often than girls (Ravichandiran et al. 2009), suggesting 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 (Hagan and Kuebli 2007). Finally, biological differences between girls and boys may also account for the use of SBS diagnosis codes with boys: As compared to girls, boys are vulnerable to benign external hydrocephalus, predisposing children to subdural hemorrhages, and to subdural hemorrhages overall, which are attributed to SBS but can occur in the absence of shaking as well (Högberg et al. 2018; Wester 2019).
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 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. Second, our possible SBS measure does not account for all SBS victims who are hospitalized nor SBS victims who remain undetected in the general population. Second, there are limitations associated with the sample and use of e-codes. One is that our sample does not include victims of SBS who were not hospitalized, including mild or fatal cases. Another is that SBS-related diagnostic codes are incomplete measures of SBS diagnosis, and do not include other factors of SBS diagnosis, including client history nor results from physical exams, ophthalmologic exams and radiological studies. As such, our results do not precisely represent the number of children experiencing SBS and instead provide information about the use of SBS diagnosis codes, an imprecise estimate of SBS diagnosis codes. Given the difficulty in surveilling SBS in the general population, we must rely on existing secondary data like the NIS to approximate the prevalence of SBS. Finally, SBS-related diagnosis codes only describe how medical professionals code abusive head injuries and cannot describe trends related to abusive parenting practices. Surveillance of child abuse itself remains a significant challenge in literature on child maltreatment, and is an issue our study cannot address (Fallon et al. 2010).