Discussion
Despite the evidence for increased hardships and hospitalizations for transition-aged patients with SCD, we lack recent, nationwide studies pertaining to the trends in this population’s mortality. Previous studies are now dated or had a narrow emphasis, focusing on specific demographics such as geographic regions. We thus embarked on a comprehensive approach to examine recent, national data regarding transition-aged hospitalizations in the SCD population. The Healthcare Cost and Utilization Project (HCUP)’s 2019 Statistical Brief #251 reported that 18-34 year-old patients comprised the majority (50.7%) of SCD stays between 2000-2016, a vast difference when compared to non-SCD admissions in which 18-34 year-olds only made up 16.3%. However, in focusing on ages 16-24 specifically, our results did not show a difference in the portion of transition-age hospitalizations between SCD and non-SCD cohorts (Table 1). The HCUP brief also highlighted various socio-economic differences between SCD and non-SCD admissions. Correspondingly, we noted transition-aged patients with SCD were more likely to have public insurance, be in the lower zip income quartile and have a discharge status of DAMA (Table 1).
Furthermore, we were interested in the mortality risk among different SCD transition-age cohorts. We were astonished to see that in comparison to teens aged 16-18, the risk in mortality was 2-fold higher for those aged 19-21, and nearly 3-fold higher for ages 22-24 (Table 2). These findings corresponded with 1999-2009 data obtained by Hamideh et al which demonstrated a sharp increase in the morality rate in patients with SCD between 15-19-years-old to 20-24-years-old.
An additional finding pertained to mortality differences based on documented sex. Female patients constituted a slight majority of patients hospitalized with sickle cell disease (Table 1), however, they were less likely to suffer in-hospital mortality when compared to their male counterparts (Table 2; p < 0.0001). These results align with a previous study which determined that pediatric male patients with SCD have a worse, more aggressive clinical course than females and an increased morbidity.
Limitations of our study are related to the nature of database utilization; specifically, the absence of granular data and the inability to track a patient over time. Due to this, cause of death and other information regarding clinical course is unobtainable. Furthermore, the structure of the NIS data was confined to inpatient admissions only and did not contain ED visits, outpatient visits or urgent care visits. Despite some limitations, our study was highly powered in detecting differences in hospitalizations and mortality associated with SCD due to the large sample size. The NIS data was composed of weighted national samples, representative of the entire population rendering the findings in this study to be generalizable.
Several groups have underscored the vulnerability of patients with chronic diseases during the transition period; the consensus is that this period is plagued by social, psychological, and physiological hardships. For patients with SCD in particular, these challenges exist in a sort of cyclic nature, where increased pain episodes and fatigue lead to anxiety and depression, decreasing a patient’s health-related quality of life and in turn further exacerbating the fatigue and pain episodes. These pain episodes, or vaso-occlusive crises, are the leading cause of SCD admissions, and serve as a primary risk factor for potential life-threatening events.
Our study has demonstrated the necessity for multifaceted improvements in the process of transitioning our pediatric patients with SCD to adult care. A 2009 survey showed that the vast majority of transitioning patients with SCD did not feel ready to transition, with only 34% of participants knowing which hospital they planned to transition to. Thus highlighting the importance of addressing barriers to transition readiness. A proposed solution to this problem has been the implementation of SCD transition programs and centers, however the efficacy and sustainability of these programs is still being monitored. Additionally, in a 2014 study regarding the risk factors for a successful transition, Andemariam et al. found that a greater distance between transition centers and patients with SCD was associated with unsuccessful transitioning. This underscores the importance of accounting for social determinants of health when addressing the transition process.
A further barrier to successful transition is a lack of knowledgeable providers. In a 2011 study that surveyed pediatric providers at several SCD centers, Sobota et al. found that only 60% of centers sent their patients to hematologists specializing in adult SCD and noted that some centers sent their patients to internist instead. Providers also noted that difficulty in finding adult SCD physicians was a large barrier for transition. This corresponds with evidence that transition-aged patients are less likely to receive disease-modifying therapies following childhood.
The final point is that age should be taken into consideration for transition. Andemariam et al. also found that an older age at the time of initiating the transition process correlated with unsuccessful transition (2014). Coupled with our findings of higher mortality with increasing transition age, it is imperative that transition readiness education begin in early adolescence.