The burden of hospital admissions for skeletal dysplasias in Sri Lanka: a population-based study

To the best of our knowledge, this study represents the first-ever examination of trends in hospital admissions for skeletal dysplasias group using population-based data. Using data from the eIMMR system, we were able to identify 606 admissions for skeletal dysplasias between 2017 and 2020. Utilizing the specific eIMMR dataset proved beneficial, as it recorded 25,748,103 (95%) out of the total 27,289,524 hospitalization episodes in Sri Lanka during this period (see Additional file 1). However, the deployment of eIMMR is still not complete, because of certain infrastructure gaps that are particularly evident in remote hospitals. According to a recent study conducted in the eastern province of Sri Lanka, data input facilities for the eIMMR system have been introduced in approximately 80% of hospitals [16]. Moreover, it is important to highlight that the eIMMR data could not be used to calculate the incidence rates of skeletal dysplasias, because multiple entries from a single patient may exist due to the lack of a unique patient identifying mechanism in the system [11]. Therefore, this preliminary study demonstrated trends in crude admission rates of overall and specific types of skeletal dysplasias. However, the hospital admission rates are also an important parameter in analysing the burden of skeletal dysplasia on health systems and for resource mobilization.

Over the course of the study period, yearly crude admission rates of skeletal dysplasias were at their highest recorded level in 2018, and the trend shows a steady drop afterward. We were unable to compare this trend to those of previous studies since there were limited worldwide data on the trends of hospital admissions for skeletal dysplasias. The total yearly number of hospital admissions for skeletal dysplasias decreased by 18.3% from 175 to 2019 to 143 in 2020. During the lockdown period brought on by the coronavirus pandemic, it has been reported that hospital admissions in Sri Lanka plummeted [17]. This could explain the considerable decrease in the number of patients hospitalized with skeletal dysplasias in 2020. On that account, we opted out post-COVID-19 data from our trend analysis and considered it as an outlier.

According to this study, the ratio of female to male hospital admissions was 1.4:1. The observed female predominance in hospital admissions for skeletal dysplasia may be attributed to a higher proportion of females being diagnosed with the condition, potentially due to sex-specific differences in disease presentation or identification. A similar female predominance was observed in a cohort of skeletal dysplasias children with short stature [18] and in several other studies that investigated birth prevalence rates of skeletal dysplasias [3, 19, 20]. This disparity might be explained by the larger proportion of female patients admitted to hospitals. Since the majority of skeletal dysplasias are autosomal disorders, theoretically an equal gender distribution is anticipated. It would be interesting to study the in-depth basis behind these observations in future epidemiological studies.

When analysing the health burden of specific disease entities, we found that admissions for osteogenesis imperfecta (OI) were the most common and accounted for the highest crude admission rate across the study period. This finding could be attributed to either a high readmission rate or a high prevalence rate of OI. Storoni et al. revealed that people with OI are hospitalized 2.9 times more frequently compared to the general population [21]. Another study conducted in the United Kingdom reported that OI patients had higher hospitalizations per year on average compared to other patients [22]. Patients with OI experience a variety of medical complications that may require a variety of surgical interventions over their lifetimes. Thus, recurring fracture episodes in OI patients may have resulted in frequent non-elective readmissions. On the other hand, OI has a high prevalence rate, which could lead to a high crude admission rate. In terms of skeletal dysplasia birth prevalence studies, larger multicentric and population-based studies reported a higher rate of OI than achondroplasia [23, 24], while some studies demonstrated comparable rates in both conditions [3, 20]. As both factors may have contributed to our finding, further research is crucial in determining whether better care is needed to reduce avoidable hospital readmissions in Sri Lanka.

In our study, the highest crude admission rate for skeletal dysplasias was noted in the 0–4 years age group. The age of diagnosis strongly associates with the peak age of hospital admissions for skeletal dysplasias, since patients must be hospitalized several times to explore the diagnosis. As skeletal dysplasias are genetic disorders that affect foetal and early childhood skeletal development, they can manifest either prenatally or in the first few months of life [25]. This could explain the higher number of preschool (0–4 years) admissions. Likewise, the age of diagnosis can vary depending on the specific type of skeletal dysplasia, with most types becoming apparent earlier in life, while others may not be diagnosed until later in childhood or even adulthood [1]. We observed that the majority of osteopetrosis cases were hospitalized in late childhood, in the age group of 10–14 years. The age of onset of osteopetrosis can vary according to three distinct clinical forms of the disease, with cases presenting in infancy (malignant, autosomal recessive), in childhood (intermediate, autosomal recessive), or in adulthood (Albers-Schönberg disease, autosomal dominant) [26]. One possible explanation could be the presence of specific genetic variants that are more commonly found in the Sri Lankan population, leading to a higher incidence of marble bone disease. Additionally, limited access to adequate medical care and diagnostic facilities may also play a role in the age of onset of osteopetrosis. The higher admission rate of childhood cases in Sri Lanka highlights the importance of early diagnosis and treatment for osteopetrosis, particularly in resource-limited settings.

Our analysis found a 54% rise in all skeletal dysplasias hospitalizations from 2017 to 2019. Firstly, it is possible that relatively low rates in the early years resulted from underreporting due to a lack of adaption to the eIMMR system. Secondly, this could be attributed to improved diagnostic ability in relation to these specific disorders. The implementation of genomic medicine into routine clinical practice may have had an effect on the number of diagnosed rare and complex disorders such as skeletal dysplasias, resulting in an increase in hospital admissions [5]. Nevertheless, osteogenesis imperfecta, achondroplasia, and osteopetrosis admissions have increased exponentially compared to other types of skeletal dysplasias during the given timeframe. It is important to note that genomic medicine is rarely offered to diagnose these three disorders in developing countries because clinical and radiological evidence is usually sufficient [27]. We might therefore conclude that the first explanation must have had a greater impact than the latter.

One of the main limitations of this study is that a few skeletal dysplasia types were excluded since they were not categorized under osteochondrodysplasias in the ICD-10 (Q77 and Q78). Because of this limitation, the burden of skeletal dysplasia hospital admissions in Sri Lanka may have been underestimated. Further the variable rates of hospital admissions required by different conditions depending on the management protocols of each skeletal dysplasia may have led to an over or underestimation of certain skeletal dysplasias. This limitation has arisen from the fact that the eIMMR in Sri Lanka is not linked to a unique patient ID. The other limitation of the study is that the eIMMR database does not provide specific details about the diagnostic process. This lack of detailed information on how the diagnosis was initially made can potentially limit the depth of the study’s analysis and understanding of the diagnostic procedures used for skeletal dysplasias.