Trends in Hospitalization Duration for Rare Diseases: A Retrospective Analysis of Sarcoidosis, Still’s Disease, and Systemic Sclerosis in Poland (2009–2018)

Background

OBJECTIVES:

Rare diseases, due to their specificity, require a separate approach in terms of predictive factors affecting the duration of hospitalization.

The main aim of this study was to identify selected predictive factors and the length of stay in selected rare autoimmune diseases in Poland. Considering the previous cycle of epidemiology research, this study included the analysis of sarcoidosis [6], systematic sclerosis [7] and adult-onset Still’s disease [8]. The secondary aim was to verify the average length of hospitalization for selected rare diseases in Poland as compared with the EU average.

This was a descriptive study. The obtained preliminary results may lay the groundwork for future analysis, such as using length of stay as an indirect hospital cost factor, assessing costs of rare diseases in Poland, evaluating factors influencing increased spending, and proposing cost optimization strategies. An analysis of predictive factors in these selected rare diseases is based on data on hospital morbidity collected in multiannual studies on public statistics.

Material and Methods

ETHICS STATEMENT:

The study protocol was submitted and reviewed by the Ethics Committee at the Medical University of Warsaw – document number: AKBE/166/2023. Written informed consent was obtained from all participants.

DATA ACQUISITION:

In this retrospective, population-based study, we analyzed hospital discharge records of patients diagnosed with sarcoidosis, Still’s disease, and systemic sclerosis. Data were obtained from the National Institute of Public Health (NIH), National Research Institute in Poland, and they covered 78 626, 3294, and 35 549 hospitalizations, respectively, which were reported in the years 2009–2018. The analyzed time period is strongly related to the previous cycle of epidemiology research.

All hospitals in Poland, except psychiatric and military facilities, are legally required to send discharge data to the Institute. The data are anonymous and include information on hospitalizations with ICD10-code diagnoses, dates of admission and discharge, birth date, sex, and place of residence. We also obtained demographic data for the general Polish population from the Central Statistical Office of Poland. We assumed that diagnoses in hospitals were based on the most current, widely used criteria.

The high degree of completeness of data on hospital morbidity results from the legal obligation imposed on inpatient healthcare units to periodically report data on hospitalizations to the National Institute of Public Health, National Institute of Hygiene. The accuracy and credibility of data result from the efficiency and accuracy of reporting by individual entities. The large group of respondents covering almost 100% of hospitalizations in Poland guaranteed the accuracy and reliability of the data analyzed in this study. Data from the national register are anonymous, but properly adjusted tools for statistical analysis made it possible to obtain data on hospitalizations and predictive factors.

STATISTICAL ANALYSIS:

To perform the statistical analyses, R software was used. We computed means and medians for continuous variables, and counts and percentages for categorical variables. The analysis broken down by hospital departments was based on the Pareto principle, and it presents entities where about 80% of all hospitalizations took place. The analysis of the length of hospitalization included first-time and subsequent hospitalizations.

LITERATURE ANALYSIS:

A literature search was performed using the PubMed electronic database. The search term used to identify the articles was the length of stay. The search was limited to full-text English-language studies published in the years 2018–2022. The reference lists of relevant studies were searched to identify additional articles.

Results

LOS VS TIMELINES:

In the analyzed period, the average length of hospitalization for selected diseases was steadily decreasing, and in 2009–2018 it was 5.39 days (standard deviation, SD=5.31) for sarcoidosis (78 626 cases), 6.22 days (SD=6.29) for scleroderma (35 549 cases), and 7.44 days (SD=9.15) for Still’s disease (3294 cases). The largest difference in the average value between 2009 and 2018 was recorded for Still’s disease, where 11.7 days and 5.81 days were reported, respectively. The difference was not as significant for other diseases, but at the end of 2018 it was less than 6 days. After 2016, the average length of hospitalization for the analyzed diseases was shorter than the average for all-cause hospitalizations in Poland and in the European Union (Figure 1).

LOS VS NUMBER OF HOSPITALIZATIONS:

The average length of stay in the group of patients with first-time hospitalization was shorter for each of the analyzed diseases as compared to the length of the second and subsequent hospitalizations. The most significant differences were observed in Still’s disease and the least significant ones in sarcoidosis. Details are presented in Table 1.

LOS VS SEX:

No significant differences were observed for the length of hospitalization between males and females. The mean length of hospitalization for sarcoidosis was 5.48 days (SD=5.30) in women and 5.31 (SD=5.31) days in men. The mean length of hospitalization for scleroderma was 6.28 days (SD=6.24) in women and 5.97 days (SD=6.50) in men. The mean length of hospitalization for Still’s disease was 7.39 days (SD=8.47) in women and 7.52 days (SD=10.0) in men. However, an increased proportion of hospitalizations of over 10 days was observed for scleroderma and Still’s disease as compared to sarcoidosis (Figure 2).

LOS VS AGE GROUPS:

Analysis by sex showed significant differences in lengths of hospitalization for Still’s disease. The longest hospitalizations were recorded in both the youngest and the oldest age groups. Similar differences were not observed in sarcoidosis and scleroderma, which showed an increase in mean and median length of hospitalization with age (Table 2).

LOS VS HOSPITAL WARDS:

A comparison of the mean length of hospitalization for the analyzed diseases in 2 wards where the percentage of hospitalization was the highest in a given disease, with the average length of hospitalization in these wards, regardless of the disease, shows that it is similar for all diseases and wards (Figure 3), except for sarcoidosis. The mean length of hospitalization in tuberculosis and lung disease wards was 7.7 days (sarcoidosis 5.2 days), internal medicine ward 6.6 days (Still’s disease 6.5 days), rheumatology ward 6.2 days (Still’s disease 6.2 days, scleroderma 6 days), and dermatology ward 5.3 days (scleroderma 5.5 days) (Figure 3). There are no data on the length of hospitalization for sarcoidosis in lung disease wards in Poland.

LOS VS MULTIMORBIDITY (VOLUME):

The mean length of hospitalization increased with each additional comorbidity, whereby 3 additional comorbidities prolonged the average hospital stay by more than 4 times. The greatest differences were observed for Still’s disease; however, the dispersion of results for 2 and 3 comorbidities was comparable to or smaller than other diseases. Details are presented in Table 3.

LOS VS MULTIMORBIDITY (TYPES):

A large variation was observed in the mean length of hospitalization for Still’s disease in the group of patients with parasitic and respiratory diseases as compared to other comorbidities. The average length of hospitalization among persons with parasitic diseases was the longest in scleroderma and sarcoidosis patients. The second most common group of comorbidities in patients with sarcoidosis was skeletal diseases. Among patients with scleroderma, these were cardiovascular diseases; however, in this group of patients, hospitalizations were clearly shorter in patients with cancer. Details are shown in Figure 4.

Discussion

STUDY ADVANTAGES AND LIMITATIONS:

This epidemiological study’s main strength is that it used population-based registry data related to hospital data, which enabled analysis of the inpatients’ characteristics and trends in length of stay of patients with sarcoidosis, scleroderma, and Still’s disease. Therefore, we were able to estimate the healthcare burden of those RDs in a large cohort of patients.

The limitation of the study is its descriptive and exploratory nature aimed at investigation of length of hospital stay as an organizational factor in the management of rare diseases. Further research and statistical analyses are needed to show the strength of the impact of individual factors on length of stay. In the long-term research perspective, it is also worth analyzing length of stay as an indirect cost-generating factor in health care. These results can be used for more efficient organization and financing of treatment of rare diseases in Poland and across the globe.

Conclusions

The issue of rare diseases in Poland is receiving increasing attention. It can be concluded that rare diseases are a special and specific group of diseases that require individual analyses, which can only be performed on the basis of large national data registers.

The main aim of this study was to analyze selected predictive factors and the length of hospital stay in chosen rare autoimmune diseases in Poland. Considering the previous cycle of epidemiology research, this study includes the analysis of sarcoidosis, systematic sclerosis, and adult-onset Still’s disease.

The study showed that hospitalizations of selected rare diseases do not cause a significant burden for the healthcare system. Therefore, the strategy that has been implemented so far in inpatient treatment of rare diseases should be continued. However, it is important to draw public and social attention to the very issue of rare diseases in order to improve the quality and availability of care for patients with rare diseases. Due to the specificity of their disease, these patients tend to have difficulties in obtaining a proper diagnosis, and it often takes a long time before they get to the right specialist and start treatment [32].

The results of the conducted research also showed that advanced age and comorbidities are important factors determining the length of hospitalization. The average length of hospital stay for selected rare diseases in Poland is not longer than the EU average, so it can be assumed that the process of inpatient treatment in Poland is optimal.

The findings for hospitalization rate and average LOS could serve as a starting point for further improvement in organization of treatment of rare diseases. Studies on the burden of RDs and their costs are crucial to the planning of resource distribution because funds for RD prevention, diagnosis, and treatment are typically distributed using a prevalence-based criterion.

Further studies are needed on holistic, systemic solutions for patients and their families. This topic requires a holistic approach, integrated activities of many groups of specialists, and decisive action. Optimization of the treatment will also be possible thanks to the use of the results of this study and further in-depth analyses.