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This study uncovers significant trends in hospitalization of patients with rheumatoid arthritis (RA) in Polish intensive care units (ICUs) and cardiac intensive care units (CICUs) from 2011 to 2021, highlighting an increase in admissions and ICU/CICU mortality, particularly in 2021, likely linked to the COVID‑19 pandemic. A key finding is a high ICU/CICU mortality rate of 39.1%, especially among older patients and those admitted urgently. This research emphasizes a critical need for early intervention and comprehensive management strategies to improve outcomes for RA patients in critical care, offering new insights into the burden of severe RA complications and their management in clinical practice.

Introduction

Rheumatoid arthritis (RA) is a chronic systemic connective tissue disease of immunological origin, characterized by nonspecific symmetrical inflammation of the joints, the occurrence of extra‑articular changes, and systemic complications, leading to disability, handicap, and premature death. RA affects approximately 0.5%–1% of the global population, with the highest incidence around the age of 80 years.^1,2 Without treatment, RA patients experience numerous exacerbations leading to disability and poor health outcomes. Early treatment can improve performance and reduce disease activity, but mortality remains similar for both early and late treatment.³

The patients with RA often develop other chronic conditions that significantly affect their health. Cardiovascular diseases are the most common cause of death in this population. One of the most critical complications of RA is coronary artery disease.^4,5 RA patients have twice the risk of heart attack and up to by 50% higher risk of cardiovascular mortality than the general population.⁶ The prevalence of type 2 diabetes is also increased in patients with RA. Glucocorticoids, used to suppress inflammation in RA, adversely affect glycemic control, and diabetes further exacerbates cardiovascular risk.⁷

Respiratory diseases are the second leading cause of death in RA patients, occurring in 30%–40% of cases. RA can affect the lung interstitium, airways, pleura, and less frequently the pulmonary vessels.⁶ Conditions such as pleuritis, bronchiolitis, and interstitial lung disease (ILD) are also associated with RA. Reports indicate that ILD develops in 5%–16% of RA patients, and its occurrence is associated with shorter survival.^8,9 Moreover, venous thromboembolic disease is more prevalent in RA patients, especially during therapy with tumor necrosis factor inhibitors and Janus kinase inhibitors.¹⁰

Chronic anemia and Felty syndrome are common complications in patients with seropositive RA.¹¹ Secondary Sjögren syndrome, present in about 10% of RA patients, further complicates the disease. Rheumatoid vasculitis, though rare, can have severe consequences, resembling polyarteritis nodosa.^11,12 Furthermore, the patients with RA have a higher likelihood of developing diseases such as Hodgkin and non‑Hodgkin lymphoma than the general population.¹³

Premature death is a common outcome of RA complications and their treatment. Serious infections, exacerbated by disease‑modifying antirheumatic drugs (DMARDs) and immune system dysfunction, pose significant risks.¹⁴ Osteopenia and osteoporosis, resulting from the disease and drug therapies, increase the risk of fractures, particularly in postmenopausal women and older adults.¹⁵ RA also affects the gastrointestinal system and kidneys, mainly through drug therapies.⁶ Depression, a frequent complication, affects patients with long‑term active disease and significant physical dysfunction.¹⁶

RA is one of the most prevalent rheumatological conditions necessitating admission to intensive care units (ICUs).^17-19 The patients with RA have a significantly elevated risk of ICU admission, as compared with the general population, with over 1% of RA individuals experiencing critical illness annually, and a cumulative 10‑year risk approaching 8%.²⁰ This increased risk is often attributed to the disease exacerbation or adverse effects of immunosuppressive therapy.^17,21 The cardiovascular and respiratory systems are the most frequently affected.^18,20

Mortality in this patient population is associated with several factors, including the severity of illness measured by the Acute Physiology and Chronic Health Evaluation (APACHE) II score, the updated Charlson Comorbidity Index, the Sequential Organ Failure Assessment (SOFA) score, the need for vasopressor support, advanced age, prolonged prothrombin time / international normalized ratio, cytopenia, and extended hospital stays.^17,19,22

Hospitalization in an ICU or a cardiac intensive care unit (CICU) indicates a severe exacerbation of the illness, often requiring advanced medical interventions and constant monitoring. Understanding the factors related to ICU or CICU admissions among RA patients is crucial for improving clinical outcomes, optimizing resource allocation, and developing preventive strategies to reduce the burden of severe complications.

The aim of this study was to characterize selected factors related to ICU/CICU hospitalizations of Polish patients diagnosed with RA over a long‑term perspective, covering the years 2011–2021. This study sought to identify the patterns and trends in hospital admissions, evaluate the impact of comorbidities, and explore the outcomes of RA patients requiring intensive care. By gaining insights into these aspects, the research aimed to contribute to better management strategies and enhanced care for the individuals suffering from this debilitating condition.

Patients and methods

This retrospective study utilized anonymized data derived from the Polish national hospital morbidity registry. The research was conducted in collaboration with the Department of Social Medicine and Public Health of Medical University of Warsaw, and institutions such as the National Institute of Public Health NIH – National Research Institute and the National Institute of Geriatrics, Rheumatology, and Rehabilitation. The study was approved by the ethics committee of the National Institute of Geriatrics, Rheumatology, and Rehabilitation in Warsaw (KBT‑4/4/2024). The ethics committee did not require an informed consent from the patients analyzed in this retrospective study and approved publication of its results. Each study procedure complied with the Declaration of Helsinki or similar standard of ethics.

High completeness of the hospital morbidity data is due to the legal obligation imposed on inpatient health care units to periodically report hospitalization data to the National Institute of Public Health – National Institute of Hygiene. The information is reported by the hospitals using the General Hospital Statistical Card Mz/Szp‑11, covering all hospitalizations within the analyzed period. The accuracy and reliability of the data result from the efficiency and precision of reporting by individual entities. The study population, encompassing nearly 100% of hospitalizations in Poland, ensures the accuracy and reliability of the utilized data.

The study inclusion criteria comprised an ICU or CICU stay code in the hospitalization record and an International Classification of Diseases, Tenth Revision (ICD‑10) code for RA (M05, M05.x, or M06, M06.x) in the reported hospital morbidity data.

Both criteria had to be met simultaneously for patient inclusion in the study. There were no exclusion criteria.

The study involved 3066 hospitalization records. Of these, 2815 hospitalizations (91.8% of all records) were in the ICUs, and 251 (8.2%) in the CICUs. The majority of hospitalizations concerned women (n = 2270; 74%). Women accounted for 74.3% of the ICU and 71.3% of the CICU hospitalizations. The age of patients ranged from 19 to 96 years (mean [SD], 65.2 [11.5] years; median, 66 [range, 19–96] years).

Results

The analysis demonstrated that 1198 patients out of the studied population (39.1%) died during their stay in the ICU/CICU. Figure 1 shows the trend lines for the number of ICU/CICU admissions and the number of deaths per year.

The chart indicates an increase in the ICU/CICU admissions and deaths in 2021, possibly related to the COVID‑19 pandemic.

In the next section, the factors related to the hospital admission were analyzed. As many as 1885 patients (63.9% of the study population) were urgently admitted to the hospital. The LOS ranged from 0 to 248 days (median [interquartile range {IQR}], 14 [7–23.75] days).

Mortality rates among the ICU patients were compared with those in the CICU, with the value of 42% in the former and 6.4% in the latter. The χ² test showed a notable relationship between the type of ICU and the occurrence of death (χ² = 123; P <⁠0.001; ϕ = 0.2).

Table 1 presents the frequency of disease groups based on ICD‑10 codes for the primary diagnosis upon admission to the first ward. It shows that the largest group consisted of patients with diseases of the circulatory system (22% of the study population), musculoskeletal system and connective tissue (19.5% of the study population), and respiratory system (16.2% of the study population). Conversely, out of specific system diseases, the notably high ICU/CICU mortality rates were observed in patients with gastrointestinal (58.5% ICU/CICU mortality), endocrine, nutritional, and metabolic diseases (61.5% ICU/CICU mortality). The longest median (IQR) LOS was associated with the diseases of the skin and subcutaneous tissue (26 [19–39] days), while the shortest with pregnancy, childbirth, and puerperium (8 [5–14.5] days), where none of the 23 patients died. This lower ICU/CICU mortality rate and shorter LOS in the pregnancy, childbirth, and puerperium group could be attributed to the generally healthier and younger population and the nature of the hospital admission related to childbirth rather than acute or severe illness.

Table 2 lists the primary wards to which the patients were admitted. The wards not shown in the Table had individual frequencies below 5%. In the analyzed population of patients with RA, the most common initial admission was to a department of trauma and orthopedic surgery, which accounted for 18.4% of all patients, primarily for elective procedures. Other common initial departments included ICU (18%), internal medicine (10.8%), hospital emergency (9.5%), general surgery (7.2%), and CICU (5.8%). In these cases, the admissions were predominantly emergencies.

Figure 2 shows the percentage of deaths among patients admitted to a hospital on an urgent vs elective basis. The data indicate a significantly higher ICU/CICU mortality rate among the patients admitted urgently, as compared with those admitted electively. Specifically, the urgent admissions accounted for a ICU/CICU mortality rate of 52.8%, whereas the elective admissions had a substantially lower ICU/CICU mortality rate of 16.1%. This disparity can be attributed to a critical nature of conditions requiring the urgent admission, where patients often present with severe, life‑threatening complications necessitating immediate medical intervention. In contrast, elective admissions typically involve preplanned procedures for managing chronic conditions or routine surgeries, allowing for better preparation and stabilization of the patient’s health status prior to admission. The literature points out that surgical patients generally have better ICU prognoses than nonsurgical ones, who may present with complex, multisystem conditions requiring intensive, multifaceted management.²³​ Our findings highlight the importance of timely and effective acute care management for reducing ICU/CICU mortality rates in emergency situations.

In the logistic regression analysis, the dependent variable was death. The predictors included sex, age, and hospital admission mode. The results are presented in Table 3.

The data included in Table 3 indicate that sex was not a predictor of ICU/CICU mortality in the studied population (P = 0.6). However, the results suggest that the older the patient is during their ICU/CICU stay, the higher the risk of death (P <⁠0.001). There is also a higher risk of death among patients admitted to the hospital on an urgent basis (P <⁠0.001).

Discussion

This study provides a comprehensive analysis of hospitalizations of patients with RA in Polish ICUs and CICUs over a decade of 2011–2021. The findings highlight significant trends and outcomes that are crucial for understanding the burden of severe RA complications and improving patient management strategies.