Abstract
Background
Pneumonia is a serious complication in Guillain-Barre syndrome (GBS) patients, associated with increased mortality, yet its risk factors remain underexplored.
Methods
Our study analyzed clinical factors linked to pneumonia in GBS patients through a retrospective review of 101 individuals admitted to Tianjin Huanhu Hospital between January 2020 and December 2023. Patients were divided into two groups based on pneumonia development after admission: GBS with pneumonia (n = 19) and GBS without pneumonia (n = 82). Clinical and blood parameters were compared between the groups. Logistic regression analysis identified predictive factors for pneumonia in these GBS patients.
Results
Significant associations were found between pneumonia and older age (P = 0.01), bulbar palsy (P = 0.017), mechanical ventilation (MV) support (P < 0.01), hypoalbuminemia (P < 0.01), hyponatremia (P < 0.01), and underlying conditions (P = 0.008). Multivariate logistic regression identified bulbar palsy, MV support and hyponatremia as significant independent risk factors for pneumonia. Finally, GBS patients with pneumonia experienced longer hospital stays and worse functional outcomes.
Conclusions
We initially identified key risk factors for pneumonia in GBS, highlighting its association with poorer prognoses.
Supplementary Information
The online version contains supplementary material available at 10.1186/s12883-026-04668-0.
Keywords: Guillain-Barré syndrome, Pneumonia, Bulbar palsy, MV, Hyponatremia, Prognosis
Introduction
Guillain-Barré syndrome (GBS) is a rare, immune-mediated disorder characterized by acute inflammatory demyelination of the peripheral nerves. This syndrome typically presents with rapidly progressive weakness, often accompanied by sensory disturbances, and can lead to a wide range of complications that significantly affect patient outcomes [1]. These complications are pneumonia, gastrointestinal disorders, urinary tract infections, headaches, skin rashes, disturbances in electrolyte balance, thrombosis, sleep disturbances, and edema. Among them, pneumonia is the most frequent complication that is involved in 56% of ventilator dependence patients and in 16% of all patients [1, 2]. The mortality rate in GBS patients is 2–10% [3]. Given the substantial impact that pneumonia has on morbidity and mortality, it is essential to identify and mitigate the risk factors associated with its occurrence in GBS patients. A comprehensive understanding of the clinical characteristics and risk factors associated with pneumonia in GBS will provide valuable insights to healthcare providers, allowing them to implement targeted strategies to reduce mortality and disability among patients. Therefore, this study is designed to identify specific risk factors that contribute to the development of pneumonia in individuals diagnosed with GBS, with the hope of informing clinical practice and improving patient care.
Methods
Patient cohort
We conducted a retrospective analysis of clinical data from 101 patients with GBS who were treated at Tianjin Huanhu Hospital between January 2020 and December 2023. The diagnostic criteria adhered to the revised guidelines established by Willison et al. in 2023 [4]. Patients under 16 years of age or those with unclear diagnoses or incomplete clinical information were excluded from the study. The study outcome was divided into GBS with pneumonia group and GBS without pneumonia group according to whether GBS patients developed pneumonia after 48 h of hospitalization. Informed consent was obtained from all participants and/or their legal guardians. Detailed flowchart information can be found in Fig. 1.
Fig. 1.
Flowchart of Patient Selection and Analysis for Identifying Pneumonia Risk Factors in GBS. The study initially assessed 178 patients, of whom 77 were excluded due to missing clinical data, uncertain diagnosis, or recurrent GBS. The final cohort comprised 101 GBS patients, categorized into two groups: those without pneumonia (n=82) and those with pneumonia (n=19). Statistical analysis identified predictors, including bulbar palsy and hyponatremia, and the need for MV could serve as predictors for pneumonia in GBS patients. Furthermore, the study emphasizes the association between pneumonia and poor outcome in patients with GBS
Definition of pneumonia in GBS patients
Pneumonia was defined as a clinical suspicion accompanied by a new or worsening infiltrate noted on chest radiographs, along with at least two of the following criteria [5]: (a) a temperature exceeding 38.3 °C, (b) the presence of purulent tracheal secretions, (c) white blood cell count greater than 12,000/mm³ or less than 4,000/mm³. Samples obtained from bronchoalveolar lavage or protected specimen catheters underwent microbiological analysis, with a result being considered positive if the colony-forming units exceeded 10^4/ml.
Observational indicators and testing methods
We utilized the clinical data to access the Hughes Functional Grading Scale (HFGS), which is evaluated the outcomes of GBS patients at discharge, with scores ranging from 0 to 6 [6]. These scores reflect functional status, indicating categories from normal functioning to death, including mild symptoms, the ability to walk independently or with assistance, being bedridden, and requiring mechanical ventilation (MV) for respiratory support. The presence of bulbar palsy was clinically evaluated based on cranial nerve involvement affecting speech or swallowing. Autonomic dysfunction was defined as dysregulation of cardiac, gastrointestinal, bladder, pupillary, blood pressure, and sweat secretion functions. Underlying diseases included hypertension, diabetes, coronary heart disease, and stroke. Blood samples from GBS patients were analyzed for liver function, serum sodium, and albumin levels at admission. All the patients were not obtained prior to treatment with intravenous immunoglobulin or plasma exchange at admission. We defined hyponatremia as a serum sodium concentration < 135mmol/L at the time of hospital admission [7]. Hypoalbuminemia was defined as a serum albumin concentration < 35 g/L at the time of hospital admission. Additionally, abnormal liver function tests were defined as a serum alanine aminotransferase (ALT) and/or aspartate aminotransferase (AST) level exceeding the upper limit of the laboratory’s normal reference range. The prognosis of GBS patients was assessed using three indicators: HFGS score at discharge, length of hospitalization, and the ability to walk two months post-discharge.
Statistical analysis
Data analysis was conducted using SPSS version 27.0. Categorical data were presented as percentages (%), and intergroup comparisons were performed using the chi-square test. Continuous variables were expressed as means ± standard deviation (x ± s), with comparisons between groups utilizing the t-test. For data with skewed distributions, the median (P25-P75) was reported, and intergroup comparisons were analyzed with the Mann-Whitney U test, applying the normal approximation method to determine P-values. Multicollinearity diagnostic tests were carried out by variance inflation factor (VIF) using SPSS 27.0. In general, it is considered that a VIF greater than 5 roughly indicates statistically significant problem of multicollinearity. We employed a multivariable logistic regression model to identify independent risk factors for pneumonia associated with GBS. A P-value of less than 0.05 was deemed statistically significant.
Results
Comparison of baseline clinical characteristics
In this study cohort, we included 101 patients with GBS, of whom 19 had pneumonia and 82 did not. One (5.3%) patient with GBS and pneumonia died during hospitalization. A comparison of clinical characteristics between the two groups indicated no significant differences regarding gender (P = 0.345), the relatively higher prevalence of onset season (P = 0.278), antecedent infection events (P = 0.805), autonomic dysfunction (P = 0.270), abnormal liver function tests (P = 0.340), electrophysiological subtype (P = 0.667), immunoglobulin (IVIG) treatment (P = 0.197) and plasma exchange (PE) treatment (P = 0.159). However, patients with pneumonia were significantly older (P = 0.010) and more likely to have bulbar palsy (P = 0.017), underlying conditions (P = 0.008), MV requirements (P < 0.001), hypoalbuminemia (P < 0.001) and hyponatremia (P < 0.001) compared to those without pneumonia. Detailed information can be found in Table 1.
Table 1.
Demographic and clinical data in GBS based on Pneumonia. Abbreviations: MV=mechanical ventilation; PE=plasma exchange; IVIG=intravenous immunoglobulin; HFGS=Hughes functional grading scale
| Clinical features | GBS without pneumonia | GBS with pneumonia | P | |
|---|---|---|---|---|
| (n = 82) | (n = 19) | |||
| Demographics | ||||
| Sex, n (%) | Male | 51 (62 2%) | 14 (73.7%) | 0.345 |
| Female | 31 (37.8%) | 5 (26.3%) | ||
| Age(years), M(P25,P75) | 52.5(38.5–60.5) | 64 (53.0–73.0) | 0.010 | |
| Season, n (%) | Winter and spring | 32 (39.0%) | 10 (52.6%) | 0.278 |
| Summer and autumn | 50 (61.0%) | 9 (47.4%) | ||
| Antecedent infection event, n (%) | None | 50 (61.0%) | 11 (57.9%) | 0.805 |
| Upper airway infection | 17 (20.7%) | 5 (26.3%) | ||
| Diarrhea | 15 (18.3%) | 3 (18.5%) | ||
| Bulbar paralysis, n (%) | No | 68 (82.9%) | 11 (57.9%) | 0.017 |
| Yes | 14 (17.1%) | 8 (42.1%) | ||
| Autonomic dysfunction, n (%) | No | 46 (56.1%) | 11 (57.9%) | 0.270 |
| Yes | 36 (43.9%) | 8 (42.1%) | ||
| MV, n (%) | No | 81 (98.8%) | 9 (47.4%) | < 0.001 |
| Yes | 1 (1.2%) | 10 (52.6%) | ||
| Electrophysiological subtype, n (%) | Demyelinating | 54 (65.8%) | 11 (57.9%) | 0.667 |
| Axonal | 26 (31.7%) | 7 (36.8%) | ||
| Normal | 0 (0%) | 0 (0%) | ||
| Equivocal/inexcitable | 2 (2.5%) | 1(5.3%) | ||
| Underlying diseases (included hypertension, diabetes, coronary heart disease, and stroke), M (P25, P75) | 0 (0–1) | 1 (0–3) | 0.008 | |
| Abnormal liver function tests, n (%) | No | 75 (91.5%) | 16 (84.2%) | 0.340 |
| Yes | 7 (85%) | 3 (15.8%) | ||
| Hypoalbuminemia, n (%) | No | 80 (97.6%) | 8 (42.1%) | < 0.001 |
| Yes | 2 (2.4%) | 11 (57.9%) | ||
| Hyponatremia, n (%) | No | 76 (92.7%) | 6 (31.6%) | < 0.001 |
| Yes | 6 (7.3%) | 13 (68.4%) | ||
| Treatment | ||||
| IVIG, n (%) | No | 25 (30.5%) | 3 (15.8%) | 0.197 |
| Yes | 57 (69.5%) | 16 (84.2%) | ||
| PE, n (%) | No | 77 (93.9%) | 16 (84.2%) | 0.159 |
| Yes | 5 (6.1%) | 3 (15.8%) | ||
Multivariable logistic regression analysis
Based on the findings in Table 1, we selected indicators that exhibited significant differences into the multicollinearity test. The VIF values for all variables were less than 5, indicating that there was no multicollinearity among the independent variables. Then we incorporated them for the multivariable logistic regression analysis. The results indicated that bulbar palsy, MV and hyponatremia were significant risk factors for pneumonia (all OR values > 1, P = 0.012, P = 0.010, P = 0.020 respectively). For more details, please refer to Table 2.
Table 2.
Multivariate regression analyses for predictors of GBS associated pneumonia
| Age | P | OR |
|---|---|---|
| 0.121 | 1.063 (0.984–1.147) | |
| Hypoalbuminemia | 0.953 | 1.080 (0.082–14.292) |
| Hyponatremia | 0.020 | 0.057 (0.005–0.637) |
| Underlying diseases | 0.657 | 0.817 (0.334–1.996) |
| Bulbar paralysis | 0.012 | 0.116(0.220–0.497) |
| MV | 0.010 | 0.052 (0.005–66.326)) |
Comparison of prognosis parameters
Comparing the outcome characteristics between the two groups, we found that patients with pneumonia had significantly higher HFGS scores at discharge (P < 0.001), longer hospital stays (P = 0.002), and a greater inability to walk independently at two months (P < 0.001) compared to those without pneumonia. For further details, please refer to Table 3.
Table 3.
Association between pneumonia and outcomes in patients with GBS
| Outcome | GBS without pneumonia | GBS with pneumonia | P | |
|---|---|---|---|---|
| (n = 82) | (n = 19) | |||
| HFGS score at discharge | 2 (0 ~ 3) | 4 (3 ~ 4) | < 0.001 | |
| Days of hospitalization | 13 (1 ~ 18) | 20 (14 ~ 31) | 0.002 | |
| Inability to walk independently at 2 months | No | 21 (25.6%) | 16 (84.2%) | < 0.001 |
| Yes | 61 (74.4%) | 3 (15.8%) | ||
Discussion
Our study revealed an incidence of pneumonia in patients with GBS, reaching up to 18.8%, and pneumonia accounts for 52.6% of GBS patients with MV requirement. Therefore, the prevention of pneumonia in GBS must be a primary therapeutic goal. However, limited attention was paid on relevant risk factors for GBS associated pneumonia. In our study, bulbar palsy, MV support and hyponatremia were the factors independently associated with pneumonia. Notably, GBS patients who develop pneumonia experience a significant increase in disability and mortality rate.
As we known, pneumonia is predominantly associated with aspiration [8] and represents a significant source of morbidity and mortality in patients suffering from acute neurological conditions. In cases of GBS, oropharyngeal dysphagia is often linked to the involvement of cranial nerves. Bulbar palsy may lead to dysphagia, dysarthria, and an increased risk of asphyxiation, thereby increasing the likelihood of aspiration pneumonia, which can ultimately compromise respiratory function. Researches had demonstrated that the microbiological profiles of pneumonia patients frequently align with those who experience aspiration [9, 10]. Consistent with prior evidence identifying bulbar palsy as a key risk factor for respiratory decline and pulmonary infection in GBS [11], our findings substantiate a correlation between the severity of bulbar weakness and pneumonia risk.
Hyponatremia is commonly observed in patients with GBS, with a reported incidence of 23% in clinical studies [12]. In our research, we identified an incidence rate of 19%. The underlying mechanism of hyponatremia is thought to involve increased secretion of antidiuretic hormones coupled with reduced sodium reabsorption due to sympathetic innervation loss in GBS patients [13, 14]. Hyponatremia can lead to pulmonary and airway edema, which may increase airway secretions and respiratory resistance, thereby elevating the risk of pneumonia, particularly in those with severe respiratory muscle paralysis. Previous studies have confirmed the GBS with hyponatremia at admission predicting more severe disease course and worse outcome [15]. Besides, a well-documented association exists between hyponatremia and both heightened disease severity and longer hospitalization in individuals with pneumonia [16].
Respiratory failure is one of the most severe symptoms in patients with GBS. While MV is considered the most effective method to prevent lung collapse, thereby improving respiratory function, it also significantly heightens the risk of pneumonia and mortality among these patients [17]. As we known, hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP) are both common iatrogenic infections associated with high morbidity and mortality rates [5, 18]. The incidence of HAP increases by as much as 6- to 20-fold in mechanically ventilated patients [19]. Pneumonia caused by multidrug-resistant pathogens is associated with increased patient mortality and morbidity [20]. Endotracheal intubation bypasses anatomical barriers, impairs mucociliary clearance, promotes the pooling of secretions above the endotracheal tube cuff, and provides a surface for biofilm formation - all of which contribute to a high risk of bacterial colonization and subsequent pneumonia. Our study was consistent with the previous studies. While the reported global incidence of VAP ranges from 7 to 43 cases per 1000 ventilator-days [21], the calculated incidence in our GBS ventilated cohort was 58.3 cases per 1000 ventilator-days (19/326), suggesting a higher risk level. This elevated risk may be associated with GBS-specific factors such as respiratory muscle weakness, bulbar palsy and autonomic dysregulation [2]. However, how can we better predict the MV outcome in GBS? Previous researches had shown that delaying intubation or prolonging the duration of MV [22] or delayed tracheostomy (> 14 days post-intubation) can increase the likelihood of developing pneumonia [10]. We must explicitly acknowledge the limitations in our study that we did not discuss the timing of intubation, the duration of ventilation, and the optimal timing for tracheostomy, which necessitates future prospective investigations to establish robust conclusions.
However, our study has several limitations that warrant consideration. First, being a retrospective study, it is subject to biases and incomplete data, and it is confined to patients from a single institution, which may result in sample bias. Second, while we identified several significant predictive factors, future research should explore other potential variables (such as microbiological culture results for respiratory secretions, the timing and duration of mechanical ventilation and functional vital capacity) and incorporate them into a more comprehensive predictive model to facilitate more accurate prognostic assessments. Third, due to the limited sample size in our study, future external validation with larger sample sizes is warranted to enhance the clinical diagnostic performance.
Conclusion
In summary, considering our retrospective study design and modest cohort size, these results should be considered preliminary and, before clinical use is considered, their prognostic relevance needs to be further defined in a larger prospective study to find out whether admission sodium level, dysphagia, and MV support gives also clinically relevant value. If so, early identification of subclinical dysphagia, correction of hyponatremia, and vigilant management of mechanical ventilation complications may represent key factors in reducing pulmonary infections in patients with GBS.
Supplementary Information
Acknowledgements
We thank Lei Chen for excellent technical support.
Abbreviations
- GBS
Guillain-Barre syndrome
- HFGS
Hughes Functional Grading Scale
- MV
Mechanical Ventilation
- VIF
Variance Inflation Factor
- ROC
Receiver Operating Characteristic
- IVIG
Immunoglobulin
- PE
Plasma Exchange
- AUC
Area Under the Curve
- ALT
Alanine Aminotransferase
- AST
Aspartate Aminotransferase
- HAP
Hospital-acquired Pneumonia
- VAP
Ventilator-associated Pneumonia
Authors’ contributions
Zhihong Shi：Conception and design; Li Chen: Analysis and manuscript writing; Hui Yang and Wenjun Feng: Collection and assembly of data; Weiwei Gao and Tingshuai Gu: Provision of study materials or patients; Ning Ren: Project & editing.
Funding
This work was funded by Tianjin Key Medical Discipline Construction Project (Grant No. TJYXZDXK-3-014B).
Data availability
The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request.
Declarations
Ethics approval and consent to participate
This retrospective study was conducted in accordance with the principles outlined in the Declaration of Helsinki and its subsequent revisions, and received approval from the Ethics Committee at Tianjin Huanhu Hospital (Tianjin, China). This study was approved by the ethical committee of Tianjin Huanhu Hospital 【No. 2024 − 280】, and written informed consent was obtained from all subjects.
Consent for publication
Not applicable.
Competing interests
The authors declare no competing interests.
Footnotes
Publisher’s note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Contributor Information
Ning Ren, Email: renning333@126.com.
Zhihong Shi, Email: shzhh1204@126.com.
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
Data Availability Statement
The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request.