Adult cystic fibrosis patients with and without infective exacerbations and their factor XII levels

Breath of fresh insight: unraveling the evolution of our understanding of cystic fibrosis pulmonary exacerbations

PURPOSE OF REVIEW

Pulmonary exacerbations are critical events with significant negative impacts in persons with cystic fibrosis, but their diagnosis and management are highly variable. Highly effective modulator therapies have greatly improved health and reduced exacerbation events, but have also reshaped how they present. This review discusses the complexities of the diagnosis and management of pulmonary exacerbations as well as the emerging work and evidence in this area.

RECENT FINDINGS

The shifting epidemiology and our understanding of risk factors for pulmonary exacerbations are discussed. As symptoms may be more subtle in the modulator context, novel technologies including studies of remote monitoring are presented. The continued relevance of pulmonary exacerbations, the heterogeneity in their management, as well as current and forthcoming clinical trials to optimize treatment approaches are detailed.

SUMMARY

In spite of the dramatic reductions in pulmonary exacerbations, airway infections persist, a proportion of persons with cystic fibrosis either on or off modulator therapies continue to experience exacerbation events, and long-term data is lacking. Innovative approaches and studies will be crucial to enable standardized and generalizable strategies to improve outcomes in persons with cystic fibrosis.

Altered intravenous drug disposition in people living with cystic fibrosis: A meta‐analysis integrating top‐down and bottom‐up data

Cystic fibrosis (CF) has been linked to altered drug disposition in various studies. However, the magnitude of these changes, influencing factors, and underlying mechanisms remain a matter of debate. The primary aim of this work was therefore to quantify changes in drug disposition (top‐down) and the pathophysiological parameters known to affect pharmacokinetics (PKs; bottom‐up). This was done through meta‐analyses and meta‐regressions in addition to theoretical PK simulations. Volumes of distribution and clearances were found to be elevated in people living with CF. These increases were larger in studies which included patients with pulmonary exacerbations. Differences in clearance were smaller in more recent studies and when results were normalized to body surface area or lean body mass instead of body weight. For the physiological parameters investigated, measured glomerular filtration rate and serum cytokine concentrations were found to be elevated in people living with CF, whereas serum albumin and creatinine levels were decreased. Possible pathophysiological mechanisms for these alterations relate to renal hyperfiltration, increases in free fraction, and inflammation. No differences were detected for cardiac output, body fat, fat free mass, hematocrit, creatinine clearance, and the activity of drug metabolizing enzymes. These findings imply that, in general, lower total plasma concentrations of drugs can be expected in people living with CF, especially when pulmonary exacerbations are present. Given the potential effect of CF on plasma protein binding and the variability in outcome observed between studies, the clinical relevance of adapting existing dosage regimens should be evaluated on a case‐by‐case basis.

Survey of current treatment practices for venous thromboembolism in patients with cystic fibrosis

BACKGROUND

Patients with cystic fibrosis (CF) and venous thromboembolism (VTE) pose therapeutic challenges including potential drug interactions between CF-related therapies and anticoagulants. Despite these challenges, there are no recommendations for VTE management specific to patients with CF. Our objective was to describe VTE treatment practices among Cystic Fibrosis Foundation (CFF)-accredited care centers and affiliate programs in the United States.

METHODS

An online survey was distributed to CF center directors. The survey included questions regarding centers' demographics and posed a series of hypothetical clinical scenarios to gather centers' VTE treatment practices including choice of anticoagulant, dosing practices, duration decisions, and monitoring efforts. Descriptive statistics were utilized to summarize the survey results.

RESULTS

The survey response rate was 56.3%. Most centers reported treating zero to five VTE episodes per year. The following anticoagulants were used most often for VTE treatment: low-molecular-weight heparin (LMWH) (73.2%), apixaban (36.6%), warfarin (35.2%), rivaroxaban (33.8%), and unfractionated heparin (18.3%). On a scale of 0 to 100, the median confidence level in managing anticoagulant therapy was 50. Many centers expressed a desire for a CF-specific VTE treatment guideline. The most commonly cited challenging clinical situations were managing anticoagulant therapy complications (26.5%) and drug-drug interactions (21.3%). For common VTE scenarios, pediatric patients were most often treated with LMWH and warfarin, whereas adult patients were more often treated with apixaban or rivaroxaban.

CONCLUSIONS

Survey results indicated CF care centers find managing VTE in patients with CF challenging and indicated that a CF-specific VTE treatment guideline would be helpful.

Role of C-reactive protein as a biomarker for prediction of the severity of pulmonary exacerbations in patients with cystic fibrosis

Background

Pulmonary exacerbation is one of the main risk factors for death in patients with cystic fibrosis. Several biomarkers have proven useful in the diagnosis and treatment of pulmonary exacerbations, although none has been associated with severity. The objective of the present study was to investigate whether C-reactive protein (CRP) level was associated with the severity of pulmonary exacerbation requiring admission to hospital in patients with cystic fibrosis.

Methods

We designed a severity index for exacerbations based on 4 clinical parameters and determined whether there was an association between CRP levels and severity of the exacerbation. We also investigated the association between CRP and baseline functional and clinical variables.

Results

Twenty-seven patients with cystic fibrosis required 62 admissions to hospital. CRP levels were not significantly associated with the severity index, although they were associated with specific patient characteristics: colonization by Pseudomonas aeruginosa, allergic bronchopulmonary aspergillosis, treatment with oral corticosteroids, and number of severe exacerbations treated with intravenous antibiotics during the previous year.

Conclusions

CRP level is not associated with the severity of pulmonary exacerbations, but it is associated with specific clinical characteristics. This simple scoring system (severity index) could prove very useful for evaluating the severity of exacerbations.

Plasma sCD14 as a biomarker to predict pulmonary exacerbations in cystic fibrosis

BACKGROUND

One in four cystic fibrosis (CF) patients diagnosed with a pulmonary exacerbation will not recover their baseline lung function despite standard treatment. This highlights the importance of preventing such events. Clinical decision-making can be improved through a simple blood test that predicts individuals at elevated short-term risk of an exacerbation.

METHODS

We obtained plasma samples from 30 stable CF patients from the St. Paul's Hospital Adult CF Clinic (Vancouver, Canada). For 15 patients, an additional plasma sample was obtained during an exacerbation. Soluble CD14 (sCD14) and C-reactive protein (CRP) were quantified using ELISA kits. Myeloperoxidase (MPO), interleukin(IL)-6, IL-1β, monocyte chemoattractant protein-1 (MCP-1), vascular endothelial growth factor (VEGF), and granulocyte colony-stimulating factor (G-CSF) were quantified using Luminex™ immunoassays. Stable state biomarker levels were examined in their ability to predict individuals that would experience a pulmonary exacerbation requiring intravenous (IV) antibiotics within 4 months. Paired stable and exacerbation plasma biomarker levels were also compared.

RESULTS

sCD14 levels were significantly higher in patients that experienced a pulmonary exacerbation requiring IV antibiotics within 4 months (p = 0.001). sCD14 cut-off value of 1450 ng/mL was associated with an area under the curve of 0.91 (95% CI 0.83-0.99) for predicting an exacerbation within 4 months of a stable visit, with a sensitivity of 100% and specificity of 82%. Plasma sCD14 levels were significantly higher during exacerbations than during periods of clinical stability (p = 0.03).

CONCLUSIONS

Plasma sCD14 is a promising biomarker for identifying CF patients who will exacerbate within 4 months of a stable visit but requires further study in larger, independent cohorts.

Systematic review of blood biomarkers in cystic fibrosis pulmonary exacerbations

BACKGROUND

Biomarkers reflective of disease activity in cystic fibrosis (CF) have the potential to improve patient care, particularly during CF pulmonary exacerbations (CFPEs). Although blood-based biomarkers have been studied in CFPE for nearly 3 decades, none have been integrated into routine clinical practice. To facilitate progress in this area, we performed a systematic review evaluating blood-based biomarkers during CFPE.

METHODS

MEDLINE, EMBASE, and CENTRAL were searched to identify relevant studies published from January 1995 to August 2012. We included all full-text studies examining systemic (blood-based) biomarkers to aid in the diagnosis of CFPE, predict outcomes of CFPE, and/or monitor the response to CFPE treatment.

RESULTS

Seventy-eight unique blood-based biomarkers have been studied to date, mainly inflammatory cytokines, acute phase reactants, and markers of oxidative stress. C-reactive protein (CRP) consistently correlated with disease activity, with a statistically significant increase from stable to exacerbation state in five of six studies, and changes in response to CFPE treatment, with a statistically significant decrease from the beginning to the end of CFPE treatment in 18 of 20 studies. Other promising biomarkers of CFPE disease activity include neutrophil elastase antiproteinase complex, IL-6, myeloperoxidase (MPO), lactoferrin, and calprotectin.

CONCLUSIONS

Although there are several blood-based biomarkers with evidence for application within the CFPE setting, CRP has been the most widely studied biomarker demonstrating the potential for clinical usefulness. Further validation studies and clinical trials are required to determine whether blood-based biomarkers can be used to ultimately improve health outcomes in the setting of a CFPE.