Multiple reaction monitoring mass spectrometry to identify novel plasma protein biomarkers of treatment response in cystic fibrosis pulmonary exacerbations

BACKGROUND

Systemic inflammation decreases with IV antibiotics during the treatment of CF pulmonary exacerbations (PEx). We used multiple reaction monitoring mass spectrometry and immunoassays to monitor blood proteins during PEx treatment to determine if early changes could be used to predict PEx outcomes following treatment.

METHODS

Blood samples from 25 PEx (22 unique adults) were collected within 24h of admission, day 5, day 10, and at IV antibiotic completion. Ninety-two blood proteins involved in host immunity and inflammation were measured.

RESULTS

Levels of several blood proteins changed from admission to end of IV antibiotics, most increasing with treatment. Early changes (admission to day 5) in fibrinogen levels had the strongest correlation with overall improvement in CFRSD-CRISS and FEV₁% predicted by the end of treatment.

CONCLUSIONS

Several plasma proteins changed significantly with IV antibiotics. Future studies will evaluate fibrinogen as an early biomarker of PEx treatment response in CF.

Survival Comparison of Patients With Cystic Fibrosis in Canada and the United States: A Population-Based Cohort Study

BACKGROUND

In 2011, the median age of survival of patients with cystic fibrosis reported in the United States was 36.8 years, compared with 48.5 years in Canada. Direct comparison of survival estimates between national registries is challenging because of inherent differences in methodologies used, data processing techniques, and ascertainment bias.

OBJECTIVE

To use a standardized approach to calculate cystic fibrosis survival estimates and to explore differences between Canada and the United States.

DESIGN

Population-based study.

SETTING

42 Canadian cystic fibrosis clinics and 110 U.S. cystic fibrosis care centers.

PATIENTS

Patients followed in the Canadian Cystic Fibrosis Registry (CCFR) and U.S. Cystic Fibrosis Foundation Patient Registry (CFFPR) between 1990 and 2013.

MEASUREMENTS

Cox proportional hazards models were used to compare survival between patients followed in the CCFR (n = 5941) and those in the CFFPR (n = 45 448). Multivariable models were used to adjust for factors known to be associated with survival.

RESULTS

Median age of survival in patients with cystic fibrosis increased in both countries between 1990 and 2013; however, in 1995 and 2005, survival in Canada increased at a faster rate than in the United States (P < 0.001). On the basis of contemporary data from 2009 to 2013, the median age of survival in Canada was 10 years greater than in the United States (50.9 vs. 40.6 years, respectively). The adjusted risk for death was 34% lower in Canada than the United States (hazard ratio, 0.66 [95% CI, 0.54 to 0.81]). A greater proportion of patients in Canada received transplants (10.3% vs. 6.5%, respectively [standardized difference, 13.7]). Differences in survival between U.S. and Canadian patients varied according to U.S. patients' insurance status.

LIMITATION

Ascertainment bias due to missing data or nonrandom loss to follow-up might affect the results.

CONCLUSION

Differences in cystic fibrosis survival between Canada and the United States persisted after adjustment for risk factors associated with survival, except for private-insurance status among U.S. patients. Differential access to transplantation, increased posttransplant survival, and differences in health care systems may, in part, explain the Canadian survival advantage.

PRIMARY FUNDING SOURCE

U.S. Cystic Fibrosis Foundation.

Clinical utility of C-reactive protein to predict treatment response during cystic fibrosis pulmonary exacerbations

Rationale

C-reactive protein (CRP) is a systemic marker of inflammation that correlates with disease status in cystic fibrosis (CF). The clinical utility of CRP measurement to guide pulmonary exacerbation (PEx) treatment decisions remains uncertain.

Objectives

To determine whether monitoring CRP during PEx treatment can be used to predict treatment response. We hypothesized that early changes in CRP can be used to predict treatment response.

Methods

We reviewed all PEx events requiring hospitalization for intravenous (IV) antibiotics over 2 years at our institution. 83 PEx events met our eligibility criteria. CRP levels from admission to day 5 were evaluated to predict treatment non-response, using a modified version of a prior published composite definition. CRP was also evaluated to predict time until next exacerbation (TUNE).

Measurements and main results

53% of 83 PEx events were classified as treatment non-response. Paradoxically, 24% of PEx events were characterized by a ≥ 50% increase in CRP levels within the first five days of treatment. Absolute change in CRP from admission to day 5 was not associated with treatment non-response (p = 0.58). Adjusted for FEV₁% predicted, admission log₁₀ CRP was associated with treatment non-response (OR: 2.39; 95% CI: 1.14 to 5.91; p = 0.03) and shorter TUNE (HR: 1.60; 95% CI: 1.13 to 2.27; p = 0.008). The area under the receiver operating characteristics (ROC) curve of admission CRP to predict treatment non-response was 0.72 (95% CI 0.61–0.83; p<0.001). 23% of PEx events were characterized by an admission CRP of > 75 mg/L with a specificity of 90% for treatment non-response.

Conclusions

Admission CRP predicts treatment non-response and time until next exacerbation. A very elevated admission CRP (>75mg/L) is highly specific for treatment non-response and might be used to target high-risk patients for future interventional studies aimed at improving exacerbation outcomes.

Patient knowledge and pulmonary medication adherence in adult patients with cystic fibrosis

BACKGROUND AND OBJECTIVES

Patient knowledge of lung function (ie, forced expiratory volume in 1 s [FEV₁]% predicted) and the intended benefits of their prescribed pulmonary medications might play an important role in medication adherence, but this relationship has not been examined previously in patients with cystic fibrosis (CF).

METHODS

All patients diagnosed with CF and without prior lung transplantation were invited to complete knowledge and self-reported medication adherence questionnaires during routine outpatient visits to the Adult CF Clinic, St Paul's Hospital, Vancouver, Canada from June 2013 to August 2014.

RESULTS

A total of 142 out of 167 (85%) consecutive adults attending CF clinic completed patient knowledge and medication adherence survey questionnaires. Sixty-four percent of the patients recalled their last FEV₁% predicted value within 5%, and 70% knew the intended benefits of all their prescribed medications. Self-reported adherence rates were highest for inhaled antibiotics (81%), azithromycin (87%), and dornase alpha (76%) and lowest for hypertonic saline (47%). Individuals who knew their FEV₁% predicted value within 5% were more likely to self-report adherence to dornase alpha (84% vs 62%, P=0.06) and inhaled antibiotics (88% vs 64%, P=0.06) compared to those who did not, but these associations were not statistically significant. There were no significant associations observed between patient knowledge of intended medication benefits and self-reported medication adherence.

CONCLUSION

Contrary to our hypothesis, disease- and treatment-related knowledge was not associated with self-reported medication adherence. This suggests other barriers to medication adherence should be targeted in future studies aiming to improve medication adherence in adults with CF.

Nontuberculous Mycobacteria in Cystic Fibrosis

Nontuberculous mycobacteria (NTM) are found in approximately 10 % of cystic fibrosis (CF) patients, but only a portion will develop NTM disease. The management of CF lung disease should be optimized, including antibiotic therapy targeted to the individual's usual airway bacteria, prior to considering treatment for NTM lung disease. Those who meet criteria for NTM lung disease may not necessarily require treatment and could be monitored expectantly if symptoms and radiographic findings are minimal. However, the presence of Mycobacterium abscessus complex (MABSC), severe lung disease, and/or anticipated lung transplant should prompt NTM therapy initiation. For CF patients with Mycobacterium avium complex (MAC), recommended treatment includes triple antibiotic therapy with a macrolide, rifampin, and ethambutol. Azithromycin is generally our preferred macrolide in CF as it is better tolerated and has fewer drug-drug interactions. MABSC treatment is more complex and requires an induction phase (oral macrolide and two IV agents including amikacin) as well as a maintenance phase (nebulized amikacin and two to three oral antibiotics including a macrolide). The induction phase may range from one to three months (depending on infection severity, treatment response, and medication tolerability). For both MAC and MABSC, treatment duration is extended 1-year post-culture conversion. However, in patients who do not achieve culture negative status but tolerate therapy, we consider ongoing treatment for mycobacterial suppression and prevention of disease progression.

Qualitative dimensions of exertional dyspnea in adults with cystic fibrosis

No studies of cystic fibrosis (CF) have systematically characterized the evolution of the qualitative dimensions of exertional dyspnea. Adults with CF (n = 25) and control individuals matched for sex, age, and body mass index (n = 25) underwent cardiopulmonary cycle exercise testing with a detailed evaluation of ventilatory and dyspnea responses. The qualitative dimensions of dyspnea were examined during each exercise stage by having subjects select phrases that best described their breathing (i.e., "work/effort," "unsatisfied inspiration," and "unsatisfied expiration"). Subjects also selected phrases that described the quality of their breathing at peak exercise using an established 15-item questionnaire, which was then clustered into different categories. Subjects with CF had greater ventilatory requirements, higher end-inspiratory and end-expiratory lung volumes (% total lung capacity), and an earlier inflection/plateau in tidal volume during exercise compared with control subjects. Increased work/effort was the dominant qualitative descriptor in both groups throughout exercise. Unsatisfied inspiration was selected by 48% of subjects with CF and 40% of controls at some point during exercise. The onset of unsatisfied inspiration in these subjects occurred at a significantly lower relative exercise intensity in subjects with CF vs. controls (72 ± 21 vs. 94 ± 11% Wmax, P < 0.01). Chest tightness was the only qualitative descriptor cluster that was selected more frequently by subjects with CF vs. controls (36 vs. 0%, respectively, P < 0.05) at peak exercise. Therapeutic interventions that reduce ventilatory requirements and improve lung volumes may delay the onset of distressing sensations such as unsatisfied inspiration and chest tightness in adults with CF.

Increased versus stable doses of inhaled corticosteroids for exacerbations of chronic asthma in adults and children

BACKGROUND

People with asthma may experience exacerbations or "attacks" during which their symptoms worsen and additional treatment is required. Written action plans may advocate doubling the dose of inhaled steroids in the early stages of an asthma exacerbation to reduce the severity of the attack and to prevent the need for oral steroids or hospital admission.

OBJECTIVES

To compare the clinical effectiveness and safety of increased versus stable doses of inhaled corticosteroids (ICS) as part of a patient-initiated action plan for home management of exacerbations in children and adults with persistent asthma.

SEARCH METHODS

We searched the Cochrane Airways Group Specialised Register, which is derived from searches of the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE and the Cumulative Index to Nursing and Allied Health Literature (CINAHL) to March 2016. We handsearched respiratory journals and meeting abstracts.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that compared increased versus stable doses of ICS for home management of asthma exacerbations. We included studies of children or adults with persistent asthma who were receiving daily maintenance ICS.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials, assessed quality and extracted data. We contacted authors of RCTs for additional information.

MAIN RESULTS

This review update added three new studies including 419 participants to the review. In total, we identified eight RCTs, most of which were at low risk of bias, involving 1669 participants with mild to moderate asthma. We included three paediatric (n = 422) and five adult (n = 1247) studies; six were parallel-group trials and two had a cross-over design. All but one study followed participants for six months to one year. Allowed maintenance doses of ICS varied in adult and paediatric studies, as did use of concomitant medications and doses of ICS initiated during exacerbations. Investigators gave participants a study inhaler containing additional ICS or placebo to be started as part of an action plan for treatment of exacerbations.The odds of treatment failure, defined as the need for oral corticosteroids, were not significantly reduced among those randomised to increased ICS compared with those taking their usual stable maintenance dose (odds ratio (OR) 0.89, 95% confidence interval (CI) 0.68 to 1.18; participants = 1520; studies = 7). When we analysed only people who actually took their study inhaler for an exacerbation, we found much variation between study results but the evidence did not show a significant benefit of increasing ICS dose (OR 0.84, 95% CI 0.54 to 1.30; participants = 766; studies = 7). The odds of having an unscheduled physician visit (OR 0.96, 95% CI 0.66 to 1.41; participants = 931; studies = 3) or acute visit (Peto OR 0.98, 95% CI 0.24 to 3.98; participants = 450; studies = 3) were not significantly reduced by an increased versus stable dose of ICS, and evidence was insufficient to permit assessment of impact on the duration of exacerbation; our ability to draw conclusions from these outcomes was limited by the number of studies reporting these events and by the number of events included in the analyses. The odds of serious events (OR 1.69, 95% CI 0.77 to 3.71; participants = 394; studies = 2) and non-serious events, such as oral irritation, headaches and changes in appetite (OR 2.15, 95% CI 0.68 to 6.73; participants = 142; studies = 2), were neither increased nor decreased significantly by increased versus stable doses of ICS during an exacerbation. Too few studies are available to allow firm conclusions on the basis of subgroup analyses conducted to investigate the impact of age, time to treatment initiation, doses used, smoking history and the fold increase of ICS on the magnitude of effect; yet, effect size appears similar in children and adults.

AUTHORS' CONCLUSIONS

Current evidence does not support increasing the dose of ICS as part of a self initiated action plan to treat exacerbations in adults and children with mild to moderate asthma. Increased ICS dose is not associated with a statistically significant reduction in the odds of requiring rescue oral corticosteroids for the exacerbation, or of having adverse events, compared with a stable ICS dose. Wide confidence intervals for several outcomes mean we cannot rule out possible benefits of this approach.

New and emerging targeted therapies for cystic fibrosis

Cystic fibrosis (CF) is a monogenic autosomal recessive disorder that affects about 70,000 people worldwide. The clinical manifestations of the disease are caused by defects in the cystic fibrosis transmembrane conductance regulator (CFTR) protein. The discovery of the CFTR gene in 1989 has led to a sophisticated understanding of how thousands of mutations in the CFTR gene affect the structure and function of the CFTR protein. Much progress has been made over the past decade with the development of orally bioavailable small molecule drugs that target defective CFTR proteins caused by specific mutations. Furthermore, there is considerable optimism about the prospect of gene replacement or editing therapies to correct all mutations in cystic fibrosis. The recent approvals of ivacaftor and lumacaftor represent the genesis of a new era of precision medicine in the treatment of this condition. These drugs are having a positive impact on the lives of people with cystic fibrosis and are potentially disease modifying. This review provides an update on advances in our understanding of the structure and function of the CFTR, with a focus on state of the art targeted drugs that are in development.

Predictors of non-referral of patients with cystic fibrosis for lung transplant evaluation in the United States

BACKGROUND

Lung transplantation is an intervention that improves survival for adult patients with cystic fibrosis (CF). Some patients with CF are never referred for lung transplant evaluation despite meeting physiologic criteria for referral.

METHODS

We performed a retrospective analysis of adult patients (≥18years of age) in the Cystic Fibrosis Foundation Patient Registry (CFFPR), eligible for their first evaluation for lung transplantation during the years 2001-2008 based on FEV1<30% predicted in two consecutive years.

RESULTS

Within the CFFPR, 1240 patients met eligibility criteria. Eight hundred and nine (65.2%) were referred for lung transplant evaluation, and 431 (34.8%) were not referred. In a multivariable model, Medicaid insurance (OR 1.79, 95% CI 1.29-2.47), older age (per 5year increase; OR 1.25, 95% CI 1.13-1.39), lack of high school graduate education (OR 2.27, 95% CI 1.42-3.64), and Burkholderia cepacia complex sputum culture positivity (OR 2.48, 95% CI 1.50-4.12) were associated with non-referral, while number of pulmonary exacerbations (OR 0.93, 95% CI 0.87-0.99) and supplemental oxygen use (OR 0.59, 95% CI 0.43-0.81) were associated with increased referral.

CONCLUSIONS

Despite meeting lung function criteria for lung transplant evaluation, 35% of patients with CF had not yet been referred to a lung transplant center. Predictors of non-referral included markers of low socioeconomic status, older age and B. cepacia complex sputum culture. Further work is needed to understand the outcomes for non-referred patients in order to refine referral recommendations in this population.

A standardized approach to estimating survival statistics for population-based cystic fibrosis registry cohorts

OBJECTIVES

Our objective was to quantify the effect of different statistical techniques, inclusion/exclusion criteria, and missing data on the predicted median survival age.

STUDY DESIGN AND SETTING

Using the Canadian cystic fibrosis registry (CCFR), the median age of survival was calculated using both the Cox proportional hazards (PH) and the life-table methods. Through simulations, we examined how the median age of survival would change when: (1) patients were excluded, (2) death dates were inaccurate, (3) patients were lost to follow-up, (4) entire years with no clinic visits were excluded even if the​ patient had a visit in subsequent years, and (5) censoring patients at their date of transplant. Simulations were run assuming 5-35% of data were affected by each scenario.

RESULTS

Over the period 2009-2013, there were 4,666 individuals in the CCFR with 240 deaths. The observed median age of survival calculated by the Cox PH method was 50.9 [95% confidence interval (CI): 47.4, 54.3] and 50.5 from the life-table method (95% CI: 47.5, 53.5). Censoring patients at their transplant date overestimated the median age of survival by 7.2 years (58.1; 95% CI: 53.3, 64.7). Simulations determined that by missing just 15% of deaths, the median age of survival can be overestimated by 3.5 years (54.4; 95% CI: 54.2, 56.1), and having 25% of patients lost to follow-up can underestimate the median age of survival by 3.3 years (47.6; 95% CI: 46.8, 47.7).

CONCLUSION

We present several recommendations to assist national cystic fibrosis registries in calculating and reporting the median age of survival in a standardized fashion. It is imperative to state the statistical method used as well as the proportion lost to follow-up and the treatment of missing data and transplanted patients. Registries must be diligent in their data collection as incomplete data can lead to overestimation and underestimation of survival.

Cardiorespiratory and sensory responses to exercise in adults with mild cystic fibrosis

The purpose of this study was to evaluate cardiorespiratory fitness and reasons for exercise curtailment in a contemporary adult cystic fibrosis (CF) cohort with mild lung disease. Adults with mild CF (n = 19, forced expiratory volume in 1 s = 95 ± 17% predicted) were age-, sex-, ethnicity-, and body mass index-matched to healthy controls (n = 19) and underwent a detailed cardiopulmonary cycle exercise test. While CF subjects had a reduced peak oxygen uptake compared with controls, the values were normal when expressed as %predicted in 14/19 (74%) of subjects. Both groups demonstrated a normal cardiovascular limitation to exercise and stopped exercise primarily because of leg fatigue. Despite not being exercise-limited by respiratory factors, there was some evidence of ventilatory abnormalities as patients with mild CF had increased end-inspiratory lung volumes and reached an inflection/plateau in tidal volume relative to minute ventilation at lower exercise intensities compared with controls. Subjects with CF were not more likely to demonstrate expiratory flow limitation compared with controls and did not have evidence of dynamic hyperinflation during exercise. Despite increased end-inspiratory lung volumes and an earlier tidal volume inflection/plateau, CF subjects did not experience higher levels of dyspnea. In an exploratory analysis, a significant inverse correlation was observed between sweat chloride and peak work rate. Adult CF subjects with relatively well preserved spirometry have normal exercise performance relative to reference values and are primarily limited by nonrespiratory factors. However, ventilatory abnormalities were detected even in this mild CF cohort and should be evaluated in future therapeutic trials focused on disease-modifying therapies in mild CF.

Discovery of novel plasma protein biomarkers to predict imminent cystic fibrosis pulmonary exacerbations using multiple reaction monitoring mass spectrometry

BACKGROUND

Despite the significant morbidity and mortality related to pulmonary exacerbations in cystic fibrosis (CF), there remains no reliable predictor of imminent exacerbation.

OBJECTIVE

To identify blood-based biomarkers to predict imminent (<4 months from stable blood draw) CF pulmonary exacerbations using targeted proteomics.

METHODS

104 subjects provided plasma samples when clinically stable and were randomly split into discovery (n=70) and replication (n=34) cohorts. Multiple reaction monitoring mass spectrometry (MRM-MS) was used to measure 117 peptides (79 proteins) from plasma. Plasma proteins with differential abundance between subjects who did versus did not develop an imminent exacerbation were analysed and proteins with fold difference >1.5 between the groups were included in an MRM-MS classifier model to predict imminent exacerbations. Performance characteristics were compared with clinical predictors and candidate plasma protein biomarkers.

RESULTS

Six proteins were included in the final MRM-MS protein panel. The area under the curve (AUC) for the prediction of imminent exacerbations was highest for the MRM-MS protein panel (AUC 0.74) in comparison to FEV1% predicted (AUC 0.55) and the top candidate plasma protein biomarkers, including C-reactive protein (AUC 0.61) and interleukin-6 (AUC 0.60). The MRM-MS protein panel performed similarly in the replication cohort (AUC 0.73).

CONCLUSIONS

Using MRM-MS, a six-protein panel measured from plasma can distinguish individuals with versus without an imminent exacerbation. With further replication and assay development, this biomarker panel may be clinically applicable for prediction of exacerbations in individuals with CF.

Association between newborn birth weight and the risk of postpartum maternal venous thromboembolism: a population-based case-control study

BACKGROUND

Postpartum venous thromboembolism (VTE) is a potentially fatal and preventable event leading to substantial short- and long-term morbidity. We sought to evaluate whether the delivery of term newborns of low or high birth weight was associated with greater risks of VTE.

METHODS AND RESULTS

In a population-based case-control study conducted in Washington State from 1987 through 2011, cases of hospitalized VTE within 3 months of delivery were identified by using selected International Classification of Diseases, Ninth Revision, Clinical Modification codes. Controls were randomly selected postpartum women without VTE, matched on birth year. Birth weight and other maternal and pregnancy characteristics were extracted from birth certificate data. Among term live singleton deliveries, we compared the risk of VTE for mothers of newborns of low and high birth weights (<2500 g and >4000 g, respectively) versus mothers of newborns of normal birth weight (2500-4000 g). Logistic regression models were adjusted for maternal age, race, education, body mass index, parity, delivery methods, gestational length, smoking, gestational diabetes mellitus, and preeclampsia. Patients with VTE (n=547) were older, had a higher body mass index, and experienced more pregnancy-related complications than controls (n=9482). In comparison with mothers of newborns with normal birth weight, mothers of newborns with low birth weight had a 3-fold increased risk of VTE, which persisted after multivariable adjustment (odds ratio, 2.98; 95% confidence interval, 1.80-4.93). Mothers of newborns with high birth weight had only a slightly increased risk of VTE, which was attenuated after multivariable adjustment (odds ratio, 1.26; 95% confidence interval, 0.99-1.61).

CONCLUSIONS

The delivery of a newborn with low birth weight is associated with a 3-fold increased risk of maternal postpartum VTE. This should be considered when assessing VTE risk at delivery.

Prevalence of symptoms of depression and anxiety in adults with cystic fibrosis based on the PHQ-9 and GAD-7 screening questionnaires

OBJECTIVE

To examine the prevalence of symptoms of depression and anxiety among patients with cystic fibrosis (CF) who were followed up at the University of Washington Adult CF clinic and to identify sociodemographic and clinical factors associated with symptoms.

METHODS

A total of 178 adults with CF were asked to complete the Patient Health Questionnaire-9 for depression and General Anxiety Disorder-7 for anxiety when clinically stable. Clinically significant symptoms of depression and anxiety were defined in the following 2 ways: (1) symptom definition-presence of moderate-to-severe symptoms based on the questionnaires and (2) composite definition-symptom definition or the use of psychiatric medications to manage symptoms. Associations between Patient Health Questionnaire-9 and General Anxiety Disorder-7 scores with sociodemographic (gender, age, age of CF diagnosis, vocation, and spousal status) and clinical factors (forced expiratory volume in 1 second, body mass index, and CF-related diabetes on insulin) were examined.

RESULTS

Of 178 patients, 153 (85%) completed the screening questionnaires. Based on the symptom definition, 7% of patients had symptoms of depression and 5% had symptoms of anxiety. Using the composite definition, 22% of patients had symptoms of depression and 10% had symptoms of anxiety. Based on the Patient Health Questionnaire-9, 5% of patients reported suicidal thoughts. In multiple linear regression analysis, only forced expiratory volume in 1 second % predicted was independently associated with Patient Health Questionnaire-9 depression scores, and no sociodemographic or clinical factors were associated with General Anxiety Disorder-7 anxiety scores.

CONCLUSIONS

We conclude that all adults with CF should be screened for symptoms of depression and anxiety given the difficulty in identifying strong clinical risk factors and the unexpected high rates of suicidal ideation.

Inhaled antibiotics for lower airway infections

Inhaled antibiotics have been used to treat chronic airway infections since the 1940s. The earliest experience with inhaled antibiotics involved aerosolizing antibiotics designed for parenteral administration. These formulations caused significant bronchial irritation due to added preservatives and nonphysiologic chemical composition. A major therapeutic advance took place in 1997, when tobramycin designed for inhalation was approved by the U.S. Food and Drug Administration (FDA) for use in patients with cystic fibrosis (CF) with chronic Pseudomonas aeruginosa infection. Attracted by the clinical benefits observed in CF and the availability of dry powder antibiotic formulations, there has been a growing interest in the use of inhaled antibiotics in other lower respiratory tract infections, such as non-CF bronchiectasis, ventilator-associated pneumonia, chronic obstructive pulmonary disease, mycobacterial disease, and in the post-lung transplant setting over the past decade. Antibiotics currently marketed for inhalation include nebulized and dry powder forms of tobramycin and colistin and nebulized aztreonam. Although both the U.S. Food and Drug Administration and European Medicines Agency have approved their use in CF, they have not been approved in other disease areas due to lack of supportive clinical trial evidence. Injectable formulations of gentamicin, tobramycin, amikacin, ceftazidime, and amphotericin are currently nebulized "off-label" to manage non-CF bronchiectasis, drug-resistant nontuberculous mycobacterial infections, ventilator-associated pneumonia, and post-transplant airway infections. Future inhaled antibiotic trials must focus on disease areas outside of CF with sample sizes large enough to evaluate clinically important endpoints such as exacerbations. Extrapolating from CF, the impact of eradicating organisms such as P. aeruginosa in non-CF bronchiectasis should also be evaluated.

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.

Cystic fibrosis: what to expect now in the early adult years

As a testimony to advances in patient care, more individuals with cystic fibrosis are surviving into their adult years than ever before. The clinical epidemiology of this complex multi-organ disease is evolving and has changed dramatically over the past two to three decades. This article discusses the emergence of chronic disease-related co-morbidities such as CF-related diabetes, chronic kidney disease, bone disease, arthropathy, and depression. It also provides an overview of the many challenges confronted by adult CF care providers.

Disparities in access to lung transplantation for patients with cystic fibrosis by socioeconomic status

RATIONALE

Although previous studies suggest that access to care for patients with cystic fibrosis (CF) does not vary appreciably by socioeconomic status (SES), disparities with respect to access to lung transplantation for patients with CF are largely unknown.

OBJECTIVES

To determine whether access to lung transplantation for patients with CF differs according to SES.

METHODS

Observational study involving 2,167 adult patients with CF from the CF Foundation Patient registry who underwent their first lung transplant evaluation between 2001 and 2009. The primary outcome was acceptance for lung transplant after initial evaluation. The main SES indicator was Medicaid status. Alternate SES indicators included race, educational attainment, ZIP code-level median household income, and driving time from residence to closest lung transplant center.

MEASUREMENTS AND MAIN RESULTS

The odds that Medicaid recipients were not accepted for lung transplant were 1.56-fold higher (95% confidence interval [CI], 1.27-1.92) than patients without Medicaid, after multivariate adjustment for demographic characteristics, disease severity, and potential contraindications to lung transplant, and before or after use of the lung allocation score. This association was independent of other SES indicators, including race, educational attainment, ZIP code-level median household income, and driving time to closest transplant center (odds ratio [OR] = 1.37; 95% CI, 1.10-1.72). Patients not completing high school (OR = 2.37; 95% CI, 1.49-3.79) and those residing in the lowest (vs. highest) ZIP code median household income category (OR = 1.39; 95% CI, 1.01-1.93) also experienced a higher odds of not being accepted for lung transplant in multivariate analysis.

CONCLUSIONS

In this nationally representative study of adult patients with CF, multiple indicators of low SES were associated with higher odds of not being accepted for lung transplant.