Factors associated with reduced FEV1 in adult patients with cystic fibrosis in a relatively affluent area

The Use of Tobramycin for Pseudomonas aeruginosa: A Review

INTRODUCTION

Pseudomonas aeruginosa is a common respiratory pathogen that contributes to chronic pulmonary infection in individuals with cystic fibrosis. Guidelines recommend early intervention upon positive P. aeruginosa culture. Tobramycin has in vitro activity against Gram-negative bacteria, including P. aeruginosa, and TOBI Podhaler is indicated for the management of individuals with cystic fibrosis with P. aeruginosa infection. The dry powder inhaler formulation decreases the time required for treatment compared with nebulized solution and therefore may improve quality of life and adherence, which have a positive impact on disease progression.

AREAS COVERED

In this review, we discuss the safety and efficacy of tobramycin inhaled powder and provide insights into appropriate individuals who might benefit from a dry powder inhaler, keeping in mind that patient preference is an important consideration for therapy selection.

EXPERT OPINION

Providing a less burdensome alternative to delivering inhaled antibiotics that is more portable with a significantly shorter administration time may help improve adherence, and therefore improve outcomes. Continued development of new antibiotics to add to current regimens for eradication and control of airway microbiology, combined with more efficient delivery systems such as tobramycin inhaled powder, will help evolve the treatment of patients with CF.

Emerging non-pulmonary complications for adults with cystic fibrosis

Improved treatments of cystic fibrosis (CF) related lung disease have resulted in increased longevity, but also increasing prevalence and severity of extrapulmonary manifestations of CF, treatment related complications, age-related conditions and psychosocial effects of longstanding chronic disease. Likewise, the recognition of mild CF phenotypes has changed the landscape of CF disease. This review outlines our current understanding of the common extrapulmonary complications of CF, as well as the changing landscape and future directions of the extrapulmonary complications experienced by patients with CF.

Prevalence and factors associated with overweight and obesity in adults with cystic fibrosis: A single-center analysis

BACKGROUND

The relation between malnutrition and pulmonary death in patients with cystic fibrosis (CF) has resulted in intensive nutritional intervention over the last few decades, leading to a significant decline in underweight and the emergence of overweight/obesity as a potential new problem.

METHODS

We performed a cross-sectional database analysis of 484 adults with CF seen at the University of Minnesota CF Center between January 2015-January 2017, to determine the prevalence and pulmonary/cardiovascular risk factors associated with overweight and obesity in this population.

RESULTS

Mean age was 35.2 ± 11.6 years. 5.2% were underweight (BMI<18.5 kg/m2), 62.6% normal weight (BMI ≥ 18.5-24.9 kg/m2), 25.6% overweight (BMI ≥ 25-29.9 kg/m2) and 6.6% obese (BMI ≥ 30 kg/m2). In the subgroup with severe genotypes, 25% had BMI ≥ 25 kg/m2. In the entire cohort, overweight/obese were likely to be older (OR = 1.04, p < 0.0001) and to have a mild CFTR genotype (OR = 3.33, p = 0.0003) and modestly elevated triglyceride levels (OR = 1.008, p < 0.0001). The prevalence of hypertension was higher in overweight (25%) and obese (31%) than normal (17%) or underweight (16%), p = 0.01. Total cholesterol levels were higher in overweight/obese versus normal/underweight (144-147 vs 123-131 mg/dL, p = 0.04) as were LDL levels (70-71 vs 53-60 mg/dL, p = 0.02), but all were within the normal range. Percent predicted FEV1 was higher in overweight/obese (78-81%) versus underweight (59%) and normal (70%), p < 0.0001, and overweight/obese experienced significantly fewer acute pulmonary exacerbations.

CONCLUSIONS

Overweight/obesity is common in adults with CF including those with severe genotypes. Lung function is better in the overweight/obese and lipid levels are within the normal range, albeit higher than in normal/underweight.

Increased Expression of Plasma-Induced ABCC1 mRNA in Cystic Fibrosis

The ABCC1 gene is structurally and functionally related to the cystic fibrosis transmembrane conductance regulator gene (CFTR). Upregulation of ABCC1 is thought to improve lung function in patients with cystic fibrosis (CF); the mechanism underlying this effect is unknown. We analyzed the ABCC1 promoter single nucleotide polymorphism (SNP rs504348), plasma-induced ABCC1 mRNA expression levels, and ABCC1 methylation status and their correlation with clinical variables among CF subjects with differing CFTR mutations. We assigned 93 CF subjects into disease severity groups and genotyped SNP rs504348. For 23 CF subjects and 7 healthy controls, donor peripheral blood mononuclear cells (PBMCs) stimulated with plasma underwent gene expression analysis via qRT-PCR. ABCC1 promoter methylation was analyzed in the same 23 CF subjects. No significant correlation was observed between rs504348 genotypes and CF disease severity, but pancreatic insufficient CF subjects showed increased colonization with any form of Pseudomonas aeruginosa (OR = 3.125, 95% CI: 1.192-8.190) and mucoid P. aeruginosa (OR = 5.075, 95% CI: 1.307-28.620) compared to the pancreatic sufficient group. A significantly higher expression of ABCC1 mRNA was induced by CF plasma compared to healthy control plasma (p < 0.001). CF subjects with rs504348 (CC/CG) also had higher mRNA expression compared to those with the ancestral GG genotype (p < 0.005). ABCC1 promoter was completely unmethylated; therefore, we did not detect any association between methylation and CF disease severity. In silico predictions suggested that histone modifications are crucial for regulating ABCC1 expression in PBMCs. Our results suggest that ABCC1 expression has a role in CFTR activity thereby increasing our understanding of the molecular underpinnings of the clinical heterogeneity in CF.

Mapping the EQ-5D index from the cystic fibrosis questionnaire-revised using multiple modelling approaches

Background

This study was designed to develop a mapping algorithm to estimate EQ-5D utility values from Cystic Fibrosis Questionnaire-Revised (CFQ-R) data.

Methods

A cross-sectional survey of adults with cystic fibrosis (CF) was conducted in the UK. The survey consisted of the CFQ-R, the EQ-5D and a background questionnaire. Eight regression models, exploring item and domain level predictors, were evaluated using three different modelling approaches: ordinary least squares (OLS), Tobit, and a two-part model (TPM). Predictive performance in each model was assessed by intraclass correlations, information criteria (Bayesian information criteria and Alkaike information criteria), and root mean square error (RMSE).

Results

The survey was completed by 401 participants. For all modelling approaches the best performing item level model included all items, and the best performing domain level model included the CFQ-R Physical-, Role- and Emotional-functioning, Vitality, Eating Disturbances, Weight, and Digestive Symptoms domains and a selection of squared terms. Overall, the item level TPM, including age and gender covariates performed best within sample validation, but OLS and TPM domain models with squared terms performed best out-of-sample and are recommended for mapping purposes.

Conclusions

Domain and item level models using all three modelling approaches reached an acceptable degree of predictive performance with domain models performing well in out-of-sample validation. These mapping functions can be applied to CFQ-R datasets to estimate EQ-5D utility values for economic evaluations of interventions for patients with cystic fibrosis. Further research evaluating model performance in an independent sample is encouraged.

Electronic supplementary material

The online version of this article (doi:10.1186/s12955-015-0224-6) contains supplementary material, which is available to authorized users.

Fatigue in cystic fibrosis

Fatigue is a debilitating symptom in patients with cystic fibrosis (CF). Although fatigue is commonly reported in these patients, an effective treatment for this symptom has not been found. The factors associated with fatigue in CF have not been investigated. We conducted a prospective, case–control study in adult patients with CF. All the patients were chronically infected with Pseudomonas aeruginosa and were enrolled in the study during disease stability. A gender and age-matched control group was also recruited. Subjective assessment included three questionnaires: the Chalder fatigue questionnaire, St Mary’s Hospital sleep questionnaire (SQ), and the scaled general health and Hillier questionnaire (GHQ). For patients with CF, spirometry, body mass index (BMI), haemoglobin level, C-reactive protein, and the burden of pulmonary exacerbations (PExs) were assessed. The control group completed all the three questionnaires, and their BMI was measured. A total of 78 participants were enrolled in the study (44 patients with CF and 34 control). Female patients with CF received antibiotics for more days than male patients with CF. The fatigue score did not differ between female and male participants in either the patients with CF or the control group; however, the fatigue score was greater for both the sexes in the patients with CF compared with the control group: p = 0.038 for female and p = 0.048 for male. The scores for the SQ and the GHQ did not differ between the two study groups. The fatigue score correlated with the total score for SQ ( p < 0.0001) in patients with CF, but not in control participants. In patients with CF and the individuals in the control group, a close correlation was found between the fatigue score and the GHQ domain-specific scores and with the total score; p < 0.0001 for patients with CF and p = 0.001 for control. No correlations were found between the fatigue score and any of the objective parameters studied.

Measures of body habitus are associated with lung function in adults with cystic fibrosis: a population-based study

BACKGROUND

Body habitus differences may explain some of the variation in lung function between individuals with cystic fibrosis (CF). We tested the hypothesis that measures of lean muscle mass and obesity are independently associated with lung function in CF.

METHODS

Cross-sectional study design using UK CF registry data from 2096 clinically stable adults.

RESULTS

Serum creatinine and BMI were positively and independently associated with FEV1 and FVC. One standard deviation increment in serum creatinine was associated with an FEV1 increase of 171ml (95% confidence intervals CI: +116 to +227ml) in males and 90ml (95% CI: +46 to +133ml) in females. Compared to the reference group of 20-24.9kg/m(2), those with a BMI<20kg/m(2) had lower FEV1 with values of -642ml (95%CI: -784 to -500ml) for males and -468ml (95%CI: -564 to -372ml) for females.

CONCLUSIONS

Prospective studies and controlled trials are required to ascertain if these associations have therapeutic potential in modifying disease progression.

Expression of PPARγ and paraoxonase 2 correlated with Pseudomonas aeruginosa infection in cystic fibrosis

The Pseudomonas aeruginosa quorum sensing signal molecule N-3-oxododecanoyl-l-homoserine lactone (3OC₁₂HSL) can inhibit function of the mammalian anti-inflammatory transcription factor peroxisome proliferator activated receptor (PPAR)γ, and can be degraded by human paraoxonase (PON)2. Because 3OC₁₂HSL is detected in lungs of cystic fibrosis (CF) patients infected with P. aeruginosa, we investigated the relationship between P. aeruginosa infection and gene expression of PPARγ and PON2 in bronchoalveolar lavage fluid (BALF) of children with CF. Total RNA was extracted from cell pellets of BALF from 43 children aged 6 months–5 years and analyzed by reverse transcription–quantitative real time PCR for gene expression of PPARγ, PON2, and P. aeruginosa lasI, the 3OC₁₂HSL synthase. Patients with culture-confirmed P. aeruginosa infection had significantly lower gene expression of PPARγ and PON2 than patients without P. aeruginosa infection. All samples that were culture-positive for P. aeruginosa were also positive for lasI expression. There was no significant difference in PPARγ or PON2 expression between patients without culture-detectable infection and those with non-Pseudomonal bacterial infection, so reduced expression was specifically associated with P. aeruginosa infection. Expression of both PPARγ and PON2 was inversely correlated with neutrophil counts in BALF, but showed no correlation with other variables evaluated. Thus, lower PPARγ and PON2 gene expression in the BALF of children with CF is associated specifically with P. aeruginosa infection and neutrophilia. We cannot differentiate whether this is a cause or the effect of P. aeruginosa infection, but propose that the level of expression of these genes may be a marker for susceptibility to early acquisition of P. aeruginosa in children with CF.

Factors associated with a shorter time until the next pulmonary exacerbation in adult patients with cystic fibrosis

Time until the subsequent exacerbation (PEx) in cystic fibrosis (CF) is a significant health outcome and one of the significant end points in clinical trials. Risk factors associated with shorter time until the next exacerbation (TUNE) have not been reported. This is a prospective study. TUNE was the number of days from the end of intravenous (IV) antibiotic treatment of a PEx until the day of start of IV antibiotics for the following PEx. Factors assessed were age, gender, site of treatment, CF-related diabetes (CFRD), allergic bronchopulmonary aspergillosis (ABPA) and infection with Pseudomonas aeruginosa (PA). In addition, we examined parameters obtained at day 14 of treatment including forced expiratory volume in the first second (FEV1), body mass index, CF respiratory symptom score, C-reactive protein (CRP) and serum cytokines. A total of 170 exacerbations in 58 adult CF patients (27 female), mean (SD) age 25.8 (6.7) years were analysed. When analysing individual variables, patients with lower FEV1, greater symptom score and higher CRP at the end of exacerbation were associated with shorter TUNE. Patients with ABPA and CFRD had a shorter TUNE than those without. When applying multiple regression analysis, factors associated with shorter TUNE were older age and lower day-14 FEV1 values. Shorter periods until the following PEx are expected in older CF patients and those with lower FEV1 at the end of course of treatment. When these risk factors are present, there may be a justification to take therapeutic steps to increase the time until the following PEx.

Evaluation of a novel sputum clearance technique--hydro-acoustic therapy (HAT) in adult patients with cystic fibrosis: a feasibility study

This study was designed to investigate the efficacy, safety and patients' acceptance of a novel system for sputum clearance--Hydro Acoustic Therapy (HAT) in patients with cystic fibrosis (CF). This is a prospective crossover study where 18 patients received 6 sessions of physiotherapy over 6 separate days. These consisted of 2 sessions of either HAT, flutter valve or and sitting in the bath with sounds without vibration (placebo) for 30 minutes each. The efficacy was investigated by measuring the weight of wet and dry sputum after each session and by change in spirometry values. The preference was assessed by a questionnaire completed by patients at the end of the study about their preference of which type of physiotherapy received. The weight of both dry and wet sputum produced was similar in the 3 arms of the study. Spirometry values but not oxygen saturation were reduced after HAT and flutter therapy sessions. HAT therapy was preferred to flutter and placebo in terms of breathlessness, ease of sputum production and relaxation. Of the patients, 70% stated that they would choose HAT as their preferred physiotherapy method compared to 0% for flutter (χ(2) = 20.3, p < 0.0001). There were no procedure-related complications in any of the 3 arms of the study. HAT was found to be safe, well tolerated and favoured by the majority of CF patients. The effect of HAT, however, on sputum production was not superior to flutter or placebo.

The size of the spleen by magnetic resonance imaging in patients with cystic fibrosis; with and without diabetes--a novel observational study

BACKGROUND

Magnetic resonance imaging (MRI) has been shown to be a useful tool to evaluate the volume of the pancreas. There is currently no information about the size of the spleen in cystic fibrosis (CF) patients.

PATIENTS AND METHODS

We investigated 51 adult volunteers: 28 pancreatic insufficient CF patients [13 with CF-related diabetes (CFRD) and 15 non-diabetic] and 23 male non-CF patients [12 with type 1 diabetes mellitus (T1DM) and 11 healthy control subjects]. Patients with known liver cirrhosis or portal hypertension were excluded. The size of the spleen was measured in all subjects by an investigator unaware of patients' clinical status. For comparison of spleen size in the four study groups only male CF patients were included. For CF patients, spleen size was compared with forced expiratory volume in 1 s (FEV(1)), body mass index (BMI), total number of days of intravenous (IV) antibiotic treatment for pulmonary exacerbations in year previous to study, levels of circulating white blood cells, glycosylated haemoglobin A1c (HbA1c), and exocrine function of the pancreas, as assessed by daily requirement of oral lipase.

RESULTS

Amongst the four study groups, spleen size was greatest in the male non-diabetic CF patients (P = 0.01). For CF patients, spleen size was greater in male compared to female patients (P = 0.012). For patients with CFRD, there was an inverse correlation between the spleen size and HbA1c (r = -0.59, P = 0.04) and the daily intake of supplementary lipase (r = -0.63, P = 0.02). The size of the spleen in patients with CFRD, but not in CF patients without CFRD, inversely correlated with the days of IV antibiotic treatment received in the year previous to the study (r = -0.67, P = 0.012). There was no correlation between spleen size and BMI, FEV1 and white blood cell counts in any group.

CONCLUSION

On MRI, the spleen size was greatest in male non-diabetic CF patients in comparison with other groups. The size of the spleen in CFRD patients was smaller when diabetes was poorly controlled, when exocrine pancreatic function was greatly impaired and in those with greater need for IV antibiotics in the year prior to the study.

Risk factors for increased need for intravenous antibiotics for pulmonary exacerbations in adult patients with cystic fibrosis

BACKGROUND

Pulmonary exacerbations (P Exs) are important in cystic fibrosis (CF). They are very common, and are associated with poor quality of life. P Exs are regarded as an important end point in clinical trials. Risk factors associated with increase in P Exs have not been examined at a large scale. This study investigates factors associated with P Exs in a large cohort of adolescent and adult patients.

PATIENTS AND METHODS

This is a cross-sectional study on data collected in the South and West Regions in England in 2002. Patients aged 16 years and over were included. Data on age, gender, FEV(1), body mass index (BMI), infection with Pseudomonas aeruginosa (Pa) and on CF-related diabetes were included in the analysis. P Ex was defined as an episode treated with IV antibiotics. Forward stepwise multiple regression analysis was performed with the number of P Exs being the independent variable. The rest of the variables were considered to be the dependent variables.

RESULTS

Data from 341 patients (194 female), mean age (SD), 24.9 (8.9) years were available. In 2002, a total of 599 P Exs were reported, median 1.00 range 0-16 P Exs. Using stepwise multiple regression analysis factors associated with increased number of P Exs were: infection with Pa (t-value -5.0, P < 0.0001), FEV(1), (t-value -4.9, P < 0.0001) and diabetes mellitus, (t-value -2.1, P = 0.04). Age, gender and BMI did not influence the annual number of exacerbations.

CONCLUSIONS

In this study, risk factors for P Exs were found to be as follows: growth of Pa in the sputum, reduced FEV1 and CF-related diabetes mellitus.

Socioeconomic status and lung function

Poverty is a major social problem in the United States and throughout much of the world. Poverty and the broader term socioeconomic status (SES) are important determinants of overall health status and many pulmonary diseases. The purpose of this study was to review the medical literature from the past 20 years addressing the relationship between SES and lung function in both children and adults. There is a significant negative correlation between lung function (primarily FEV1 and FVC) and SES. This relationship exists even after adjusting for smoking status, occupational exposures, and race. The magnitude of the effect of low SES on lung function is variable, but FEV1 reductions of >300 mL in men and >200 mL in women have been reported. SES is an important determinant of lung function and an underrecognized contributor to pulmonary disease.

Incidence and risk factors for multiple antibiotic-resistant Pseudomonas aeruginosa in cystic fibrosis

BACKGROUND

Infection with multiple antibiotic-resistant Pseudomonas aeruginosa (MARPA) in individuals with cystic fibrosis (CF) has caused much concern among caregivers, yet little is known about the risks associated with acquiring resistance. The main objective of the study was to estimate the incidence and identify risk factors for the acquisition of MARPA among individuals with CF.

METHODS

Five-year cohort study of individuals followed in the Cystic Fibrosis Foundation Registry from 1998 through 2002.

RESULTS

Demographics, anthropometrics, spirometry, respiratory culture results, comorbidities, antibiotic usage, and hospitalizations were collected. Of the 4,293 patients with P aeruginosa infection during the study period, MARPA developed in 341. The overall incidence of MARPA was 1.8%/yr. Independent risk factors for MARPA included CF-related diabetes mellitus (hazard ratio [HR], 1.64; 95% confidence interval [CI], 1.11 to 2.43), long-term inhaled tobramycin usage (HR, 2.08; 95% CI, 1.56 to 2.77), and care at a CF center with a baseline MARPA prevalence in the top quartile (HR, 2.00; 95% CI, 1.31 to 3.04). Frequent courses of IV antibiotics and repeated hospitalizations were also found to independently increase the risk for MARPA.

CONCLUSIONS

Infection with MARPA is common among patients with CF. Diabetes, long-term inhaled tobramycin usage, and frequent acute pulmonary exacerbations requiring hospitalization or IV antibiotics increase the risk for MARPA. Receiving CF care at a center with a high prevalence of resistant Pseudomonas also increases the risk for MARPA in patients with CF. Further study is needed to investigate the mechanisms of acquiring resistant strains and the clinical impact of MARPA on CF outcomes.