Clinical characteristics of cystic fibrosis patients prior to lung transplantation: An international comparison between Canada and the United States

Clinical, paraclinical, and genetic profile of patients with cystic fibrosis from Colombian Caribbean

Background

Cystic fibrosis (CF) is a serious autosomal recessive disorder. Early diagnosis, comorbidity prevention, and control are cornerstones for a quality life and for improving life expectancy. In Colombian Caribbean, where there is a genetically admixed population, CF is an orphan disease affecting children and adults, and it remains a challenging issue to be addressed carefully. This work describes the genetic, clinical, and paraclinical profiles of CF patients from Cartagena de Indias, Colombia.

Methods

Thirty-six patients were included in the study. The subjects were identified and evaluated through the Regional Program for CF patients. CFTR gene mutations, anthropometric parameters, microbiological infections, and pulmonary function were analyzed. Data on demographic parameters, pharmacological treatments, and comorbidities were reported. Frequency and percentages were established for the categorical variables and mean or median for the quantitative variables. In addition, comparisons were made by sex.

Results

The average age of the patients was 11.9 ± 5.3 years and the median age at diagnosis was 14 months. 55.5% were women and 44.5% were men. The mean values for weight, height, and body mass index were 35 ± 17.6 kg, 139.9 ± 28 cm, and 16.5 ± 2.9 kg/m², respectively. The clinical manifestations that occurred more frequently were steatorrhea (65.4%) and recurrent pneumonia (46.2%). Chronic airway infection with Pseudomonas aeruginosa was identified in 71.4% of the cases and the p.F508del mutation was found in 47.2% of the subjects.

Conclusion

The current profile of CF patients from the Colombian Caribbean showed some concerning features, such as nutritional status; however, progress in early diagnosis and clinical follow-up could contribute to improve the general conditions of patients. It is necessary to continue efforts to increase the life expectancy and quality of life of the patients.

Marginal association of fasting blood glucose with the risk of cystic fibrosis-related diabetes

OBJECTIVES

Cystic fibrosis-related diabetes (CFRD) may be diagnosed by fasting blood glucose ≥ 7.0 mmol/L and/or glucose ≥ 11.1 mmol/L following oral glucose tolerance test (OGTT). We compared the role of fasting and stimulated glucose for diagnosis of CFRD.

METHODS

We performed a cross-sectional review of the prevalence of fasting glycemic abnormalities and Kaplan-Meier survival analysis of risk of progression to CFRD according to baseline fasting glucose in the prospective Montreal Cystic Fibrosis Cohort.

RESULTS

Isolated fasting hyperglycemia was detected in only 8% of participants at study onset. Eighty percent of subjects had isolated post-challenge hyperglycemia on their first OGTT meeting criteria for CFRD. Kaplan Meier survival analysis demonstrated that impaired fasting glucose (IFG) alone is not a risk factor for CFRD. Subjects with combined IFG and impaired glucose tolerance at baseline (IGT) had the highest risk of progression to CFRD.

CONCLUSION

Post-prandial elevations in blood glucose are more common at diagnosis of CFRD. While IGT is a significant risk factor for CFRD, IFG alone is uncommon and does not increase the risk of CFRD. Patients with both IGT and IFG have the highest risk of CFRD.

The impact of the high emergency lung transplantation program in cystic fibrosis in France: insight from a comparison with Canada

INTRODUCTION

France implemented a high emergency lung transplantation (HELT) program nationally in 2007. A similar program does not exist in Canada. The objectives of our study were to compare health outcomes within France as well as between Canada and France before and after the HELT program in a population with Cystic Fibrosis (CF).

METHODS

This population-based cohort study utilised data from the French and Canadian CF registries. A cumulative incidence curve assessed time to transplant with death without transplant as competing risks. The Kaplan-Meier method was used to estimate post-transplant survival.

RESULTS

Between 2002 and 2016, there were 1075 (13.0%) people with CF in France and 555 (10.2%) people with CF in Canada who underwent lung transplantation. The proportion of lung transplant increased in France after the HELT program was initiated (4.5% versus 10.1%) whereas deaths pre-transplant decreased from 85.3% in the pre-HELT to 57.1% in the post-HELT period. Between 2008-2016, people in France were significantly more likely to receive a transplant (Hazard Ratio (HR) 1.56, 95% CI 1.37-1.77, p<0.001) than die (HR 0.55, 95% CI 0.46-0.66, p<0.001) compared to Canada. Post-transplant survival was similar between the countries and there was no difference in survival when comparing pre- and post-HELT period in France.

CONCLUSION

Following the implementation of the HELT program, people living with CF in France were more likely to receive a transplant than die. Post-transplant survival in the post-HELT period in France did not change compared to the pre-HELT period, despite potentially sicker patients being transplanted, and is comparable to Canada.

Peak glucose during an oral glucose tolerance test is associated with future diabetes risk in adults with cystic fibrosis

AIMS/HYPOTHESIS

Cystic fibrosis-related diabetes (CFRD) affects up to 50% of adults with cystic fibrosis (CF) and its presence is associated with adverse effects on nutritional status and pulmonary function. Early diagnosis could minimise CFRD morbidity, yet current methods of an OGTT at 0 and 2 h yield unreliable results. Our aim was to determine which indices from a 2 h OGTT with sampling every 30 min might improve prediction of CFRD.

METHODS

Cross-sectional analysis at baseline (n = 293) and observational prospective analysis (n = 185; mean follow-up of 7.5 ± 4.2 years) of the Montreal Cystic Fibrosis Cohort were performed. Blood glucose and insulinaemia OGTT variables were studied in relation to lung function (forced expiratory volume in 1 s [FEV1]), BMI and risk of developing CFRD.

RESULTS

At baseline, maximum OGTT glucose (G_max) was negatively associated with FEV1 (p = 0.003). Other OGTT values, including classical 2 h glucose, were not. A higher G_max was associated with lower insulin secretory capacity, delayed insulin peak timing and greater pancreatic insufficiency (p < 0.01). G_max was positively associated with the risk of developing CFRD (p = 0.0029); no individual with a G_max < 8 mmol/l developed CFRD over the following decade. No OGTT variable correlated to the rate of change in BMI or FEV1.

CONCLUSIONS/INTERPRETATION

In adults with CF, G_max is strongly associated with the risk of developing CFRD; G_max < 8 mmol/l could identify those at very low risk of future CFRD. G_max is higher in individuals with pancreatic insufficiency and is associated with poorer insulin secretory capacity and pulmonary function.

The Impact of Resistant Bacterial Pathogens including Pseudomonas aeruginosa and Burkholderia on Lung Transplant Outcomes

Pseudomonas and Burkholderia are gram-negative organisms that achieve colonization within the lungs of patients with cystic fibrosis, and are associated with accelerated pulmonary function decline. Multidrug resistance is a hallmark of these organisms, which makes eradication efforts difficult. Furthermore, the literature has outlined increased morbidity and mortality for lung transplant (LTx) recipients infected with these bacterial genera. Indeed, many treatment centers have considered Burkholderia cepacia infection an absolute contraindication to LTx. Ongoing research has delineated different species within the B. cepacia complex (BCC), with significantly varied morbidity and survival profiles. This review considers the current evidence for LTx outcomes between the different subspecies encompassed within these genera as well as prophylactic and management options. The availability of meta-genomic tools will make differentiation between species within these groups easier in the future, and will allow more evidence-based decisions to be made regarding suitability of candidates colonized with these resistant bacteria for LTx. This review suggests that based on the current evidence, not all species of BCC should be considered contraindications to LTx, going forward.

Bridging the survival gap in cystic fibrosis: An investigation of lung transplant outcomes in Canada and the United States

BACKGROUND

Previous literature in cystic fibrosis (CF) has shown a 10-year survival gap between Canada and the United States (US). We hypothesized that differential access to and survival after lung transplantation may contribute to the observed gap. The objectives of this study were to compare CF transplant outcomes between Canada and the US and estimate the potential contribution of transplantation to the survival gap.

METHODS

Data from the Canadian CF Registry and the US Cystic Fibrosis Foundation Patient Registry supplemented with data from United Network for Organ Sharing were used. The probability of surviving after transplantation between 2005 and 2016 was calculated using the Kaplan‒Meier method. Survival by insurance status at the time of transplantation and transplant center volume in the US were compared with those in Canada using Cox proportional hazard models. Simulations were used to estimate the contribution of transplantation to the survival gap.

RESULTS

Between 2005 and 2016, there were 2,653 patients in the US and 470 in Canada who underwent lung transplantation for CF. The 1-, 3-, and 5-year survival rates were 88.3%, 71.8%, and 60.3%, respectively, in the US compared with 90.5%, 79.9%, and 69.7%, respectively, in Canada. Patients in the US were also more likely to die on the waitlist (p < 0.01) than patients in Canada. If the proportion of who underwent transplantation and post-transplant survival in the US were to increase to those observed in Canada, we estimate that the survival gap would decrease from 10.8 years to 7.5 years.

CONCLUSIONS

Differences in waitlist mortality and post-transplant survival can explain up to a third of the survival gap observed between the US and Canada.

Influence of pre-diabetic and pancreatic exocrine states on pulmonary and nutritional status in adults with Cystic Fibrosis

BACKGROUND

In 1992, a landmark study demonstrated clinical deterioration in respiratory function and nutritional status prior to the onset of cystic fibrosis-related diabetes (CFRD). We re-evaluated this outcome.

METHODS

The Montreal Cystic Fibrosis Cohort is a prospective CFRD screening study. We performed a 6-year retrospective analysis of nutritional parameters and FEV₁ (%) in subjects who developed incident CFRD and in controls who maintained normoglycemia (NG). In the former group, data was collected over 6 years prior to diabetes onset.

RESULTS

Subjects (n = 86) had a mean age of 31.7 ± 8.1 years, BMI of 23.0 ± 4.0 kg/m2, and FEV1% of 70.1 ± 24.2%. Eighty-one percent had pancreatic insufficiency (PI). Patients were grouped as follows: NG+PS (pancreatic sufficient) (n = 16), NG+PI (pancreatic insufficient) (n = 21), CFRD+PS (n = 3) and CFRD+PI (n = 46). At their most recent screen NG+PS subjects had significantly greater BMI, as compared to NG+PI and CFRD+PI groups (26.2 ± 3.6 kg/m² vs 22.6 ± 4.2 kg/m² vs 22.1 ± 3.5 kg/m², p = 0.0016). FEV₁ was significantly greater in the NG+PS group (91.5 ± 16.8% vs 67.8 ± 25.3% vs 63.5 ± 22.2%, p = 0.0002). The rates of change in weight, BMI, fat mass (%), and FEV₁ prior to the most recent visit (NG+PS, NG+PI groups) or to the diagnosis of de novo CFRD were similar between groups.

CONCLUSION

In a contemporary context, CFRD onset is not preceded by deterioration in BMI, fat mass, or pulmonary function. Low BMI and FEV₁ are more closely associated with PI than a pre-diabetic state.

Hepatic enzyme ALT as a marker of glucose abnormality in men with cystic fibrosis

AIM

Cystic fibrosis (CF) patients are at high risk of developing CF-related diabetes (CFRD). In non-CF patients, liver disease, specifically steatosis and non-alcoholic fatty liver disease (NAFLD), is strongly associated with type 2 diabetes. We compared glycemic status and metabolic profiles in CF patients according to a biomarker of hepatic injury, alanine aminotransferase (ALT).

METHODS

We conducted a cross-sectional study among 273 adult CF patients recruited from the Montreal CF Cohort. A 2-hour oral glucose tolerance test (OGTT) was performed to collect glucose and insulin measures every 30 minutes. Fasting ALT levels and anthropometric measures were also obtained. Patients were categorized into 2 groups based on ALT cut-off of 25 U/L.

RESULTS

Patients in the high ALT group were mostly men (83%), had higher mean weight and BMI (p<0.001) and showed elevated glucose levels throughout OGTT (p≤0.01). When stratified by sex, only men with high ALT showed significantly higher weight (p<0.001), higher glycemic values at 60, 90 and 120 minutes of OGTT (p≤0.01), higher frequency of de novo CFRD (20.5% vs 8.2%, p = 0.04) as well as lower insulin sensitivity than men with normal ALT (p = 0.03). ALT levels were strongly associated with HOMA-IR in CFRD patients (p = 0.001, r2 = 0.28).

CONCLUSIONS

Adult CF men with higher ALT show an increased frequency of dysglycemia and de novo CFRD, lower insulin sensitivity and higher eight. Our data suggests that ALT levels could be an interesting tool to guide targeted diabetes screening, particularly among CF men. Prospective studies are needed to confirm these observations.

Sputum microbiota is predictive of long-term clinical outcomes in young adults with cystic fibrosis

BACKGROUND

Complex polymicrobial communities infect cystic fibrosis (CF) lower airways. Generally, communities with low diversity, dominated by classical CF pathogens, associate with worsened patient status at sample collection. However, it is not known if the microbiome can predict future outcomes. We sought to determine if the microbiome could be adapted as a biomarker for patient prognostication.

METHODS

We retrospectively assessed prospectively collected sputum from a cohort of 104 individuals aged 18-22 to determine factors associated with progression to early end-stage lung disease (eESLD; death/transplantation <25 years) and rapid pulmonary function decline (>-3%/year FEV₁ over the ensuing 5 years). Illumina MiSeq paired-end sequencing of the V3-V4 region of the 16S rRNA was used to define the airway microbiome.

RESULTS

Based on the primary outcome analysed, 17 individuals (16%) subsequently progressed to eESLD. They were more likely to have sputum with low alpha diversity, dominated by specific pathogens including Pseudomonas. Communities with abundant Streptococcus were observed to be protective. Microbial communities clustered together by baseline lung disease stage and subsequent progression to eESLD. Multivariable analysis identified baseline lung function and alpha diversity as independent predictors of eESLD. For the secondary outcomes, 58 and 47 patients were classified as rapid progressors based on absolute and relative definitions of lung function decline, respectively. Patients with low alpha diversity were similarly more likely to be classified as experiencing rapid lung function decline over the ensuing 5 years when adjusted for baseline lung function.

CONCLUSIONS

We observed that the diversity of microbial communities in CF airways is predictive of progression to eESLD and disproportionate lung function decline and may therefore represent a novel biomarker.