Country to country variation: what can be learnt from national cystic fibrosis registries

The clinical features that contribute to poor bone health in young Australians living with cystic fibrosis: A recommendation for BMD screening

BACKGROUND

For Australians living with cystic fibrosis (CF), increased longevity means greater consideration needs to be given to long-term endocrine sequelae such as CF-related bone disease. Deficits in bone mass accrual are most likely to occur during childhood and adolescence. Current guidelines in Australia suggest repeat dual-energy X-ray absorptiometry (DXA) scans every 2 years. This study aims to stratify clinical factors that determine future bone health in the Australian CF population and use this to guide a more streamlined approach to bone health screening.

METHODS

This study was a retrospective audit of all patients diagnosed with CF who were treated at the Royal Children's Hospital Melbourne, Australia from 2000 to 2016 (n = 453). Two hundred and two patients had a DXA scan in the study period (191 with height-adjusted data) and 111 patients had more than one scan (108 with height-adjusted data). An investigation into the associations between bone mineral density (BMD) Z score and potential risk factors was conducted using DXA and historical data.

RESULTS

The main predictor of future BMD was the previous BMD Z score (p < .001). Other factors found to be determinants of BMD included nutritional status, lung function (FEV₁ ), age, history of previous fracture, oral corticosteroid use, and the number of hospital admissions. However, after adjusting for previous BMD, evidence of an association remained only with nutritional status, FEV₁ , and number of hospital admissions.

CONCLUSION

Second yearly scans may be unnecessary in children with an adequate DXA score on the initial scan who remain clinically stable. However, clinical deterioration in those whose BMD was previously normal, may require closer monitoring of bone health. We propose a guideline for the frequency of DXA monitoring in relation to clinical risk factors.

A helper-dependent adenoviral vector rescues CFTR to wild-type functional levels in cystic fibrosis epithelial cells harbouring class I mutations

Cystic fibrosis (CF) is a genetic disorder affecting multiple organs, including the pancreas, hepatobiliary system and reproductive organs; however, lung disease is responsible for the majority of morbidity and mortality. Management of CF involves CF transmembrane conductance regulator (CFTR) modulator agents including corrector drugs to augment cellular trafficking of mutant CFTR as well as potentiators that open defective CFTR channels. These therapies are poised to help most individuals with CF, with the notable exception of individuals with class I mutations where full-length CFTR protein is not produced. For these mutations, gene replacement has been suggested as a potential solution.In this work, we used a helper-dependent adenoviral vector (HD-CFTR) to express CFTR in nasal epithelial cell cultures derived from CF subjects with class I CFTR mutations.CFTR function was significantly restored in CF cells by HD-CFTR and reached healthy control functional levels as detected by Ussing chamber and membrane potential (FLIPR) assay. A dose-response relationship was observed between the amount of vector used and subsequent functional outcomes; small amounts of HD-CFTR were sufficient to correct CFTR function. At higher doses, HD-CFTR did not increase CFTR function in healthy control cells above baseline values. This latter observation allowed us to use this vector to benchmark in vitro efficacy testing of CFTR-modulator drugs.In summary, we demonstrate the potential for HD-CFTR to inform in vitro testing and to restore CFTR function to healthy control levels in airway cells with class I or CFTR nonsense mutations.

Preliminary national report on cystic fibrosis epidemiology in Tunisia: the actual state of affairs

AIM

To establish a preliminary national report on clinical and genetic features of cystic fibrosis (CF) in Tunisian children as a first measure for a better health care organization.

METHODS

All children with CF diagnosed by positive sweat tests between 1996 and 2015 in children's departments of Tunisian university hospitals were included. Data was recorded at diagnosis and during the follow-up from patients' medical records.

RESULTS

In 12 departments, 123 CF children were collected. The median age at diagnosis was 5 months with a median diagnosis delay of 3 months. CF was revealed mostly by recurrent respiratory tract infections (69.9%), denutrition (55.2%), and/or chronic diarrhea (41.4%). The mean sweat chloride concentration was 110.9mmol/L. At least one mutation was found in 95 cases (77.2%). The most frequent mutations were Phe508del (n=58) and E1104X (n=15). Fifty-five patients had a Pseudomonas Aeruginosa chronic colonization at a median age of 30 months. Cirrhosis and diabetes appeared at a mean age of 5.5 and 12.5 years respectively in 4 patients each. Sixty-two patients died at a median age of 8 months. Phe508del mutation and hypotrophy were associated with death (p=0.002 and p<0.001, respectively).

CONCLUSION

CF is life-shortening in Tunisia. Setting-up appropriate management is urgent.

The importance of data issues when comparing cystic fibrosis registry outcomes between countries: Are annual review FEV1 in the UK only collected when subjects are well?

RATIONALE, AIMS AND OBJECTIVE

Cross-country comparisons of cystic fibrosis (CF) outcomes can potentially identify variation in care but are dependent on data quality. An important assumption is that the UK annual review FEV₁ is only collected during periods of clinical stability. If this assumption does not hold, results of FEV₁ comparisons may be biased in favour of registries with encounter-based FEV₁ . We aimed to test the assumption that CF annual reviews in the UK are only performed during periods of clinical stability.

METHOD

Prospective encounter-based data collected in Sheffield (n = 174) was used to establish whether annual review FEV₁ were always collected during periods of clinical stability and to determine the group-level discrepancy between annual review vs best FEV₁ . We then went on to quantify the group-level discrepancy between annual review and best annual FEV₁ readings within the UK registry (n = 2995) to determine if the differences observed in Sheffield also apply to the wider UK data.

RESULTS

Sheffield results showed a group-level discrepancy between best and annual review FEV₁ of -2.5% (95% CI -3.95% to -1.2%) for annual reviews performed during periods of clinical stability (n = 50). The group-level discrepancy is larger at -8.0% (95% CI -11.2% to -4.9%) among annual reviews performed during periods of clinical instability (n = 13). Therefore, the magnitude of this group-level discrepancy is a surrogate for the proportion of clinically stable annual reviews-smaller discrepancy indicates a higher proportion of clinically stable annual reviews and vice versa. The overall group-level discrepancy in the UK registry (-5.6%, 95% CI -5.9 to -5.4%) was similar to Sheffield (-6.1%, 95% CI -7.1 to -5.1%). Around 20% of the clinician reviewed, annual reviews in Sheffield were performed during periods of clinically instability.

CONCLUSIONS

Annual review FEV₁ underestimates lung health of adults with CF in the UK and may bias cross-country comparisons.

Bone mineral density is related to lung function outcomes in young people with cystic fibrosis-A retrospective study

INTRODUCTION

Improvements in the medical management of cystic fibrosis (CF) in recent years have resulted in increased prevalence of long-term sequelae of the condition, such as low bone mineral density (BMD) and hence an increased risk of fractures in later life. Aim To explore the interaction between BMD and lung function, nutrition, and genotype.

METHODS

This study was a retrospective audit of 202 children with CF from August 2000 to January 2016 to investigate associations between BMD Z-scores with clinical status, nutrition, and genetics using dual-energy absorptiometry X-ray data from the Royal Children's Hospital Melbourne, Australia.

RESULTS

Severity of both lung disease (P < 0.0001) and nutritional status (P < 0.05) was found to be strongly associated with BMD Z-scores.

CONCLUSIONS

This is the biggest study to date to provide further evidence that the severity of pulmonary disease is related to BMD in CF patients and therefore screening guidelines for bone health in children with CF should target individuals with the poorest clinical status.

Background and Epidemiology

Cystic fibrosis (CF) is the most common autosomal-recessive disease in white persons. Significant advances in therapies and outcomes have occurred for people with CF over the past 30 years. Many of these improvements have come about through the concerted efforts of the CF Foundation and international CF societies; networks of CF care centers; and the worldwide community of care providers, researchers, and patients and families. There are still hurdles to overcome to continue to improve the quality of life, reduce CF complications, prolong survival, and ultimately cure CF. This article reviews the epidemiology of CF, including trends in incidence and prevalence, clinical characteristics, common complications, and survival.