34 HOW TO TREAT : CYSTIC FIBROSIS
34 HOW TO TREAT : CYSTIC FIBROSIS
16 JUNE 2023 ausdoc . com . au treatment that will be required in modulator-treated patients is unclear , and we await ongoing follow-up studies from both national and international registries .
CASE STUDIES
Case study one
SOPHIA , four months old , is brought to the GP as she has a wet cough and poor weight gain . She was born at 38 weeks ’ gestation , with a birthweight of 3.5kg ( 50-85th centile ), and had normal antenatal scans .
On day two of life , she developed vomiting and abdominal distension and had failed to pass meconium . Sophia was transferred to a tertiary paediatric hospital , where she was successfully treated for an uncomplicated meconium ileus with a sodium meglumine diatrizoate enema . Her NBS was negative , with a normal IRT , and no further investigations for CF were performed despite meconium ileus being a risk factor .
When Sophia was two months old , she had a viral illness and has continued to cough daily since . Her parents describe her as being irritable but feeding well , taking both breastmilk and formula top-ups . They have noted that her stools are “ smelly and oily ”.
On examination , Sophia weighs 4kg ( 3rd-15th centile ), she is afebrile and her oxygen saturation is 99 %. She has mild subcostal recessions , but no crackles are heard on auscultation . A wet cough is noted during the consultation . Her abdomen is mildly distended but soft and non-tender , and oil is seen in the stool .
She has a negative viral panel , but S . aureus is cultured on bacterial oropharyngeal swab . She is started on amoxycillin / clavulanic acid to treat prolonged wet cough and urgently referred to a local paediatrician for investigation of faltering growth and further workup of CF .
The paediatrician orders a sweat test that returns a sweat chloride result of 80mmol / L , which is diagnostic of CF . A faecal elastase test is consistent with pancreatic insufficiency ( less than 200 µ g / g ).
She is referred to a CF team at her closest tertiary hospital . Diagnosis is confirmed with genetic testing , and Sophia is found to be homozygous
How to Treat Quiz .
1 . Which THREE systems are primarily affected by CF ? a Respiratory . b Gastrointestinal . c Cardiovascular . d Reproductive .
2 . Which TWO statements regarding the pathophysiology of CF are correct ? a CFTR mutations result in identical clinical presentation in all patients . b Clinical manifestations of CF are caused by a defect in the CFTR protein . c A CFTR mutation stops sodium secretion and allows unrestrained chloride absorption . d The mutation results in dehydration of the airway surface liquid and defective mucus clearance .
3 . Which ONE is not a gastrointestinal feature of CF ? a Pancreatic insufficiency . b Irritable bowel syndrome . c Constipation and delayed gastric emptying . d Gastro-oesophageal reflux .
4 . Which TWO are common infectious agents in respiratory exacerbations in those with CF ? a S . aureus . b M . tuberculosis . c P . aeruginosa . d M . pneumoniae .
5 . Which THREE statement regarding the diagnosis of CF are correct ? a Most patients are diagnosed on clinical presentation . b Prenatal testing is offered to couples where both parents are confirmed CF carriers . c Meconium ileus on the routine 18-20-week morphology scan may indicate CF . d Reproductive carrier testing will be available on the MBS in November 2023 .
Figure 9 . Spirometry report of a 15 year old male with cystic fibrosis . Results show abnormal spirometry consistent with very severe obstructive defect ( FEV 1
Z score > -4 ). The flow-volume loop shows an obstructive pattern with reduced flow and expiratory prolongation .
FVC = forced vital capacity ; PEF = peak expiratory flow ; LLN = lower limit of normal .
F508del . She is started on pancreatic enzymes , fat-soluble vitamins , salt , regular chest physiotherapy and lowdose prophylactic oral flucloxacillin .
Case study two
Mark , 16 , presents to his GP accompanied by his mum . He has CF and a twoweek history of productive cough , which is worse at night , and mild exercise intolerance . There is obvious tension between Mark and his mum as he has not been doing his airway clearance treatments . His baseline FEV 1
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6 . Which TWO statements regarding the postnatal diagnosis of CF are correct ? a IRT can be falsely elevated in children with meconium ileus . b CF is most commonly diagnosed on NBS . c Delay sweat testing until the child is at least six months old . d A sweat test is diagnostic if the level of chloride is greater than 60mmol / L .
7 . Which THREE are features of CF in preschoolers ? a Finger clubbing . b Faltering growth . c Hyponatraemia and dehydration . d Oedema from prolonged malabsorption .
8 . Which TWO statements regarding the management of CF are correct ?
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Figure 10 . Abdominal X-ray of seven-year-old female showing faecal loading and dilated small bowel , suggesting distal intestinal obstruction syndrome .
CYSTIC FIBROSIS
Figure 11 . Clubbing .
is 82 %, and when well , he only has small amounts of white sputum with his airway clearance . He also reports his appetite is reduced and he has not been taking PERT ( pancrelipase 10,000 IU ) with every meal .
On examination , Mark ’ s weight is down 1kg compared with his last clinic correspondence two months earlier . He has crackles in his right upper lobe , his oxygen saturation is 95 % and he has mild clubbing ( see figure 11 ). Coughing during the consultation yields yellow – green
a PEP is the cornerstone of treatment from school age through the lifespan . b FEV 1 is used to assess the severity of lung disease . c A high-energy and high-fat diet is recommended . d Fewer than 15 % of patients with CF have pancreatic insufficiency .
9 . Which THREE medications are appropriate in CF ? a Hypertonic saline . b Insulin . c CFTR modulators . d Calcium supplementation .
10 . Which THREE statements regarding the complications of CF are correct ? a Haemoptysis is a major cause of morbidity and mortality . b All respiratory exacerbations require hospital admission . c Annual screening for CFRD with OGTT is currently recommended from the age of 10 . d Children and adolescents with CF have higher rates of anxiety and depression . mucopurulent sputum that is sent for culture . Mark is started on 10 days of trimethoprim / sulfamethoxazole as he commonly grows S . aureus and S . maltophilia in his surveillance sputums .
Mark is reviewed by his CF team . His FEV 1 is 74 %, and his sputum sample has grown P . aeruginosa . He is offered treatment with oral ciprofloxacin and a month of nebulised tobramycin at home . As he had not been able to get back into a routine with his airway clearance , the hospital in the home team provides support for two weeks to help establish a routine . The physiotherapist combines his hypertonic saline and PEP to reduce treatment time and suggests a portable nebuliser to offer flexibility around where he can complete nebulised treatments .
The dietitian reviews Mark ’ s PERT dosing and changes him to a higher -dose tablet so he has fewer tablets to take when away from home .
The psychologist starts working with Mark to help with ongoing adherence to treatments .
CONCLUSION
CF is the most prevalent life-limiting inherited disease in Australia . While the condition is currently incurable and has a reduced life expectancy , the average age of survival is increasing . The disease is no longer viewed as a disease of childhood only but one seen in adults as well .
The emergence of new CFTR modulating medications over the past 20 years has significantly improved life expectancy , with adults constituting more than 50 % of Australian patients with CF .
Improvements in time to diagnosis and new treatment options , such as modulator medications , have resulted in improvements in the natural history of the disease . Despite these new treatments , improving awareness and compliance to prevent infection , treat acute exacerbation and comply with treatments to maximise quality of life and long-term survival remains important .
The Federal Government has announced that reproductive carrier testing for three conditions , including CF , will be listed on the MBS in November 2023 .
RESOURCES
• Cystic Fibrosis Australia provides information for patients and clinicians , along with the data registry annual report : bit . ly / 41RRkPD
• CFTR2 site provides information about specific variant or variant combinations : bit . ly / 3mVGVUj
• Cystic Fibrosis Mutation Database : bit . ly / 3UY1iwF
• Thoracic Society of Australia and New Zealand ; Nutrition Guidelines for Cystic Fibrosis in Australia and New Zealand : bit . ly / 3Ha1kvL
Declaration of interest statement Dr Prentice received honorarium from Vertex Pharmaceuticals and the Thoracic Society of Australia and New Zealand / Vertex clinical fellowship .
References Available on request from howtotreat @ adg . com . au