predicting risks of asthma recurrence stephen watt consultant in respiratory and hyperbaric medicine...
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Predicting risks of asthma recurrence
Stephen WattConsultant in Respiratory and Hyperbaric
MedicineAberdeen Royal Infirmary
AsthmaHazards at work
• Inability to do job (restricted work capacity)
• Frequent periods of illness• Sudden incapacity to do critical tasks• Exposure to sensitisers• Outcome of acute episodes in remote
locations
AsthmaAssessment of fitness for work
• “Certificate of fitness”–misleading and misunderstood– often rigid application of guideline
• Medical assessment = risk assessment– transparent– logical– understood by patients
Asthma
• Definition – no gold standard• Clinical diagnosis– Cough, wheeze, breathlessness, chest
tightness + variable airflow obstruction– Pathology involves airway hyper-
responsiveness and inflammation
• Very common
Asthma in Children
• Diagnosis– Cough, SOB occur with viral infections– Frequency, diurnal variation, triggers, atopy, family
history, response to Rx
• Prognosis– Age > 2 - < 2– Sex – Female > Male– Frequency of episodes– Severity– Atopy– Family history– Abnormal lung functuion
Asthma in Adults
• Patterns of disease– Episodic
• atopy, infection, exercise
– Persistent• Severity
– Mild (acute episode history)– Moderate – Severe (therapy history)
– Brittle– Cough variant
• Impact of therapy
Prevalence
• Problems with diagnosis– Wheeze ever, episode in last year, treatment =
8.1%– 2001 health survey
• Wheeze in last year 15-20% age up to 55• Diagnosis of asthma 10-15% age up to 55
• Very common
Asthma mortality
• Approx 1200 asthma deaths in UK pa
• Age specific mortality– Children and adults <45 = >1 per
100,000– Adults 45 – 64 = 2 per 100,000– Adults > 65 = 10 per
100,000
Asthma morbidity
• Is survival dependent on benefit of medical care?
Asthma morbidity
• Asthma is common cause for hospital admission
• But–Multiple admissions– Cause for admission• Poor compliance, panic, co-morbidity
– Small number are life threatening
Predicting the risk• Risk in this age group is very small• Risk factors for death– Age– Poor lung function– Co-morbidity– Previous severe episodes (hospital admissions)– Previous near fatal episode– Poor compliance with treatment– No diagnosis
• Proportion of deaths occur without diagnosis
Assessing the risk
• Medical history– Age of onset– Severity (current treatments)– Symptoms (when well and when unwell)– Frequency of episodes– Control of episodes (Self management)–Monitoring PEF (where appropriate)
• Lung function
November 2008
Lung function tests
• FEV1– best of three satisfactory attempts–most reproducible test– SD is 0.5 litres• Normality 95% confidence limits = predicted
normal +- 1.67 * 0.5• Percent predicted value not helpful!
– remember ethnic correction factors
What can asthmatics do?
• Almost all jobs dependent on assessment–Manual labouring– Athletics– Police– (Firemen)– (Diver)
Where do asthmatics work?
• Altitude• Offshore• Polar regions
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