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Screening older patients for obstructive airways disease
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1. ANTONY CROCKETT
1. Elm Tree Surgery
2. Shrivenham
3. Swindon SN6 8AG, UK

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Many studies have shown an increase in the number of cases of obstructive airways disease (asthma and chronic obstructive airways disease) in all age groups over the last few decades.1 ,2In the elderly, breathlessness is a common symptom3 and is increasingly common with age.4 A large number of patients with this symptom will have obstructive airways disease5 ,6 and estimates of the proportion of the elderly population who have evidence of chronic airways obstruction range from 20%7 ,8 to 30%.6 Some elderly subjects with objective evidence of obstructive airways disease will not have received a formal diagnosis6 ,9 and will not be receiving any specific treatments.9 Many patients may be untroubled by their symptoms10 or have adapted to them.5In response to these findings, several authors have recommended screening for obstructive airways disease in elderly patients.11 ,12 The premise is that the prevalence of respiratory symptoms in the elderly is high and therefore a considerable proportion of elderly subjects will have obstructive airways disease. Screening in primary care will identify those with obstructive airways disease, allowing therapeutic intervention to be applied which will lead to reduced morbidity and mortality in the treated subjects. However, before general practices invest the resources into screening for obstructive airways disease in the elderly, there must be good evidence for their doing so.

As there are no cures for obstructive airways disease, much attention has been focused on whether early detection and subsequent suitable interventions will prevent worsening of the condition and will lead to improved quality and quantity of patients’ lives. The earliest detection will be screening of previously undiagnosed individuals who are asymptomatic or whose symptoms are insufficient for the patient to seek medical attention. Effective screening requires the early detection of disease for which safe treatment is available but which, if left untreated, progresses to disability and death.

There is increasing evidence that early intervention with treatments for asthma, especially inhaled corticosteroids, has a substantial impact on later morbidity and may lead to long term remission.13-15 In chronic obstructive pulmonary disease (COPD), however, the delayed introduction of inhaled corticosteroids does not appear to be harmful.15 ,16 Moreover, patients with the mildest COPD do not seem to benefit at all from taking inhaled corticosteroids17-19 nor from any other intervention except stopping smoking.20 ,21 There are great benefits from early interventions in younger people with obstructive airways disease but the benefits of early diagnosis and intervention in the elderly are less clear.

In this issue of Thorax Dickinsonet al 22 report the results of a study of screening older patients with obstructive airways disease and concluded that screening asymptomatic elderly patients in a semi-rural practice was not worthwhile. The study screened a random sample of 353 patients aged 60–75 years using peak flow diaries, symptom questionnaires, and respiratory function tests. Thirty newly diagnosed patients were identified (8% of the screened population), eight of whom had asthma and the remainder COPD. No patient had severe disease. Six patients accepted treatment (1.2% of the screened population), five with asthma and one with COPD.

These results fail to confirm the large burden of unmet need described in other UK studies6 ,9 but concur with the findings of a large Dutch study2 that no evidence of significant untreated disease could be found. Dickinson et al also identified far fewer patients than a two year Dutch study undertaken by Van den Boom et al on 1155 subjects aged 25–70 years.23 Like the study by Dickinson et al, patients with known obstructive airways disease were excluded. Extrapolation of the Dutch study showed that 7.7% of the population had persistent increased bronchial hyperreactivity (BHR) and decreased lung function, another 12.5% had signs of BHR and a rapid decline in lung function, and a further 19.4% had mild objective signs of obstructive airways disease.

Dickinson et al estimated that finding 30 new patients with obstructive airways disease, six of whom were willing to accept treatment, required 331 hours of nurse time and 18 hours of doctor time. No estimations of staff and practice organisation costs, equipment, transportation, and patient costs were made but, assuming that nurse time costs £10 an hour and doctor time £50 an hour, each newly diagnosed patient cost at least £140 (US$225) and each newly treated patient cost £700 (US$1120). It is possible that some of the relatively high initial costs may be offset by long term health outcomes.24 ,25

The question remains, then, whether general practices should screen their elderly patients for obstructive airways disease. On the available evidence the answer must be no, or at least not yet. Screening for any disorder carries with it ethical considerations as well as those of resource allocation and utilisation. If we wish to screen patients who have no symptoms, or symptoms insufficient for them to seek medical attention, we must be sure that there are effective and safe treatment options that will prevent or slow down the progress of their condition. For elderly patients with mild obstructive airways disease there is no convincing evidence that any therapeutic intervention will lead to long term benefit. Screening large sections of a population in primary care will require a great deal of a practice’s financial, personnel and organisational resources, for all of which there are already many competing demands. Finding patients and giving them a diagnosis is not necessarily the same as providing effective treatment.

Screening for obstructive airways disease in other age groups may be more worthwhile. Most of the evidence supporting early therapeutic intervention is from studies in childhood asthma and screening for obstructive airways disease in children may be more cost effective and beneficial to our patients. In the prevention of COPD, or early intervention, the single most important factor is stopping cigarette smoking, and the resources of the primary health care team may be better spent preventing patients from smoking and helping those who smoke to stop. The methods used by Dickinson et al and in the Dutch studies involved questionnaires and respiratory function testing. These methods are time consuming and expensive and may need repeating at intervals of up to two years. However, screening by symptom scores alone,10 peak flow variability,26 or reversibility of airflow obstruction in response to a bronchodilator27 ,28 have all been shown to lack sensitivity. Measuring BHR may be a more reliable and discriminatory test for obstructive airways disease,29especially in the elderly,30 but it is impractical for use in a primary care setting.

The study by Dickinson et al is evidence that screening for obstructive airways disease in elderly patients in primary care is probably a poor use of scarce practice resources. Those resources are better allocated to screening for obstructive airways disease in younger age groups, to smoking prevention and cessation or, in the absence of practical tests for BHR, to adding spirometric tests to the other checks carried out at opportunistic or planned health screening.