Pneumonia: There Are Ways To Avoid It! So Concludes A Major Multicentre Study Conducted In Spain

Main Category: Respiratory / Asthma
Article Date: 29 May 2008 - 0:00 PDT

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Community-acquired pneumonia - in other words, pneumonia caught outside hospital - can be prevented, according to a Spanish report to be published in the forthcoming issue of the ERJ, the peer-reviewed scientific publication of the European Respiratory Society (ERS).

By comparing over 1,300 patients with control subjects, the Spanish team identified both risk factors to be avoided and potentially protective elements.

The risk factors include regular contact with children, abrupt temperature fluctuations in the workplace, smoking, excessive alcohol consumption and certain treatments involving inhalers.

As to the protective elements, the authors list vaccination against influenza and pneumococcus, and dental hygiene.

Common in most developed countries, community-acquired pneumonia, which frequently results from influenza, is a major cause of infectious morbidity and mortality. The incidence (and perhaps the death rate) could be reduced through action on certain modifiable risk factors, according to Jordi Almirall (Intensive Care Unit, Hospital de Mataró, Barcelona, Spain), writing in the forthcoming issue of the ERJ.

While population studies on this subject are still rare, it seems to be established that smoking, antecedents of respiratory infection or a chronic lung condition (such as asthma) are independent risk factors for pneumonia, as are low body weight and diabetes. However, a meta-analysis drawing on ten studies was unable to establish with certainty what role was played by some other factors, including medicines, high alcohol consumption, or socio-demographic characteristics.

Over 1,300 cases under scrutiny

To refine these data, Jordi Almirall and his team, working with numerous colleagues in the PACAP Study Group, decided to conduct a case-control study in a large area on Spain's eastern coast, where 95% of residents are covered by the national health service. The target population consisted of almost 860,000 people aged fourteen and upwards; patients from 64 primary care centres participated in the study. For thirteen months, all suspected cases of pneumonia acquired outside hospital were prospectively recorded by both private and public sector doctors.

In addition to a clinical examination, all patients were given a chest X-ray to confirm diagnosis. The X-ray was repeated for control purposes on the fifth day and then once a month until complete recovery. In total, the ERJ article's authors registered 1,833 suspected cases of community-acquired pneumonia, in 394 (21.5%) of which the diagnosis was later, however, revoked. The study eventually retained 1,336 patients, as well as 1,326 control subjects of the same age, sex and geographical area. More than half (52.9%) of the patients were men, aged 58.9 years on average. The women (47.1%) had an average age of 54.6. Six out of ten patients were treated at home, while the remainder were hospitalised.

Things to avoid: promiscuity, children and pets!

Using multivariate analysis, the team identified a number of independent risk factors for pneumonia, some of which were controversial or even unknown. Particular emphasis was placed on factors that were felt to be avoidable.

For example, the study confirms that heavy smoking increases pneumonia risk, although this drops off significantly from the second year after quitting. However, the harmful effect of passive smoking is noted for the over-65s. Heavy drinking (over 40 g of alcohol daily) also increases the risk of pneumonia for men. And the risk is multiplied by 2.64 where there are abrupt fluctuations in workplace temperature!

"Basic research on humans and animals has shown that breathing in cold air cools the nasal epithelium, and this drop in temperature within the nose weakens the airways' defence against infections" the authors explain.

Living with more than ten people is also a risk factor, as is living with children or having contact with pets.

Logically, the study also finds that existing respiratory or heart conditions (including asthma, chronic bronchitis and heart failure) can facilitate the onset of pneumonia. For example, the risk is more than doubled (relative risk of 2.28) for patients with a recent upper airway infection.

Other important independent risk factors include hospital admission in the previous five years, previous CAP confirmed by chest radiography, and epilepsy. Additionally, some medical treatments also appear to be risk factors, the ERJ article points out. In particular, this applies to amiodarone (used to treat heart failure), oxygen therapy and corticosteroid treatment. While it is well known that oral corticosteroids increase susceptibility to infection, one study also found this effect with inhaled corticosteroids, Almirall observes.

One of the most surprising findings of this study, however, was the role played by inhalers in increasing susceptibility to infection: users' risk of pneumonia is then multiplied by 1.5! It is particularly true when a chamber spacer (designed to facilitate the delivery of the medicine) is used.

"We need to do more research and find out the reasons for this before announcing it to patients," reasons Almirall, who is currently conducting further analysis of his results to try and find the explanation for this effect.

Dental hygiene's protective effect

In parallel to these evident risk factors, the authors of the ERJ article have identified certain protective factors. For example, patients who had visited the dentist within the previous month had a 30% lower risk of pneumonia, and significant protection was also offered by influenza vaccination (-20%) and pneumococcus vaccination (-46%).

"Timely, correct treatment of upper airway infections, promotion of dental hygiene and vaccinations, avoidance of certain drugs and medical explorations of the airways, and a reduction of the risk of airway contamination by bacteria are the main preventive measures that doctors should recommend, together with smoking cessation and a close clinical follow-up of at-risk patients, particularly those with recent community-acquired pneumonia or hospitalisation, asthma, chronic obstructive pulmonary disease or epilepsy," Almirall concludes.

Title of original article-
New evidence of risk factors for community-acquired pneumonia: a population-based study

The European Respiratory Journal is the peer-reviewed scientific publication of the European Respiratory Society (more than 8,000 specialists in lung diseases and respiratory medicine in Europe, the United States and Australia).

European Respiratory Journal