Concept and use of the guidelines

Cough is one of the most frequent complaints for which patients seek medical care throughout the world. The exact prevalence of cough in Japan is unknown, but in the UK, 10–15% of the entire population have a daily cough, and in the USA, over 100 million dollars are spent each year on treatment of cough. The aetiology of cough ranges from the selfresolving common cold to life-threatening cardiac disease and lung cancer. Even if the underlying disease has a good prognosis, the energy expended due to cough decreases patient quality of life (QOL). In addition to being a discomfort for patients, cough due to severe acute respiratory syndrome (SARS) and tuberculosis spreads the risk of infection to family, friends and associates. The presence of rhonchi or rales on physical examination or abnormal findings on CXR makes the diagnosis of cough relatively easy, but in the absence of these findings, many patients may complain of a cough for several weeks without a diagnosis. A recent increase in patients with unexplained cough has been noted both by generalists and specialists in pulmonary medicine. Physicians often focus on symptomatic treatment of cough, but suppression of a productive cough with copious sputum production or cough due to aspiration may worsen the patient’s condition. For this reason, the Japanese Respiratory Society has decided to publish the ‘Cough Guidelines’. These guidelines broadly define cough based on duration as acute cough lasting less than 3 weeks, prolonged cough lasting 3–8 weeks and chronic cough lasting longer than 8 weeks. The guidelines are also divided into general and special topics. The special topics include acute cough, prolonged and chronic cough and cough in specific populations (paediatric patients, elderly patients and patients with underlying disease). The authors include paediatricians, internists and ENT specialists. Figure 1.1 shows the incidence of aetiology of cough for each period defined in the guidelines. The most common cause of acute cough is respiratory tract infection, whereas prolonged and chronic coughs of longer duration are more likely due to a non-infectious cause. A consensus report on cough published in the USA has been used in Japan, but many clinicians believe that underlying disease prevalence differs between patients with cough in Japan and Western countries. For example, of the three main causes of chronic cough in Western countries, cough-variant asthma, postnasal drip and gastroesophageal reflux disease (GERD), the latter two are not as prevalent in Japan. Therefore, these guidelines are not necessarily based on reports from Western countries, but are rather designed specifically for Japan. Cough is a common symptom, and the true value of these guidelines is that they are intended not only for pulmonary specialists, but also for the many generalist physicians who provide front-line care for most of these patients. For disorders presenting with persistent or chronic cough, these guidelines offer both simplified diagnostic criteria that can be used in general clinics where special tests are not needed, as well as more stringent diagnostic criteria requiring special tests that can only be performed in larger general or university hospitals with departments of pulmonary medicine. These guidelines are aimed at the differential diagnosis and treatment of common disorders seen in clinical practice. They are not all-inclusive of some