The practice guideline 'Asthma in adults' from the Dutch College of General Practitioners was revised on the basis of the developments over the last years. The most important modifications are as follows: - 'Asthma with persistent obstruction' was replaced by the double diagnosis 'Asthma and COPD'. - The prednisone test to distinguish asthma from chronic obstructive pulmonary disease (COPD) is no longer recommended. - Spirometry is currently preferred for the diagnosis of asthma. An increase of the forced expiratory volume in 1 second (FEV1) of > or = 12% compared with baseline or in case of a smaller lung volume (FEV1 < 1.67 liters) of > or = 200 ml (therefore, no longer > or = 9% of the predicted value) supports the diagnosis 'asthma'. - As of 2007, the guidelines from the Dutch College of General Practitioners for COPD and asthma in adults are divided into two separate practice guidelines: the practice guideline 'COPD' and the practice guideline 'Asthma in adults'.