Abstract: The invention provides a method for estimating if a patient suffering from Chronic Obstructive Pulmonary Disease (COPD) is approaching an exacerbation. Data with connected data indicative of levels of blood oxygen saturation obtained from the patient and their respective time of measurements are received, and a processor executes an algorithm involving: 1) calculating a statistical measure, e.g. a regression, of the level of blood oxygen saturation data taking into account available data within a time window with a limited length back in time, e.g. 30 days back in time, and 2) estimating if the patient is approaching an exacerbation by comparing a value obtained from said statistical measure to a reference value. Finally, an output indicative of a result of said estimation is generated. The method can ensure that COPD patients, e.g. in tele homecare, are properly treated before suffering from a severe exacerbation that could necessitate hospitalization.