The subjects enrolled in the study are required to have a diagnosis of OSA confirmed by sleep studies with polygraphy (PS) and / or polysomnography(PSG). Prior to enrolment in the study, all patients are informed in detail about the study and signed the consent form to participate. A randomisation process will follow using a random number generator in Statistical Package for the Social Sciences (SPSS) to systematically assign patients to one group or another, with allocation concealment. Responsible for randomization are prescribers.

The control group intervention. The patients will follow the standard of care, which consists of starting therapy in the home, where the nurse perform training in the use of CPAP equipment, mask adjustment, and safety and maintenance instructions. For follow-up, the patient is always visited at home or telephone, with a frequency established by the Portuguese Society of Sleep(Day 7, Day 21 and Day 180). The follow-up procedure consists of reviewing the CPAP hour meter and resolving any incidents that may have arisen, with the necessary corrective actions (change of mask, positive reinforcement, explanation of specific aspects).

The intervention group 'PIMA' (Personalized Adherence Improvement Plan, based on the Spanish acronym), starts the treatment with the educational and training program called MEntA (Motivational Interview for Adherence). MEntA intervention consists of one session lasting approximately 60 minutes, which is divided into two blocks: educational activity and training activity. In the first block, nurse explains the concepts of sleep apnoea and the symptoms, while a patient shows the CPAP treatment and how to optimize this to the fullest. This block is reinforced with documentation in hard copy and digital format. The second block on training activity was based on working with the treatment, equipment, safety, hygiene and advice. MEntA uses the MI to the treatment of OSA with CPAP. In fact, the nurse uses MI not only at the beginning of therapy, but also in every contact that the patient has with the patient throughout the treatment (subsequent follow-up visits, phone calls, etc). For the PIMA group, the nurse was specifically trained to give this intervention to patients, including a training session with a clinical psychologist.

After the educational and training program, the nurse performs the stratification process to know a series of patient characteristics that will allow identifying the best care plan to obtain the best results in adherence and quality of life. The stratification labels that determine the personalized intervention plan are obtained from two types of variables: personal and modulation variables.With the psychological and clinical variables, in this first visit, "predictive" information is obtained on how the patient's adherence will be: high adherence, moderate adherence or low adherence. Taking this information into account, the care plan will start considering how the patient is and their situation with respect to adherence. Low or moderate adherence relative face plans are more intensive than high adherence relative care plans. In follow-up visits (whose frequency depends on the level of adherence), psychological and clinical variables are reviewed and the patient's adherence is added. Depending on their evolution, the care plan is adapted. For patients with low adherence, telemonitoring is used with hours of compliance, the Apnea-hypoanea index(AHI) and air leak.