Although laboratory PSG is the standard test used to diagnose OSA, the evidence shows that, among patients with a high pretest probability of moderate-to-severe OSA, portable monitoring devices can be used at home for diagnosis when access to laboratory sleep studies and sleep specialists is limited. Results obtained from using portable monitoring devices at home may be less accurate compared to portable monitoring conducted in a laboratory or with laboratory PSG. Some studies show no difference in short-term compliance and response to continuous positive airway pressure (CPAP) therapy when portable monitoring and CPAP autotitration at home are compared with laboratory-based PSG diagnosis and CPAP titration.