OBJECTIVES It is estimated that the prevalence of moderate-to-severe SA (apnoea-hypopnoea index >15/h) is 10%. Approximately 11% of SA patients have comorbid COPD, which worsens sleep quality and desaturations. This study investigated the effects of PAP therapy on all-cause mortality and cost of illness (COI) in patients with SA and COPD in Germany. A statutory health insurance (SHI) perspective was taken. METHODS A total of >4 million individuals covered by the SHI database were analysed (≈5% of the German SHI population). PAP therapy was initiated in 4,068 patients with SA (PAP group). Propensity score matching was used to define a control group (CG) of 4,068 SA patients matched for age, sex, risk factors/aetiology, region and medication who received usual care (no PAP). Of these, 1,300 patients in the PAP group and 1,192 patients in the CG had comorbid COPD. This subgroup of patients was followed for 3 years after initiation of PAP therapy. RESULTS Total COI was higher in the PAP group versus CG in the first year of follow-up (€8,697 vs €6,999, p<0.0001). However, during the second and third year the difference in COI between the PAP and CG was smaller (year 2: €7,340 vs €7,316, p<0.0048; year 3: €6,847 vs €6,714, p<0.001). PAP recipients had a significantly lower 3-year mortality rate compared with CG (8.2% vs 11.7%, p<0.001; relative risk reduction 30.1%). CONCLUSIONS SA patients with COPD treated with PAP showed significantly reduced mortality and morbidity. Total COI was higher in PAP recipients versus CG over the first 3 years of follow-up, but the difference between groups decreased over time. A follow-up period of ≥5 years may be required to show beneficial economic outcomes in SA patients receiving PAP therapy.