INTRODUCTION: Patients with pulmonary hypertension (PH) often have comorbid sleep apnea (SA), but the prevalence, severity, and clinical characteristics of PH patients with SA have not been well studied. METHODS: Using a combination of the keywords "pulmonary hypertension" and "sleep apnea," the PubMed, Embase, Web of Science, and Scopus databases were searched for articles reporting the prevalence, severity, and clinical characteristics of PH patients with SA that were available through June 25, 2024. RESULTS: Of the 7969 studies, 39 were included in the final analysis. Prevalence of obstructive and central SA was 45.4% [39.2%, 51.6%]) and 9.3% [6%, 14.2%], respectively. The mean apnea hypopnea index (AHI) of patients with obstructive SA and PH was 18 [13.6, 22.4] with a standard error of 2.2. Subgroup analysis revealed that 51.4% [38.4%, 64.2%] had mild SA, 28% [22.5%, 33.6%] had moderate, and 20% [15.2%, 25%] had severe SA. PH patients with SA were characterized by male sex (odds ratio (OR) = 1.86 [1.45, 2.37], P <
0.002), older age (mean difference (MD) = -9.37 [-14.23, -4.43], P <
0.002), and higher body mass index (BMI) (MD = -2.16 [-3.32, -1.00], P <
0.002) compared to those without SA. However, mean pulmonary arterial pressure (mPAP) was not significantly different between SA and non-SA (MD = -2.4 [-5.1, 0.3], P = 0.078). Meta-regression showed no significant association between mPAP and AHI among patients with PH and SA (P = 0.13). CONCLUSION: Our study found that SA is common in PH patients with certain clinical characteristics. We recommend conducting sleep studies in all PH patients, especially in older, overweight male patients.