OBJECTIVE:Treatment of obstructive sleep apnoea (OSA) has been shown to reduce blood pressure (BP). However, the effect size is modest and treatment of OSA is not recommended as the only treatment target when treating hypertension. Despite the limited effect of continuous positive airway pressure (CPAP) therapy on BP, it is likely that certain phenotypes of OSA patients respond better to CPAP than others. The aim of the present systematic review and meta-analysis was to identify potential predictors for BP response in patients with OSA undergoing CPAP treatment.(Figure is included in full-text article.) DESIGN AND METHOD:A systematic search was conducted in three databases (MEDLINE, Embase and Web of Science) using terms exploring three domains (obstructive sleep apnoea, CPAP, clinical trial) based on the following inclusion criteriai) randomised controlled clinical trials published between January 1st 1960 to December 31st 2017 including a reasonable control group; iii) OSA diagnosis using polysomnography; iv) age >18 years; v) OSA severity of at least 5 AHI/h. The random effect model was fitted to estimate the pooled BP reductions calculated as the difference between the BP change (end-treatment minus baseline) in the CPAP and control group. Moreover, the original estimates have been stratified according to selected patient characteristics. RESULTS:Out of 2445 articles, 59 RCTs were included (n = 7,329 subjects) comparing CPAP with control groups. CPAP was associated with a net reduction in systolic BP of −2.12 (95% CI −2.82 to −1.42) mmHg and in diastolic BP of −1.97 (95% CI −2.46 to −1.48) mmHg, favouring treatment of OSA using CPAP (both p-values < 0.001). The subgroup analysis showed that systolic BP reduction was greater in subjects younger than 60 years (−2.88 fro age 40–50, −2.78 for age 50–60 and −0.61 for age more than 60 years, p = 0.007) and in patients with controlled BP at baseline versus uncontrolled BP (−1.45 vs −4.14, p = 0.002) (Figure 1). CONCLUSIONS:Younger patients (< 60 years) with uncontrolled blood pressure at baseline are more likely to experience significant BP reductions with CPAP therapy. Phenotypisation of specific cohorts of patients can guide clinicians to target OSA treatment and help to optimise patients’ cardiovascular risk.