| Summary: | It is unclear whether OSA is an independent risk factor for hypertension and whether CPAP treatment reduces blood pressure (BP). We conducted a randomised parallel controlled trial of 4 weeks therapeutic versus sub-therapeutic CPAP treatment (as a control) in men with OSA (Epworth Score (ESS) >10, >4% SaO2 dips >10 per hour). We measured 24-hour BP at home using the TM-2420 ambulatory BP monitoring system before and after treatment. Diary cards were used to report sleep and wake periods. BP changes with treatment were compared between groups using independent samples T-Tests. 85 patients completed the trial. Median (range), age 50 (33-73) years; Body Mass Index 33.7 (24.9-53.9); ESS 16 (10-24); SaO2 dip rate 32.1 (10.6-101.3) and similar between groups. Machine use hours CPAP per night was equivalent between therapeutic 5.4 (2.3-9) and control groups 5.5 (0.4-10). The groups had similar baseline 24 hour BP, mean (SD) therapeutic 132.7 (14.5) / 85.3 (9.5), controls 132.5 (16.6)/84.5 (9.1). Change in BP with Treatment Systolic(mmHg) Diastolic(mmHg) Overall Wake Sleep Overall Wake Sleep Therapeutic -2.4 -1.4 -5.8 -1.6 -1.9 -2.0 n=41 (1.4) (1.4) (1.8) (1.3) (1.4) (1.4) Control +1.4 +2.8 -0.4 +0.6 +1.5 -0.8 n=44 (1.3) (1.4) (1.7) (0.8) (.86) (1.3) p value <0.05 <0.05 <0.04 ns <0.05 ns Mean change (SEM) in Systolic and Diastolic BP by treatment group. Post treatment, sleep period systolic BP was also significantly different on a between groups comparison of means, therapeutic mean (SD) 118.1 (13.3) mmHg versus control 125.6 (18.4), p<0.05. These results support OSA as an independent risk factor for the elevation of blood pressure in men, and shows a blood pressure fall with CPAP treatment.
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