Self-monitoring of blood pressure in patients with hypertension related multi-morbidity: Systematic review and individual patient data meta-analysis

Background: Studies have shown that self-monitoring of blood pressure (BP) is effective when combined with co-interventions, but its efficacy varies in the presence of some co-morbidities. This study examined whether self-monitoring can reduce clinic BP in patients with hypertension-related co-morbidity. Methods: A systematic review was conducted of articles published in Medline, Embase and the Cochrane Library up to January 2018. Randomised controlled trials of self-monitoring of BP were selected and individual patient data (IPD) were requested. Contributing studies were prospectively categorised by whether they examined a low/high intensity co-intervention. Change in BP and likelihood of uncontrolled BP at 12-months were examined according to number and type of hypertension-related co-morbidity in a one-stage IPD meta-analysis. Results: A total of 22 trials were eligible, 16 of which were able to provide IPD for the primary outcome, including 6,522 (89%) participants with follow-up data. Self-monitoring was associated with reduced clinic systolic BP compared to usual care at 12-month follow-up, regardless of the number of hypertension-related co-morbidities (-3.12 mmHg, [95%CI -4.78, -1.46 mmHg]; p value for interaction with number of morbidities = 0.260). Intense interventions were more effective than low-intensity interventions in patients with obesity (p<0.001 for all outcomes), and possibly stroke (p<0.004 for BP control outcome only), but this effect was not observed in patients with coronary heart disease, diabetes or chronic kidney disease. Conclusions: Self-monitoring lowers BP regardless of the number of hypertension-related co-morbidities, but may only be effective in conditions such obesity or stroke when combined with high intensity co-interventions.