Blood pressure (BP) variability is an independent risk factor for cardiovascular adverse events over and beyond the BP level. The clinical significance of BP variability has been extensively studied in the past few decades. Inconsistency between measurement methods has complicated the exploitation of BP variability in clinical practice. This thesis aims at defining optimal methods for assessing selfmeasured home BP variability. 

The data for this thesis was gathered from three studies. Study sample I consisted of 527 individuals recruited from the general population or newly-diagnosed hypertensives. The participants had BP measured in the clinic, at home as well as undergoing 24-hour ambulatory BP monitoring. Study sample II consisted of 2103 participants of the Finn-Home study, a population sample in which BP measurements were made in the clinic and at home. Study sample III consisted of 6238 individuals who participated in the Finn-Home, Ohasama, Tsurugaya, and Didima population studies and were included in the IDHOCO (International Database for HOme blood pressure in relation to Cardiovascular Outcome). 

In study sample I, we observed that estimates of BP variability measured with office, home, and ambulatory monitoring correlated only weakly with each other. In study sample II, we observed that home blood pressure was slightly higher on Mondays than during the weekend. We also demonstrated that the risk of cardiovascular outcomes related to systolic/diastolic home BP variability could be reliably assessed using 3/7 measurement days. In study sample III, we defined outcome- riven thresholds for increased home BP variability. 

The results of this thesis can assist clinicians and guidelines on how best to identify those patients with increased BP variability who have an increased cardiovascular risk. It should, however, be kept in mind that the incremental prognostic value of BP variability over traditional cardiovascular risk factors, including BP itself, is modest.