 Patients in the CALIBER database who had high blood pressure the Clinical Practice Research Datalink CPRD and consenting to data linkage. High blood pressure was defined as the record of 3 systolic or diastolic high blood pressure readings within a one year period, or 2 systolic or diastolic high blood pressure readings within a 6 month period in CPRD. High blood pressure measurements were defined as in the eighth Joint National Committee 2014 JNC8 guidelines for patient management, that is 14090mmHg for individuals aged less than 60 years old, and 15090mmHg for those of 60 years. 