Resistant hypertension is high blood pressure that does not respond to treatment with at least three blood-pressure lowering drugs. Often, patients need a fourth drug to help lower their blood pressure. The cause of resistant hypertension is not definitively known, but it is thought that poor adherence to drugs is a contributing factor. In other words, because patients may not take their medications correctly, their blood pressure does not come down. If the patient has some problems taking three drugs, these should be addressed before adding a fourth; as this adds to the medication taking burden for the patient, increases the risk of side-effects and increases the risk of drug-drug interactions. At present, it is not known how well patients adhere to three drugs before having a fourth agent added. This study aims to explore whether individuals who start a fourth drug were adherent to their three drug regimen. Additionally, it aims to explore what patient level factors eg age, gender and other illnesses help to predict adherence.
Individuals who have uncontrolled hypertension on three anti-hypertensive drugs often require the addition of a fourth anti-hypertensive drug. The benefit of this is centred on lowering blood pressure, but the risk is adding to the patientÂ’s medication burden and increasing potential for drug-drug interactions. Poor medication adherence is a potential cause of Resistant Hypertension (uncontrolled hypertension on three or more anti-hypertensive drugs), but it is unknown how adherent patients are to their three drug regimens before a fourth drug is added. In a population of individuals who initiate four anti-hypertensive drugs, we will calculate the proportion of individuals who were adherent to their three drug regimen before addition of fourth agent. Our proxy measure of adherence will rely on prescribing data in CPRD and will be calculated as the average proportion of days covered for all drugs in the year prior to initiating the fourth drug. This will be a descriptive analysis. We will also assess how adherence to three drugs predicts adherence to four drugs using multivariable logistic regression. Lastly, we will assess the patient level factors that are associated with adherence to anti-hypertensive drugs, both in three drug and in four drug regimens using multivariable logistic regression.
There are no clinical outcomes in this study, rather the outcome is adherence to drug therapy.
Sarah-Jo Sinnott - Chief Investigator - Not from an Organisation
Sarah-Jo Sinnott - Corresponding Applicant - Not from an Organisation
Alice Dawson - Collaborator - London School of Hygiene & Tropical Medicine ( LSHTM )
Dorothea Nitsch - Collaborator - London School of Hygiene & Tropical Medicine ( LSHTM )
Elizabeth Williamson - Collaborator - London School of Hygiene & Tropical Medicine ( LSHTM )
Ian Douglas - Collaborator - London School of Hygiene & Tropical Medicine ( LSHTM )
Laurie Tomlinson - Collaborator - London School of Hygiene & Tropical Medicine ( LSHTM )
Liam Smeeth - Collaborator - London School of Hygiene & Tropical Medicine ( LSHTM )
HES Admitted Patient Care;Practice Level Index of Multiple Deprivation