118OLDER PEOPLE REMAIN ON BLOOD PRESSURE AGENTS DESPITE BEING HYPOTENSIVE RESULTING IN INCREASED MORTALITY AND HOSPITAL ADMISSION

Abstract

Introduction: The use of antihypertensives in older people in order to prevent cardiovascular events is well established. In older people anti-hypertensive medication can cause adverse effects related to hypotension. The aim of this study was to assess the prevalence of low BP in the presence of antihypertensive treatment and its impact on outcomes in a primary care population of older people. Method(s): Data extracted from primary care databases by an automated Clinical Advisory System were analysed. Data were obtained from 13 actively participating General Practices. Inclusion criteria were: a serum creatinine test, a BP measurement between 30/06/11 and 01/01/12, age over 70 years at first screening. Result(s): 11,167 patients aged 70 and over were analysed 6,373 (57.1%) female. The patients were taking between 0 and 5 antihypertensive medications at index (definition of index was first BP after 30 June 2011): 34.1% were taking an ACEI, 17.6% a diuretic, 16.4% an ARB, 13.2% a Calcium-Channel Blocker, 13.0% a betablocker, 3.9% an alphablocker and 0.4% a centrally-acting antihypertensive. 128 patients had a systolic blood pressure (SBP) < 100 mmHg at index, of these 69.5% were taking anti-hypertensives; 346 people had index SBP 100-109 mmHg, of these 64.5% were taking anti-hypertensives; 823 people had a SBP of 110-119 mmHg (64.6% were taking anti-hypertensives). Unadjusted analysis of survival by index SBP strata indicated that one-year survival was poorer in those with lower BP (97.1% in those with BP > 120 mmHg compared to 83.6% in those with BP < 100 mmHg). Binary logistic regression analysis indicated age, gender, index BP < 100 mmHg and average systolic BP < 100 mmHg in one year pre-index and index diagnoses of stroke and heart failure were significantly associated with mortality. Over one-year's follow-up, 10.6% of patients had an episode of acute kidney injury (AKI). Of the 128 patients with index systolic BP < 100mmHg 30 patients (23%) had an episode of AKI in follow-up compared to 11% in those with systolic BP>=100 mmHg (Chi2 20.9, p < 0.05). Variables significantly associated with AKI included age, gender, index SBP < 100 mmHg, current number of antihypertensive groups and index diagnoses of diabetes, stroke, CKD and HF. Of 44 patients with average BP < 100 mmHg, 7(16%) had AKI in follow-up. 1637 patients were admitted to hospital once over the one-year follow-up, 755 twice, 1438 three or more times. Variables significantly associated with admission were age (1.03, 1.02-10.4), male gender (0.89, 0.82-0.97) and average systolic BP less than 100 mmHg (1.68, 1.18-2.41) and index diagnoses of coronary heart disease (1.51, 1.25-1.83), stroke (1.54, 1.19-1.99) and heart failure (1.90, 1.35-2.66). Discussion(s): In this study a small but clinically significant number of older patients remained on anti-hypertensive medication despite hypotension. Hypotension was associated with AKI, hospital admission and mortality. However, it is not possible to say whether the hypotension was the result of a severe illness which was the primary cause of admission or if it was the hypotension itself which caused the admission. Some hypotensive patients also had a diagnosis of heart failure (HF) and it is possible that hypotension in these patients was a direct result of this and antihypertensives were continued to manage their underling condition. In conclusion this study suggests there is scope for medication review and intervention in older patients on antihypertensives to reduce the risk of adverse incidents associated with hypotension.