Hypertension is 1 of the most prevalent cardiovascular risk factors; nevertheless, some studies have reported that the antecedent of hypertension does not impair prognosis in patients with established cardiovascular disease. The objective of this study was to describe the impact of hypertension on readmission and 1-year mortality in patients admitted to a single cardiology hospitalization unit. All consecutive hospitalizations in a single cardiology department through 10 months were included, and 1-year follow-up was performed. Clinical antecedents, risk factors, and main discharge diagnoses were collected. A total of 1,007 patients were included (mean age 71.1 ± 13.5 years). The antecedent of hypertension was present in 69.0%, and these patients had older mean age and higher prevalence of risk factors and previous cardiovascular disease. No differences in hospital discharge main diagnoses were observed according to the antecedent of hypertension. During a mean follow-up period of 404.82 ± 122.2 days, patients with hypertension had higher rates of rehospitalization for cardiac causes (31.1% vs 17.9%, p = 0.01) and of total (17.4% vs 9.3%, p <0.01) and cardiovascular (13.9% vs 5.9%, p <0.01) mortality. Multivariate analysis identified the antecedent of hypertension as an independent risk factor for cardiovascular readmission (hazard ratio 1.46, 95% confidence interval 1.10 to 1.98) and the combined end point of readmission or mortality (hazard ratio 1.45, 95% confidence interval 1.12 to 1.88); no independent association was observed for total mortality. In conclusion, hypertension was present in most patients admitted to a cardiology unit, and they had higher rates of rehospitalization and mortality at 1-year follow-up.
Hypertension in 1 of the most prevalent risk factors, especially in patients with established cardiovascular disease. Hypertension is an independent and strong risk factor for cardiovascular disease, although several studies have challenged the prognostic impact of the antecedent of hypertension after a cardiovascular event, such as acute coronary syndromes (ACS) or heart failure (HF). The objective of our study was to describe the current profile of patients with the antecedent of hypertension and its impact on 1-year rates of mortality and hospital readmission in a cohort of consecutive patients admitted to a single cardiology department.
Methods
An observational and prospective study was carried out at a single center. All patients admitted to the cardiology department during a 10-month period (December 1, 2008, and September 30, 2009) were included. A total of 1,235 hospital admissions were collected, but 228 (18.5%) were rehospitalizations of patients already included in the study, so the final sample size was 1,007 patients. The ethics committee of the hospital approved the study protocol, and informed consent was obtained. All risk factors, clinical antecedents, treatments, complementary tests, and main diagnoses at discharge were collected from all patients. From March to July 2010, 1-year follow-up was performed by reviewing clinical reports or the database of the hospital or by telephone. All medical practice of patients related to our hospital performed in primary care is made by a single informatics system. Similarly, all emergency calls, visits to the emergency room of the hospital, and hospital readmissions are registered in a single informatics application. With these 2 tools, most readmissions can be ascertained, except those occurring outside the hospital area. Vital status was determined by phone calls.
The primary end point was total mortality (cardiovascular and noncardiovascular death) at 1-year follow-up. Secondary end points were hospital admission cardiovascular disease (ACS, HF, stroke, arrhythmia, or revascularization) and the combined end point of total mortality or hospital readmission for cardiovascular cause.
The antecedent of hypertension was registered when patients had such previous diagnosis or were receiving specific treatments. Glomerular filtration rate was estimated from serum creatinine values using the Modification of Diet in Renal Disease (MDRD) study equation. ACS diagnosis was based on the presence of typical clinical symptoms of chest pain and electrocardiographic changes indicative of myocardial ischemia or lesion and/or elevation of serum markers of myocardial damage; ACS were classified as ST-segment elevation or non–ST-segment elevation ACS according to electrocardiographic findings. When HF was the main diagnosis at discharge, left ventricular dysfunction HF was defined if the ejection fraction was <50%; HF with preserved ejection fraction was coded for patients with diagnoses of HF, ejection fractions >50%, and evidence of diastolic dysfunction. Severe aortic valve stenosis was considered the main diagnosis for patients admitted with symptoms of HF, chest pain without evidence of ACS, or syncope in whom echocardiography showed severe valvular stenosis (mean gradient ≥40 mm Hg or valvular area <1.0 cm 2 ).
Statistical analysis was performed using SPSS version 15.0 (SPSS, Inc., Chicago, Illinois). Quantitative variables are presented as mean ± SD. Chi-square tests were used to analyze possible differences in clinical features between subgroups. Survival analysis were performed using Cox regression models by forward conditional inclusion of variables that obtained p values <0.10 in the univariate analysis or could have plausible clinical implications. Statistically significant differences were accepted at p <0.05.
Results
From December 1, 2008, to September 30, 2009, a total of 1,235 hospital admissions were collected, and after excluding readmissions of patients originally included (288 patients [18.5%]), 1,007 patients constituted the study population. As listed in Table 1 , the antecedent of hypertension was present in 69.0% of the patients, and it was the most prevalent cardiovascular risk factor. Patients with hypertension had an older mean age and a higher prevalence of risk factors and previous cardiovascular disease. Regarding biochemical determinations, no differences were observed according to the antecedent of hypertension, despite lower glomerular filtration rates and higher fasting glucose in patients with hypertension ( Table 2 ).
| Variable | Total (n = 1,007) | Hypertension | p Value | |
|---|---|---|---|---|
| No (n = 312) | Yes (n = 695) | |||
| Men | 56.1% | 60.9% | 54.0% | 0.04 |
| Age (years) | 71.1 ± 13.5 | 66.5 ± 15.8 | 73.1 ± 11.7 | <0.01 |
| Diabetes mellitus | 31.6% | 18.9% | 37.3% | <0.01 |
| Current smoker | 17.8% | 26.6% | 13.8% | <0.01 |
| Dyslipidemia | 42.5% | 28.5% | 48.8% | <0.01 |
| Coronary heart disease | 28.9% | 18.9% | 33.4% | <0.01 |
| Heart failure | 10.3% | 4.8% | 12.8% | <0.01 |
| Intermittent claudication | 4.2% | 2.9% | 4.7% | 0.17 |
| Atrial fibrillation | 15.6% | 8.7% | 18.7% | <0.01 |
| Stroke | 7.0% | 4.5% | 8.1% | 0.04 |
| Valvular heart disease | 4.0% | 2.6% | 4.6% | 0.13 |
| Chronic obstructive pulmonary disease | 10.4% | 4.8% | 12.9% | 0.03 |
| Ejection fraction (%) | 57.0 ± 11.2 | 57.2 ± 10.7 | 56.9 ± 11.4 | 0.67 |
| Variable | Total | Hypertension | p Value | |
|---|---|---|---|---|
| No | Yes | |||
| Hemoglobin (g/dl) | 13.3 ± 6.1 | 13.9 ± 7.7 | 13.0 ± 5.2 | 0.08 |
| Creatinine (mg/dl) | 1.1 ± 0.4 | 1.0 ± 0.4 | 1.1 ± 0.5 | 0.1 |
| Glomerular filtration rate (ml/min/1.72 m 2 ) | 74.6 ± 29.6 | 83.0 ± 34.9 | 71.0 ± 26.3 | <0.01 |
| Total cholesterol (mg/dl) | 172.1 ± 95.0 | 169.6 ± 41.1 | 173.2 ± 110.7 | 0.65 |
| Low-density lipoprotein (mg/dl) | 99.7 ± 63.0 | 100.1 ± 31.5 | 99.6 ± 72.5 | 0.92 |
| High-density lipoprotein (mg/dl) | 41.9 ± 20.5 | 41.6 ± 15.1 | 42.1 ± 22.5 | 0.79 |
| Triglycerides (mg/dl) | 119.0 (92.0–162.0) | 119.0 (93.0–154.5) | 119.5 (92.0–166.0) | 0.46 |
| Glycemia (mg/dl) | 113.0 ± 44.0 | 105.1 ± 28.1 | 116.3 ± 48.7 | 0.03 |
| Glycosylated hemoglobin in patients with diabetes (%) | 7.8 ± 1.5 | 8.0 ± 1.8 | 7.8 ± 1.4 | 0.50 |
The main diagnoses at discharge are listed in Table 3 and it can be observed that only non–ST-segment elevation ACS and hypertensive emergencies were more frequent in patients with hypertension; in consequence, patients with hypertension received similar treatments at hospital discharge, except for higher use of aspirin, angiotensin receptor blockers, diuretics, anticoagulants, insulin, and oral antidiabetic agents ( Table 4 ) . Of the 1,007 patients, 30 (2.97%) died in hospital, and no difference was found according to the presence or absence of the antecedent of hypertension (3.2% vs 2.6%, p = 0.62). Complete follow-up of discharged patients was achieved in 96.4% of the sample, with a mean follow-up period of 402.5 ± 122.2 days. Patients with hypertension had higher rates of total mortality (17.4% vs 9.3%, p <0.01), mainly driven by differences in cardiovascular mortality (13.9% vs 5.9%, p <0.01); no differences were observed in noncardiovascular mortality rates (3.6% vs 3.6%, p = 0.98). Patients with hypertension also had higher rates of readmission for cardiovascular causes (31.1% vs 17.9%, p = 0.01) and the combined end point of total mortality or cardiovascular rehospitalization (40.9% vs 23.7%, p <0.01).
| Diagnosis | Total | Hypertension | p Value | |
|---|---|---|---|---|
| No | Yes | |||
| Non–ST-segment elevation ACS | 17.1% | 13.8% | 18.6% | 0.06 |
| Nonischemic chest pain | 23.3% | 26.3% | 22.0% | 0.14 |
| HF with preserved ejection fraction | 11.9% | 9.3% | 13.1% | 0.08 |
| Left ventricular dysfunction HF | 7.6% | 5.1% | 8.8% | 0.25 |
| ST-segment elevation ACS | 8.4% | 11.9% | 6.9% | 0.01 |
| Atrial fibrillation | 7.0% | 8.3% | 6.3% | 0.25 |
| Vagal syncope | 5.3% | 5.8% | 5.0% | 0.63 |
| Valvular aortic stenosis | 3.4% | 2.6% | 3.7% | 0.34 |
| Sinus dysfunction | 3.4% | 2.9% | 3.6% | 0.56 |
| Pericarditis/pericardial effusion | 1.5% | 2.9% | 0.9% | 0.01 |
| Hypertension emergency | 1.3% | 0.3% | 1.7% | 0.05 |
| Other | 9.8% | 10.8% | 9.4% | — |
| Medication | Total | Hypertension | p Value | |
|---|---|---|---|---|
| No | Yes | |||
| Statins | 76.1% | 69.3% | 77.1% | 0.08 |
| β blockers | 61.4% | 57.9% | 62.8% | 0.22 |
| Aspirin | 62.8% | 55.5% | 65.9% | <0.01 |
| Proton pump inhibitors | 51.4% | 49.3% | 52.4% | 0.46 |
| Clopidogrel | 39.8% | 35.4% | 41.7% | 0.12 |
| Angiotensin receptor blockers | 35.9% | 10.0% | 47.0% | <0.01 |
| Angiotensin-converting enzyme inhibitors | 33.9% | 34.9% | 33.5% | 0.71 |
| Diuretics | 32.8% | 15.8% | 40.0% | <0.01 |
| Oral antidiabetic agents | 21.6% | 16.3% | 23.8% | 0.02 |
| Calcium channel blockers | 17.2% | 6.7% | 21.8% | <0.01 |
| Oral anticoagulants | 15.2% | 10.5% | 17.2% | 0.02 |
| Nitrates | 14.8% | 10.5% | 16.6% | 0.04 |
| Insulin | 8.8% | 5.3% | 10.3% | 0.01 |
| Eplerenone | 4.9% | 3.8% | 5.3% | 0.40 |
| Ezetimibe | 4.0% | 1.0% | 4.4% | 0.08 |
| Doxazosin | 2.2% | 1.0% | 2.7% | 0.15 |
| Fibrates | 2.2% | 1.0% | 2.7% | 0.15 |
| Digoxin | 1.6% | 1.0% | 1.8% | 0.39 |
A multivariate analysis, adjusted for age, risk factors, and medical treatments at discharge, was performed to identify risk factors for cardiovascular readmission, mortality, or the combined end point ( Table 5 ). The antecedent of hypertension was an independent risk factor for cardiovascular readmission ( Figure 1 ) but not for total mortality ( Figure 2 ) ; the antecedent of hypertension was associated with higher rates of mortality or cardiovascular rehospitalization ( Figure 3 ) .
| Variable | CV Rehospitalization | Mortality | CV Rehospitalization or Mortality | |||
|---|---|---|---|---|---|---|
| HR (95% CI) | p Value | HR (95% CI) | p Value | HR (95% CI) | p Value | |
| Age | 1.02 (1.01–1.03) | <0.01 | 1.07 (1.05–1.09) | <0.01 | 1.03 (1.02–1.04) | <0.01 |
| Female gender | 1.15 (0.89–1.48) | 0.29 | 0.67 (0.48–0.94) | 0.02 | 0.81 (0.65–1.02) | 0.07 |
| Hypertension | 1.46 (1.10–1.98) | 0.02 | 1.37 (0.90–2.08) | 0.14 | 1.45 (1.12–1.88) | <0.01 |
| Diabetes | 1.33 (1.03–1.71) | 0.03 | 1.22 (0.86–1.73) | 0.28 | 1.14 (0.90–1.43) | 0.29 |
| Previous HF | 1.62 (1.17–2.24) | <0.01 | 2.62 (1.82–3.77) | <0.01 | 1.52 (1.17–1.98) | <0.01 |
| Previous coronary heart disease | 1.30 (1.01–1.68) | 0.04 | 1.20 (0.84–1.72) | 0.31 | 1.15 (0.90–1.46) | 0.26 |
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