a Cardiology Department B, Bispebjerg Hospital, Rigshospitalet, University of Copenhagen, Blegdamsvej 9, Copenhagen 2100, Denmark
b Cardiology Department, The Western Infirmary, Glasgow and MRC Clinical Research Initiative in Heart failure, Glasgow University, UK
Received October 14, 2003; revised June 7, 2004; accepted June 17, 2004 * Corresponding author. Tel.: +45-3545-2141; fax: +45-3545-2568 (E-mail: own{at}dadlnet.dk).
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Abstract |
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METHODS AND RESULTS: Twelve randomly selected general practices (GP) were screened for patients receiving ACE-inhibitor, digoxin, or loop diuretic treatment. The first 500 volunteers of 959 potential subjects were invited to a cardiac examination after exclusion of 235 frail, physically or mentally disabled patients. A diagnosis of heart failure during hospital admission (Hospital-HF, n=102) was more related (p<0.05) to male sex (45% vs. 21%), advanced age (73 vs. 70 years), breathlessness (75% vs. 62%), LV systolic dysfunction (47% vs. 20%), objective cardiac abnormality (92% vs. 65%) and higher 4-year mortality (33% vs. 15%) than patients taking loop diuretics due to signs and symptoms of heart failure in GP (GP-HF). Patients without clinical heart failure (n=301) had the same survival but less symptoms and cardiac abnormalities than GP-HF patients.
CONCLUSION: A surplus morbidity and mortality was related to a hospital-based rather than a GP based diagnosis of HF. Patients managed in GP were different from patients entering previous clinical trials of heart failure. We estimate that the pool of patients hospitalised with systolic heart failure would be increased from 1.3 to 1.4 more if all patients from primary care were included.
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Introduction |
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In the pan-European IMPROVEMENT study most patients with heart failure were appropriately investigated but that study mainly looked at patients in whom the primary care physicians were confident of the diagnosis.6 Very few studies have objectively characterised patients that were treated for the signs and symptoms of heart failure in primary care without being referred to a secondary physician. Previous studies indicate that only 2050% of such patients from primary care would actually have heart failure due to LV systolic dysfunction.4,711 Extrapolating from previous studies we hypothesised that patients with a clinical label of heart failure from primary care would have less cardiac abnormalities, a better survival and therefore not the same benefit of medical treatment as hospitalised patients.
Unfortunately, very few studies provide objective information about the patients that are solely treated by primary care physicians. Knowing these issues would help to estimate how many patients in general practice would have heart failure according to modern criteria, their mortality risk, and how many are deprived of an effective medical treatment. The aim of the present work was to compare clinical and aetiological aspects of patients treated for heart failure in the community and to examine the effect of whether the heart failure label was attained in general practice or during a hospital admission.
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Methods |
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Inclusion and exclusion criteria
The drug search resulted in 1194 subjects. After consultation with the general practitioners 235 subjects were excluded from further investigation because they were dead (n=25), too frail, hospitalised, or residing in a nursing home (n=173), had moved away from Glasgow (n=12) or had attended another screening study (n=25). According to the protocol only 500 subjects were planned to undergo extensive examination and these were selected as the first 500 subjects of the remaining 959 eligible subjects who would accept the invitation. The target of 500 was considered large enough to represent different practices and to contain at least a 100 subjects with LV systolic dysfunction provided the prevalence would be at least 20% of systolic dysfunction. Screening ceased on July 1996 when the target of 500 examined patients had been reached.
Criteria of heart failure
The present criteria had to circumvent the fact that general practitioners did not systematically write down explicit diagnosis for their patients. Obviously GPs would be more confident of the diagnosis if a patient had been referred to and investigated in a hospital (Hospital-HF). But since all patients have not been referred, many patients are treated for the signs and symptoms of heart failure solely by the clinical judgment of the GP (GP-HF). Instead of asking the GP about the final diagnosis, we allocated patients to the GP-HF group according to the GPs description of symptoms and subsequent treatment as inferred from review of GP case notes. Patients who could not be classified as Hospital-HF or GP-HF were considered as a reference group without any sign of heart failure (non-HF). The following definitions were used.
Hospital-HF was based on explicit information from an outpatient visit or a hospital admission where the patient had been given the diagnosis of heart failure, an equivalent diagnostic term, or if objective tests had shown significant and symptomatic LV systolic dysfunction, valvulopathy or cardiomyopathy.
GP-HF was diagnosed in the case of a history of breathlessness, swollen ankles, fluid retention, or an abnormal chest X-ray in a patient in combination with a current prescription of a loop diuretic. An abnormal chest X-ray was a cardiothoracic ratio (CTR)>50%, enlarged left ventricle, pleural effusion, upper lobe venous diversion, or interstitial or alveolar oedema. As it was a clinical label there was no requirement of an objective determination of cardiac function or an explicit diagnosis according to the ESC criteria, but it was noted whether these issues had been mentioned in the record.
Non-HF patients were defined as the remaining subjects who received heart failure therapy but did not meet the criteria for Hospital-HF or GP-HF.
Questionnaire and routine tests
A self-reported questionnaire was obtained for all subjects giving details of physician diagnosed angina, myocardial infarction, diabetes, stroke, drug therapy, and answers to the Medical Research Council (MRC) Breathlessness questions.12 Hypertension was based on self-report or a measured systolic blood pressure >160 mmHg or diastolic >95 mmHg using a random zero sphygmomanometer (mean of two readings). Pulmonary function tests were performed and airway obstruction defined as a FEV1/FVC<0.7 or FEV1<1.5 litre. Plasma BNP was measured by use of the Shionogi assay (Shionoria, Japan).
Electrocardiography
The standard 12-lead electrocardiograms (ECGs) were coded independently to other data. A left bundle branch block (LBBB), wide QRS (⩾0.12 s), pathological Q waves, major ST/T segment abnormality, or left ventricular hypertrophy (LVH) were noted in that order (see legend of Table 3 for definitions). Borderline findings were adjudicated by consensus.
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Follow-up
The date and cause of death was identified by flagging each patient's record with the Registrar General for Scotland on December 31, 2000.
Data analysis
Differences between study groups were evaluated by a 2 test using the Yates contingency correction. Variables of rank were examined by the KruskallWallis test. Two-tailed tests of significance are reported and p-values below 0.05 are considered statistically significant.
Survival was estimated using the method of KaplanMeier, and differences in survival between groups were evaluated by the log-rank test. Paired comparison showed no difference in survival between the reference group and GP-HF so these were grouped together. A Cox proportional hazards model evaluated the effect of GP-HF on mortality after adjusting for sex and age. The assumption of proportional hazards between Hospital-HF and the rest was assessed by visual judgment of the logarithm of minus logarithm of the survival estimates adjusted for age and sex.
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Results |
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Clinical characteristics
One would expect to find more symptomatic and more severe patients in the hospital group, while those with milder and more controllable symptoms would be managed in the GP. Table 1 shows that half the heart failure patients were managed in a hospital, and these were older, had more symptoms and more self-reported heart disease.
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Objective documentation of heart failure
Original data regarding the possible mechanism of heart failure are presented in Tables 2 and 3. Hospital-HF patients had significantly more abnormal hearts (84%) than the GP-HF (56%) and non-HF group (43%). The GP-HF group had more of atrial fibrillation and enlarged atrium as compared with the non-HF group. Table 3 shows that only 5% (four patients) of Hospital-HF had no obvious reason for the symptoms, as compared with 13% of the GP-HF and 25% of the non-HF group. Considering all the heart failure patients, 33% had significant LVSD while 30% had a completely normal LV function with no valvular disease, no LV hypertrophy or atrial fibrillation.
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Management of heart failure
Table 4 shows that the GP case notes already contained evidence of cardiac disease in 95% of Hospital-HF and 64% of GP-HF. Only 45% of GP-HF patients had a previous cardiac function test performed compared with 93% of the Hospital-HF group. The data does not indicate why only 45% were referred to an objective test or if the GPs thought such a test would be unnecessary. There was no difference in the use of chest X-rays or ECGs between non-HF and GP-HF patients.
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Mortality
About 44 of non-HF patients, 14 of GP-HF, and 34 of Hospital-HF died during the follow-up period with a median time of 3.5 years. Fig. 1 shows that GP-HF and non-HF patients both had a 4-year mortality of 15% (pair-wise log rank test, p=0.99), significantly less than 33% in the Hospital-HF group (pair-wise log rank test, p<0.001). In a Cox regression model, there was an independent prognostic value of age (HR=1.6 per 10-year, 95% CI from 1.3 to 2.0, p<0.001) and Hospital-HF (HR=1.9, 95% CI from 1.2 to 3.0, p=0.007), but not of GP-HF (Hazard ratio=0.9, 95% CI from 0.5 to 1.7, p=0.76) or sex (HR=1.5 for male, 95% CI from 1.0 to 2.3, p=0.067). No other variables were tested in this model. There was a non-significant decrease of hazard with time, meaning that risk of Hospital-HF in the first 12 years after examination might have been slightly underestimated.
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Discussion |
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This large descriptive study of patients receiving heart failure medication in the community gives some insight into the sort of patients thought to have heart failure in general practice. It documents that more severe cases of heart failure are being referred to the hospitals, and these patients are most comparable to the heart failure patients included in the randomised clinical trials with respect to a high proportion of LV systolic dysfunction, ischaemic heart disease, and male sex.
Other studies
The prevalence and characteristics of heart failure in the community are described in at least six studies, but two did not include echocardiography,7,8 and three performed echocardiography in only a proportion of their patients.4,911 With respect to clinical characteristics of patients with suspected heart failure in general practice all studies agree that:4,7,15,16 the majority are women, only 1 in 5 have LVSD,4,1618 10% have valvular disease,16,17,19 and half have a normal function and structure of the left ventricle and atrium.4,9
In this study half the heart failure patients had been hospitalised, while other studies reported from one-third4 to three-quarters.7,18 Loose criteria for getting a clinical label of heart failure in general practice may explain these differences. Less than 10% of hospitalised HF patients had alternative explanations for heart failure symptoms, which compares with 9% in another study.17
The gradual increase of BNP across subgroups support the finding of increased echocardiographic cardiac abnormalities from non-HF to GP-HF and Hospital-HF. But concentrations are also affected by age and treatment so further analyses about the diagnostic/prognostic value will be reported in other papers.
The 1.6% overall prevalence of suspected or documented heart failure is in line with other population-based studies.4,8,20 Assuming 40% of these have systolic dysfunction, then the prevalence of heart failure due to systolic dysfunction will be about 0.60.7%, which is consistent with the estimates in other studies from England and Copenhagen.2,4
Management
Management of heart failure in the community was only described in a few other studies. The European IMPROVEMENT Survey indicated that most patients with heart failure are appropriately investigated, although this finding might be as a result of high rates of hospital admissions. The present study supports the idea that referred patients have been adequately investigated while those suspected of heart failure in general practice were not. The use of chest X-rays and electrocardiograms were comparable to another study from the UK.7 Just 65% of the GP-HF group had documentation of a cardiac function test performed. The use of ACE-inhibitors was low when compared to the number of patients thought to have heart failure, but not when compared to the number of cases with LV systolic dysfunction. The present study was made before β-blocker and spironolactone were recommended drug regimes.
Mortality
The similar mortality of GP-HF and non-HF patients was also seen in a recent GP based study from Copenhagen.21 In that study both groups had a surplus mortality as compared with matched control subjects from Copenhagen. The overall mortality in the Copenhagen study was considerably larger than in the present study. This is likely to be caused by the present study's selection of volunteer participants after exclusion of the most elderly and fragile subjects, while patients studied in Copenhagen were unselected and older.
Methodological issues/limitations
Selection bias from the selection procedures cannot be entirely avoided. However, a fair representation of primary care physicians was intended by random inclusion of at least 15 different GPs. This strategy should account for the differences in the way primary care physicians would diagnose, document and treat patients with suspected heart failure.
The findings of the present study are limited to volunteer patients in the community. The high number of exclusions and withdrawals may have led to underestimation of the prevalence as well as morbidity and mortality. Other studies also frequently experience an examination rate of 50% of the target population, while home-based echocardiography may increase the attendance rate to about 80%.11
Patients were identified through a computerised search of relevant drugs. The same screening strategy would be relevant today, perhaps with addition of spironolactone. Adding β-blockers to the search would not increase sensitivity of screening but only include more false negatives as β-blockers are widely used in hypertension and ischaemic heart disease. We had foreseen to include a large group of patients receiving cardiovascular drugs without subjective or objective signs of heart failure. They were included in the analysis as a relevant reference group as they are comparable to patients studied in the HOPE trial where the effect of ramipril was assessed in patients at high risk.
Perspective
The prevalence of patients thought to have heart failure in the community is quite high, but patients constitute a very different group from the heart failure patients treated in hospitals. This means that epidemiological data from clinical trials cannot be automatically extrapolated to patients with suspected heart failure in the community. Symptomatic heart failure leading to hospitalisation is strongly associated with increased cardiac dysfunction and mortality. The non-hospitalised patients are often female, they are often insufficiently diagnosed and treated, and at least half of them will have some cardiac dysfunction upon cardiac examination. Objective cardiac testing is needed in every patient with suspected heart failure to guide the physician regarding the underlying pathology, treatment and prognosis. Using natriuretic peptides in the workup of diagnoses is helpful in untreated patients but their role still remains to be clarified in patients receiving cardiovascular treatment as in the present case.
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Acknowledgments |
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References |
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