Rapid Measurement of B-Type Natriuretic Peptide - Article Example

Rapid Measurement of B-Type Natriuretic Peptide In patients who have acute dyspnea, the finding is that rapidly measuring B-type natriuretic peptide levels has great utility in diagnosing the presence or absence of congestive failure of the heart, complementing other clinical data available (Maisel et al. 161). 47 percent of patients had for their final diagnosis of congestive failure of the heart as the cause of the dyspnea (count 744). There was a negative finding of congestive failure of the heart in 49 percent of the population (count 770). Five percent had dyspnea due to causes other than congestive failure of the heart (count 72). On their own, the measurements of the B-type natriuretic peptides had a greater level of accuracy with regard to determining dyspnea as being caused by the congestive failure of the heart. This is in comparison to other means of determination, to lab values, historical findings, or even physical findings. At a 100 pg per mL cutoff, the accuracy of diagnosis of B-type natriuretic peptide measurements was pegged at 83.4 percent. 96 percent negative predictive value was observed for levels of the peptide of lower than 50 pg per mL. In statistical analyses, such B-type natriuretic peptide measurements, on their own, was an addition to the strength of power of prediction with regard to pinpointing which patients had congestive failure of the heart, complementing a slew of other commonly used clinical variables for such predictions. This is true for such statistical tests as multiple logistic regression, to which the peptide measurements lend themselves to being a strong predictor of the presence of congestive heart failure in patients measured for the peptide levels (Maisel et al. 161). 2. Clinical Question Is the quick measurement of the levels of B-type natriuretic peptide in patients with dyspnea a good predictor of the presence or absence of congestive failure of the heart in such patients, and at what levels of do such measurements have strong predictive power? (Maisel et al.) SECTION II - Background 1. Purpose of the Research To determine the predictive power of measured B-type natriuretic peptide levels in patients with dyspnea, where measurements are taken concomittant to patient admission in the emergency room, and where the diagnosis is dyspnea. (Maisel et al.) 2. Study Design The study is prospective, which means that measurements of peptide levels are taken on patients with dyspnea as they come into the emergency room, rather than relying on existing data from previous studies, or from the medical records. The diagnosis of the cardiologists of the establishment or non-establishment of congestive failure of the heart for each of the patients is the control and the point of comparison with regard to the accuracy of prediction of measurements of peptide levels (Maisel et al.) 3. Study Time Span and Setting The setting of the study are the emergency rooms in seven locations, one each in Norway and in France and five locations in the US. The study was from April of 1999 all the way to December of 2000 (Maisel et al. 162) 4. “Outcome” of Interest Whether the levels of B-type natriuretic peptides measured in patients with cute dyspnea strongly predicted or discounted the presence of congestive heart failure in such patients, and how accurate are the predictions, and at what measurement levels. 5. Importance of the Research to the Medical Establishment If levels of B-type natriuretic peptides strongly predict the presence or absence of congestive failure of the heart in patients suffering from dyspnea to an acute degree, such measurements can become standard and can be used in conjunction with other established medical tests and procedures to improve diagnosis and protocols for treatment of dyspnea as well as congestive failure of the heart, where both are present (Maisel et al.). SECTION III – Study Design 1. Study Size The sample population was 1586 patients (Maisel et al) 2. Inclusion Criteria People diagnosed with acute dyspnea upon admission to the emergency room. The key symptom of greatest prominence had to be breath shortness (Maisel et al. 162) 3. Exclusion Criteria Patients with clear indication of dyspnea not being tied to congestive heart failure as a secondary condition (e.g. trauma patients, patients with “cardiac tamponade”); patients below 18 years old; patients with renal failure or acute myocardial infarction diagnoses; patients who had anginas that were not stable, except those who showed dyspnea as the key symptom in the emergency room (Maisel et al. 162) 4. Brief Methodology Outline Levels of B-type natriuretic peptides were taken for patients who met the inclusion criteria. The predictive power of statistically analyzed peptide measurement levels were compared to diagnoses of two cardiologists,and the predictions of other clinical tests, with regard to the presence or absence of congestive failure of the heart (Maisel et al.) 5. On whether patients, clinicians, and personnel of study were blind to the diagnostic test Clinicians/cardiologists who diagnosed patients for the presence of congestive failure of the heart were blind to the results of the measurements of the peptide levels (Maisel et al.) 6. On the similarity of the participants to the study to typical ER patients, applicability of results/findings Participants were typical dyspnea cases, taken from seven different locations, prospectively and as they came, during a random interval of time. Yes the participants were similar to typical emergency room patients, so the findings have universal applicability (Maisel et al.) SECTION IV- Relevance 1. On whether findings will have a direct bearing on my patients' health, whether patients will care about research findings Yes and yes. With proper and quick diagnosis proper interventions can be applied. Patients suffering from dyspnea can be screened for congestive failure of the heart, and cardiac interventions can be rapidly undertaken if the peptide measurement tests establish such. The rapid nature of the measurement and the rapid ability to generate results/diagnoses is of importance in patients suffering from heart failure, because the time from heart failure to brain death is very short, and there is only a short window of time wherein heart failure victims can be rescued from death (Maisel et al.) 2. Test availability In hospital and ER settings the bedside assay can be made standard, and the laboratory can make testing for peptide levels a standard procedure as well (Maisel et al) 3. Would the information change congestive heart failure diagnosis in 2012 If true, the information can be helpful and can change diagnosis protocols, to include rapid peptide level measurements. Such measurements can complement standard diagnostic procedures and clinical tests for the establishment of congestive heart failure, as the study suggests (Maisel et al.) SECTION V- Validity 1. Addressed Disease Congestive heart failure with dyspnea as the most visible symptom (Maisel et al.) 2. Diagnostic test evaluated Measurement of levels of B-type natriuretic peptide levels in emergency room patients presented with dyspnea, via bedside assay (Maisel et al.) 3. Meaning of Gold Standard. The Gold Standard in the Journal Article The gold standard is the definitive authority or the final authority, the most accurate authority on the accuracy of a diagnosis. Here the gold standard for the diagnosis of congestive heart failure is the combination of cardiologist assessments and the battery of clinical tests made available in the seven facilities (Maisel et al.) 4. Reasonableness of the Test, Strengths and Limits The test is reasonable and fairly straightforward, necessitating only an assay, with the procedure done with the patient in bed in the emergency room, relatively non-invasive and portable. These are its key strengths, together with of course its high predictive power in the establishment or the ruling out of congestive heart failure as the underlying cause of the dyspnea. That the study had to exclude a certain population of [people who go to the ER short of breath means that more studies need to be done with regard to the limits of the power of prediction of such a test (Maisel et al.) 5. Description of the test method, replicability The assay itself was described in a straightforward manner, necessitating a simple blood test from a sample taken at bedside, and with the assay itself likewise done by the method of bedside. The procedure is described in detail, is simple and easily replicable (Maisel et al.) 6. Test Characteristics a) From Figure 3, At 100 pg per mL, the B-type Natriuretic Peptide sensitivity is 90 percent, and a 76 percent specificity, and an 83 percent accuracy as far as making the differentiation between other dyspnea causes on the one hand and congestive failure o the heart on the other. From the literature we know that specificity pertains to the confirmatory power of a certain test, while sensitivity pertains to the ability of a test to rule out the presence of a condition. The 90 percent sensitivity value affirms the strong and highly useful positive predictive value of the test at such measured BNP levels (Maisel et al. 164-165; Duke University Medical Center Library). b) Computing for the likelihood ratios or LR at 100 pg per mL measured BNP: >> b.1. For the negative test result, the LR is also simply (1-sensitivity)/ specificity, or LR = 0.10/0.76 = 0.1316 >> b.2 For the positive result, LR is also simply sensitivity/(1-specificity), or LR = 0.90/0.24 = 3.75 The low LR for the negative test result implies that the test is a good predictor for the ruling out of the presence of congestive heart failure in patients with dyspnea. The high LR for the positive test, meanwhile, confirms that the test is very useful in affirming the presence of congestive heart failure in patients with acute dyspnea (Maisel et al 164-165; Duke University Medical Center Library) 7. Inclusion of appropriate patient spectrum for test application in clinical practice The sample was striated across sex, but was overrepresented by people around 64 plus or minus 17 years of age. It excluded people below 18, and had conditions as specified by the exclusion criteria described here earlier. The participant patient spectrum is somewhat narrowed because of these, and therefore somewhat limits the application of the test in actual clinical practice (Maisel et al.) 8. Disease Prevalence For the sample population, disease prevalence as far as congestive heart failure goes was pegged at 47 percent (Maisel et al.) Works Cited Duke Medical Center Medical Library. “Likelihood Ratios”. Duke University. 2012. 31 March 2012. Maisel, Allan et al.. “Rapid Measurement of B-Type Natriuretic Peptide in the Emergency Diagnosis of Heart Failure”. The New England Journal of Medicine 347 (3). 18 July 2002. Read More