N-terminal pro-B-type Natriuretic Peptides' Prognostic Utility Is Overestimated in Meta-analyses Using Study-specific Optimal Diagnostic Thresholds.

BACKGROUND: N-terminal fragment B-type natriuretic peptide (NT-proBNP) prognostic utility is commonly determined post hoc by identifying a single optimal discrimination threshold tailored to the individual study population. The authors aimed to determine how using these study-specific post hoc thresholds impacts meta-analysis results. METHODS: The authors conducted a systematic review of studies reporting the ability of preoperative NT-proBNP measurements to predict the composite outcome of all-cause mortality and nonfatal myocardial infarction at 30 days after noncardiac surgery. Individual patient-level data NT-proBNP thresholds were determined using two different methodologies. First, a single combined NT-proBNP threshold was determined for the entire cohort of patients, and a meta-analysis conducted using this single threshold. Second, study-specific thresholds were determined for each individual study, with meta-analysis being conducted using these study-specific thresholds. RESULTS: The authors obtained individual patient data from 14 studies (n = 2,196). Using a single NT-proBNP cohort threshold, the odds ratio (OR) associated with an increased NT-proBNP measurement was 3.43 (95% CI, 2.08 to 5.64). Using individual study-specific thresholds, the OR associated with an increased NT-proBNP measurement was 6.45 (95% CI, 3.98 to 10.46). In smaller studies (<100 patients) a single cohort threshold was associated with an OR of 5.4 (95% CI, 2.27 to 12.84) as compared with an OR of 14.38 (95% CI, 6.08 to 34.01) for study-specific thresholds. CONCLUSIONS: Post hoc identification of study-specific prognostic biomarker thresholds artificially maximizes biomarker predictive power, resulting in an amplification or overestimation during meta-analysis of these results. This effect is accentuated in small studies.

The prognostic value of pre-operative and post-operative B-type natriuretic peptides in patients undergoing noncardiac surgery: B-type natriuretic peptide and N-terminal fragment of pro-B-type natriuretic peptide: a systematic review and individual patient data meta-analysis.

OBJECTIVES: The objective of this study was to determine whether measuring post-operative B-type natriuretic peptides (NPs) (i.e., B-type natriuretic peptide [BNP] and N-terminal fragment of proBNP [NT-proBNP]) enhances risk stratification in adult patients undergoing noncardiac surgery, in whom a pre-operative NP has been measured. BACKGROUND: Pre-operative NP concentrations are powerful independent predictors of perioperative cardiovascular complications, but recent studies have reported that elevated post-operative NP concentrations are independently associated with these complications. It is not clear whether there is value in measuring post-operative NP when a pre-operative measurement has been done. METHODS: We conducted a systematic review and individual patient data meta-analysis to determine whether the addition of post-operative NP levels enhanced the prediction of the composite of death and nonfatal myocardial infarction at 30 and ≥180 days after surgery. RESULTS: Eighteen eligible studies provided individual patient data (n = 2,179). Adding post-operative NP to a risk prediction model containing pre-operative NP improved model fit and risk classification at both 30 days (corrected quasi-likelihood under the independence model criterion: 1,280 to 1,204; net reclassification index: 20%; p < 0.001) and ≥180 days (corrected quasi-likelihood under the independence model criterion: 1,320 to 1,300; net reclassification index: 11%; p = 0.003). Elevated post-operative NP was the strongest independent predictor of the primary outcome at 30 days (odds ratio: 3.7; 95% confidence interval: 2.2 to 6.2; p < 0.001) and ≥180 days (odds ratio: 2.2; 95% confidence interval: 1.9 to 2.7; p < 0.001) after surgery. CONCLUSIONS: Additional post-operative NP measurement enhanced risk stratification for the composite outcomes of death or nonfatal myocardial infarction at 30 days and ≥180 days after noncardiac surgery compared with a pre-operative NP measurement alone.

Postoperative B-type natriuretic peptide for prediction of major cardiac events in patients undergoing noncardiac surgery: systematic review and individual patient meta-analysis.

BACKGROUND: It is unclear whether postoperative B-type natriuretic peptides (i.e., BNP and N-terminal proBNP) can predict cardiovascular complications in noncardiac surgery. METHODS: The authors undertook a systematic review and individual patient data meta-analysis to determine whether postoperative BNPs predict postoperative cardiovascular complications at 30 and 180 days or more. RESULTS: The authors identified 18 eligible studies (n = 2,051). For the primary outcome of 30-day mortality or nonfatal myocardial infarction, BNP of 245 pg/ml had an area under the curve of 0.71 (95% CI, 0.64-0.78), and N-terminal proBNP of 718 pg/ml had an area under the curve of 0.80 (95% CI, 0.77-0.84). These thresholds independently predicted 30-day mortality or nonfatal myocardial infarction (adjusted odds ratio [AOR] 4.5; 95% CI, 2.74-7.4; P < 0.001), mortality (AOR, 4.2; 95% CI, 2.29-7.69; P < 0.001), cardiac mortality (AOR, 9.4; 95% CI, 0.32-254.34; P < 0.001), and cardiac failure (AOR, 18.5; 95% CI, 4.55-75.29; P < 0.001). For greater than or equal to 180-day outcomes, natriuretic peptides independently predicted mortality or nonfatal myocardial infarction (AOR, 3.3; 95% CI, 2.58-4.3; P < 0.001), mortality (AOR, 2.2; 95% CI, 1.67-86; P < 0.001), cardiac mortality (AOR, 2.1; 95% CI, 0.05-1,385.17; P < 0.001), and cardiac failure (AOR, 3.5; 95% CI, 1.0-9.34; P = 0.022). Patients with BNP values of 0-250, greater than 250-400, and greater than 400 pg/ml suffered the primary outcome at a rate of 6.6, 15.7, and 29.5%, respectively. Patients with N-terminal proBNP values of 0-300, greater than 300-900, and greater than 900 pg/ml suffered the primary outcome at a rate of 1.8, 8.7, and 27%, respectively. CONCLUSIONS: Increased postoperative BNPs are independently associated with adverse cardiac events after noncardiac surgery.

Prognostic value of plasma N-terminal pro-B-type natriuretic peptide concentration in patients with normal and impaired left ventricular systolic function undergoing surgery for abdominal aortic aneurysm.

INTRODUCTION: Implantation of an aortic-bifemoral prosthesis is characterised by a high (> 5%) rate of perioperative cardiovascular events. The main aim of the study is to demonstrate the usefulness of the determination of NT-proBNP concentration as a method of risk stratification of left ventricular dysfunction in patients subjected to surgery for aortic-bifemoral prosthesis implantation. MATERIAL AND METHODS: Forty consecutive patients were examined and subjected to aortic-bifemoral prosthesis implantation. The examined patients were divided into two groups: 1) with normal left ventricular systolic function and EF ≥ 58% (group I), 2) with left ventricular systolic dysfunction and EF < 58% (group II). RESULTS: In group I the median EF before surgery was 69.5% and the concentration of NT-proBNP 141.5 pg/ml. On day 7 after surgery respective values were EF 65.5%, NT-proBNP 498.55 pg/ml. In group II the median EF before surgery was 54%, and NT-proBNP concentration 303.9 pg/ml. CONCLUSIONS: The concentration of plasma NT-proBNP before surgery well correlated with left ventricular ejection fraction. The values of NT-proBNP > 303.9 pg/ml strongly correlated with increased risk of left ventricular systolic dysfunction after surgery and they seem to have high prognostic value for the occurrence of cardiovascular events in this group of patients. The determination of NT-proBNP level on day 7 after surgery strongly correlated with the decrease of left ventricular ejection fraction in patients after the prosthesis implantation. It is a valuable diagnostic and prognostic factor of circulatory system efficiency before making a decision to discontinue hospitalization.

Assessment of blood flow in posterior ciliary arteries and its correlation with intraocular and arterial blood pressures in patients with open angle glaucoma.

BACKGROUND: At present, the vascular theory of glaucomatous neuropathy is still the subject of intensive scientific studies aiming at settling the relationship between the development of glaucomatous neuropathy and vascular factors. Therefore the purpose of this study was to assess the blood flow parameters in the posterior ciliary artery and middle cerebral artery in patients with glaucoma and the correlation of glaucomatous changes with flow in vessels supplying the retina, choroid and anterior segment of the optic nerve in patients with glaucoma with and without coexisting arterial hypertension. MATERIAL/METHODS: The study comprised 50 patients who were divided into two groups: group I - 25 patients (50 eyes) with primary open angle glaucoma (POAG) without coexisting arterial hypertension; and group II - 25 patients (50 eyes) with POAG with diagnosed and treated arterial hypertension. RESULTS: The median of the mean maximal velocity in posterior ciliary arteries was 10.4 cm/s in patients from group I. In patients with POAG and arterial hypertension the median of the mean maximal velocity in posterior ciliary arteries was 8.95 cm/s (p<0.002). In group I the median of the Gosling pulsatility index (PI) in posterior ciliary arteries was 1.0, whereas in group II the median was 1.16 (p<0.002). The median of the pulsatility transmission index (PTI) for cerebral and ocular vessels was 1.3 in group I, whereas in group II the median was 1.38 (p<0.02). CONCLUSIONS: The coexistence of arterial hypertension in glaucoma patients significantly worsens microcirculation in the area of posterior ciliary arteries and may be the cause of accelerated progression of glaucomatous neuropathy.