Phenylalanine blood levels and clinical outcomes in phenylketonuria: a systematic literature review and meta-analysis.

Blood phenylalanine (Phe) levels provide a practical and reliable method for the diagnosis and monitoring of metabolic status in patients with phenylketonuria (PKU). To assess the reliability of blood Phe levels as a predictive biomarker of clinical outcomes in the development of treatments for PKU, a systematic literature review and meta-analysis of published trials of PKU, which included Phe level and neurological and dietary compliance outcome measures, was conducted. Within-study correlations between Phe level and intelligence quotient (IQ) were extracted from 40 studies. Significant, proportional correlations were found during critical periods (from 0 to 12 years of age) for early-treated patients with PKU (r=-0.35; 95% confidence interval [CI]: -0.44 to -0.27), where each 100 micromol/l increase in Phe predicted a 1.3- to 3.1-point reduction in IQ. Similar significant correlations were observed between IQ and mean lifetime Phe level for early-treated patients (r=0.34; 95% CI: -0.42 to -0.25), where each 100 micromol/l increase in Phe predicted a 1.9- to 4.1-point reduction in IQ. Moderate correlations were found between concurrent Phe level and IQ for early-treated patients. In conclusion, these results confirm a significant correlation between blood Phe level and IQ in patients with PKU, and support the use of Phe as a predictive biomarker for IQ in clinical trials.

A comparison of the accuracy of two minimally invasive breast biopsy methods: a systematic literature review and meta-analysis.

OBJECTIVE: The primary objective was to quantify and compare the accuracy and failure rates of directional vacuum assisted biopsy (DVAB) and core needle biopsy (CNB) when used under stereotactic (ST) guidance to biopsy suspicious breast lesions identified with screening mammography. METHODS: We performed a systematic review of the literature published from January 1996 to July 2004, reporting all-comers populations in Western-style health care systems (i.e., North America, Europe, Australia or New Zealand), referred after screening mammography for breast biopsy using DVAB or CNB under ST guidance. Meta-analyses were conducted for DVAB and CNB, using open surgical biopsy and/or long-term clinical and/or mammogram follow-up as the diagnostic reference standard. The main outcomes of interest were those of greatest clinical relevance, i.e., miss rates and underestimation rates for malignancy. Also, technical failure rate and non-diagnostic rate were assessed for each biopsy method. RESULTS: Thirty-five studies qualified for the review. There were 12 studies with a DVAB group (n=5,119 patients), and 25 studies with a CNB group (n=6,236). There were no studies including both a DVAB and a CNB group, thus precluding any direct, within-study comparisons of accuracy. Overall agreement rate between DVAB and the reference standard was 97.3%, and between CNB and the reference standard, 93.5%. The frequency of technical failures with CNB was slightly higher than DVAB (5.7 vs. 1.5%), as was the frequency of non-diagnostic samples (2.1 vs. 0%). Of the non-diagnostic CNB samples, 23% were subsequently found to be malignant on reference standard. In multivariate analyses using four covariates (procedure type, geographic location, reference standard, and patient position), there were no significant predictors of agreement rates, but some variables were significant predictors of miss rates. For benign to malignant upgrades, study location was a significant predictor, with more upgrades in non-NA locations. For atypia to malignant upgrades, the type of procedure was a significant predictor, with more underestimations in CNB studies. CONCLUSION: The best available evidence suggests that, in screening populations referred for minimally invasive breast biopsy biopsy requiring ST guidance, DVAB may provide lower miss and underestimation rates for clinically relevant diagnoses than does CNB.

Warfarin anticoagulation and outcomes in patients with atrial fibrillation: a systematic review and metaanalysis.

OBJECTIVE: To examine the relationship between international normalized ratio (INR) and outcomes (major bleeding events and strokes) in patients with atrial fibrillation (AF) receiving anticoagulation with warfarin. METHODS: A systematic review and metaanalysis of studies published in the English language between January 1, 1985, and October 30, 2002, was performed. MEDLINE (PubMed), Current Contents, and relevant reference lists were searched. Studies enrolling patients with nonvalvular AF receiving warfarin anticoagulation were eligible for inclusion if they reported stroke and/or major bleeding events in relation to INR, or time spent in therapeutic range. The risk of bleeds in overanticoagulated patients (INR > 3) and the risk of strokes in underanticoagulated patients (INR < 2) were assessed. RESULTS: Twenty-one studies (6,248 patients) met all inclusion criteria. Of the 21 studies, a target conventional INR of 2 to 3 was used in 9 studies. An INR < 2, compared with an INR > or = 2, was associated with an odds ratio (OR) for ischemic events of 5.07 (95% confidence interval [CI], 2.92 to 8.80). An INR > 3, compared with an INR < or = 3, was associated with an OR for bleeding events of 3.21 (95% CI, 1.24 to 8.28). On average, in the four studies with a target INR range of 2 to 3, patients with AF receiving warfarin spent 61% of time within, 13% of time above, and 26% below the therapeutic range. CONCLUSION: Available evidence indicates that in patients with nonvalvular AF, the risk of ischemic stroke with insufficient warfarin anticoagulation (INR < 2), and the risk of bleeding events with overanticoagulation (INR > 3) are significantly higher relative to patients with AF maintained within the recommended INR of 2 to 3. However, the published data are sparse, heterogeneous, and primarily reported from clinical trials. More studies evaluating clinical outcomes in relation to INR are needed, especially in a real-world setting.