The influence of diagnostic subgroups, patient- and hospital characteristics for the validity of cardiovascular diagnoses-Data from a Norwegian hospital trust

BACKGROUND

Cardiovascular discharge diagnoses may serve as endpoints in epidemiological studies if they have a high validity. Aim was to study if diagnoses-specific characteristics like type, sub-categories, and position of cardiovascular diagnoses affected diagnostic accuracy.

METHODS

Patients (n = 7,164) with a discharge diagnosis of acute myocardial infarction, heart failure or cerebrovascular disease were included. Data were presented as positive predictive values (PPV) and sensitivity.

RESULTS

PPV was high (≥88%) for acute myocardial infarction (n = 2,189) (except for outpatients). For heart failure (n = 4,026) PPV was 67% overall, but higher (>99%) when etiology or echocardiography was included. For hemorrhagic (n = 257) and ischemic (n = 1,034) strokes PPVs were 87% and 80%, respectively, with sensitivity of 79% and 75%. Transient ischemic attacks (n = 926) had PPV 56%, but sensitivity 86%. Primary diagnoses showed higher validity than subsequent diagnoses and inpatient diagnoses were more valid than outpatient diagnoses (except for transient ischemic attack). The diagnoses of acute myocardial infarction and heart failure where most valid when placed at cardiology units, while ischemic stroke when discharged from an internal medicine unit.

CONCLUSIONS

The diagnoses of acute myocardial infarction and stroke had excellent validity when placed during hospital stays. Similarly, heart failure diagnoses had excellent validity when echocardiography was performed before placing the diagnosis, while overall the diagnoses of heart failure and transient ischemic attack were less valid. In conclusion, the results indicate that cardiovascular diagnoses based on objective findings such as acute myocardial infarction and stroke have excellent validity and may be used as endpoints in clinical epidemiological studies with less rigid validation.

Phosphate isosteres in medicinal chemistry

The phosphate group is at the heart of an enormous number of biological processes. The simple phosphorylation or dephosphorylation of a protein can have a wide range of consequences, including effects on its biological activity, its interaction with other proteins, and on its subcellular location. Abnormal levels of protein phosphorylation have been linked to a wide range of diseases including cancer and diabetes. Consequently, proteins that recognise the phosphate moiety have become an attractive target for therapeutic development. The most prevalent medicinal chemistry research examines the interactions of phosphorylated tyrosine residues; however, the role of phosphate groups on serine or threonine residues, in nucleotides, DNA and RNA, on sugars, and lipid mediators such as lysophosphatidic acid should not be overlooked. Investigations have focused on the non-catalytic phosphotyrosine-recognising domains such as Src homology 2 (SH2) and phosphotyrosine binding (PTB) domains, as well as catalytic proteins such as protein tyrosine phosphatase 1B (PTP1B). The utilisation of the phosphate moiety as part of an inhibitor is severely limited by the enzymatic lability and poor cellular bioavailability of this highly charged recognition element. The development of phosphate isosteres attempts to address these issues by introducing a non-scissile bond and utilizing groups with less charge that are still able to interact favourably with the target protein in much the same way as the phosphate group does. Many phosphate mimics retain the phosphorus atom such as in the highly successful fluoromethylenephosphonates, whereas others have lost the tetrahedral phosphate geometry and are based on the combination of one or more carboxylate groups that generally reduce the overall charge of the molecule. This review focuses on the recent developments and the use of phosphate isosteres in medicinal chemistry, covering roughly the past four years.

Glycosidase mechanisms

Insights into glycosidase mechanisms have come from X-ray crystallographic studies on complexes with substrate analogs and inhibitors, representing all the intermediate species along the reaction coordinate. Site-directed mutagenesis continues to play a significant role in understanding mechanisms, but is also proving important in generating glycosidases of modified mechanism or specificity.