Intracranial hemorrhage risk and new thrombolytic therapies in acute myocardial infarction

Thrombolytic therapy for acute myocardial infarction (AMI) has reduced mortality at the expense of additional intracranial hemorrhages. To determine whether this trade-off has been optimized, a decision analysis was performed using pooled data to determine the further reductions in mortality required to justify increased intracranial hemorrhage rates from more potent thrombolytic and adjunctive antithrombotic regimens that intravenous streptokinase. Pooled data from large clinical trials suggest that streptokinase has a 0.07% nonfatal intracranial hemorrhage rate. Approximately 54% of these result in major/moderate disability and 46% in recovery or minor residual. The early mortality rate in all AMI patients treated with thrombolytic therapy is 9.8%; it is 6.8% in patients with inferior wall AMI and 17.9% in elderly patients. If a new thrombolytic regimen provides a 1% absolute reduction in early mortality compared with streptokinase therapy, approximately a > or = 3.2% nonfatal intracranial hemorrhage rate is justified to obtain this survival benefit. For a 10% relative reduction in mortality risk, the maximal acceptable nonfatal intracranial hemorrhage rates are 2.2% for inferior wall AMI, 3.2% for all patients and 5.9% for elderly patients. Whereas intracranial hemorrhage is a catastrophic complication of thrombolytic therapy in the treatment of patients with AMI, thrombolytic regimens that result in significantly higher rates of intracranial hemorrhage than those observed with streptokinase may be preferable at surprisingly smaller additional reductions in mortality. In addition to evaluating new thrombolytic and antithrombotic regimens, this analysis, in conjunction with models that predict patient-specific intracranial hemorrhage risks and mortality benefits from thrombolytic therapy, can provide a framework for matching AMI patients with optimal thrombolytic regimens.

A comparison of administrative versus clinical data: coronary artery bypass surgery as an example. Ischemic Heart Disease Patient Outcomes Research Team

Health services researchers rely heavily on administrative data bases, but incomplete or incorrect coding may bias risk models based on administrative data. The best method for validating administrative data is to collect detailed information about the same cases from independent sources, but this approach may be too costly or technically difficult. We used data on coronary artery bypass surgery from four sites (Duke University; Minneapolis--St Paul; California; and Manitoba) to demonstrate an alternative approach for assessing diagnostic coding and to explore the implications of miscoding. The first two sites have clinical data; the second two have administrative data. The prevalences of 14 comorbidities and the associated risk ratios for short-term mortality were compared across data sets. Some comorbidities could not be precisely mapped to ICD-9-CM. Chronic or asymptomatic conditions such as mitral insufficiency, cardiomegaly, previous myocardial infarction, tobacco use, and hyperlipidemia were far less prevalent in administrative data than in clinical data. The prevalence of diabetes, unstable angina, and congestive heart failure were similar in administrative and clinical data. Estimates of relative risk derived from clinical data equalled or surpassed those derived from administrative data for all conditions. Hospitals should be encouraged to improve reporting of coexisting conditions on discharge abstracts and claims. In the meantime, researchers using administrative data should assess the vulnerability of their risk models to bias caused by selective underreporting.

Discordance of databases designed for claims payment versus clinical information systems. Implications for outcomes research

OBJECTIVE

To determine the suitability of insurance claims information for use in clinical outcomes research in ischemic heart disease.

DESIGN

Concordance study of two databases.

SETTING

Tertiary care referral center.

PATIENTS

A total of 12,937 consecutive patients hospitalized for cardiac catheterization for suspected ischemic heart disease between July 1985 and May 1990.

INTERVENTIONS

Two-by-two tables were used to compute overall and kappa measures of agreement comparing clinical versus claims data for 12 important predictors of prognosis in patients with ischemic heart disease.

MEASUREMENTS

Kappa statistics (agreement adjusted for chance agreement) were used to quantify agreement rates.

RESULTS

Agreement rates between the clinical and claims databases ranged from 0.83 for the diagnosis of diabetes to 0.09 for the diagnosis of unstable angina (kappa values). Claims data failed to identify more than one half of the patients with prognostically important conditions, including mitral insufficiency, congestive heart failure, peripheral vascular disease, old myocardial infarction, hyperlipidemia, cerebrovascular disease, tobacco use, angina, and unstable angina, when compared with the clinical information system.

CONCLUSIONS

Our results suggest that insurance claims data lack important diagnostic and prognostic information when compared with concurrently collected clinical data in the study of ischemic heart disease. Thus, insurance claims data are not as useful as clinical data for identifying clinically relevant patient groups and for adjusting for risk in outcome studies, such as analyses of hospital mortality.

Innervation of the posterior fossa dura of the cat

This study was designed to identify the location of neurons giving rise to fibers innervating the posterior fossa dura in the cat using horseradish peroxidase (HRP, Sigma, Type VI). Investigations since the 19th century have implicated innervation by cranial nerves V, VII, IX, X and XII and the upper cervical nerves, C1-3. The meninges of the posterior fossa of 14 cats was exposed using one of three surgical approaches: (1) a suboccipital craniectomy and C1 laminectomy, (2) a parieto-occipital craniectomy with removal of the occipital lobe and bony tentorium exposing the meninges over the cerebellum, or (3) an anterior approach through the upper neck, exposing the dura of the ventral surface of the caudal brainstem. A unilateral, curvilinear incision was made in the dura and HRP was applied to the exposed dural edges. Following 48 hours the animals were sacrificed and fixed by perfusion. Cranial nerve ganglia of V, VII, IX, X, dorsal root ganglia (DRG) of C1-3, and superior cervical ganglia (SCG) were removed bilaterally, sectioned and processed with tetramethylbenzidine (TMB). HRP labeled cells were located bilaterally, always more ipsilaterally, in DRG of C1, C2, C3, and SCG with application of HRP to all three regions of the dura. Labeled cells were also located in trigeminal ganglia and superior ganglia of CN X, occasionally bilaterally, depending on the site of application. No HRP was ever identified in neurons of the geniculate ganglion, inferior ganglion of CN X or superior or inferior ganglia of CN IX. This information is valuable to an understanding of the innervation of intracranial structures and the problems of head pain.