Prescribing patterns and outcomes of venous thromboembolism prophylaxis in hospitalized medical and cancer patients: Observations from the Ottawa Hospital

Guidelines suggest broad use of pharmacologic prophylaxis to prevent venous thromboembolism (VTE) in hospitalized medical patients, however little 'real-world' data exists to support this. Our goal was to describe the use of thromboprophylaxis among general medical and cancer patients admitted to hospital, compare VTE and bleeding outcomes according to use of thromboprophylaxis, and to determine what variables influence prescribing patterns and outcomes. Patients admitted to the general medical and oncology services at The Ottawa Hospital between 2010 and 2015 were retrospectively reviewed and classified according to whether they received initial, delayed, or no pharmacologic thromboprophylaxis during their first hospitalization. Patients with an alternate indication for anticoagulation or those admitted with a bleeding event were excluded from analysis. The primary efficacy outcome was any symptomatic VTE during index hospitalization or within 90 days of discharge, and the primary safety outcome was clinically relevant bleeding during the index hospitalization. 17,262 patients were included in our final analysis. General medical patients selected to receive no, initial, or delayed thromboprophylaxis had 0.4%, 0.7%, and 2.4% rates of VTE; and 0.2%, 0.7%, and 1.5% rates of clinically relevant bleeding complications, respectively. Cancer patients had significantly higher rates of VTE: 3.3%, 3.9%, and 5.0%; and 0.9%, 0.7%, and 3.0% rates of clinically relevant bleeding among those selected to receive no, initial, or delayed thromboprophylaxis, respectively. Overall, our study suggests that broad use of pharmacologic thromboprophylaxis may be unnecessary in select low-risk general medical patients and may be less effective in cancer patients in whom new studies are indicated.

Hospital-acquired Clostridium difficile infection: an institutional costing analysis

BACKGROUND

Healthcare-acquired Clostridium difficile infection (HA-CDI) is a common infection and a financial burden on the healthcare system.

AIM

To estimate the hospital-based financial costs of HA-CDI by comparing time-fixed statistical models that attribute cost to the entire hospital stay to time-varying statistical models that adjust for the time between admission, diagnosis of HA-CDI, and discharge and that only attribute HA-CDI costs post diagnosis.

METHODS

A retrospective cohort study was conducted (April 2008 to March 2011) using clinical and administrative costing data of inpatients (≥15 years) who were admitted to The Ottawa Hospital with stays >72 h. Two time-fixed analyses, ordinary least square regression and generalized linear regression, were contrasted with two time-dependent approaches using Kaplan-Meier survival curve.

FINDINGS

A total of 49,888 admissions were included and 366 (0.73%) patients developed HA-CDI. Estimated total costs (Canadian dollars) from time-fixed models were as high as $74,928 per patient compared to $28,089 using a time-varying model, and these were 1.47-fold higher compared to a patient without HA-CDI (incremental cost $8,997 per patient). The overall annual institutional cost at The Ottawa Hospital associated with HA-CDI was as high as $10.07 million using time-fixed models and $1.62 million using time-varying models.

CONCLUSION

When calculating costs associated with HA-CDI, accounting for the time between admission, diagnosis, and discharge can substantially reduce the estimated institutional costs associated with HA-CDI.

International variation in the definition of 'main condition' in ICD-coded health data

Hospital-based medical records are abstracted to create International Classification of Disease (ICD) coded discharge health data in many countries. The 'main condition' is not defined in a consistent manner internationally. Some countries employ a 'reason for admission' rule as the basis for the main condition, while other countries employ a 'resource use' rule. A few countries have recently transitioned from one of these approaches to the other. The definition of 'main condition' in such ICD data matters when it is used to define a disease cohort to assign diagnosis-related groups and to perform risk adjustment. We propose a method of harmonizing the international definition to enable researchers and international organizations using ICD-coded health data to aggregate or compare hospital care and outcomes across countries in a consistent manner. Inter-observer reliability of alternative harmonization approaches should be evaluated before finalizing the definition and adopting it worldwide.

USE OF AN ELECTRONIC DATA WAREHOUSE TO ENHANCE CARDIAC SURGICAL SITE SURVEILLANCE AT A LARGE CANADIAN CENTRE

Background/Purpose: Surgical site infection surveillance to determineincidence is a key infection control activity. Case detection is labour-intensive, therefore most infection control programs use manual or simple electronic mechanisms to “trigger” chart review. However, such “trigger” mechanisms are also labour-intensive, and often of poor specificity. Our objective is to develop a complex trigger mechanism using data from an electronic data warehouse, to improve specificity of surveillance of surgical site infection compared to current trigger mechanisms. Methods: We will derive an electronic trigger tool for cardiac surgical site infection surveillance using a nested case-control design, among a cohort of all patients undergoing coronary artery bypass grafting, cardiac valve repairor replacement, or heart transplant at the University of Ottawa Heart Institute, from July 1 2004 to June 30 2007. We will perform a systematic literature review to identify potential trigger factors to include in the model, then construct the trigger tool by backwards stepwise logistic regression. The best-fit model will be used to calculate the probability of surgical site infection. We will select the threshold probability to use in surveillance by visual inspection of receiver-operator-characteristic curves. The accuracy of this electronic trigger mechanism will be compared to pre-existing manual and simple electronic mechanisms using relative true positive ratios and relative false positive ratios. Results/Conclusions: We have selected 200 cases of surgical site infection and 541 controls from among 3744 procedures performed during the study period. As of the date ofthis abstract we are still undertaking the systematic review.

Accuracy of coding for possible warfarin complications in hospital discharge abstracts

BACKGROUND

Hospital discharge abstracts could be used to identify complications of warfarin if coding for bleeding and thromboembolic events are accurate.

OBJECTIVES

To measure the accuracy of International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9CM) codes for bleeding and thromboembolic diagnoses.

SETTING

University affiliated, tertiary care hospital in Ottawa, Canada.

PATIENTS

A random sample of patients discharged between September 1999 and September 2000 with an ICD-9-CM code indicating a bleeding or thromboembolic diagnosis.

METHODS

Gold-standard coding was determined by a trained chart abstractor using explicit standard diagnostic criteria for bleeding, major bleeding, and acute thromboembolism. The abstractor was blinded to the original coding. We calculated the sensitivity, specificity, positive, and negative predictive values of the original ICD-9CM codes for bleeding or thromboembolism diagnoses.

RESULTS

We reviewed 616 medical records. 361 patients (59%) had a code indicating a bleeding diagnosis, 291 patients (47%) had a code indicating a thromboembolic diagnosis and 36 patients (6%) had a code indicating both. According to the gold standard criteria, 352 patients experienced bleeding, 333 experienced major bleeding, and 188 experienced an acute thromboembolism. For bleeding, the ICD-9CM codes had the following sensitivity, specificity, positive and negative predictive values [95% CI]: 93% [90-96], 88% [83-91], 91% [88-94], and 91% [87-94], respectively. For major bleeding, the ICD-9CM codes had the following sensitivity, specificity, positive and negative predictive values: 94% [91-96], 83% [78-87], 87% [83-90], and 92% [88-95], respectively. For thromboembolism, the ICD-9CM codes had the following sensitivity, specificity, positive and negative predictive values: 97% [94-99], 74% [70-79], 62% [57-68], and 98% [96-99], respectively. By selecting a sub-group of ICD-9CM codes for thromboembolism, the positive predictive value increased to 87%.

CONCLUSION

In our centre, the discharge abstract could be used to identify and exclude patients hospitalized with a major bleed or thromboembolism. If coding quality for bleeding is similar in other hospitals, these ICD-9-CM diagnostic codes could be used to study population-based warfarin-associated hemorrhagic complications using administrative databases.

Thrombolysis in deep vein thrombosis: is there still an indication?

The most accepted therapy for DVT consists of anticoagulation with unfractionated heparin or low molecular weight heparin, followed by variable duration oral anticoagulation but thrombolytic therapy has been proposed in addition to standard anticoagulation. This paper reviews the literature on post thrombotic syndrome, the natural history of vein patency after therapy, and we perform a systematic review, using accepted standards for meta-analysis, to determine the outcomes when thrombolytic therapy is used to treat DVT. We demonstrate that thrombolytic therapy for DVT results in a significant increase in the risk of major hemorrhage and a significant increase in the rate of vein patency. However, although thrombolytic therapy is advantageous over anticoagulation as measured by early vein patency, a benefit in terms of a reduction in PTS risk, is unproven. Our review also shows that there is no evidence that there is a difference in efficacy between thrombolytic agents or that local therapy differs from systemic therapy. Finally, the potential role of catheter directed therapy is unknown since appropriate trials have not been performed but it is reasonable to use catheter directed therapy in patients with phlegmasia cerulea dolens. We conclude that more work is needed to define the role of thrombolytic therapy but it is too early to abandon this therapeutic modality.

Validation of a clinical decision aid to discontinue in-hospital cardiac arrest resuscitations

CONTEXT

Most patients undergoing in-hospital cardiac resuscitation do not survive to hospital discharge. In a previous study, we developed a clinical decision aid for identifying all patients undergoing resuscitation who survived to hospital discharge.

OBJECTIVE

To validate our previously derived clinical decision aid.

DESIGN, SETTING, AND PARTICIPANTS

Data from a large registry of in-hospital resuscitations at a community teaching hospital in Georgia were analyzed to determine whether patients would be predicted to survive to hospital discharge (ie, whether their arrest was witnessed or their initial cardiac rhythm was either ventricular tachycardia or ventricular fibrillation or they regained a pulse during the first 10 minutes of chest compressions). Data from 2181 in-hospital cardiac resuscitation attempts in 1987-1996 involving 1884 pulseless patients were analyzed.

MAIN OUTCOME MEASURE

Comparison of predictions based on the decision aid with whether patients were actually discharged alive from the hospital.

RESULTS

For 327 resuscitations (15.0%), the patient survived to hospital discharge. For 324 of these resuscitations, the patients were predicted to survive to hospital discharge (sensitivity = 99.1%, 95% confidence interval, 97.1%-99.8%). In 269 resuscitations, patients did not satisfy the decision aid and were predicted to have no chance of being discharged from the hospital. Only 3 of these patients (1.1%) were discharged from the hospital (negative predictive value = 98.9%), none of whom were able to live independently following discharge from the hospital.

CONCLUSION

This decision aid can be used to help physicians identify patients who are extremely unlikely to benefit from continued resuscitative efforts.

Derivation of a clinical decision rule for the discontinuation of in-hospital cardiac arrest resuscitations

BACKGROUND

Most patients undergoing in-hospital cardiac resuscitation will not survive to hospital discharge.

OBJECTIVE

To derive a decision rule permitting the discontinuation of futile resuscitation attempts by identifying patients with no chance of surviving to hospital discharge.

PATIENTS AND METHODS

Patient, arrest, and outcome data for 1077 adult patients undergoing in-hospital cardiac resuscitation was retrieved from 2 randomized clinical trials involving 5 teaching hospitals at 2 university centers. Recursive partitioning was used to identify a decision rule using variables significantly associated with death in hospital.

RESULTS

One hundred three patients (9.6%) survived to hospital discharge. Death in hospital was significantly more likely if patients were older than 75 years (P<.001), the arrest was unwitnessed (P = .003), the resuscitation lasted longer than 10 minutes (P<.001), and the initial cardiac rhythm was not ventricular tachycardia or fibrillation (P<.001). All patients died if there was no pulse 10 minutes after the start of cardiopulmonary resuscitation, the initial cardiac rhythm was not ventricular tachycardia or fibrillation, and the arrest was not witnessed. As a resuscitation rule, these parameters identified all patients who survived to hospital discharge (sensitivity, 100%; 95% confidence interval, 97.1%-100%). Resuscitation could have been discontinued for 119 (12.1%) of 974 patients who did not survive, thereby avoiding 47 days of postresuscitative care.

CONCLUSIONS

A practical and highly sensitive decision rule has been derived that identifies patients with no chance of surviving in-hospital cardiac arrest. Prospective validation of the rule is necessary before it can be used clinically.