We observed a 21% reduction in symptomatic VTE with the use of physician alerts. This rate trended toward but did not achieve statistical significance. The overall rate of VTE prophylaxis was low, despite fewer than half of patients in the intervention group receiving any preventive measures. However, patients for whom a physician alert was issued were more than twice as likely to receive VTE prophylaxis.
In our prior trial of electronic alerts, the reduction in symptomatic VTE was 41%, compared with 21% in the present study. This was surprising because the median age was 73 years in this study compared with 63 years in the electronic alert study. A history of VTE was present in 30% in this study compared with 20% in the electronic alert trial. The older patient population and higher rate of prior VTE should have provided the substrate for higher baseline VTE rates and for greater reductions in symptomatic DVT and PE than we observed. Based upon the event rate in this trial, we would have needed to enroll approximately 9,000 patients to detect a significant difference (with 80% power) in symptomatic VTE between the two groups.
The most likely explanation for the lesser reduction in symptomatic VTE in this trial is the fundamental difference between the two trials: human versus computer alerts. We had thought that the “personal touch” of direct staff communication with the Attending Physician might be more effective than an impersonal computer-generated alert in raising awareness of a patient’s VTE risk, encouraging prophylaxis utilization, and reducing symptomatic VTE events. However, based on our data, it is likely that a computer alerting system is inherently more effective. Computer-based systems can provide direct access to a wide range of decision-support tools, including evidence-based practice guidelines, that would not be possible through a human alerting system.5, 6
A computer-based alerting system, such as the one used in our previous trial, may be more difficult to ignore because it forces the clinician to acknowledge the alert before the clinician can continue using the electronic medical record or order entry program.7
Finally, computer-based alerting systems aimed at improving VTE prophylaxis may maintain effectiveness over time better than a human alerting system.8
Nevertheless, we do recognize that there were no direct comparisons between the two alerting modalities and that the setting of the two studies was different.
While a smaller reduction in symptomatic VTE was noted with human alerts compared with computer alerts, VTE prophylaxis was ordered more often in the intervention group of the current trial (46%) compared with the intervention group of the prior study (33%). Although lower than expected, the reduction in symptomatic VTE may have reached significance if prophylaxis rates in the intervention group had been higher. For each 0.1% decrease in symptomatic VTE, the current study required a 4% increase in prophylaxis utilization. The trial would have achieved statistical significance if there had been an additional absolute decrease in symptomatic VTE of 0.6%, yielding a VTE rate of 2.1%. A prophylaxis rate of 74% rather than the observed 46% should have reduced the rate of symptomatic VTE to the target of 2.1%.
The decrease in the rate of symptomatic VTE in the control group of the current investigation may represent a possible time trend. There may be greater emphasis on early mobilization of hospitalized patients now compared with five years ago. At the conclusion of the previous electronic alert trial, we discontinued randomization and issued electronic alerts for all patients in a cohort of 866 patients who were high-risk for VTE and not receiving prophylaxis.9
The rate of symptomatic VTE within 90 days decreased to 5.1% in this follow-up cohort.9
In another study of hospitalized medical patients, the rate of clinically diagnosed DVT or PE within 90 days of hospital discharge was estimated to be as low as 1.6%.10
In the current trial, both the intervention and control groups had low rates of VTE prophylaxis, despite numerous studies demonstrating the safety and efficacy of pharmacological11–15
and mechanical16, 17
modalities, as well as guidelines supporting the use of VTE prophylaxis in high-risk patients.18, 19
Patients in the intervention group received VTE prophylaxis less than half of the time, while those in the control group were prescribed prophylactic measures less than a quarter of the time. These findings are consistent with multiple recent studies demonstrating underutilization of VTE prophylaxis as an international public health crisis.20–24
The majority of patients not receiving VTE prophylaxis and subsequently enrolled in the study (82%) were hospitalized medical patients. Similar to our previous trial, nearly 80% of these hospitalized medical patients had malignancy. Our observation of underutilization of VTE prophylaxis is consistent with previous data regarding VTE prevention among hospitalized patients on the Medical Service.25
In addition, 40% of patients enrolled in the study were older than 75 years, and VTE is particularly problematic in hospitalized elderly patients.26
The education of healthcare providers about the risk of VTE in hospitalized medical patients is critical.27
Hospital Grand Rounds, Continuing Medical Education courses, and Risk Management programs can increase VTE awareness among healthcare providers. Furthermore, VTE prevention in hospitalized patients is considered an important measure of healthcare quality.28, 29
Underutilization of VTE prophylaxis is a problem of such magnitude that organizations such as Medicare, the National Quality Forum, and the Joint Commission are focusing on a policy-based approach to VTE prevention. For example, the Centers for Medicare & Medicaid Services has announced that DVT or PE following total knee and hip replacement procedures are considered “never events”, and hospitals are no longer being reimbursed for this surgical complication, effective on October 1, 2008.30
Finally, patient advocacy groups, such as the North American Thrombosis Forum (www.natfonline.org
), National Alliance for Thrombosis and Thrombophilia (www.stoptheclot.org
), and the Coalition to Prevent DVT (www.preventdvt.org
), increase public awareness and empower patients to participate in VTE prevention.
Our study may be limited by the possibility of diagnostic bias because the administration of prophylaxis was not blinded, and testing for VTE was not routinely performed unless symptoms were present. It is possible that physicians were more likely to pursue diagnostic testing for VTE for patients with symptoms who had not received prophylaxis than for those who had received prophylaxis. In addition, diagnostic testing may not have been performed in symptomatic patients with a limited life expectancy or contraindications to anticoagulation, resulting in an underestimation of events. Since most physicians treated both intervention and control patients, it is possible that receiving a physician alert for patients in the intervention group also affected the utilization of prophylaxis in the control group. In both the previous study of electronic alerts and our current trial, we wanted to select a study population in which there would be 100% consensus that every selected patient should receive VTE prophylaxis. Therefore, we utilized a VTE risk score that would permit us to capture an unequivocally high-risk population (cumulative risk score of at least 4 points). We acknowledge that a subset of patients with lower cumulative VTE risk scores would also be considered appropriate for VTE prophylaxis in clinical practice.
Our data suggest that a strategy of manually screening patients for VTE risk and alerting healthcare providers about high-risk patients who are not receiving prophylactic measures increases prophylaxis utilization and trends toward reduction of symptomatic VTE. However, a human alerting system does not appear to be as effective as a computer-based decision support strategy. Increasing resources for computer-based decision support strategies and medical informatics may enhance effectiveness of VTE prevention measures.
Despite published guidelines for VTE prevention, underutilization of prophylaxis in hospitalized patients remains problematic. We previously described a novel system utilizing electronic alerts to prevent symptomatic VTE in hospitalized patients. We created a computer program linked to the patient database to identify hospitalized patients at high risk for VTE who were not receiving prophylaxis and randomize notification (versus no notification) of physicians caring for these patients. The physicians in the intervention group received electronic alerts urging them to order prophylaxis. This resulted in a 41% reduction in symptomatic VTE at 90 days compared with the control group. Because it required an intricate electronic notification system and medical informatics support, this strategy could not be easily implemented by most hospitals. Therefore, we devised a clinical trial that employed a “human,” rather than electronic, alerting system. 2,493 patients were randomized to the intervention group, in which the Attending Physician was alerted by another hospital staff member by direct page, versus the control group, in which no alert was issued. Patients whose physicians were alerted were more than twice as likely to receive VTE prophylaxis. Although a “human” alerting system more than doubled VTE prophylaxis utilization, the ensuing 21% reduction in symptomatic VTE at 90 days did not achieve statistical significance (p=0.31). Increasing resources for computer-based decision support strategies may enhance effectiveness of VTE prevention measures.