Today almost 14 million Americans have established coronary artery disease, which increases their risk for a future ACS event.19
Delay in contacting the health care system in the face of cardiac symptoms remains a major obstacle to definitive treatment of patients with acute myocardial infarction and may contribute to out-of-hospital cardiac deaths. The study reported here was the first randomized controlled trial designed specifically for a population at high risk for a future ACS event and targeting a reduction in prehospital delay. We documented the effects of a face-to-face, tailored education and counseling intervention on prehospital delay time (the primary hypothesis), as well as EMS and aspirin use, as well as utilization of the ED (secondary hypotheses). The primary hypothesis was rejected. While aspirin use was significantly higher in the experimental group, the use of EMS was not significantly different. However, utilization of ED resources was not significantly increased by the intervention.
The intervention was designed to encourage patients to personalize the message to seek care quickly in the face of ACS symptoms and to counter emotional coping mechanisms such as denial that might lead to prolonged prehospital delay time. The intervention protocol was based on the recommendations of the National Heart Attack Alert Program5
and the findings were particularly disappointing given the tailored nature of the intervention and the high risk status of the sample for a future ACS event. Unlike previous interventions designed for community-dwelling individuals,7,10
the current study was tailored for patients aware of their risk for a future ACS event who could be expected to be more attentive to health messages than individuals living in the community.
Upon reflecting on the negative study findings of no difference in median prehospital delay times between the two experimental groups, several interpretations can be offered. First, data collection may have provided an unintended form of intervention in the control group. All patients enrolled in the current study completed questionnaires at baseline, 3 and 12 months following enrollment and responded to questions in which they were asked to identify cardiac symptoms, describe their attitudes toward seeking help quickly if symptoms occurred, and state the level of their belief that the medical system had treatments that would help them if they sought care quickly. Reflecting on these questions at three different times and actively responding in writing to each of them may have sensitized control patients to the importance of seeking care early. Perhaps a third study arm that represented a true control without periodic assessment of knowledge, attitudes and beliefs would have revealed that the data collection process itself was a form of intervention. The fact that, with the exception of the Physicians Health Study (median delay time of 114 minutes),20
the delay times in both the experimental and control groups was shorter than in all previous studies reported to date10
supports this interpretation.
Second, another explanation for the lack of effect of the face-to-face tailored intervention may be that the information presented did not address the variability of onset and the differing symptoms of ACS adequately or was not of sufficient intensity or duration to address the patients’ denial or inappropriate attribution of symptoms. The education and counseling session was delivered by a research nurse, not the patient’s physician. The latter may have been able to adapt the information provided the patient to the unique medical history, including the nature of previous ACS symptoms and patterns of response. Similarly, the fact that patients in the experimental group were more likely to call the EMS if ACS symptoms occurred early in the study (i.e., in the first six months from enrollment) suggests that repetition of the information might increase the saliency of the intervention.
A third interpretation relates to difference between the two study groups. Despite randomization, there were significantly more women in the experimental group than the control group (34 vs. 30 percent respectively, p=0.02). This difference may have contributed to the finding of no difference in median delay times, although gender was used as a covariate in the analysis. Although gender was not significantly different in the two groups who sought care for ACS symptoms (38 vs 32 percent in the experimental and control groups respectively, p=0.11), the difference in percentages may have favored longer median delay times in the experimental group. Some investigators6
have noted that women delay longer than men in seeking care for cardiac symptoms, although the reason for this difference by gender remains unknown. Similarly, the two groups who presented to the ED for symptoms of ACS were significantly different in their annual incomes and ambulance insurance, with the experimental group reporting lower income and less insurance coverage. Both factors would favor longer delays in the experimental group if patients were concerned about the cost of care and therefore may have contributed to the finding of no difference between the groups; however, these differences were handled as covariates in the analysis and therefore do not provide a strong explanation for the findings of no difference in prehospital delay times.
We were surprised at the high EMS use in both groups, which was twice the level of the 33% EMS use documented in REACT at baseline7
or the National Registry of Myocardial Infarction.21
Our findings may be a reflection of the large proportion of patients recruited from Australia and New Zealand (44%) where ambulance use is generally high and is covered by universal health care. In fact, 87% of all patients in the study had insurance coverage for EMS use, which may have contributed to the high ambulance use and the relatively short prehospital delay. Many investigators7,22
have noted the importance of accessing EMS to reduce prehospital delay time, as well as minimize delay to treatment once the patient is admitted to the hospital.
Although the intervention did not influence prehospital delay times or EMS use, it did result in a significantly higher percentage of patients who took aspirin in the face of acute symptoms. It is important to note that researchers have suggested that self treatment is a source of delay,23
and therefore the recommendation to take aspirin prior to hospital arrival is no longer given.24
However, our findings suggest that patients are willing to adopt this behavior, which is a relatively simple one compared to calling EMS. The significant difference between groups on this one outcome underscores the complexity of designing an intervention that will reduce the many psychological barriers to calling 911 that exist for patients and their family members in the face of ACS symptoms. Behaviors such as taking aspirin appear to be easier to change than calling EMS or seeking care in an ED immediately upon onset of cardiac symptoms.
One of the concerns about conducting a large-scale intervention to decrease prehospital delay in ACS is that patients will become anxious and emergency department utilization will increase inappropriately. It is important to note that the intervention did not increase emergency room use in the experimental group, a finding that is similar to that of other community intervention studies.7,18,25