Acute myocardial infarction (AMI) is the major cause of premature mortality in the UK and other western countries.^1,2 The importance of prompt administration of thrombolytic therapy has lead to public education programmes to reduce time between onset of symptoms and treatment. This period consists of patient delay, transport time, and hospital time from admission to treatment.³ Patient delay is defined as time from onset of signs and symptoms of an AMI to when medical assistance is sought.⁴ Patient delay combined with transport time is referred to as prehospital delay.

The UK National Service Framework recommends public education programmes encouraging people to call an ambulance in the event of symptoms suggestive of myocardial infarction.¹ We conducted a systematic review to investigate the effectiveness of interventions aiming to reduce patient and/or prehospital delay.

METHODS

The review was undertaken according to the Centre for Reviews and Dissemination’s (CRD) systematic review guidelines.⁵ Fifteen electronic databases, the internet, and bibliographies of included studies were searched, and experts in the field of cardiac care were contacted. Studies were included if they assessed an intervention aimed at reducing patient and/or prehospital delay, reported either patient and/or prehospital delay as the outcome, and were randomised controlled trials (RCTs), controlled trials, or before and after studies. Articles were assessed for inclusion independently by two reviewers, and data extraction and quality assessment were carried out by one reviewer and checked by a second reviewer. Disagreements were resolved through discussion and, if necessary, by recourse to a third reviewer. Study validity was assessed using a checklist adapted from CRD’s guidelines,⁵ and a previous systematic review.⁶ Studies were synthesised in a narrative format along with appropriate summary tables.

RESULTS

Eleven studies, evaluating media/public education campaigns, met inclusion criteria.^7–17 One of these also examined one to one education.¹⁷ Two were RCTs,^16,17 one was a controlled trial,¹⁵ and eight were before and after studies.^7–14 Table 1 summarises duration of the intervention and outcome measurement of studies.

Table 2 summarises the content of interventions. The primary outcome examined in all studies was patient and/or prehospital delay. Other outcomes were mortality rates and the use of health resources.

Prehospital and patient delay time

Two RCTs^16,17 and six before and after studies^8,9,11–14 examined prehospital delay. Three before and after studies reported a statistically significant reduction in delay after the intervention.^8,9,11 In one of these studies there were also statistically significant increases in percentage of persons delaying less than one hour and less than six hours.¹¹ Another before and after study reported a statistically significant increase in percentage of persons delaying two hours or less.¹² Neither RCT reported any statistically significant effects of the intervention. This was also the case for two of the before and after studies.^13,14

The controlled trial¹⁵ and three before and after studies^7,9,10 examined patient delay. The controlled trial reported a statistically significant increase in percentage of patients in the intervention group calling their general practitioner after compared with before the intervention. However, these findings were not compared with the control group. One before and after study found a statistically significant reduction in median delay.⁹ The other two found no statistically significant difference in the percentage of people seeking help within different time periods^7,10 or in median delay.⁷

Use of health resources

Two RCTs^16,17 and three before and after studies^8,9,13 examined the effect of the intervention on emergency department visits. One RCT reported a statistically significant increase in the overall number of visits for chest pain throughout the campaign period,¹⁶ one before and after study reported a statistically significant increase in mean number of visits per day,⁸ and another before and after study showed a statistically significant increase in the mean number of visits per week.⁹

One RCT¹⁶ and one before and after study⁹ examined calls made to emergency switchboards. Both found statistically significant increases in the number of calls made after the intervention.

None of the three before and after studies examining use of ambulance/medic transport reported a statistically significant difference in this outcome from before to after the intervention.^8–10

Mortality rate

One RCT¹⁷ and one before and after study⁸ examined mortality rates. Neither reported any statistically significant effects of the intervention on mortality.

Study quality

Methodological quality of studies was generally poor. Studies were flawed with regard to issues concerning the sample, inclusion criteria, statistical analyses, outcome assessment, and reporting of information relating to intervention content and participants.

DISCUSSION

There is limited evidence that community wide media based or one to one educational interventions were successful in reducing delay time and they may have resulted in an increase in calls made to emergency switchboards and emergency department visits. However, because of the types of study designs used and methodological deficiencies of studies, it is unclear how much weight can be given to these findings. Evidence for the effectiveness of interventions came mainly from before and after studies suggesting a need for caution in attributing any reported effects to the actual intervention.

Studies that were effective in reducing delay appeared similar to those that were ineffective in terms of population, duration of intervention, main outcome measured, baseline delay, and year in which conducted. Few studies provided information relating to frequency and intensity of interventions for a similar assessment of these factors.

Implications for future research

It may be beneficial for interventions to emphasise importance of thrombolytic therapy in preventing death or disability, and make it acceptable for people to access emergency services without fear that they are wasting NHS resources or that their symptoms are not serious enough.^18,19 It might be useful to evaluate how patients (and their partners/family) make the decision to call for help before advocating interventions. It may also be appropriate to target education at high risk groups, including family members. However, there is a need to educate the public at large to call an ambulance if they witness what could be an AMI.

Future research requires an appropriate design with baseline measurement of delay time, a reasonable follow up period, and specification of frequency, intensity, and content of the intervention. As the ultimate aim of such interventions is to save lives, mortality should be measured. Such studies are needed before any firm conclusion can be drawn.