Summary
Background
Regionalization of care for ST-segment elevation myocardial infarction (STEMI) has been advocated, although its effect on processes of care and clinical outcomes remains uncertain.
Aim
To assess the impact of a regional system of care on provision of reperfusion therapy for STEMI patients relative to control hospitals.
Methods
We analysed the original data from two nationwide prospective cohort studies conducted in 2000 and 2005, respectively. Overall, 160 hospitals participated in both studies, including seven hospitals involved in a regional system of care implemented in the Northern Alps in 2002 and 153 control hospitals located in other French areas.
Results
A total of 102 and 2377 STEMI patients were enrolled in Northern Alps and control hospitals, respectively. Overall, patients enrolled in 2005 were more likely to receive any reperfusion therapy (60% vs 52%; P < 0.001), prehospital fibrinolysis (33% vs 15%; P < 0.001), and primary percutaneous coronary intervention (32% vs 26%; P < 0.001) than those enrolled in 2000. However, the regional system of care was associated with a larger absolute change in the use of prehospital fibrinolysis (45.0 vs 17.0; P = 0.02) and rescue or early routine coronary angiography or intervention after fibrinolysis (35.3 vs 15.2; P = 0.01). Patients enrolled in 2005 had lower adjusted hazard ratios for death (0.70, 95% confidence interval 0.57–0.87; P = 0.001), with no significant interaction between study groups.
Conclusion
Regionalization of care for STEMI patients improves access to reperfusion therapy, although its impact on clinical outcomes deserves further study.
Résumé
Contexte
Les recommandations préconisent une coordination régionale de la prise en charge de l’infarctus du myocarde avec sus-décalage du segment ST (STEMI).
Objectif
Évaluer l’impact d’un réseau de soins dédié à la prise en charge des patients avec un STEMI.
Méthodes
Nous avons analysé les données originales provenant de deux études de cohorte prospectives multicentriques conduites en France en 2000 et 2005. Au total, 160 hôpitaux ont participé aux deux études, dont sept hôpitaux impliqués dans un réseau de soins mis en place en 2002 dans les Alpes du Nord et 153 hôpitaux témoins situés sur le reste du territoire national.
Résultats
Cent deux patients ont été inclus dans les hôpitaux des Alpes du Nord et 2377 dans les hôpitaux situés sur le reste du territoire national. Globalement, les patients recrutés en 2005 avaient plus souvent eu accès à une fibrinolyse préhospitalière (33 % versus 15 % ; p < 0,001) ou à une angioplastie coronaire percutanée primaire (32 % versus 26 % ; p < 0,001). Cependant, le réseau de soins était associé à une augmentation plus importante de la proportion de patients avec une fibrinolyse préhospitalière (45 % versus 17 % ; p = 0,02) et une angioplastie coronaire percutanée secondaire ou de sauvetage (35 % versus 15 % ; p = 0,01). Le risque de décès était plus faible en 2005 (0,70, intervalle de confiance à 95 % 0,57–0,87 ; p = 0,001), sans qu’on puisse mettre en évidence de différence en fonction du groupe.
Conclusion
La mise en place d’un réseau de soins a amélioré l’accès aux stratégies de revascularisation des patients admis avec un STEMI dans les hôpitaux des Alpes du Nord.
Background
Prompt coronary reperfusion therapy for ST-segment elevation myocardial infarction (STEMI) limits infarct size and improves survival . Current guidelines advocate primary percutaneous coronary intervention (PCI) as the preferred method for reperfusion in STEMI as long as the expected time from the first medical contact to the coronary balloon inflation is less than 2 hours . Otherwise, patients should receive fibrinolysis therapy, preferably administered prehospital , and then be directed to a PCI-capable centre where coronary angiography and intervention can be performed in a time window of 3–24 hours .
Unfortunately, STEMI registries consistently report delays in reperfusion that exceed those recommended by guidelines and substantial proportions of patients who are denied any reperfusion therapy . Because the reasons for these observations are partly related to systemic barriers , systems of care have been developed through regional networks to broaden the use of reperfusion therapy and to facilitate timely access to primary PCI for patients presenting to hospitals without PCI capability .
Several studies have reported a significant reduction in time to reperfusion therapy and increased access to primary PCI following the implementation of regional systems of care for STEMI . However, these studies did not include regional or national comparators , lacked a historical control group or had limited generalizability because of their location in large urban areas .
Pooling the original data from two prospective cohort studies, we examined the impact of a regional system of care on the provision of reperfusion therapy for STEMI patients relative to a nationwide sample of control hospitals.
Methods
Study design
We retrospectively designed a controlled pre- and postintervention study evaluating a regional system of care that was implemented in October 2002 in the Northern Alps in France. Pre- and postintervention data were extracted from the USIC 2000 and French registry of Acute ST-elevation and non-ST-elevation Myocardial Infarction (FAST-MI) studies, which were conducted in 2000 and 2005, respectively. To adjust for secular trends and sudden changes , hospitals located in other French mainland areas served as controls.
The rationale, design and primary outcomes of the USIC 2000 and FAST-MI studies have been described in detail elsewhere . Briefly, the two studies were nationwide prospective observational cohort studies designed to collect complete and representative data on processes of care and clinical outcomes for patients with acute myocardial infarction who were admitted to participating hospitals over a 1-month period in France.
Study sites
The USIC 2000 and FAST-MI studies involved 316 and 222 hospitals with intensive care units, respectively. Of these, 160 hospitals participated in both studies, including seven Northern Alps hospitals involved in the regional system of care and 153 control hospitals ( Table 1 ).
| Characteristics | Northern Alps hospitals ( n = 7) | Control hospitals ( n = 153) |
|---|---|---|
| Ownership | ||
| Public | 6 (85.7) | 112 (73.2) |
| Private, for-profit | 1 (14.3) | 32 (20.9) |
| Private, not-for-profit | – (–) | 7 (4.6) |
| Veterans Affairs | – (–) | 2 (1.3) |
| Academic hospitals | 1 (14.3) | 27 (17.6) |
| Region | ||
| Paris and surrounding area | – (–) | 26 (17.0) |
| Northwest | – (–) | 26 (17.0) |
| Northeast | – (–) | 49 (32.0) |
| Southeast | 7 (100) | 26 (17.0) |
| Southwest | – (–) | 26 (17.0) |
| Licensed beds | ||
| < 200 | 1 (14.3) | 42 (27.5) |
| 200–599 | 4 (57.1) | 81 (52.9) |
| ≥ 600 | 2 (28.6) | 30 (19.6) |
| Cardiac procedure capabilities a | ||
| Cardiac catheterization | 4 (57.1) | 94 (61.4) |
| PCI | 3 (42.9) | 90 (58.8) |
| CABG | 2 (28.6) | 39 (25.5) |
a In 2000, four Northern Alps and 92 control hospitals had cardiac catheterization capabilities, two Northern Alps and 82 control hospitals had percutaneous coronary capabilities and two Northern Alps and 35 control hospitals had coronary artery bypass graft capabilities.
Patients
Physicians at participating hospitals enrolled consecutive patients 24 hours/day, 7 days/week, over a 1-month period (i.e. in November 2000 for the USIC 2000 study and in October 2005 for the FAST-MI study). Adult patients were eligible if they had: concentrations of serum markers of myocardial necrosis (creatine kinase, creatine kinase-MB, troponin I or troponin T) that were more than twice the upper limit of the normal range; and either symptoms consistent with acute myocardial infarction or electrocardiographic changes in at least two contiguous leads (Q waves ≥ 0.04 seconds in duration, persistent ST-segment elevation or depression ≥ 0.1 mV). The time from symptom onset to intensive care unit admission had to be less than 48 hours.
For the present analysis, we focused on patients with ST-segment elevation or a presumed new Q wave or left bundle-branch block on the first electrocardiogram recorded. The number of patients enrolled in the two original studies determined the sample size and no formal calculation of sample size was performed for this post hoc analysis.
Data collection
Using a case report form, attending physicians or clinical research technicians collected detailed information on demographics, cardiovascular history, risk factors, comorbid conditions, treatments prior to admission, presenting characteristics, cardiac procedures, medications used within 48 hours of admission and discharge medications. We also documented the characteristics of the admitting hospital (i.e. location in the Northern Alps, academic status, ownership, region, number of licensed beds and cardiac procedure capabilities). Hospitals were identified as academic hospitals based on whether or not they were affiliated with a university . Consistent with a previous study , we defined PCI centres as hospitals that offered emergency PCI 24 hours/day, 7 days/week.
Regional system of care
The RESeau d’URgences CORonariennes (RESURCOR) is a co-ordinated regional system of care for STEMI, which was implemented in the Northern Alps in October 2002. It involves all 15 acute care hospitals (including three PCI centres), three emergency medical system call centres and 12 mobile emergency care units, regardless of their affiliation. The Northern Alps is a predominantly mountainous area covering 15,000 km 2 , with an estimated population of 1,860,000 inhabitants and large seasonal variations due to tourism. The median distance and driving time from each community hospital to the closest PCI centre were 63 km (range 4.5–132 km) and 43 minutes (range 10–88 minutes), respectively. The rationale and primary outcomes of the RESURCOR have been reported in detail elsewhere .
As part of the RESURCOR, a triage algorithm and a set of treatment protocols for coronary reperfusion were established according to published guidelines and available resources, and were approved by representatives of the emergency medical system call centre, mobile emergency care unit, emergency department, coronary care unit and interventional staff. The triage algorithm and treatment protocols were disseminated through pocket cards ( Fig. 1 ) and booklets, and were made available on a dedicated website ( www.renau.org ). The recommendations were reviewed and eventually updated according to the most recent published evidence on a yearly basis.
Briefly, the triage algorithm recommended that physicians at emergency medical system call centres who received a call from a patient with symptoms suggestive of acute myocardial infarction lasting less than 12 hours dispatch a mobile emergency care unit . Mobile emergency care units were staffed by emergency or critical care physicians who might administer prehospital fibrinolysis or activate the closest catheterization laboratory en route for primary PCI, depending on anticipated delays in reperfusion. Emergency department physicians at hospitals without PCI capability evaluated self-transported STEMI patients with symptoms lasting less than 12 hours for reperfusion with either primary PCI at the closest PCI centre or hospital fibrinolysis. Our triage protocol advocated that patients undergo rescue PCI after failed fibrinolysis and routine early coronary angiography and intervention within 12 hours of successful fibrinolysis . Patients transferred for primary PCI were transported by mobile emergency care units and taken directly to the catheterization laboratory without re-evaluation in the emergency department.
An ongoing registry collected prospective detailed data on time to treatment, clinical baseline characteristics and coronary angiography findings, to provide each hospital with feedback on aggregated quality data. Physicians were invited to an annual meeting where the overall policy of the RESURCOR and the trends in timely reperfusion therapy were presented and discussed .
Outcome measures
The primary effectiveness outcome was the receipt of any reperfusion therapy, either with primary PCI or fibrinolysis. The secondary effectiveness outcomes included the receipt of prehospital fibrinolysis, any (i.e. either prehospital or hospital) fibrinolysis, primary PCI and rescue or routine early coronary angiography or intervention after fibrinolysis.
The clinical outcome was 1-year all-cause mortality. Death was determined from medical records and follow-up telephone interviews with the patients’ relatives or their primary care physician 1 year after the index admission. The living status of patients lost to follow-up was ascertained using their birthplace census record.
Statistical analysis
Categorical variables were expressed as frequency and percentage and continuous variables as median and 25th and 75th percentiles (interquartile range [IQR]). Differences in baseline characteristics and acute medications between pre- and postintervention periods within each study group were compared using the Wilcoxon rank sum test for continuous variables and the chi-square test or Fisher’s exact test when appropriate for categorical variables.
To account for the study design, we compared the primary and secondary effectiveness outcomes using a logistic regression model that contained the study group (i.e. Northern Alps versus control hospitals), study period (pre- versus postintervention period) and a first-order interaction between study group and period. We computed absolute change between 2000 and 2005 within each study group, then we derived differences in change between study groups from the logistic regression models . We computed P values and 95% confidence intervals based on the standard errors estimated by the delta method.
We used Kaplan–Meier estimates and the stratified log-rank test to compare the cumulative 1-year mortality across study groups between 2000 and 2005. In multivariable analysis, we estimated hazard ratios for death using a Cox proportional hazard model after adjusting for age, gender, systolic blood pressure and previous myocardial infarction.
Two-sided P values less than 0.05 were considered statistically significant. All analyses were performed using Stata version 11.0 (Stata Corporation, College Station, TX, USA).
Results
The analytical sample comprised 2479 STEMI patients, including 102 patients admitted to seven Northern Alps hospitals and 2377 patients admitted to 153 control hospitals. More patients were enrolled in 2005 than in 2000 in both study groups (34 and 1076 in 2000 vs 68 and 1301 in 2005, respectively).
The median age for all patients was 66 years (IQR, 53–77 years), 1762 (71%) were men, 512 (21%) presented with a Killip class II or higher and 1373 (55%) were admitted by a mobile emergency care unit. In 2005, a higher percentage of patients were admitted to PCI centres and had a medical history of hypertension in both study groups ( Table 2 ). Enrolment in 2005 was also associated with higher blood pressure on admission, higher prevalence of family history of coronary artery disease and more frequent use of statins for control hospitals only, although our study was likely to be underpowered to detect differences of similar magnitude for the Northern Alps study group. In contrast, patients admitted to control hospitals in 2005 were less likely to report delayed presentation or a medical history of previous myocardial infarction or peripheral vascular disease.
