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Cardiac medication prescribing and adherence after acute myocardial infarction in Chinese and South Asian… Lai, Emily J; Grubisic, Maja; Palepu, Anita; Quan, Hude; King, Kathryn M; Khan, Nadia A Sep 18, 2011

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RESEARCH ARTICLE Open AccessCardiac medication prescribing and adherenceafter acute myocardial infarction in Chinese andSouth Asian Canadian patientsEmily J Lai1*, Maja Grubisic2, Anita Palepu1, Hude Quan3, Kathryn M King3 and Nadia A Khan1AbstractBackground: Failure to adhere to cardiac medications after acute myocardial infarction (AMI) is associated withincreased mortality. Language barriers and preference for traditional medications may predispose certain ethnicgroups at high risk for non-adherence. We compared prescribing and adherence to ACE-inhibitors (ACEI), beta-blockers (BB), and statins following AMI among elderly Chinese, South Asian, and Non-Asian patients.Methods: Retrospective-cohort study of elderly AMI survivors (1995-2002) using administrative data from BritishColumbia. AMI cases and ethnicity were identified using validated ICD-9/10 coding and surname algorithms,respectively. Medication adherence was assessed using the ‘proportion of days covered’ (PDC) metric with a PDC≥ 0.80 indicating optimal adherence. The independent effect of ethnicity on adherence was assessed usingmultivariable modeling, adjusting for socio-demographic and clinical characteristics.Results: There were 9926 elderly AMI survivors (258 Chinese, 511 South Asian patients). More Chinese patientswere prescribed BBs (79.7% vs. 73.1%, p = 0.04) and more South Asian patients were prescribed statins (73.5% vs.65.2%, p = 0.001). Both Chinese (Odds Ratio [OR] 0.53; 95%CI, 0.39-0.73; p < 0.0001) and South Asian (OR 0.78; 95%CI, 0.61-0.99; p = 0.04) patients were less adherent to ACEI compared to Non-Asian patients. South Asian patientswere more adherent to BBs (OR 1.3; 95%CI, 1.04-1.62; p = 0.02). There was no difference in prescribing of ACEI, noradherence to statins among the ethnicities.Conclusion: Despite a higher likelihood of being prescribed evidence-based therapies following AMI, Chinese andSouth Asian patients were less likely to adhere to ACEI compared to their Non-Asian counterparts.Keywords: medication adherence, acute myocardial infarction, ethnicityBackgroundAcute myocardial infarction (AMI) is one of the leadingcauses of death across multiple ethnic groups in NorthAmerica. Landmark clinical trials established the efficacyof medications in reducing morbidity and mortality asso-ciated with AMI [1-3]. The morbidity and mortality bene-fits observed in these trials were largely among patientswho were highly adherent. However, in real-world settings,typical adherence rates for prescribed medications are50%, and are even lower in developing countries [4,5].Medication non-adherence is associated with substantialworsening of disease, increased health care costs, anddeath [6-9]. From re-hospitalizations to lost workdays, thecollective economic burden of non-adherence is estimatedto be over $100 billion per year.Non-adherence is a multidimensional phenomenon,affected by socio-economic status, health systems, diseasestates, pharmacological therapies, and patient beliefs [5].Whether patient ethnicity plays a role in medicationadherence is unclear [5,10]. To date, the literature yieldsvariable results [11-14] with little data on medicationadherence in Chinese and South Asian populations, thelargest, and fastest growing, ethnic groups in NorthAmerica. Language barriers, mistrust of Western medi-cine, and preference for traditional therapies couldadversely impact medication adherence in these groups.* Correspondence: emjela@gmail.com1Department of Medicine, University of British Columbia, 10th floor - 2775relS Laut., Vancouver, BC V5Z 1M9, CanadaFull list of author information is available at the end of the articleLai et al. BMC Cardiovascular Disorders 2011, 11:56http://www.biomedcentral.com/1471-2261/11/56© 2011 Lai et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative CommonsAttribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction inany medium, provided the original work is properly cited.Furthermore, different ethnicities may react differently tothe medications. For example, Asian patients have beennoted to have a greater risk for adverse effects fromACEI [15]. Therefore, we compared prescribing andadherence to evidence-based therapies [ACE inhibitors(ACEI), beta-blockers (BB), and HMG-CoA reductaseinhibitors (statin)] using a large multi-ethnic cohort ofelderly Chinese, South Asian, and Non-Asian survivors ofAMI.MethodsOur research conformed to the Helsinki Declaration andto local legislation. Ethics approval was obtained fromThe University of British Columbia Providence HealthCare Research Ethics Board.Data SourcesWe used hospital discharge administrative data in Brit-ish Columbia (BC), Canada to identify index cases ofAMI between April 1st, 1994 and January 1st, 2002(Figure 1). This database contains information on co-morbid conditions, hospital characteristics, and demo-graphic data. Since Canada has a universal health insur-ance system, this data is available for all hospitalizedpatients in the province.Medication prescription (for any of ACEI, BB, or statin)was determined by linkage to the BC Pharmacare prescrip-tion database. These medication classes were selectedbecause of their proven mortality benefit in secondaryprevention of cardiovascular events [1-3,16-19]. The Phar-macare database contains records of all outpatient pre-scriptions filled in BC by residents aged 65 years or olderincluding date of prescription fill and days of medicationsupplied. Previous studies demonstrate excellent accuracywith prescription claims databases [0.7% error rate] [20].By restricting our analysis to patients aged 66 years andolder, we minimize the effects of patient costs on adher-ence as these individuals pay a deductible on medications34,973 AMI cases April 1, 1994 – January 1, 2002 10,089 AMI cohort Excluded patients: - with an AMI within 1 yr prior to index admission - less than 65 years old - who died within 15 months of index admission - who were not BC residents - with erroneous PHN - who did not fill a prescription for ACEI, BB, statin, CCB, or diuretic within 3 months of discharge from hospital for index admission Excluded prescription data earlier than April 1, 1999 6,682 Prescribing cohort 9,926 Adherence cohort Excluded patients with < 2 refills Figure 1 Patient Flow Diagram. ACEI = angiotensin converting enzyme inhibitor, AMI = acute myocardial infarction, BB = beta-blocker, BC =British Columbia, CCB = calcium channel blocker, PHN = personal health number, statin = HMG-CoA reductase inhibitor.Lai et al. BMC Cardiovascular Disorders 2011, 11:56http://www.biomedcentral.com/1471-2261/11/56Page 2 of 8up to Cdn$200/year, which was increased to Cdn$275/year on January 1st, 2002. All medication costs above thisdeductible are paid by Pharmacare.Study populationThe cohort consisted of patients aged 66 years or olderwho were discharged from hospital with a most responsi-ble diagnosis of AMI. To identify index AMI cases, weused the International Classification of Diseases (ICD9/ICD10) coding algorithms for hospital administrative data[ICD9 410.x; ICD10: I21.x]. These coding algorithms forAMI have been extensively validated against multi-centrechart audits [21-23]. We only included patients who sur-vived at least 1 year and 3 months after the hospitaladmission, to allow for a sufficient time period to calculatemedication adherence and excluded non-BC residents.Identification of ethnicityEthnicity is the common and/or inherited traits shared bypeople of the same race, ancestry, background and/or cul-ture [24,25]. As self-reported ethnicity is not available inadministrative databases, we used surname algorithms tocategorize patient ethnicity as Chinese (from China, Tai-wan or Hong Kong) or South Asian (from Pakistan, Indiaor Bangladesh). The remaining patients will be referred toas ‘Non-Asian’ although 7% of this non-Chinese, non-South Asian group is a visible minority according to theCanadian Census [26]. To identify patients of Chinese des-cent, we used Quan’s surname algorithm that has a sensi-tivity of 78%, a specificity of 99.7% and a positive predictivevalue of 81% compared to self-reported ethnicity using theCanadian Community Health Survey [27]. The Nam Peh-chan surname algorithm has a 90-94% sensitivity, a 99.4%specificity and a positive predictive value of 63-96% fordetermining South Asian ethnicity [28,29].PrescribingSince the Pharmacare database only includes data on pre-scription medications, we limited our selections to ACEIs,BBs, statins, calcium-channel blockers (CCB), and diuretics.Calcium-channel blockers and diuretics were included tocontrast the prescribing of cardiac medications with provenand non-proven mortality benefit. Angiotensin II receptorblockers (ARBs) were not included in our analysis as theseagents were not part of post-AMI guidelines during thestudy period. We collected data on prescribing, within the3 months prior to AMI and at 1 year after AMI. Since pre-scribing patterns change over time, we restricted our col-lection period to April 1st, 1999 to March 31st, 2003 tobetter reflect more recent prescribing practices.Assessment of adherenceWe used the ‘proportion of days covered’ (PDC), a com-monly used metric for evaluating medication adherence.The PDC represents the number of days a patient had amedication available, divided by the days observed [6,30].Patients had to obtain a supply of medication within 3months of hospital discharge. We used prescription datafrom April 1st, 1994 to March 31st, 2003 to ensure wehad an adequate sample size. To better reflect long-termmedication adherence, we used an observation period of1 year after the first-filled prescription [6]. A previousstudy of AMI patients demonstrated longer assessmentsof adherence were not significantly different from a one-year measurement [6]. We calculated the PDC for a sin-gle class of medication, as well as the PDC for any one ofACEI, BB, or statin prescriptions, since our interest wasin adherence to any or all proven therapies. We definedadherence as a PDC of ≥ 80%, and suboptimal adherenceas a PDC < 80%. The 80% cut-point is similar to thatused in other medication adherence studies and is asso-ciated with mortality benefit after AMI compared toother levels of adherence [6,30].Other variablesWe adjusted for several factors that have previously beenshown to affect medication adherence, including previoususe of the drug and number of medications (see Table 1for list) [6,30-33]. We also adjusted for the number ofhospital re-admissions within the year post-AMI as thisreflects periods where patients are less likely to fill pre-scriptions [5,6]. To control for severity of illness onadmission between ethnic groups, we used the clinicaland demographic variables from the validated OntarioAMI mortality prediction rule [34].Statistical analysisBaseline characteristics were compared between ethnicgroups using chi-square testing for categorical variablesand ANOVA for continuous variables. Missing values,found in measures of socio-economic status quintile (<4.8%), were excluded from the analysis (see Table 1). Mul-tivariable logistic regression models, adjusting for age, sex,residential distance from hospital, income quintile, admis-sion year, number of baseline medications, number of re-admissions to hospital, prior use of same medication, andcomorbid conditions from the Ontario AMI predictionrule, were constructed to examine the independent rela-tionship between adherence (PDC ≥ 80%) and ethnicity.Logistic regression model assumptions were satisfied. Sta-tistical significance was defined as a 2-tailed p < 0.05. Allanalyses were performed using SAS statistical softwareversion 9.1 (SAS Institute Inc, Cary, NC).ResultsBaseline characteristicsOf 9926 patients who met inclusion criteria, 258 (2.6%)were Chinese, 511 (5.1%) were South Asian, and 9157Lai et al. BMC Cardiovascular Disorders 2011, 11:56http://www.biomedcentral.com/1471-2261/11/56Page 3 of 8(92.3%) were categorized as Non-Asian. Table 1 illus-trates baseline socio-demographic and clinical character-istics between the three ethnic groups. Chinese andSouth Asian patients tended to reside in urban areasand comprised a larger proportion of the lower incomequintiles than Non-Asian patients. There were moreChinese and South Asian patients with diabetes, conges-tive heart failure, kidney disease, hypertension, andmore Chinese patients with cerebrovascular disease.Both Chinese and South Asian patients were prescribeda greater number of total medications within 3 monthsof hospital discharge.Prescribing of evidence-based therapiesIn all ethnic groups, there were significant increases inprescriptions for evidence-based therapies after dis-charge from hospital for AMI (Table 2). However,despite the high risk of re-infarction, 25% of patients didnot fill a prescription for any evidence-based therapies.Compared to Non-Asian patients, Chinese patients weremore likely prescribed BBs, while South Asian patientswere more likely prescribed statins. There was no signif-icant difference in ACEI prescribing between the ethnicgroups. There was also no difference in prescribing ofCCBs between the ethnic groups. While more Non-Asian patients were prescribed diuretics prior to AMI,there was no difference in diuretic prescriptions betweenthe ethnic groups post-AMI.Adherence to evidence-based therapiesThe majority (79.9%) of patients were adherent to at leastone of the three evidence-based therapies (Table 3). Inthe unadjusted analysis, there was no significant differ-ence between the ethnic groups for adherence to any oneof ACEI, BB, or statin medication (82.6% South Asian vs.76.4% Chinese vs. 79.9% Non-Asian patients). ExaminingTable 1 Patient characteristics according to ethnicityCharacteristic Chinese South Asian Non-Asian p-valueN = 258 N = 511 N = 9157Age, n (%)65-69 years 66 (25.6) 167 (32.7) 2297 (25.1) 0.000670-74 years 63 (24.4) 143 (28) 2330 (25.5) 0.4075-79 years 62 (24) 104 (20.4) 2111 (23.1) 0.34≥ 80 years 67 (26) 97 (19) 2419 (26.4) 0.001Female, n (%) 93 (36.1) 204 (39.9) 3718 (40.6) 0.33Income, n (%) *< $30,569 83 (32.2) 129 (25.2) 2165 (23.6) < 0.0001$30,570-43,147 78 (30.2) 138 (27) 1735 (19) < 0.0001$43,148 - 54,103 36 (14) 110 (21.5) 1642 (17.9) < 0.0001$54,104 - 68,206 23 (8.9) 62 (12.1) 1609 (17.6) < 0.0001$68,207 - 221,991 35 (13.6) 55 (10.8) 1559 (17) < 0.0001> 50km to hospital, n (%) 12 (4.7) 74 (14.5) 3181 (34.7) < 0.0001Number of hospitalizations, mean (SD) 0.18 (0.49) 0.31 (0.66) 0.3 (0.64) < 0.0001Total # of medications†, mean (SD) 7.51 (3.81) 8.18 (3.9) 7.32 (3.63) 0.011Prior use of ACEI, BB, or statin‡, n (%) 109 (42.3) 188 (36.8) 3376 (36.9) 0.21Comorbidities, n (%)Diabetes 67 (26) 152 (29.8) 1526 (16.7) < 0.0001CHF 58 (22.5) 110 (21.5) 1570 (17.2) 0.004Cardiac 40 (15.5) 60 (11.7) 1392 (15.2) 0.10PAD 7 (2.7) 4 (0.8) 342 (3.7) 0.0016Hypertension 98 (38) 160 (31.3) 2402 (26.2) < 0.0001Cerebrovascular 12 (4.7) 9 (1.8) 203 (2.2) 0.03Kidney disease 15 (5.8) 16 (3.1) 180 (2) < 0.0001Abbreviations: ACEI = angiotensin-converting-enzyme inhibitor; BB = beta-blocker; CHF = congestive heart failure; PAD = peripheral arterial disease; PDC =proportion of days covered.* Missing socio-economic status data was < 4.8% (1.6% Chinese, 3.4% South Asians, 4.9% Non-Asians).† Within 3 months of discharge from index admission date.‡ Within 3 months prior to index admission date.Lai et al. BMC Cardiovascular Disorders 2011, 11:56http://www.biomedcentral.com/1471-2261/11/56Page 4 of 8individual classes of medications, there was a smallerproportion of Chinese patients adhering to ACEI and alarger proportion of South Asian patients adhering toBBs relative to Non-Asian patients. Adherence to statinswas similar across all ethnic groups. Adherence to CCBsand diuretics was also similar across all ethnicities,although adherence rates for diuretics were low in allgroups.In the adjusted analysis, Chinese patients were lesslikely to adhere to ACEI, compared to Non-Asians, [OR0.53; 95%CI: 0.39-0.73]. Chinese patients, overall, werealso less likely to be adherent to any of ACEI, BB, orstatin medication [OR 0.70; 95%CI: 0.51-0.95]. Com-pared to Non-Asians, South Asians were less likely to beadherent to ACEI [OR 0.78; 95%CI: 0.61-0.99] but morelikely to be adherent to BBs [OR 1.3; 95%CI: 1.04-1.62].Among the medications with less evidence for cardio-protection, there was no significant difference in adher-ence to CCBs, but South Asian patients were less likelyto adhere to diuretics compared to Non-Asian patients.DiscussionIn this study, elderly Chinese and South Asian patientswere as or more likely to be prescribed evidence-basedtherapies following AMI compared to their Non-Asiancounterparts. However, adherence varied by medicationclass in the ethnic groups.Overall prescribing rates for secondary prevention ofAMI were poor for statin medications (68%) but higherfor ACEI and BB medications (77-78%). Overall prescrib-ing of these medications was similar to those in otherstudies [6,35]. Appropriately, we saw a decrease in pre-scribing for CCBs. We found that Chinese and SouthAsian patients were more likely to be prescribed BBs andstatins compared to Non-Asian patients. Reasons for thisare unclear; prescribing physicians may consider Chineseand South Asian patients to be at higher cardiac risk,necessitating more aggressive management. Studiesdemonstrate that South Asian patients, for example, aremore or just as likely to receive invasive cardiovascularprocedures following AMI, compared to their Non-Asiancounterparts [36]. Alternatively, Chinese and SouthAsian patients may have been more likely to fill their pre-scriptions once discharged from hospital compared toNon-Asian patients. Non-Asian patients tended to resideoutside of urban areas where access to medical follow-upwas perhaps more limited, potentially resulting in feweropportunities to fill prescriptions.This study found that elderly Chinese patients were lesslikely to adhere to any evidence based therapy followingTable 3 Adherence to cardiac medications (PDC ≥ 80%) according to ethnicity and medicationMedication Chinese South Asian Non-Asian p-value Adj. OR (95%CI)* Adj. OR (95%CI)*Chinese vs. Non-Asian p-value South Asian vs. Non-Asian p-valueACEI, % 63.5 71.4 75 < 0.001 0.53 (0.39-0.73) < 0.001 0.78 (0.61-0.99) 0.04BB, % 54.1 63.4 56.4 0.02 0.85 (0.63-1.15) 0.29 1.3 (1.04-1.62) 0.02Statin, % 80.8 85.4 81 0.19 0.83 (0.52-1.35) 0.46 1.26 (0.88-1.79) 0.21CCB, % 64 68.4 65.5 0.73 0.84 (0.51-1.38) 0.49 1.07 (0.74-1.53) 0.73Diuretic, % 35.9 33.8 39.5 0.18 0.84 (0.55-1.28) 0.41 0.73 (0.54-0.99) 0.04ACEI, BB, or statin, % 76.4 82.6 79.9 0.12 0.70 (0.51-0.95) 0.02 1.01 (0.79-1.29) 0.92Abbreviations: ACEI = angiotensin-converting-enzyme inhibitor; Adj. OR = adjusted odds ratio; BB = beta-blocker; CCB = calcium-channel blocker; PDC =proportion of days covered* odds ratios adjusted for age, gender, residential distance from hospital, socio-economic status, admission year, number of baseline medications, number ofre-admissions to hospital, prior use of same medication, and comorbiditiesTable 2 Medication prescribing according to ethnicity 3 months prior to AMI and 1 year post AMI, n (%)Medication 3 months prior to AMI 1 year post AMIChinese(n = 150)South Asian(n = 224)Non-Asian(n = 3697)p-value Chinese(n = 197)South Asian(n = 370)Non-Asian(n = 6115)p-valueACEI 66 (44) 86 (38.4) 1586 (42.9) 0.39 157 (79.7) 293 (79.2) 4621 (75.6) 0.13BB 56 (37.3) 66 (29.5) 1134 (30.7) 0.2 157 (79.7) 286 (77.3) 4472 (73.1) 0.03*Statin 40 (26.7) 69 (30.8) 973 (26.3) 0.34 132 (67) 272 (73.5) 3987 (65.2) 0.004†ACEI, BB, or Statin 110 (73.3) 154 (68.8) 2641 (71.4) 0.59 194 (98.5) 360 (97.3) 5867 (95.9) 0.09CCB 61 (40.7) 84 (37.5) 1312 (35.5) 0.37 66 (33.5) 131 (35.4) 1856 (30.4) 0.09Diuretic 42 (28) 76 (33.9) 1568 (42.4) < 0.001 104 (52.8) 189 (51.2) 2990 (48.9) 0.42Abbreviations: ACEI = angiotensin-converting-enzyme inhibitor; AMI = acute myocardial infarction; BB = beta-blocker; CCB = calcium-channel blocker.* For BBs: Chinese vs. Non-Asian, p = 0.04; South Asian vs. Non-Asian, p = 0.08.† For statins: Chinese vs. Non-Asian, p = 0.6; South Asian vs. Non-Asian, p = 0.001.Lai et al. BMC Cardiovascular Disorders 2011, 11:56http://www.biomedcentral.com/1471-2261/11/56Page 5 of 8AMI relative to Non-Asian patients. To our knowledge,this is the first study evaluating the adherence to second-ary prevention medications following AMI in Chineseand South Asian patients. In addition to the factors asso-ciated with non-adherence found in the general popula-tion, non-adherence in these ethnic populations may befurther amplified by language barriers [37-40] and differ-ences in health literacy [40-42] among ethnoculturalgroups. Furthermore, ethnocultural patients may have apreference for alternative or natural therapies [43-45],and some may perceive that antihypertensive therapy isnot beneficial [46]. Furthermore, differences in healthbeliefs and strong Eastern views of care (e.g. viewing dis-ease as a result of fate and avoidance of medical visits)are associated with poor adherence to treatment recom-mendations [47]. Intriguingly, even within the same classof medication, we found that adherence varied by patientethnicity with the greatest proportion of suboptimaladherence for ACEI in both Chinese and South Asianpatients. This observation raises suspicion that the differ-ences in adherence may be, at least in part, attributed togreater adverse effect profiles within these ethnic groups.In a systematic review of cardiovascular drug utilization,ACEI-induced cough was more prevalent in Asianpatients than in the general population, although SouthAsian patients were not studied separately [15]. Adher-ence to statins was similar across ethnic groups despitethe fact that, in post-marketing surveillance, rosuvastatinwas associated with greater statin-induced myopathy inAsian patients [48].This study had several limitations. First, we only used aproxy measurement for adherence using prescriptionsclaims data. Although this approach does not ensure thatthe medications were ingested, prescription claims datahighly correlates with home inventory pill counts, as wellas serum measures of drug presence [49-51]. As with allobservational studies, we were limited by residual con-founders since we were unable to assess other factorsassociated with non-adherence such as dementia anddepression. Similarly, we did not have access to otherclinical information such as left ventricular functionor creatinine, but we attempted to adjust for some ofthe clinical variables by including the diagnosis of CHFor kidney disease, for example, in Table 1. We did notinclude Angiotensin receptor blockers (ARBs) in our ana-lysis. These agents have become more widely used sincethe study period, and are often prescribed for patientswho experience negative side effects from ACEI, therebypotentially impacting adherence to any renin-angioten-sin-aldosterone agent (either ACEI or ARBs). Finally, weinvestigated medication adherence among major ethnicgroups in Canada who were elderly; these results maynot be generalized to other ethnic groups or to youngerpatients within these groups.ConclusionsCompared to their Non-Asian counterparts, South Asianand Chinese elderly patients are just as likely or morelikely to receive proven secondary prevention therapies.However, in this cohort of high cardiac risk patients, 25%of patients did not fill a prescription for these therapies,suggesting greater need to improve prescribing in all eth-nic groups following AMI. Chinese patients were lesslikely to be adherent to any secondary prevention medica-tion and specifically, ACEI therapy. South Asian patientswere also less likely to be adherent to ACEI therapy rela-tive to their Non-Asian counterparts. This study identifiesan at-risk group of patients that require aggressive moni-toring, follow-up and support to optimize adherence.Future studies evaluating underlying cultural barriers toadherence are needed to develop culturally-tailored inter-ventions to improve adherence. The disproportionatelylower adherence to ACEI in South Asian and Chinesepatients, raises suspicion that both of these groups maysuffer greater adverse effects associated with ACEI.AcknowledgementsThe Canadian Institutes of Health Research provided funding for the study.Salary support for the co-authors was provided by the Canadian Institutes ofHealth Research (HQ, AP, NAK), Michael Smith Foundation for Health Research(AP), and Alberta Heritage Foundation for Medical Research (HQ, KMK). NAKand MG had full access to all of the data in the study and take responsibilityfor the integrity of the data and the accuracy of the data analysis.Author details1Department of Medicine, University of British Columbia, 10th floor - 2775relS Laut., Vancouver, BC V5Z 1M9, Canada. 2Center for Health Evaluation andOutcomes Sciences, St. Paul’s Hospital, 620B - 1081 Burrard St., Vancouver,BC V6Z 1Y6, Canada. 3Department of Community Health Sciences, Universityof Calgary, TRW Bldg 3rd floor - 3280 Hospital Dr NW, Calgary, AB T2N 4Z6,Canada.Authors’ contributionsAll authors listed have contributed sufficiently to the project to be includedas authors. All authors contributed to the acquisition and analysis/interpretation of data, as well as revised the manuscript. In addition, EJLdrafted the manuscript and NAK contributed to the conception and design.All authors have given final approval of the version to be published.Competing interestsThe authors declare that they have no competing interests.Received: 28 January 2011 Accepted: 18 September 2011Published: 18 September 2011References1. First International Study of Infarct Survival collaborative group: Randomizedtrial of intravenous atenolol among 16,027 cases of suspected acutemyocardial infarction: ISIS-1. Lancet 1986, 2:57-66.2. Heart Outcomes Prevention Evaluation Study Investigators: Effects of anangiotensin-converting-enzyme inhibitor, ramipril, on cardiovascularevents in high-risk patients. N Engl J Med 2000, 342:145-53.3. Heart Protection Study Collaborative Group: MRC/BHF Heart ProtectionStudy of cholesterol lowering with simvastatin in 20 536 high-riskindividuals: a randomized placebo-controlled trial. Lancet 2002, 360:7-22.4. 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Am J Epidemiol 1995, 142:1104-12.Pre-publication historyThe pre-publication history for this paper can be accessed here:http://www.biomedcentral.com/1471-2261/11/56/prepubdoi:10.1186/1471-2261-11-56Cite this article as: Lai et al.: Cardiac medication prescribing andadherence after acute myocardial infarction in Chinese and South AsianCanadian patients. BMC Cardiovascular Disorders 2011 11:56.Submit your next manuscript to BioMed Centraland take full advantage of: • Convenient online submission• Thorough peer review• No space constraints or color figure charges• Immediate publication on acceptance• Inclusion in PubMed, CAS, Scopus and Google Scholar• Research which is freely available for redistributionSubmit your manuscript at www.biomedcentral.com/submitLai et al. BMC Cardiovascular Disorders 2011, 11:56http://www.biomedcentral.com/1471-2261/11/56Page 8 of 8

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