Statin use in the secondary prevention of coronary heart disease in pr
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《英国医生杂志》
1 Medicines Monitoring Unit, Health Informatics Centre, Division of Medicine and Therapeutics, Ninewells Hospital and Medical School, Dundee DD1 9SY, 2 MRC Health Services Research Collaboration, Department of Social Medicine, University of Bristol, Bristol BS8 2PR, 3 Tayside Centre for General Practice, Division of Community Health Sciences, University of Dundee, Dundee DD2 4BF
Correspondence to: T M MacDonald t.m.macdonald@dundee.ac.uk
Objective To compare the social and demographic profiles of patients who receive statin treatment after myocardial infarction and patients included in randomised trials. To estimate the effect of statin use in community based patients on subsequent all cause mortality and cardiovascular recurrence, contrasting effects with trial patients.
Design Observational cohort study using a record linkage database.
Setting Tayside, Scotland (population size and characteristics: about 400 000, mixed urban and rural).
Subjects 4892 patients were discharged from hospital after their first myocardial infarction between January 1993 and December 2001. 2463 (50.3%) were taking statins during an average follow-up of 3.7 years (3.1% in 1993 and 62.9% in 2001).
Main outcome measures All cause mortality and recurrence of cardiovascular events.
Results 319 deaths occurred in the statin treated group (age adjusted rate 4.1 per 100 person years, 95% confidence interval 3.2 to 4.9), and 1200 in the statin untreated group (12.7 per 100 person years, 11.1 to 14.3). More older people and women were represented in the population of patients treated with statins than among those recruited into clinical trials (mean age 67.8 v 59.8; women 39.6% v 16.9%, respectively). The effects of statins in routine clinical practice were consistent with, and similar to, those reported in clinical trials (adjusted hazard ratio for all cause mortality 0.69, 95% confidence interval 0.59 to 0.80; adjusted hazard ratio for cardiovascular recurrence 0.82, 0.71 to 0.95).
Conclusions The community effectiveness of statins in those groups that were not well represented in clinical trials was similar to the efficacy of statins in these trials.
Statins are effective cholesterol lowering agents and are prescribed for prevention of cardiovascular events. Several large clinical trials (the Scandinavian simvastatin survival study (4S), the cholesterol and recurrent events (CARE) study, the long term intervention with pravastatin in ischaemic disease (LIPID) study, and the Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto Miocardico Prevenzione (GISSI-P) study)1-4 of secondary prevention of coronary heart disease have shown that statins reduce the risk of death by about 30%. However, it is common for clinical trials to apply selection criteria that may protect the internal validity of the trial at the expense of reducing the applicability of the trial's findings to the wider population of patients seen in routine clinical practice. Consequently, patients who are prescribed statins in the "real world" may differ systematically from those people who receive statins in clinical trials and may have different outcomes from those reported in trials.
We reviewed the literature relating to the effects of statin treatment on cardiovascular outcomes, but we found no studies that directly compared the sociodemographic profile and clinical outcomes between patients routinely treated in the community and in clinical trials. However, a recent paper has shown that the effect of statins prescribed in general practice had similar effects on serum cholesterol concentrations to that seen in trials.5 We recently reported a meta-analysis that included 27 secondary prevention trials of statins published up to December 2001.6 This analysis showed that the mean age of patients was 59.8, the proportion of female patients was 16.9%, and statins reduced mortality by 21% (relative risks 0.79, 95% confidence interval 0.73 to 0.85). We characterised those subjects who received statin treatment in the community after myocardial infarction; we estimated the effect of statin use on subsequent all cause mortality and cardiovascular recurrence; and we compared the sociodemographic profile and clinic outcome between these community based patients and clinical trial patients.
Methods
We carried out a cohort study in the population (about 400 000, mixed urban and rural) of Tayside in Scotland, using the record linkage database of the Tayside medicine monitor unit. The database has been described previously.7 It contains several data sets, including all dispensed community prescriptions, hospital discharge data, mortality data, biochemistry data, sociodemographic descriptors, and other data that are linked by a unique patient identifier, the community health index number. The data have been validated by inspection of general practitioners' records8 9 and made anonymous for the purposes of research.
Study population and patients
The study population was composed of all residents of Tayside who were registered with a general practitioner between 1993 and 2001 inclusive (the "study window"), or from 1 January 1993 until their date of death if they died before the end of the study window.
The study patients were composed of those people in the study population who were discharged from Tayside hospitals during the study window with an incident myocardial infarction. We divided patients into two groups after their hospital episode: statin users and non-statin users.
Outcomes
The study outcomes were all cause mortality and cardiovascular events, defined as a new non-fatal myocardial infarction or cardiovascular mortality during the follow-up period. We defined all cause mortality from mortality data from the General Register Office and cardiovascular mortality as ICD-9 codes 390-459 and ICD-10 codes I00-I99.
Statistical analysis
We summarised data as means with standard deviations for continuous variables and as numbers (percentages) of subjects for categorical variables. We used 2 and t tests to determine significant differences. We also used Cochran-Armitage trend tests if there were more than two categorical variables. In the analyses of the outcomes we calculated adjusted hazard ratios with 95% confidence intervals in Cox regression models with a time dependent variable for statin use. The other covariates in the models were age, sex, Carstairs deprivation category,10 and the different types of cardiovascular co-medication during the follow-up period: blockers, angiotensin converting enzyme (ACE) inhibitors, other antihypertensive drugs, antiplatelet drugs, nitrates, warfarin, calcium channel blockers, hormone replacement therapy, oral contraceptives, steroids, non-steroidal anti-inflammatory drugs, disease modifying antirheumatic drugs, previous disease histories of angina, stroke, heart failure, peripheral vascular disease, diabetes mellitus, obstructive airway disease, cancer, renal failure, and rheumatoid arthritis. We used SAS, version 8.0 (SAS Institute, Cary, North Carolina, USA) for all statistical analyses.
Results
A total of 4892 patients were included in the study. Of these, 2463 (50.3%) were treated with statins during an average follow-up of 3.7 years. In the group treated with statins, 319 patients died (age adjusted rate 4.1 per 100 person years, 95% confidence interval 3.2 to 4.9), and in the group not treated with statins 1200 died (12.7 per 100 person years (11.1 to 14.3)). Table 1 shows the characteristics of statin users and non-users. Statin use was more common in younger patients. Men were more likely to be prescribed statins than women. Statin use rose significantly from 3.1% in 1993 to 62.9% in 2001 (trend test, P < 0.001). Statin use in older patients also rose over the study period. However, statin use did not change significantly between the sexes or with social deprivation.
Table 1 Distribution of statin use in patients after myocardial infarction, Tayside, 1993-2001. Values are numbers (percentages) of patients unless otherwise indicated
Five statins (atorvastatin, cerivastatin, fluvastatin, pravastatin, and simvastatin) were available during the study period, and simvastatin was the most commonly used statin in Tayside patients. About 80% of statin use was simvastatin, at a median daily dose of 10 mg.
Proportions of older and female patients in the community in Tayside were higher than in clinical trials (mean age 67.8 (62.9 for statin users and 72.7 for non-users) v 59.8; women 39.6% (37.1 for statin users and 42.1 for non-users) v 16.9%, respectively). Table 2 shows the details of the multivariate analysis. Statin reduced all cause mortality by 31% (95% confidence interval 20% to 41%) and recurrent myocardial infarction or cardiovascular death by 18% (5% to 29%). Antiplatelet drugs, blockers, nitrates, calcium blockers, and angiotensin converting enzyme inhibitors were also each independently associated with diminished risk except antihypertensive drugs and warfarin. Compared with patients who had had a myocardial infarction who did not take any cardiovascular drugs, statin users who took up to two other cardiovascular drugs had lower risks of cardiovascular events (hazard ratio 0.70, 95% confidence interval 0.50 to 0.97 for statin plus one cardiovascular drug and 0.73, 0.58 to 0.91 for statin plus two cardiovascular drugs). The risk of cardiovascular events did not differ between those statin users who took more than two additional cardiovascular drugs and those post-myocardial infarction patients who received no drug treatments.
Table 2 Adjusted hazard ratios with 95% confidence intervals for cardiovascular recurrence and all cause mortality after myocardial infarction in the community, 1993-2001
We also did subgroup analyses of older patients (aged 65) and women. In the group of women, 633 patients died (crude rate 9.1 per 100 person years, 8.5 to 9.8), and in the group of older patients, 1286 died (13.0 per 100 person years, 12.3 to 13.6). The adjusted hazard ratios of mortality in patients receiving statin treatment were 0.63 (0.49 to 0.80) for female and 0.72 (0.61 to 0.84) for older patients (table 2). The numbers needed to treat with statin for 3.7 years for all cause mortality were 21 for overall, 20 for women, and 20 for older people (for non-fatal myocardial infarction, the numbers needed to treat were 35, 20, and 35, respectively).
Discussion
4S group. Randomised trial of cholesterol lowering in 4444 patients with coronary heart disease: the Scandinavian simvastatin survival study (4S). Lancet 1994;344: 1383-9.
Sacks FM, Pfeffer MA, Moye LA, Rouleau JL, Rutherford JD, Cole TG, et al. The effect of pravastatin on coronary events after myocardial infarction in patients with average cholesterol levels. Cholesterol and Recurrent Events Trial Investigators. N Engl J Med 1996;335: 1001-9.
LIPID Study Group. Prevention of cardiovascular events and death with pravastatin in patients with coronary heart disease and a broad range of initial cholesterol levels. The Long-Term Intervention with Pravastatin in Ischaemic Disease (LIPID) Study Group. N Engl J Med 1998;339: 1349-57.
GISSI-P Study Group. Results of the low-dose (20 mg) pravastatin GISSI Prevenzione trial in 4271 patients with recent myocardial infarction: do stopped trials contribute to overall knowledge? GISSI Prevenzione Investigators (Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto Miocardico). Ital Heart J 2000;1: 810-20.
Hippisley-Cox J, Cater R, Pringle M, Coupland C. Cross sectional survey of effectiveness of lipid lowering drugs in reducing serum cholesterol concentration in patients in 17 general practices. BMJ 2003;326: 689.
Bartlett C, Doyal L, Ebrahim S, Davey P, Bachmann M, Egger M, et al. The causes and effects of socio-demographic exclusions from clinical trials. Health Technol Assess Rep (in press).
Evans JMM, MacDonald TM. The Tayside Medicines Monitoring Unit (MEMO). In: Strom BL, ed. Pharmacoepidemiology. 3rd ed. Chichester: John Wiley, 2000: 361-74.
Donnan PT, Dougall HT, Sullivan FM. Optimal strategies for identifying patients with myocardial infarction in general practice. Fam Pract 2003;20: 706-10.
Sullivan FM, McEwan N, Murphy G. Regional repositories, reintermediation and the new GMS contract: cardiovascular disease in Tayside. Inform Prim Care 2003;11: 215-21.
Carstairs V. Deprivation and health in Scotland. Health Bull (Edinb) 1990;48: 162-75.
Benson K, Hartz AJ. A comparison of observational studies and randomized, controlled trials. N Engl J Med 2000;342: 1878-86.
Walker AM. Confounding by indication. Epidemiology 1996;7: 335-6
Scottish Intercollegiate Guidelines Network. Secondary prevention of coronary heart disease following myocardial infarction. SIGN publication No 41. Edinburgh 2000. www.sign.ac.uk/guidelines/fulltext/41/index.html (accessed 15 Feb 2005).
Smeeth L, Ebrahim S. DINS, PINS, and things—clinical and population perspectives on treatment effects. BMJ 2000;321: 950-3.
Gottlieb SS, McCarter RJ, Vogel RA. Effect of beta-blockade on mortality among high-risk and low-risk patients after myocardial infarction. N Engl J Med 1998;339: 489-97.
Baigent C, Sudlow C, Collins R, Peto R. Collaborative meta-analysis of randomised trials of antiplatelet therapy for prevention of death, myocardial infarction, and stroke in high risk patients. BMJ 2002;324: 71-86.
Wald N, Law M. A strategy to reduce cardiovascular disease by more than 80%. BMJ 2003;326: 1419.
EUROASPIRE I and II Group. Clinical reality of coronary prevention guidelines: a comparison of EUROASPIRE I and II in nine countries. Lancet 2001;357: 995-1001.
Heart Protection Study Collaborative Group. MRC/BHF heart protection study of cholesterol lowering with simvastatin in 20,536 high-risk individuals: a randomised placebo-controlled trial. Lancet 2002;360: 7-22.
Shepherd J, Blauw GJ, Murphy MB, Bollen EL, Buckley BM, Cobbe SM, et al. PROspective study of pravastatin in the elderly at risk. Pravastatin in elderly individuals at risk of vascular disease (PROSPER): a randomised controlled trial. Lancet 2002;360: 1623-30.
Wei L, Wang J, Thompson P, Wong S, Struthers AD, MacDonald TM. Adherence to statin treatment and readmission of patients after myocardial infarction: a six year follow up study. Heart 2002;88: 229-33.
Scottish health survey 1995. Vol I. Edinburgh: Stationery Office 1997; 140-1. (Chapter 4: Smoking.)
MacDonald TM, Morant SV, Robinson GC, Shield MJ, McGilchrist MM, Murray FE, McDevitt DG. Association of upper gastrointestinal toxicity of non-steroidal anti-inflammatory drugs with continued exposure: cohort study. BMJ 1997;315: 1333-7.
((Li Wei, research fellow1, Shah Ebrahim, )
Correspondence to: T M MacDonald t.m.macdonald@dundee.ac.uk
Objective To compare the social and demographic profiles of patients who receive statin treatment after myocardial infarction and patients included in randomised trials. To estimate the effect of statin use in community based patients on subsequent all cause mortality and cardiovascular recurrence, contrasting effects with trial patients.
Design Observational cohort study using a record linkage database.
Setting Tayside, Scotland (population size and characteristics: about 400 000, mixed urban and rural).
Subjects 4892 patients were discharged from hospital after their first myocardial infarction between January 1993 and December 2001. 2463 (50.3%) were taking statins during an average follow-up of 3.7 years (3.1% in 1993 and 62.9% in 2001).
Main outcome measures All cause mortality and recurrence of cardiovascular events.
Results 319 deaths occurred in the statin treated group (age adjusted rate 4.1 per 100 person years, 95% confidence interval 3.2 to 4.9), and 1200 in the statin untreated group (12.7 per 100 person years, 11.1 to 14.3). More older people and women were represented in the population of patients treated with statins than among those recruited into clinical trials (mean age 67.8 v 59.8; women 39.6% v 16.9%, respectively). The effects of statins in routine clinical practice were consistent with, and similar to, those reported in clinical trials (adjusted hazard ratio for all cause mortality 0.69, 95% confidence interval 0.59 to 0.80; adjusted hazard ratio for cardiovascular recurrence 0.82, 0.71 to 0.95).
Conclusions The community effectiveness of statins in those groups that were not well represented in clinical trials was similar to the efficacy of statins in these trials.
Statins are effective cholesterol lowering agents and are prescribed for prevention of cardiovascular events. Several large clinical trials (the Scandinavian simvastatin survival study (4S), the cholesterol and recurrent events (CARE) study, the long term intervention with pravastatin in ischaemic disease (LIPID) study, and the Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto Miocardico Prevenzione (GISSI-P) study)1-4 of secondary prevention of coronary heart disease have shown that statins reduce the risk of death by about 30%. However, it is common for clinical trials to apply selection criteria that may protect the internal validity of the trial at the expense of reducing the applicability of the trial's findings to the wider population of patients seen in routine clinical practice. Consequently, patients who are prescribed statins in the "real world" may differ systematically from those people who receive statins in clinical trials and may have different outcomes from those reported in trials.
We reviewed the literature relating to the effects of statin treatment on cardiovascular outcomes, but we found no studies that directly compared the sociodemographic profile and clinical outcomes between patients routinely treated in the community and in clinical trials. However, a recent paper has shown that the effect of statins prescribed in general practice had similar effects on serum cholesterol concentrations to that seen in trials.5 We recently reported a meta-analysis that included 27 secondary prevention trials of statins published up to December 2001.6 This analysis showed that the mean age of patients was 59.8, the proportion of female patients was 16.9%, and statins reduced mortality by 21% (relative risks 0.79, 95% confidence interval 0.73 to 0.85). We characterised those subjects who received statin treatment in the community after myocardial infarction; we estimated the effect of statin use on subsequent all cause mortality and cardiovascular recurrence; and we compared the sociodemographic profile and clinic outcome between these community based patients and clinical trial patients.
Methods
We carried out a cohort study in the population (about 400 000, mixed urban and rural) of Tayside in Scotland, using the record linkage database of the Tayside medicine monitor unit. The database has been described previously.7 It contains several data sets, including all dispensed community prescriptions, hospital discharge data, mortality data, biochemistry data, sociodemographic descriptors, and other data that are linked by a unique patient identifier, the community health index number. The data have been validated by inspection of general practitioners' records8 9 and made anonymous for the purposes of research.
Study population and patients
The study population was composed of all residents of Tayside who were registered with a general practitioner between 1993 and 2001 inclusive (the "study window"), or from 1 January 1993 until their date of death if they died before the end of the study window.
The study patients were composed of those people in the study population who were discharged from Tayside hospitals during the study window with an incident myocardial infarction. We divided patients into two groups after their hospital episode: statin users and non-statin users.
Outcomes
The study outcomes were all cause mortality and cardiovascular events, defined as a new non-fatal myocardial infarction or cardiovascular mortality during the follow-up period. We defined all cause mortality from mortality data from the General Register Office and cardiovascular mortality as ICD-9 codes 390-459 and ICD-10 codes I00-I99.
Statistical analysis
We summarised data as means with standard deviations for continuous variables and as numbers (percentages) of subjects for categorical variables. We used 2 and t tests to determine significant differences. We also used Cochran-Armitage trend tests if there were more than two categorical variables. In the analyses of the outcomes we calculated adjusted hazard ratios with 95% confidence intervals in Cox regression models with a time dependent variable for statin use. The other covariates in the models were age, sex, Carstairs deprivation category,10 and the different types of cardiovascular co-medication during the follow-up period: blockers, angiotensin converting enzyme (ACE) inhibitors, other antihypertensive drugs, antiplatelet drugs, nitrates, warfarin, calcium channel blockers, hormone replacement therapy, oral contraceptives, steroids, non-steroidal anti-inflammatory drugs, disease modifying antirheumatic drugs, previous disease histories of angina, stroke, heart failure, peripheral vascular disease, diabetes mellitus, obstructive airway disease, cancer, renal failure, and rheumatoid arthritis. We used SAS, version 8.0 (SAS Institute, Cary, North Carolina, USA) for all statistical analyses.
Results
A total of 4892 patients were included in the study. Of these, 2463 (50.3%) were treated with statins during an average follow-up of 3.7 years. In the group treated with statins, 319 patients died (age adjusted rate 4.1 per 100 person years, 95% confidence interval 3.2 to 4.9), and in the group not treated with statins 1200 died (12.7 per 100 person years (11.1 to 14.3)). Table 1 shows the characteristics of statin users and non-users. Statin use was more common in younger patients. Men were more likely to be prescribed statins than women. Statin use rose significantly from 3.1% in 1993 to 62.9% in 2001 (trend test, P < 0.001). Statin use in older patients also rose over the study period. However, statin use did not change significantly between the sexes or with social deprivation.
Table 1 Distribution of statin use in patients after myocardial infarction, Tayside, 1993-2001. Values are numbers (percentages) of patients unless otherwise indicated
Five statins (atorvastatin, cerivastatin, fluvastatin, pravastatin, and simvastatin) were available during the study period, and simvastatin was the most commonly used statin in Tayside patients. About 80% of statin use was simvastatin, at a median daily dose of 10 mg.
Proportions of older and female patients in the community in Tayside were higher than in clinical trials (mean age 67.8 (62.9 for statin users and 72.7 for non-users) v 59.8; women 39.6% (37.1 for statin users and 42.1 for non-users) v 16.9%, respectively). Table 2 shows the details of the multivariate analysis. Statin reduced all cause mortality by 31% (95% confidence interval 20% to 41%) and recurrent myocardial infarction or cardiovascular death by 18% (5% to 29%). Antiplatelet drugs, blockers, nitrates, calcium blockers, and angiotensin converting enzyme inhibitors were also each independently associated with diminished risk except antihypertensive drugs and warfarin. Compared with patients who had had a myocardial infarction who did not take any cardiovascular drugs, statin users who took up to two other cardiovascular drugs had lower risks of cardiovascular events (hazard ratio 0.70, 95% confidence interval 0.50 to 0.97 for statin plus one cardiovascular drug and 0.73, 0.58 to 0.91 for statin plus two cardiovascular drugs). The risk of cardiovascular events did not differ between those statin users who took more than two additional cardiovascular drugs and those post-myocardial infarction patients who received no drug treatments.
Table 2 Adjusted hazard ratios with 95% confidence intervals for cardiovascular recurrence and all cause mortality after myocardial infarction in the community, 1993-2001
We also did subgroup analyses of older patients (aged 65) and women. In the group of women, 633 patients died (crude rate 9.1 per 100 person years, 8.5 to 9.8), and in the group of older patients, 1286 died (13.0 per 100 person years, 12.3 to 13.6). The adjusted hazard ratios of mortality in patients receiving statin treatment were 0.63 (0.49 to 0.80) for female and 0.72 (0.61 to 0.84) for older patients (table 2). The numbers needed to treat with statin for 3.7 years for all cause mortality were 21 for overall, 20 for women, and 20 for older people (for non-fatal myocardial infarction, the numbers needed to treat were 35, 20, and 35, respectively).
Discussion
4S group. Randomised trial of cholesterol lowering in 4444 patients with coronary heart disease: the Scandinavian simvastatin survival study (4S). Lancet 1994;344: 1383-9.
Sacks FM, Pfeffer MA, Moye LA, Rouleau JL, Rutherford JD, Cole TG, et al. The effect of pravastatin on coronary events after myocardial infarction in patients with average cholesterol levels. Cholesterol and Recurrent Events Trial Investigators. N Engl J Med 1996;335: 1001-9.
LIPID Study Group. Prevention of cardiovascular events and death with pravastatin in patients with coronary heart disease and a broad range of initial cholesterol levels. The Long-Term Intervention with Pravastatin in Ischaemic Disease (LIPID) Study Group. N Engl J Med 1998;339: 1349-57.
GISSI-P Study Group. Results of the low-dose (20 mg) pravastatin GISSI Prevenzione trial in 4271 patients with recent myocardial infarction: do stopped trials contribute to overall knowledge? GISSI Prevenzione Investigators (Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto Miocardico). Ital Heart J 2000;1: 810-20.
Hippisley-Cox J, Cater R, Pringle M, Coupland C. Cross sectional survey of effectiveness of lipid lowering drugs in reducing serum cholesterol concentration in patients in 17 general practices. BMJ 2003;326: 689.
Bartlett C, Doyal L, Ebrahim S, Davey P, Bachmann M, Egger M, et al. The causes and effects of socio-demographic exclusions from clinical trials. Health Technol Assess Rep (in press).
Evans JMM, MacDonald TM. The Tayside Medicines Monitoring Unit (MEMO). In: Strom BL, ed. Pharmacoepidemiology. 3rd ed. Chichester: John Wiley, 2000: 361-74.
Donnan PT, Dougall HT, Sullivan FM. Optimal strategies for identifying patients with myocardial infarction in general practice. Fam Pract 2003;20: 706-10.
Sullivan FM, McEwan N, Murphy G. Regional repositories, reintermediation and the new GMS contract: cardiovascular disease in Tayside. Inform Prim Care 2003;11: 215-21.
Carstairs V. Deprivation and health in Scotland. Health Bull (Edinb) 1990;48: 162-75.
Benson K, Hartz AJ. A comparison of observational studies and randomized, controlled trials. N Engl J Med 2000;342: 1878-86.
Walker AM. Confounding by indication. Epidemiology 1996;7: 335-6
Scottish Intercollegiate Guidelines Network. Secondary prevention of coronary heart disease following myocardial infarction. SIGN publication No 41. Edinburgh 2000. www.sign.ac.uk/guidelines/fulltext/41/index.html (accessed 15 Feb 2005).
Smeeth L, Ebrahim S. DINS, PINS, and things—clinical and population perspectives on treatment effects. BMJ 2000;321: 950-3.
Gottlieb SS, McCarter RJ, Vogel RA. Effect of beta-blockade on mortality among high-risk and low-risk patients after myocardial infarction. N Engl J Med 1998;339: 489-97.
Baigent C, Sudlow C, Collins R, Peto R. Collaborative meta-analysis of randomised trials of antiplatelet therapy for prevention of death, myocardial infarction, and stroke in high risk patients. BMJ 2002;324: 71-86.
Wald N, Law M. A strategy to reduce cardiovascular disease by more than 80%. BMJ 2003;326: 1419.
EUROASPIRE I and II Group. Clinical reality of coronary prevention guidelines: a comparison of EUROASPIRE I and II in nine countries. Lancet 2001;357: 995-1001.
Heart Protection Study Collaborative Group. MRC/BHF heart protection study of cholesterol lowering with simvastatin in 20,536 high-risk individuals: a randomised placebo-controlled trial. Lancet 2002;360: 7-22.
Shepherd J, Blauw GJ, Murphy MB, Bollen EL, Buckley BM, Cobbe SM, et al. PROspective study of pravastatin in the elderly at risk. Pravastatin in elderly individuals at risk of vascular disease (PROSPER): a randomised controlled trial. Lancet 2002;360: 1623-30.
Wei L, Wang J, Thompson P, Wong S, Struthers AD, MacDonald TM. Adherence to statin treatment and readmission of patients after myocardial infarction: a six year follow up study. Heart 2002;88: 229-33.
Scottish health survey 1995. Vol I. Edinburgh: Stationery Office 1997; 140-1. (Chapter 4: Smoking.)
MacDonald TM, Morant SV, Robinson GC, Shield MJ, McGilchrist MM, Murray FE, McDevitt DG. Association of upper gastrointestinal toxicity of non-steroidal anti-inflammatory drugs with continued exposure: cohort study. BMJ 1997;315: 1333-7.
((Li Wei, research fellow1, Shah Ebrahim, )