Secondary prevention in coronary heart disease: baseline survey of provision in general practiceBMJ 1998; 316 doi: https://doi.org/10.1136/bmj.316.7142.1430 (Published 09 May 1998) Cite this as: BMJ 1998;316:1430
- Neil C Campbell, clinical research fellowa (, )
- Joan Thain, health visitorb,
- H George Deans, lecturer in clinical psychologya,
- Lewis D Ritchie, Mackenzie professor of general practicea,
- John M Rawles, honorary senior lecturerc
- a Department of General Practice and Primary Care, University of Aberdeen, Foresterhill Health Centre, Aberdeen AB25 2AY
- b Grampian Healthcare, Denburn Health Centre, Aberdeen AB25 1QB
- c Medicines Assessment Research Unit, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD
- Correspondence to: Dr Campbell
- Accepted 16 December 1997
Objective: To determine secondary preventive treatment and habits among patients with coronary heart disease in general practice.
Design: Process of care data on a random sample of patients were collected from medical records. Health and lifestyle data were collected by postal questionnaire (response rate 71%).
Setting: Stratified, random sample of general practices in Grampian.
Subjects: 1921 patients aged under 80 years with coronary heart disease identified from pre-existing registers of coronary heart disease and nitrate prescriptions.
Main outcome measures: Treatment with aspirin, β blockers, and angiotensin converting enzyme inhibitors. Management of lipid concentrations and hypertension according to local guidelines. Dietary habits (dietary instrument for nutritional evaluation score), physical activity (health practice indices), smoking, and body mass index.
Results: 825/1319 (63%) patients took aspirin. Of 414 patients with recent myocardial infarction, 131 (32%) took β blockers, and of 257 with heart failure, 102 (40%) took angiotensin converting enzyme inhibitors. Blood pressure was managed according to current guidelines for 1566 (82%) patients but lipid concentrations for only 133 (17%). 673 of 1327 patients (51%) took little or no exercise, 245 of 1333 (18%) were current smokers, 808 of 1264 (64%) were overweight, and 627 of 1213 (52%) ate more fat than recommended.
Conclusion: In terms of secondary prevention, half of patients had at least two aspects of their medical management that were suboptimal and nearly two thirds had at least two aspects of their health behaviour that would benefit from change. There seems to be considerable potential to increase secondary prevention of coronary heart disease in general practice.
Patients with coronary heart disease can benefit from both medical and lifestyle secondary prevention measures
This study found that half of patients with coronary heart disease in general practice had at least two missed opportunities for effective medical interventions
Nearly two thirds of patients with coronary heart disease in general practice had two or more high risk lifestyle factors that would benefit from change
There seems to be plenty of opportunity for improving secondary prevention of coronary heart disease in general practice
Editorial by van der Weijden and Grol and p 1434
The 1996 health promotion package for British general practitioners represented a huge change from the previous highly prescriptive health promotion banding scheme. It aims to offer “flexibility to develop a wide range of approaches to health promotion.”1 Reducing mortality from coronary heart disease remains a priority, and as one approach to this, general practitioners have been encouraged to target patients with established coronary heart disease for secondary prevention.2
There is convincing evidence that secondary prevention is effective. 3 4 Reductions in mortality have been found with aspirin treatment,5 blood pressure control,6 and lowering of lipid concentrations, 7 8 and selected patients have benefited from β blockers9 and angiotensin converting enzyme inhibitors.10 Exercise,11 stopping smoking,12 dietary modifications, 3 4 and, in obese patients, weight loss13 have also been found to reduce risks from coronary heart disease.
Little is known, however, about current secondary preventive practices and treatment among patients in primary care. There is potential for greater uptake among patients discharged from hospital after coronary events,14 but most patients with coronary heart disease are cared for in general practice.15 We studied secondary preventive treatment and habits among patients with coronary heart disease registered in general practice so that we could assess what could be achieved by targeting secondary prevention in primary care.
Subjects and methods
This study was undertaken in preparation for a randomised trial of secondary prevention clinics in general practice. All 89 Grampian general practices were divided into four groups by size and location (urban or rural), and a random sample that provided the same percentage from each group was obtained by pulling names from a hat. Our target sample was 2000 case notes for review and 1400 (70%) questionnaire responses. Based on a prevalence of coronary heart disease of 3% and a limit of 150 case notes per practice, we estimated that 18 practices should provide sufficient patients. Twenty eight practices were invited to participate in the study and 19 were recruited.
Patients who were less than 80 years old and had been prescribed nitrates or had coronary heart disease were identified by computer or manual searches of pre-existing morbidity and prescribing records. (Previous studies have reported that morbidity records are 80% sensitive for myocardial infarction and 60% for angina,16 and nitrate prescriptions are 73% sensitive for angina.17) We identified 3172 patients, which represented 2.3% of the total (all ages) practice populations (135 581).
We had placed a limit of 150 patients per practice for data collection, so 937 patients were excluded by selecting every third or fourth patient (depending on the reduction required in each practice) from alphabetical lists at larger practices. On 73 occasions, when two patients lived at the same address, one was selected by tossing a coin. Case notes were reviewed to ensure that patients were documented by hospital letter or general practitioner as having coronary heart disease, which resulted in 95 exclusions. In addition, 18 patients had died, 11 had moved away, and notes for 38 patients were unobtainable. Seventy nine patients who were terminally ill, had dementia, or were housebound with serious comorbidity were excluded because comprehensive prevention may not have been appropriate. This left a total of 1921.
Data collection and analysis
Data on prescriptions for cardiac and secondary preventive drugs, blood pressure and lipid recordings, relevant medical conditions, and allergies were collected from the medical records. Lifestyle data were collected by postal survey, but 31 patients were excluded at the request of their general practitioners. The response rate was 71% (1343/1890). The questionnaire included the health practices index18 and dietary assessment with the dietary instrument for nutritional evaluation (DINE), a validated instrument for measuring dietary fat.19
We used Microsoft Access to manage the data and SPSS for WINDOWS release 6.0 for analysis. The χ2 test and independent samples t test respectively were used for comparing proportions and means between respondents and non-respondents. To provide cumulative ratings for medical management and health behaviour, the number of missed opportunities for secondary prevention was calculated for each respondent according to the following criteria. For medical management one point was allocated for aspirin not taken nor contraindicated (allergy or active peptic ulceration)5; β blockers not taken nor contraindicated (allergy, heart failure, asthma, or peripheral vascular disease) in patients with recent (past five years) myocardial infarction9 or angiotensin converting enzyme inhibitors not taken nor contraindicated (allergy or renal contraindication) in patients with heart failure10; blood pressure management outside British Hypertension Society guidelines20; cholesterol management outside local guidelines (which recommend lipid lowering drugs for cholesterol concentrations >5.2 mmol/l).21 For health behaviour one point was allocated for little or no physical activity18; current smoking12; obesity (body mass index ≥25)18; and high fat diet (≥83 g/day).19
The study was approved by the Grampian Health Board and University of Aberdeen joint ethics committee. Case notes were audited with the consent of general practitioners, and responding patients gave informed consent to the study.
Table 1 compares the characteristics of respondents and non-respondents with regard to demography and secondary prevention. There were few differences, but a higher proportion of respondents than non-respondents were prescribed aspirin and β blockers and had had recent cholesterol and blood pressure checks.
Full analysis of aspirin treatment was conducted on questionnaire data because 332 of 825 patients (40%) who reported taking aspirin obtained it over the counter. Table 2 shows the use of aspirin according to patients' history of infarction. After patients with allergy to aspirin or active peptic ulcers were excluded, 784 out of 1233 (64%) took aspirin. The proportion rose to 69% (536/ 775) when patients with dyspepsia or taking warfarin were also excluded.
β Blockers were taken by 598 (31%) of all 1921 patients and by 131 (32%; 95% confidence interval 27% to 36%) of 414 patients who had had a myocardial infarction in the past five years. After the 550 (29%) patients with contraindications (asthma, heart failure, peripheral vascular disease) or previous side effects were excluded, 520 of the remaining 1371 patients (38%) took β blockers.
In all, 185 (10%) patients took angiotensin converting enzyme inhibitors. Of 257 patients with a diagnosis of heart failure, 102 (40%; 34% to 46%) took angiotensin converting enzyme inhibitors. Previous side effects were documented for 12 patients, of whom six continued to take the drugs.
Of all 1921 patients, 1761 (92%) had had their blood pressures checked in the past three years (table 3). In the 1692 patients managed in general practice and checked within three years, mean systolic pressure was 142 mm Hg (SD 20.5, range 80 to 230 mm Hg) and mean diastolic pressure was 81 mm Hg (SD 10.0, range 34 to 130 mm Hg). In all, 1566 patients (82%; 95% confidence interval 80% to 83%) had normal blood pressure or mild to moderate hypertension that was receiving attention (treated or recently checked).
Four hundred and eighty patients (25%) had had their total cholesterol concentrations checked within the past three years (table 3), and the mean cholesterol concentration for the 451 patients managed in general practice was 6.5 mmol/l (SD 1.18, range 3.1 to 9.8 mmol/l). At the time of the study, local guidelines21 advised treatment for patients under 65 years so data from this group were analysed separately. Of 783 patients, 311 (40%) had had cholesterol measured, and the mean concentration for the 292 patients managed in general practice was 6.5 mmol/l (1.16, range 3.1 to 9.8 mmol/l). Cholesterol concentrations were ⩽5.2 mmol/l or moderately raised (5.3 to 7.8 mmol/l) and receiving attention for 133 patients (17%; 95% confidence interval 14% to 20%).
Table 4 shows the physical activity, smoking status, body mass index, and dietary fat intake of the subjects. In all, 673 of 1327 patients (51%; 48% to 53%) took little or no exercise, 245 of 1333 (18%; 16% to 20%) were current smokers, 808 of 1264 (64%; 61% to 67%) were overweight, and 627 of 1213 (52%; 49% to 55%) ate more fat than recommended. Only 626 respondents (47%) ate at least six portions of fruit a week and 442 (33%) ate at least six portions of vegetables (other than potatoes).
Table 5 shows the number of measures of medical and lifestyle secondary prevention that were not being addressed in the patients that responded to the questionnaire. Only 10% of patients would not have benefitted from further changes in lifestyle and only 7% were receiving all the medical management for optimal secondary prevention of coronary heart disease.
We have attempted to measure the use of secondary prevention in Grampian general practice. Patient response rates were good, but to assess the possible effect of respondent bias we compared available data for respondents and non-respondents. Non-respondents were slightly less likely to have had aspirin or β blockers prescribed or their blood pressures or cholesterol levels checked in the past three years. This suggests that sampling error was modest but that our results may overestimate preventive practices by non-respondents.
Treatment with aspirin for patients with coronary heart disease can reduce vascular events by 33%,5 but we found that less than two thirds of patients took aspirin. The highest uptake was among patients with recent myocardial infarction (85%). A similar figure was reported in the ASPIRE study (action on secondary prevention through intervention to reduce events) of hospital patients in 1996.14 However, only half of general practice patients who had not had a recent myocardial infarction took aspirin. This suggests considerable potential for increased uptake, especially among the majority of patients with angina treated in general practice.
β Blockers have achieved mortality reductions of 20% following myocardial infarction,9 and angiotensin converting enzyme inhibitors have reduced mortality in patients with heart failure.10 However, in this study less than a third of patients in general practice with recent myocardial infarction took β blockers. Side effects and contraindications were present for nearly a quarter of patients, which may have contributed to the low uptake but does not explain it fully. Our findings, again, mirror those of the ASPIRE study14 and confirm that use of β blockers in patients who have had a myocardial infarction was similar to that in those with no infarction. Less than half our patients with a diagnosis of heart failure took angiotensin converting enzyme inhibitors. This may reflect low rates of referral for evaluation of heart failure or low rates of treatment.
The British Hypertension Society advocates aggressive treatment of hypertension for patients with coronary heart disease.20 In this study more than 90% of patients had received blood pressures checks within the past three years and more than 90% of these were managed in accordance with guidelines. In contrast, lipid management was largely neglected, despite the existence of local guidelines advocating cholesterol lowering for patients with coronary heart disease and total cholesterol concentrations above 5.2 mmol/l.21 General practitioners may have been awaiting more convincing evidence of benefit from clinical trials before intervening. This evidence has now been provided by two large randomised trials which were published around the time of our study. 7 8
Lifestyle changes can modify coronary heart disease22 and reduce mortality from it. Exercise programmes have reduced death rates after myocardial infarction by 20%,11 and stopping smoking is associated with halving of mortality.12 Reductions in mortality from dietary changes have been attributed to a protective effect from certain foods, particularly fruit and vegetables, in addition to cholesterol lowering. 3 4 Weight loss in obese patients reduces coronary risk both independently and by improving lipid concentrations, blood pressure, and glucose tolerance.13
Most patients in this study undertook little or no physical activity, and a fifth were current smokers. Half of patients ate too much fat, and consumption of fruit and vegetables was low. Nearly two thirds of patients were overweight. These findings reveal considerable capacity for secondary prevention through changes in lifestyle. Intervention in general practice, however, is only warranted if it achieves meaningful changes. In general, this has proved difficult, 23 24 but health promotion directed at patients with angina has been found to be effective at increasing physical activity and improving diet.25 Moreover, reductions in symptoms and mortality were also reported. Another study found that patients at highest risk responded best to health promotion,23 and this suggests that benefit might be derived from targeting all patients with coronary heart disease for health promotion.
Virtually all patients in general practice with coronary heart disease had at least one aspect of their medical management that would benefit from change and half had at least two. In addition, nearly all patients reported at least one high risk behaviour and nearly two thirds had at least two. There is a gap, therefore, between the current situation and “optimal” secondary prevention. How much the gap might be closed by intervention in general practice requires further study, but several difficulties can be anticipated. Patients can be advised to change behaviour and informed about treatments but may not accept the advice. Polypharmacy may complicate treatment, and comorbidity may have higher priority for doctor and patient. However, there seems to be potential for substantial benefits to patients with coronary heart disease by targeting them for secondary prevention in general practice.
We thank Aboyne Medical Practice, Benreay Practice, Dr Crowley, Danestone Medical Practice, Elmbank Group, Dr Grieve and Partners, Kemnay Medical Practice, Kincorth Medical Practice, King Street Medical Practice, The Laich Medical Practice, Dr MacFarquhar and Partners, Drs Mackie and Kay, Old Machar Medical Practice, Rubislaw Medical Group, Seafield Medical Practice, Skene Medical Practice, Spa-Well Medical Group, Turriff Medical Practice, and Victoria Street Medical Group for taking part in this project. Thanks to Sandra Skilling for help with data collection and Jeremy Grimshaw for help with study design.
Contributors: All authors participated in the study proposal. NCC collected and analysed the data and drafted the paper. JT assisted with recruitment and data collection and edited the paper. HGD, LDR, and JMR discussed core ideas and edited the paper. NCC and LDR are guarantors.
Funding: Health Services and Public Health Research Committee of the Chief Scientist Office at the Scottish Office.
Conflict of interest: None.