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How many CHD patients are there?


One of the main priorities of the UK National Service Framework for coronary heart disease is secondary prevention in patients with preexisting coronary heart disease. To do this, patient registers are clearly needed to ensure that advice and treatment according to best evidence can be delivered effectively. A knowledge of prevalence, and how to develop and run registers is needed. A study from south London in a large population provides some answers and key pointers [1].


The setting was 69 practices with a population of 380,000 patients, of whom 104,000 (27%) were over 44 years of age. Participation was high, with 63 practices and 92% of the population participating. Most (80%) of the practices used a single computer record system (EMIS). Data were collection between September 2000 and May 2001.

Patients were identified by searching records for particular codes or prescriptions of cardiovascular drugs. Some records were hand searched. An age limit of over 44 years was set because CHD is rare in younger patients.

There had to be a confirmed diagnosis of CHD with supporting evidence from diagnostic tests, procedures like coronary revascularisation, or documentary evidence from hospital correspondence. Information was also obtained about risk factors and blood pressure and cholesterol recording, and current treatment.


There were 6,800 patients both over 44 years and with CHD, with crude prevalence rates of 8.0% in men and 5.2% in women. Age-specific prevalence is shown in Figure 1.

Figure 1: Age-specific prevalence of CHD in women and men

Recording of risk factors was not complete (Table 1). While most of these patients had blood pressure recorded in the previous five years, cholesterol, BMI and smoking status recording was less than complete. Nor was control complete. Substantial minorities of patients had above optimal blood pressure and cholesterol.

Table 1: Recording of risk factors in primary care in south London - percentage of CHD patients with risk factor recorded or with poorly-controlled risk factor

Percent of CHD patients
Blood pressure recorded in previous 5 years
Blood pressure above optimal
Any cholesterol recorded
Cholesterol recorded in previous 2 years
Cholesterol above 5 mmol/L
BMI recorded in previous 2 years
BMI above 30 kg/sq metre
Smoking status recorded in previous 2 years
Current smoker
Prescribed statin
Prescribed aspirin

In a subgroup of practices it was possible to examine how well multiple risk factors were controlled. Most patients had at least one risk factor poorly controlled (Figure 2). Prescribing of statins and aspirin was higher in men than in women (Table 1).

Figure 2: Percentage of women and men with poorly controlled risk factors


There were two main messages. First, this gives a handle on just how many patients in a UK primary care population have coronary heart disease. There will be about 2,100 per 100,000 population, given that the population in this study were younger than the UK average. Second, it tells us that at the beginning of 2001 a significant proportion had multiple risk factors that were poorly controlled. Initiatives like the NSF and new incentives for primary care were designed to help reduce this deficit.

The authors, though, make a telling comment, that general practices need help to make the best use of their computer systems to facilitate the collection of data for registers, like this CHD register. IT plus evidence plus incentives should begin to make a difference, and get the evidence into practice. It will also help organisations make an informed estimate about the likely burden of disease and the costs likely to be incurred in guideline implementation.


  1. K Carroll et al. Prevalence and management of coronary heart disease in primary care: population-based cross-sectional study using a disease register. Journal of Public Health Medicine 2003 25: 29-35.

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