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Physician compliance with published guidelines on lipid-lowering

 

Clinical bottom line

Many different types of studies from different parts of the world have demonstrated that physicians are not initiating appropriate lipid-lowering therapy in the majority of at risk individuals, according to current guidelines.


Many studies show that the use of lipid-lowering treatments falls a long way short of recommendations set out in the various published guidelines for prevention of coronary heart disease. These studies vary in design and include chart review of selected groups [1-5], national surveys [6, 7, 8], and analysis of the General Practice Research Database (GPRD) [9]. The studies were conducted in the USA and Europe, and the most of the selected groups were secondary prevention groups. Despite the differing populations and study methods, each with their own potential biases, the studies are consistent in reporting poor physician compliance with guidelines for their own region, in terms of identifying patients eligible for treatment, initiating treatment, and achieving treatment goals (cholesterol levels).

The main findings from two studies are presented in Tables 1 and 2, as examples.

Table 1: Results from a national cross sectional survey [7]

 

Patient Group
Number
% (95% CI)
Total
13,586
With valid cholesterol measurement
10,569
T-C 5 mmol/L or more
7133
67.5 (66.5-68.4)
T-C:HDL-C 5 or more
2804
26.5 (25.7-27.4)
Taking lipid-lowering drug
237
2.2 (1.9-2.5)
Age 16-75 with CHD and eligible for drug treatment*
385
Taking lipid-lowering drug
114
30 (25-34)
T-C less than 5 mmol/L
50
44 (35-53)**
No CHD but 10 year risk above 30% and T-C 5 mmol/L or more***
122
Taking lipid-lowering drug
4
3
T-C less than 5 mmol/L
5****
4
* using Joint British recommendations [9]
** among those taking lipid-lowering drug
*** of 6304 patients without CHD who provided sufficient data for calculation
**** none of these patients were taking lipid-lowering drug
CHD=coronary heart disease; T-C=total cholesterol; HDL-C=high density lipoprotein cholesterol

 

Table 2: Results from an analysis of patients admitted to a coronary care unit with acute myocardial infarction [2]

 

Patient Group
Number
%
Total
177
Mean age (years)
66
Male/Female
114/63
History of hyperlipidaemia
17
9.6
T-C above 5 mmol/L
98*
58
Recorded history of CHD
62
35
With CHD and taking lipid-lowering drug
12
19
*of 168 patients in whom lipid profile was measured

 

Of the 149 patients who survived, 101 (68%) were discharged from hospital taking a statin, but 63% of these were on a dose below that shown to reduce cardiovascular events in clinical trials.

In a study of patients on stable lipid-lowering treatments, which assessed success in achieving National Cholesterol Education Program LDL-C goals, drug therapy was better than non-drug therapy, and statins were better than other drug therapies [11]. However, only 40% of those receiving a statin as monotherapy achieved LDL-C target levels. The investigators found that patient non-compliance could not account for the high rates of failure, and that high doses of drugs were seldom used. They suggest that more aggressive treatment is required if treatment goals are to be met.

A study using the GPRD has found large differences between practices in the use of statins in a primary care setting [9], and also large differences in the age and sex of patients given statins. Only about 10% of the differences could be accounted for by variation in the prevalence of ischaemic heart disease.

Smith et al [1] found that differences in quality of lipid-lowering therapy for CHD patients attending either a cardiology clinic or cardiology private practice were accounted for by variation in individual physician prescribing habits, rather than any patient characteristics. Another study has shown that the likelihood of being prescribed a statin is associated with a number of patient characteristics [8], which are shown in Table 3.

Table 3: Patient characteristics for which there was significant variation in prescribing of statins [8]

 

Patient characteristic
Odds ratio* (95%CI)
less than 65 years old 1.0 [reference]
65-74 years old 0.57 (0.38-0.85)
75 years old or more 0.11 (0.06-0.21)
non smoker 1.0 [reference]
smoker 0.49 (0.29-0.84)
Myocardial infarction 1.0 [reference]
angina 0.62 (0.42-0.91)
* adjusted for age and sex (sex only for age variable)

 

Other characteristics for which no significant variation was found include sex, family history of CVD, diabetes, hypertension, obesity, and a number of social measures.

We know that statin prescribing is increasing, and the data for some of these studies were collected four to five years ago, so we might expect that the situation is improving as physicians become more familiar with guidelines and confident about the benefit and harm of statin therapy. The study from Smith et al [1] found improvement between 1994 and 1998. The changes to the NCEP guidelines in 2001 have altered the treatment-eligible population, targeting more younger and elderly subjects, requiring more detailed assessment of risk, and bringing more individuals into the category requiring aggressive treatment [12]. This may have the effect of making physician compliance in the USA appear worse until they catch up with the new recommendations.

Older people

Of particular concern is the apparent under use of statins in elderly patients. This is probably because earlier statin trials did not enrol patients over 75 years old. More recently, in the HPS [13] 28% of patients were 70 years or more at study entry, and PROSPER [14] studied only patients aged 70-82 years. Both trials demonstrated efficacy in these elderly patients, who are at high risk of cardiovascular events.

Ownership

An interesting study of general practitioners in Lothian, Scotland, an area with high rates of CHD, has looked at how doctors use evidence to make decisions about prescribing statins [15]. It showed that doctors were reasonably clear about the benefits and social and economic issues relating to statin use in secondary prevention, but not primary prevention. They rarely read and appraised clinical trials, and trial data were incorporated in to clinical practice only when they were confirmed by other sources (e.g. postgraduate meetings, hospital consultants, the media, and local prescribing advisors), and after a local consensus had emerged. Local guidelines were more widely trusted and used than national guidelines, while pharmaceutical company guidelines were distrusted and rejected. The authors suggested that strategies to maximise the use of clinical evidence in practice should build on local consensus.

Other suggestions to improve physician compliance have concentrated on enabling strategies (e.g. prompts attached to patients' notes), reinforcing strategies (e.g. feedback through routine audit), development of standardised treatment plans, and tracking and follow-up of missed appointments.

Comment

Many different types of studies from different parts of the world have demonstrated that physicians are not initiating appropriate lipid-lowering therapy in the majority of at risk individuals, according to current guidelines. There is variation between doctors in their willingness to assess patients for risk, to use drug therapy, and to use effective doses or combinations of drugs to achieve therapeutic goals.

Reference

  1. DA Smith et al. Comparison of physician-managed lipid-lowering care in patients with coronary heart disease in two time periods (1994 and 1999). Am J Cardiol 2001 88: 1417-9.
  2. CG Missouris et al. Coronary heart disease in the statin and aspirin era: are results of clinical trials being put into practice? Eur J intern Med 2001 12: 490-5.
  3. KL Sloan et al. Frequency of serum low-density lipoprotein cholesterol measurement and frequency of results ≤ 100 mg/dl among patients who had coronary events. Am J Cardiol 2001 88: 1143-6.
  4. Frolkis JP et al. Physician Noncompliance With the 1993 National Cholesterol Education Program (NCEP-ATPII) Guidelines. Circulation 1998 98: 851-5.
  5. EUROASPIRE. A European Society of Cardiology survey of secondary prevention of coronary heart disease: principal results. Eur Heart J 1997 18: 1569-82.
  6. TJ Hoereger et al. Treatment patterns and distribution of low-density lipoprotein cholesterol levels in treatment-eligible United States adults. Am J Cardiol 1998 82: 61-5.
  7. P Primatesta, N Pouter. Lipid concentrations and the use of lipid-lowering drugs: evidence from a national cross sectional survey. BMJ 2000 321: 1322-5.
  8. FDA Reid et al. Use of statins in the secondary prevention of coronary heart disease: is treatment equitable? Heart 2002 88: 15-9.
  9. A Majeed et al. Age, sex and practice variations in the use of statins in general practice in England and Wales. J Public Health Med 2000 22: 275-9.
  10. D Wood et al. Joint British recommendations on prevention of coronary heart disease in clinical practice. Heart 1998 80(suppl 2): 1-29.
  11. TA Pearson et al. The Lipid Treatment Assessment Project (L-TAP). Arch Intern Med 2000 2000: 459-7.
  12. DO Fedder et al. New National Cholesterol Education Program III guidelines for primary prevention of lipid-lowering drug therapy. Projected impact on the size, sex, and age distribution of the treatment-eligible population. Circulation 2002 105: 152-6.
  13. 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.
  14. J Shepherd et al. Pravastatin in elderly individuals at risk of vascular disease (PROSPER): a randomised controlled trial. Lancet 2002 360: 1623-30.
  15. K Fairhurst, G Huby. From trial data to practical knowledge: qualitative study of how general practitioners have accessed and used evidence about statin drugs in their management of hypercholesterolaemia. BMJ 1998 317: 1130-4.