Simplifying the language of evidence to improve patient care

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Applied Evidence

Simplifying the language of evidence to improve patient care

J Fam Pract. 2004 February;53(2):111-120

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References

1. Evidence-based medicine . A new approach to teaching the practice of medicine. JAMA 1992;268:2420-2425.

2. Slawson DC, Shaughnessy AF, Bennett JH. Becoming a medical information master: feeling good about not knowing everything. J Fam Pract 1994;38:505-513.

3. Shaughnessy AF, Slawson DC, Bennett JH. Becoming an information master: a guidebook to the medical information jungle. J Fam Pract 1994;39:489-499.

4. Siwek J, Gourlay ML, Slawson DC, Shaughnessy AF. How to write an evidence-based clinical review article. Am Fam Physician 2002;65:251-258.

5. Systems to rate the strength of scientific evidence. Summary, evidence report/technology assessment: number 47. AHRQ pub. no. 02-E015, March 2002. Agency for Healthcare Research and Quality, Rockville, Md. Available at: www.ahrq.gov/clinic/epcsums/strengthsum.htm. Accessed on November 13, 2003.

6. Harris RP, Helfand M, Woolf SH, Lohr KN, Mulrow CD, Teutsch SM, et al. Current methods of the U.S. Preventive Services Task Force: a review of the process. Am J Prev Med 2001;20(3 suppl):21-35.

7. Clarke M, Oxman AD. Cochrane reviewer’s handbook 4.0. The Cochrane Collaboration, 2003. Available at: www.cochrane.org/resources/handbook/handbook.pdf. Accessed on November 13, 2003.

8. Gyorkos TW, Tannenbaum TN, Abrahamowicz M, Oxman AD, Scott EA, Millson ME, et al. An approach to the development of practice guidelines for community health interventions. Can J Public Health 1994;85(suppl 1):S8-S13.

9. Briss PA, Zaza S, Pappaioanou M, et al. Developing an evidence-based guide to community preventive services—methods. Am J Prev Med 2000;18(1 suppl):35-43.

10. Greer N, Mosser G, Logan G, Halaas GW. A practical approach to evidence grading. Jt Comm J Qual Improv 2000;26:700-712.

11. Guyatt GH, Haynes RB, Jaeschke RZ, et al. Users’ guides to the medical literature: XXV. Evidence-based medicine: principles for applying the users’ guides to patient care. JAMA 2000;284:1290-1296.

12. Major cardiovascular events in hypertensive patients randomized to doxazosin vs chlorthalidone: the antihypertensive and lipid-lowering treatment to prevent heart attack trial (ALLHAT) JAMA 2000;283:1967-1975.

13. Echt DS, Liebson PR, Mitchell LB, et al. Mortality and morbidity in patients receiving encainide, flecainide, or placebo. N Engl J Med 1991;324:781-788.

14. Lepor H, Williford WO, Barry MJ, et al. The efficacy of terazosin, finasteride, or both in benign prostatic hyperplasia. N Engl J Med 1996;335:533-539.

15. Moseley JB, O’Malley K, Petersen NJ, et al. A controlled trial of arthroscopic surgery for osteoarthritis of the knee. N Engl J Med 2002;347:81-88.

16. Dwyer T, Ponsonby AL. Sudden infant death syndrome: after the “back to sleep” campaign. BMJ 1996;313:180-181.

17. Yusuf S, Dagenais G, Pogue J, Bosch J, Sleight P. Vitamin E supplementation and cardiovascular events in high-risk patients. N Engl J Med 2000;342:154-160.

18. Moayyedi P, Soo S, Deeks J, Delaney B, Innes M, Forman D. Pharmacological interventions for non-ulcer dyspepsia. Cochrane Database Syst Rev 2003;(1):CD001960.-

19. Rossouw JE, Anderson GL, Prentice RL, et al. Risks and benefits of estrogen plus progestin in healthy postmenopausal women: principal results from the Women’s Health Initiative randomized controlled trial. JAMA 2002;288:321-333.

20. Intensive blood-glucose control with sulphonylureas or insulin compared with conventional treatment and risk of complications in patients with type 2 diabetes (UKPDS 33). Lancet 1998;352:837-853.

21. Meunier PJ, Sebert JL, Reginster JY, et al. Fluoride salts are no better at preventing new vertebral fractures than calcium-vitamin D in postmenopausal osteoporosis: the FAVO Study. Osteoporos Int 1998;8:4-12.

22. MacMahon S, Collins R, Peto R, Koster RW, Yusuf S. Effects of prophylactic lidocaine in suspected acute myocardial infarction. An overview of results from the randomized, controlled trials. JAMA 1988;260:1910-1916.

23. Grumbach K. How effective is drug treatment of hypercholesterolemia? A guided tour of the major clinical trials for the primary care physician. J Am Board Fam Pract 1991;4:437-445.

24. Heidenreich PA, Lee TT, Massie BM. Effect of beta-blockade on mortality in patients with heart failure: a metaanalysis of randomized clinical trials. J Am Coll Cardiol 1997;30:27-34.

25. Centre for Evidence-Based Medicine. Levels of evidence and grades of recommendation. Available at: www.cebm.net/levels_of_evidence.asp. Accessed on November 13, 2003.

26. Family Practice Inquiries Network. (FPIN). Available at: www.fpin.org. Accessed on November 13, 2003.

TABLE 1
How recommendations are graded for strength, and underlying individual studies are rated for quality

In general, only key recommendations for readers require a grade of the “Strength of Recommendation.” Recommendations should be based on the highest quality evidence available. For example, vitamin E was found in some cohort studies (level 2 study quality) to have a benefit for cardiovascular protection, but good-quality randomized trials (level 1) have not confirmed this effect. Therefore, it is preferable to base clinical recommendations in a manuscript on the level 1 studies.
Strength of recommendation	Definition
A	Recommendation based on consistent and good-quality patient-oriented evidence.*
B	Recommendation based on inconsistent or limited-quality patient-oriented evidence.*
C	Recommendation based on consensus, usual practice, opinion, disease-oriented evidence,* or case series for studies of diagnosis, treatment, prevention, or screening
Use the following scheme to determine whether a study measuring patient-oriented outcomes is of good or limited quality, and whether the results are consistent or inconsistent between studies.
Study quality	Type of Study
Study quality	Diagnosis	Treatment/prevention/screening	Prognosis
Level 1—good-quality patient-oriented evidence	Validated clinical decision rule	SR/meta-analysis of RCTs with consistent findings	SR/meta-analysis of good-quality cohort studies
	SR/meta-analysis of high-quality studies	High-quality individual RCT^‡ All-or-none study^§	Prospective cohort study with good follow-up
	High-quality diagnostic cohort study^†
Level 2—limited-quality patient-oriented evidence	Unvalidated clinical decision rule	SR/meta-analysis lower-quality clinical trials or of studies with inconsistent findings	SR/meta-analysis of lower-quality cohort studies or with inconsistent results
	SR/meta-analysis of lower-quality studies or studies with inconsistent findings	Lower-quality clinical trial^‡ or prospective cohort study Cohort study	Retrospective cohort study with poor follow-up
	Lower-quality diagnostic cohort study or diagnostic case-control study^§	Case-control study	Case-control study Case series
Level 3—other evidence	Consensus guidelines, extrapolations from bench research, usual practice, opinion, other evidence disease-oriented evidence (intermediate or physiologic outcomes only), or case series for studies of diagnosis, treatment, prevention, or screening
Consistency across studies
Consistent	Most studies found similar or at least coherent conclusions (coherence means that differences are explainable); or If high-quality and up-to-date systematic reviews or meta-analyses exist, they support the recommendation
Inconsistent	Considerable variation among study findings and lack of coherence; or If high-quality and up-to-date systematic reviews or meta-analyses exist, they do not find consistent evidence in favor of the recommendation
*Patient-oriented evidence measures outcomes that matter to patients: morbidity, mortality, symptom improvement, cost reduction, and quality of life. Disease-oriented evidence measures intermediate, physiologic, or surrogate end points that may or may not reflect improvements in patient outcomes (ie, blood pressure, blood chemistry, physiologic function, and pathologic findings).
† High-quality diagnostic cohort study: cohort design, adequate size, adequate spectrum of patients, blinding, and a consistent, well-defined reference standard.
‡ High-quality RCT: allocation concealed, blinding if possible, intention-to-treat analysis, adequate statistical power, adequate follow-up (greater than 80 percent).
§ In an all-or-none study, the treatment causes a dramatic change in outcomes, such as antibiotics for meningitis or surgery for appendicitis, which precludes study in a controlled trial.
SR, systematic review; RCT, randomized controlled trial

TABLE 2
Examples of inconsistency between disease-oriented and patient-oriented outcomes

Therapy	Disease-oriented outcome	Patient-oriented outcome
Doxazosin for blood pressure¹²	Reduces blood pressure	Increases morality in African Americans
Lidocaine for arrhythmia following acute myocardial infarction¹³	Suppresses arrhythmias	Increases mortality
Finasteride for benign prostatic hypertrophy¹⁴	Improves urinary flow rate	No clinically important change in symptom scores
Sleeping infants on their stomach or side¹⁶	Knowledge of anatomy and physiology suggests that this will decrease the risk of aspiration	Increases risk of sudden infant death syndrome
Vitamin E for heart disease¹⁷	Reduces levels of free radicals	No change in mortality
Histamine antagonists and proton pump inhibitors for nonulcer dyspepsia¹⁸	Significantly reduces gastric pH levels	Little or no improvement in symptoms in patients with non-gastroesophageal reflux disease, nonulcer dyspepsia
Arthroscopic surgery for osteoarthritis of the knee¹⁵	Improves appearance of cartilage after debridement	No change in function or symptoms at 1 year
Hormone therapy¹⁹	Reduces low-density lipoprotein cholesterol, increases high-density lipoprotein cholesterol	No decrease in cardiovascular or all-cause mortality; an increase in cardiovascular events in all-cause mortality; an increase in cardiovascular events in women older than 60 years (Women’s Health Initiative) with combined hormone therapy
Insulin therapy in type 2 diabetes mellitus²⁰	Keeps blood sugar below 120 mg/dL (6.7 mmol/l)	Does not reduce overall mortality
Sodium fluoride for fracture prevention²¹	Increases bone density	Does not reduce fracture rate
Lidocaine prophylaxis following acute myocardial infarction²²	Suppresses arrhythmias	Increases mortality
Clofibrate for hyperlipidemia²³	Reduces lipids	Does not reduce mortality
Beta-blockers for heart failure²⁴	Reduces cardiac output	Reduces mortality in moderate to severe disease

TABLE 3
Examples of how to apply the SORT in practice

Example 1: While a number of observational studies (level of evidence—2) suggested a cardiovascular benefit from vitamin E, a large, well-designed, randomized trial with a diverse patient population (level of evidence—1) showed the opposite. The strength of recommendation against routine, long-term use of vitamin E to prevent heart disease, based on the best available evidence, should be A.
Example 2: A Cochrane review finds 7 clinical trials that are consistent in their support of a mechanical intervention for low back pain, but the trials were poorly designed (ie, unblinded, nonrandomized, or with allocation to groups unconcealed). In this case, the strength of recommendation in favor of these mechanical interventions is B (consistent but lower-quality clinical trials).
Example 3: A meta-analysis finds 9 high-quality clinical trials of the use of a new drug in the treatment of pulmonary fibrosis. Two of the studies find harm, 2 find no benefit, and 5 show some benefit. The strength of recommendation in favor of this drug would be B (inconsistent results of good-quality, randomized controlled trials).
Example 4: A new drug increases the forced expiratory volume in 1 second (FEV₁) and peak flow rate in patients with an acute asthma exacerbation. Data on symptom improvement is lacking. The strength of recommendation in favor of using this drug is C (disease-oriented evidence only).