A 55-year-old woman with stage 3 chronic kidney disease secondary to polycystic kidney disease has a blood pressure of 118/62 mm Hg. Apart from enlarged kidneys to palpation, her physical examination is unremarkable, and she has no symptoms. Her only medication is amlodipine 10 mg once daily. Several members of her family have a history of coronary artery disease.
Laboratory testing yields the following results:
|Patient value||Reference range|
|Serum creatinine (mg/dL)||2.5||0.6–1.1|
|Estimated glomerular filtration rate|
|Urinary protein (mg/24 hr)||110||<150|
|LDL cholesterol (mg/dL)||125||<130|
|HDL cholesterol (mg/dL)||55||≥46|
|Total cholesterol (mg/dL)||210||125–200|
QUESTION: Which one of the following types of medication — statin, angiotensin-receptor blocker, beta-blocker, loop diuretic, or aspirin — is most likely to reduce this patient’s risk for a major cardiovascular event?
To answer this question, you’ll need to be familiar with the results reported by the SHARP study (Baigent et al., Lancet 2011 Jun 15; 377:2181); the recent results from a systematic review for the U.S. Preventive Services Task Force and for an American College of Physicians Clinical Practice Guideline (Fink et al., Ann Intern Med 2012 Apr 18; 156:570); and a meta-analysis of patients with chronic kidney disease (Palmer et al., Ann Intern Med 2012 Mar 21; 156:445). It might also be helpful to know the family practice guidelines on chronic kidney disease as endorsed by the American Academy of Family Physicians (AAFP).
Which Family Practice Guidelines Should You Know?
There are dozens of family practice guidelines available online, but which ones should you know, both for your clinical every day and for the ABFM exam?
Dr. Mark T. Nadeau, Senior Reviewer for NEJM Knowledge+ Family Medicine Board Review, suggests that in addition to the necessary long-term study of every subject area, it may be helpful to focus particular attention on the following topics:
- Congestive heart failure
- Chronic kidney disease
- Chronic lung disease
- Breast cancer
- Prostate cancer
- Lung cancer
- Thyroid cancer
The ABFM exam blueprint can also be helpful in developing your strategy to prepare for the ABFM exam. The latest version of this blueprint suggests that, in addition to the two modules of questions you choose at the time of the examination (worth 26% of the total score), the largest percentage of questions on the test are in the areas of respiratory (10%), cardiovascular (9%), and musculoskeletal (9%) medicine. (For more information, see the NEJM Knowledge+ blog post on Exploring Exam Blueprints — Family Medicine.)
How the AAFP Evaluates Guidelines
The AAFP aggregates or endorses evidence-based clinical practice guidelines that are relevant to family medicine and that meet AAFP criteria. According to the AAFP web site, clinical practice guidelines that have been developed by external organizations go through a structured review process, after which a decision is made to place them into one of three acceptance categories, as follows:
(1) ENDORSED — the AAFP fully endorses the guideline.
(2) AFFIRMATION OF VALUE — the guideline does not meet the requirements for full endorsement or if the AAFP cannot endorse all recommendations but provides some benefit for family physicians.
(3) NOT ENDORSED — the AAFP does not endorse the guideline and the reasons are stated.
Experts Say: Study Family Practice Guidelines and Topics Regularly and Broadly
Dr. Paul Gordon, Deputy Reviewer for NEJM Knowledge+ Family Medicine Board Review, says that although it is tempting to focus only on the topics that are relevant to your particular practice, the actual exam will include questions from all areas, so it is important to be knowledgeable across the breadth of family medicine. He is an advocate of the regular use of study tools such as the NEJM Knowledge+ Family Medicine Board Review.
Dr. Nadeau agrees that it is very important to study regularly, as preparing for the AAFP exam is a 3-year preparation and should not be done last minute. He believes that it is important to have a personalized study strategy that will give you broad coverage of every topic area. He also says that the AAFP journal, American Family Physician, has review articles that, over a 6-to-7-year period, try to cover topic areas that are generally covered by the Board, so you should read each issue of the AAFP journals, front to back. And lastly, Dr. Nadeau says to be sure to read high-quality review material on a regular basis from a source that gives broad coverage of all topic areas that may occur on the Board exam.
The Correct Choice
The case example at the beginning of this blog post is from a question in NEJM Knowledge+, and the correct choice is to initiate treatment with a statin.
The benefit of lipid-lowering agents in preventing major adverse cardiovascular events in patients with dyslipidemia is well established in the general population, but data specifically in patients with chronic kidney disease are limited. Patients with chronic kidney disease have a higher risk for cardiovascular disease than the general population, because they have both traditional risk factors (such as hypertension) and nontraditional risk factors (such as alterations in mineral metabolism).
The Study of Heart and Renal Protection (SHARP) trial, the first randomized placebo-controlled trial to show that lowering LDL cholesterol prevents major cardiovascular events in patients with chronic kidney disease, showed a significant benefit from simvastatin plus ezetimibe during a median follow-up of 4.9 years. The risks for myopathy and hepatitis were similar in the placebo group and the active-treatment group. Because it is unclear whether ezetimibe provides additional benefit beyond a statin alone, it is reasonable to start with statin monotherapy. At enrollment, the mean age of SHARP participants was 62 years, the mean estimated glomerular filtration rate was 27 mL/min/1.73 m2, and the mean LDL cholesterol level was 107 mg/dL. Thus, the applicability of this trial’s results to young patients with only mild renal impairment, or to patients with very low LDL cholesterol levels at baseline, is unclear.
There is insufficient evidence about the cardioprotective effectiveness of angiotensin-converting–enzyme inhibitors, angiotensin-receptor blockers, beta-blockers, or loop diuretics in nondiabetic patients with stage 1 to 3 chronic kidney disease and no clinical evidence of heart disease.
According to a recent meta-analysis (Palmer SC et al., Ann Intern Med 2012 Mar 21; 156:445), the benefits of antiplatelet therapy in patients with chronic kidney disease are unclear and potentially outweighed by the increased risk for bleeding.
Family Practice Guidelines in NEJM Knowledge+
The case-based questions in NEJM Knowledge+ refer to current guidelines in adult and pediatric medicine topics. While learning in our adaptive system, you’ll encounter references to guidelines, studies, and meta-analysis that affect clinical decisions and are expected knowledge for the ABFM exam. The above case, feedback, and citations are just one example from our bank of over 4000 questions that can help you feel confident in your knowledge of family practice as you head into the boards.