Key Papers in SDM

Key References on Shared Decision Making, Patient Decision Aids, and their Implementation

Classic References

The following three papers describe how the outcome data on prostatectomy collected in Maine and the accompanying decision analysis might be used to address unwanted variations in surgery. In the first study, the majority of practicing urologists in Maine allowed their patients to be interviewed before and serially after a prostatectomy for benign prostatic hyperplasia for this study. The focus was on patient-reported outcomes, including symptom severity and quality of life. The second study used a decision analysis addressing whether or not to have surgery for BPH. The analysis demonstrated that the most important drivers of whether or not surgery was of value were patients’ feelings about their symptoms and the potential effects of surgery.  Together, these three papers were awarded the “Article of the Year Award” from the Association for Health Services Research (now AcademyHealth) in 1989.

  • Fowler FJ Jr, Wennberg JE, Timothy RP, Barry MJ, Mulley AG Jr, Hanley D.

Symptom status and quality of life following prostatectomy. JAMA. 1988 May

27;259(20):3018-22. PubMed PMID: 2452905.

https://www.ncbi.nlm.nih.gov/pubmed/?term=2452905

  • Barry MJ, Mulley AG Jr, Fowler FJ, Wennberg JW. Watchful waiting vs immediate

transurethral resection for symptomatic prostatism. The importance of patients’

preferences. JAMA. 1988 May 27;259(20):3010-7. PubMed PMID: 2452904.

https://www.ncbi.nlm.nih.gov/pubmed/?term=2452904

  • Wennberg JE, Mulley AG Jr, Hanley D, Timothy RP, Fowler FJ Jr, Roos NP, Barry

MJ, McPherson K, Greenberg ER, Soule D, et al. An assessment of prostatectomy for

benign urinary tract obstruction. Geographic variations and the evaluation of

medical care outcomes. JAMA. 1988 May 27;259(20):3027-30. PubMed PMID: 2452906.

https://www.ncbi.nlm.nih.gov/pubmed/?term=2452906

 

The following two ground breaking studies by Braddock and his associates featured tape recordings of discussions between physicians and their patients making medical decisions.  They systematically assessed the quality of the discussions against a specified set of criteria that included the extent to which risks and benefits were discussed and whether or not physicians made sure their patients understood their options.  The results showed that features of good decision making were commonly missing from these discussions.  At the time they were published, these articles helped make the case that significant changes were needed in patient-physician interactions if the patient’s voice was to be reflected in medical decisions.

The investigators studied audiotapes of primary care visits in Portland Oregon. They found that while discussions leading to decisions were common, there was little evidence of shared decision making. Physicians frequently described the nature of the decision, less frequently discussed risks and benefits, and rarely assessed the patient’s understanding of the decision.

  • JF Braddock CH 3rd, Edwards KA, Hasenberg NM, Laidley TL, Levinson W. Informed

decision making in outpatient practice: time to get back to basics. JAMA. 1999

Dec 22-29;282(24):2313-20. PubMed PMID: 10612318.

https://www.ncbi.nlm.nih.gov/pubmed/?term=10612318

  • JF Braddock CH 3rd, Fihn SD, Levinson W, Jonsen AR, Pearlman RA. How doctors and

patients discuss routine clinical decisions. Informed decision making in the

outpatient setting. J Gen Intern Med. 1997 Jun;12(6):339-45. PubMed PMID:

9192250; PubMed Central PMCID: PMC1497128.

https://www.ncbi.nlm.nih.gov/pubmed/?term=9192250

 

The following classic paper lays out a theoretical framework for shared decision making in health care encounters. The authors describe four key characteristics of SDM: (1) that at least two participants-physician and patient be involved; (2) that both parties share information; (3) that both parties take steps to build a consensus about the preferred treatment; and (4) that an agreement is reached on the treatment to implement.

  • Charles C, Gafni A, Whelan T. Shared decision-making in the medical encounter:

what does it mean? (or it takes at least two to tango). Soc Sci Med. 1997

Mar;44(5):681-92. PubMed PMID: 9032835.

https://www.ncbi.nlm.nih.gov/pubmed/?term=9032835

 

Dr. Eddy describes a framework for developing clinical practice guidelines, which he called “practice policies.” He describes how evidence on outcome probabilities is combined with the preferences of informed patients to generate recommendations of different strengths: standard, guidelines, and options. Modern guidelines tend to focus on outcome probabilities, and often neglect patient preferences.

  • Eddy DM. Clinical decision making: from theory to practice. Designing a practice policy. Standards, guidelines, and options. 1990 Jun 13;263(22):3077,3081,3084. PubMed Central PMID: 2322221.

https://www.ncbi.nlm.nih.gov/pubmed/2342221

 

The main contribution of this paper is the description of Mulley’s Shared Decision Making framework that differs from other conceptualizations of SDM by taking a systems approach to understanding and improving the quality of medical decisions. The framework highlights two main feedback loops—the first focused on making decisions more knowledge-based through collecting evidence on outcomes and the second focused on making decisions more patient-centered though collecting evidence on patients’ subjective experience of those outcomes. Both of these streams of data are needed for high quality decision support tools, such as decision aids, that can then be used to improve quality of future decisions. 

  • Sepucha K, Mulley AG Jr. A perspective on the patient’s role in treatment

decisions. Med Care Res Rev. 2009 Feb;66(1 Suppl):53S-74S. doi:

10.1177/1077558708325511. Epub 2008 Nov 10. PubMed PMID: 19001081.

https://www.ncbi.nlm.nih.gov/pubmed/?term=19001081

 

Kahneman and Tversky’s groundbreaking research documented systematic biases in the way that people viewed decisions, interpreted probabilities and outcomes, and formed preferences that deviated from the assumptions of rational theories of decision making.  They created prospect theory as an alternative to expected utility theory. that used psychological principles to explain and better predict decision behavior and preferences. Prospect theory incorporates psychological principles and behavioral findings to better predict actual decision making behavior. For example, one key element of the theory is that it does not assume a constant risk attitude, rather it predicts that people tend to be risk averse for gains, and risk seeking for losses. 

  • Tversky A, Kahneman D. Judgment under Uncertainty: Heuristics and Biases.

Science. 1974 Sep 27;185(4157):1124-31. PubMed PMID: 17835457.

https://www.ncbi.nlm.nih.gov/pubmed/?term=17835457

  • Tversky A and Kahneman D. The Framing of Decisions and the Psychology of Choice. Science. 1981. 211(4481):453-8.   PubMed PMID: 7455683. https://www.ncbi.nlm.nih.gov/pubmed/7455683

 

Conceptual References

This widely-cited New England Journal Perspective argues that shared decision making is the highest form of patient centered care. When fateful health decisions loom and patients and their families must live with the consequences, incorporating what they value into the decision is particularly critical.

  • Barry MJ, Edgman-Levitan S. Shared decision making–pinnacle of

patient-centered care. N Engl J Med. 2012 Mar 1;366(9):780-1. doi:

10.1056/NEJMp1109283. PubMed PMID: 22375967.

https://www.ncbi.nlm.nih.gov/pubmed/?term=22375967

 

This follow-up article to the Perspective above emphasizes that SDM is not an end in and of itself, but a means to the real goal: better quality health decisions. Ways to measure the quality of health decisions are discussed, as well as the link between SDM and truly informed consent.

 

This King’s Fund report from the UK outlines why shared decision making is important, what it involves, and implications for the National Health Services. The paper goes on to discuss challenges in implementation and how they might be overcome.

  • Coulter A, Collins A. Making Shared Decision-Making a Reality. No decision about me, without me. UK: The Kings Fund; 2011.

https://www.kingsfund.org.uk/sites/default/files/Making-shared-decision-making-a-reality-paper-Angela-Coulter-Alf-Collins-July-2011_0.pdf

 

Building on the evidence that patients are not routinely informed and involved in decisions, this paper reviews ways to increase the rate at which shared decision making occurs.  Valuable steps discussed include incentives for the use of the good quality decision aids, using technology to collect data about what patients know, and their preferences, to be shared with their providers, and monitoring how well informed and involved patients are when decisions are made.

  • Fowler FJ Jr, Levin CA, Sepucha KR. Informing and involving patients to

improve the quality of medical decisions. Health Aff (Millwood). 2011

Apr;30(4):699-706. doi: 10.1377/hlthaff.2011.0003. PubMed PMID: 21471491.

https://www.ncbi.nlm.nih.gov/pubmed/?term=21471491

 

Discusses the potential for SDM to improve the informed consent process and reduce health care disparities based on race/ethnicity, gender and geography through shared decision making. (See also the Arterburn and Ibrahim studies in the next section.)

  • King JS, Eckman MH, Moulton BW. The potential of shared decision making to

reduce health disparities. J Law Med Ethics. 2011 Mar;39 Suppl 1:30-3. doi:

10.1111/j.1748-720X.2011.00561.x. PubMed PMID: 21309892.

https://www.ncbi.nlm.nih.gov/pubmed/?term=21309892

 

Mulley and colleagues make the point that clinicians often make decisions unaware of patients’ preferences. They call this type of error “silent misdiagnosis,” in analogy to clinical misdiagnosis. 

  • Mulley AG, Trimble C, Elwyn G. Stop the silent misdiagnosis: patients’

preferences matter. BMJ. 2012 Nov 8;345:e6572. doi: 10.1136/bmj.e6572. Review.

PubMed PMID: 23137819.

https://www.ncbi.nlm.nih.gov/pubmed/?term=23137819

 

The National Quality Forum (NQF) advances a new framework for shared decision making including a consensus definition. NQF also proposes a national certification system for patient decision aids, based largely on the IPDAS quality criteria.

  • National Quality Forum. National Quality Partners Playbook: Shared Decision Making In Healthcare [Internet]. Washington, DC; 2018

http://www.qualityforum.org/National_Quality_Partners_Shared_Decision_Making_Action_Team.aspx

 

The authors discuss health policy initiatives that can help facilitate shared decision making in clinical practice. These options include ways to reduce barriers to clinician participation, engaging patients, and building SDM into systems of care.

 

This Perspective discusses elements of the Affordable Care Act designed to advance SDM. Unfortunately, while these provisions were made part of the law, their implementation was never funded.

  • Oshima Lee E, Emanuel EJ. Shared decision making to improve care and reduce

costs. N Engl J Med. 2013 Jan 3;368(1):6-8. doi: 10.1056/NEJMp1209500. PubMed

PMID: 23281971.

https://www.ncbi.nlm.nih.gov/pubmed/?term=23281971

 

This statement, authored by 58 participants from 18 countries in a Salzburg symposium, emphasized the importance of SDM across countries and cultures. The statement calls on clinicians; researchers editors, and journalists; patients; and policy makers to take specific steps to encourage SDM implementation in health care internationally.

 

This paper fills a gap in the literature on implementation of shared decision making in routine care. Sepucha and colleagues summarize the key lessons learned over more than a decade of efforts to integrate shared decision making into routine care across a large urban hospital.

  • Sepucha KR, Simmons LH, Barry MJ, Edgman-Levitan S, Licurse AM, Chaguturu SK. Ten Years, Forty Decision Aids, And Thousands Of Patient Uses: Shared Decision Making At Massachusetts General Hospital. Health Aff (Millwood). 2016 Apr;35(4):630-6. doi: 10.1377/hlthaff.2015.1376. PubMed PMID: 27044963. https://www.ncbi.nlm.nih.gov/pubmed/?term=Sepucha+KR+aND+Licurse

 

This Viewpoint discusses the policy implications of SDM and its ability to improve the informed consent process. As the authors state, “Common definitions, trusted certified decision aids, clinician engagement, strategies to enable seamless integration into practice, and a commitment to rigorous evaluation and improvement will be needed to achieve genuine shared decision making that is embraced by clinicians and the patients for whom they provide care and guidance.  

  • Spatz ES, Krumholz HM, Moulton BW. Prime Time for Shared Decision Making. 2017 Apr 4;317(13):1309-1310. doi: 10.1001/jama.2017.0616. PubMed PMID: 28384834.

https://www.ncbi.nlm.nih.gov/pubmed/28384834

 

Research Investigations

The value of decision aids in controlled studies has been well documented, but the challenge has been to get them widely used as part of routine practice.    This paper reports on a landmark study of the effects of widespread integration of decision aids at Group Health in Washington when patients were faced with decisions about hip and knee replacement surgery.

  • Arterburn D, Wellman R, Westbrook E, Rutter C, Ross T, McCulloch D, Handley M,

Jung C. Introducing decision aids at Group Health was linked to sharply lower hip

and knee surgery rates and costs. Health Aff (Millwood). 2012 Sep;31(9):2094-104.

doi: 10.1377/hlthaff.2011.0686. PubMed PMID: 22949460. https://www.ncbi.nlm.nih.gov/pubmed/?term=22949460

 

In a study of about 1000 men in two health systems who viewed a patient decision aid on PSA testing, interest in PSA testing decreased, but about a third of well-informed men still wanted PSA screening. Participants who wanted to discuss PSA screening with their clinicians were significantly more likely to do so if they had first reviewed a decision aid.

  • Barry MJ, Wexler RM, Brackett CD, Sepucha KR, Simmons LH, Gerstein BS,

Stringfellow VL, Fowler FJ Jr. Responses to a Decision Aid on Prostate Cancer

Screening in Primary Care Practices. Am J Prev Med. 2015 Oct;49(4):520-5. doi:

10.1016/j.amepre.2015.03.002. Epub 2015 May 8. PubMed PMID: 25960395. https://www.ncbi.nlm.nih.gov/pubmed/?term=25960395

 

This paper reports the results of a national survey of nearly 3000 patients 40 or older who made medical decisions.  The survey covered 10 common decisions, three for long-term medications, three for cancer screening, and four types of surgery.  When respondents described the decision making processes, the quality of their involvement varied by decision type.  While decision making for surgery for lower back pain and osteoarthritis of the knee was comparatively good, the important contribution of this study was to document how much decision making needs to improve, particularly for decisions about taking medications and about screening for cancer.

  • Fowler FJ Jr, Gerstein BS, Barry MJ. How patient centered are medical

decisions?: Results of a national survey. JAMA Intern Med. 2013 Jul

8;173(13):1215-21. doi: 10.1001/jamainternmed.2013.6172. PubMed PMID: 23712194.

https://www.ncbi.nlm.nih.gov/pubmed/?term=23712194

 

One commonly cited obstacle to using shared decision making is the reported perception that many patients do not want to be informed or involved.  These investigators report on the results of 6 focus groups with patient about participating in decision making.  The authors found no evidence of a reluctance on the part of patients to collaborate with physicians in making decisions, but they found a widespread perception that physicians did not want patient participation and that patients were concerned that they would be perceived as “difficult” if they spoke up about their own views and preferences when decisions were made.

  • Frosch DL, May SG, Rendle KA, Tietbohl C, Elwyn G. Authoritarian physicians

and patients’ fear of being labeled ‘difficult’ among key obstacles to shared

decision making. Health Aff (Millwood). 2012 May;31(5):1030-8. doi:

10.1377/hlthaff.2011.0576. PubMed PMID: 22566443.

https://www.ncbi.nlm.nih.gov/pubmed/?term=22566443

 

One of the strong arguments for the use of decision aids is that it is difficult to do a good job of explaining risks and benefits to patients.  Particularly when statistics are involved, it matters how the information is communicated.  This is one of several studies by these researchers that demonstrates that poor presentations are incomprehensible to some lower numeracy older folks, but that the majority can understand statistics, indeed as well as high numeracy students, if the presentations are done properly.

  • Galesic M, Gigerenzer G, Straubinger N. Natural frequencies help older adults

and people with low numeracy to evaluate medical screening tests. Med Decis

Making. 2009 May-Jun;29(3):368-71. doi: 10.1177/0272989X08329463. Epub 2009 Jan 6. PubMed PMID: 19129155.

https://www.ncbi.nlm.nih.gov/pubmed/?term=19129155

 

In this randomized trial, a patient decision aid increased rates of total knee replacement among African-American patients. This same decision aid had reduced rates of TKR in a well-insured majority population. This results suggests SDM supported by decision aids may be a tool to address health care disparities.

  • Ibrahim SA, Blum M, Lee GC, Mooar P, Medvedeva E, Collier A, Richardson D. Effect of a Decision Aid on Access to Total Knee Replacement for Black Patients With Osteoarthritis of the Knee: A Randomized Clinical Trial. JAMA Surg. 2017 Jan 18;152(1):e164225. doi: 10.1001/jamasurg.2016.4225. Epub 2017 Jan 18. PubMed PMID: 27893033

https://www.ncbi.nlm.nih.gov/pubmed/27893033

 

In this cluster-randomized trial, offering patients more colorectal cancer screening options than colonoscopy alone resulted in a higher proportion of participants undergoing CRC screening, especially among racial and ethnic minorities.

  • Inadomi JM, Vijan S, Janz NK, Fagerlin A, Thomas JP, Lin YV, Muñoz R, Lau C,

Somsouk M, El-Nachef N, Hayward RA. Adherence to colorectal cancer screening: a

randomized clinical trial of competing strategies. Arch Intern Med. 2012 Apr

9;172(7):575-82. doi: 10.1001/archinternmed.2012.332. PubMed PMID: 22493463;

PubMed Central PMCID: PMC3360917.

https://www.ncbi.nlm.nih.gov/pubmed/?term=22493463

 

One of the most important reasons for involving patients in decision making is to ensure that their goals and preferences are reflected in the decisions.  If doctors make the decisions largely on their own, they have to rely on their perceptions of what patients care about.  This study asked breast cancer patients and breast cancer physicians to rate the importance of various issues potentially related to deciding how to treat breast cancer.  They found that there were some major differences between physicians and patients in what they thought was important, strongly reinforcing the value of making sure the patients’ own voices are heard.

  • Lee CN, Dominik R, Levin CA, Barry MJ, Cosenza C, O’Connor AM, Mulley AG Jr,

Sepucha KR. Development of instruments to measure the quality of breast cancer

treatment decisions. Health Expect. 2010 Sep;13(3):258-72. doi:

10.1111/j.1369-7625.2010.00600.x. Epub 2010 Jun 9. PubMed PMID: 20550591; PubMed

Central PMCID: PMC2919601.

https://www.ncbi.nlm.nih.gov/pubmed/?term=20550591

 

Informed patients are a key goal for SDM and one of the most commonly measured outcomes in patient decision aid evaluations. This study compared patients’ responses to a question that asked them how informed they were about the treatments to their ability to answer several specific knowledge questions about the treatments. The main finding, of no correlation between patients’ perceptions and their knowledge scores, suggests that patients are not able to accurately assess their own knowledge. To determine if someone is well informed requires specific knowledge questions.

  • Sepucha KR1, Fagerlin A, Couper MP, Levin CA, Singer E, Zikmund-Fisher BJ. How does feeling informed relate to being informed? The DECISIONS survey. Med Decis Making. 2010 Sep-Oct;30(5 Suppl):77S-84S. doi: 10.1177/0272989X10379647. PubMed PMID: 20881156.

https://www.ncbi.nlm.nih.gov/pubmed/?term=20881156

 

Relational coordination is a theory of organizational performance that emphasizes the importance of communication for highly functioning teams. It has been applied to health care and it has been shown to predict better quality and efficiency. The investigators studied whether the amount of relational coordination in primary care practices was associated with successful implementation of patient decision aids. Although it was a small study, they found that the practices that engaged more effectively as a team (i.e. higher relational coordination) were more likely to engage their patients in medical decisions (i.e. use more decision aids).

  • Tietbohl CK, Rendle KA, Halley MC, May SG, Lin GA, Frosch DL. Implementation

of Patient Decision Support Interventions in Primary Care: The Role of Relational

Coordination. Med Decis Making. 2015 Nov;35(8):987-98. doi:

10.1177/0272989X15602886. Epub 2015 Aug 27. PubMed PMID: 26314727.

https://www.ncbi.nlm.nih.gov/pubmed/?term=26314727

 

One of the fundamental questions asked about shared decision making and the use of decision aids is how they affect costs: does getting patients informed about options increase their appetite for medical interventions or decrease their interest in interventions with limited value? This study was a major experiment in which patients were randomized to more or less intensive health coaching, supported by decision aids.  The results reported in these two complementary analyses of the same experiment show that the use of preference-sensitive surgeries and overall patient costs were reduced with more intensive use of coaching and decision aids.

  • Veroff D, Marr A, Wennberg DE. Enhanced support for shared decision making

reduced costs of care for patients with preference-sensitive conditions. Health

Aff (Millwood). 2013 Feb;32(2):285-93. doi: 10.1377/hlthaff.2011.0941. PubMed

PMID: 23381521.

https://www.ncbi.nlm.nih.gov/pubmed/?term=23381521

  • Wennberg DE, Marr A, Lang L, O’Malley S, Bennett G. A randomized trial of a

telephone care-management strategy. N Engl J Med. 2010 Sep 23;363(13):1245-55.

doi: 10.1056/NEJMsa0902321. PubMed PMID: 20860506.

https://www.ncbi.nlm.nih.gov/pubmed/?term=20860506

 

One of the arguments for recommending that physicians use high quality decision aids, rather than trying to transmit the information themselves that patients need to know, is that it is not reasonable to think that physicians have all the information that patients need to know and they are not necessarily skilled at communicating complex information in a clear way.  Another issue, demonstrated very clearly in this report of a survey of primary care physicians, is that physicians are often confused about statistics that are crucial to understanding decisions: in this case, statistics related to cancer screening tests.

  • Wegwarth O, Schwartz LM, Woloshin S, Gaissmaier W, Gigerenzer G. Do

physicians understand cancer screening statistics? A national survey of primary

care physicians in the United States. Ann Intern Med. 2012 Mar 6;156(5):340-9.

doi: 10.7326/0003-4819-156-5-201203060-00005. PubMed PMID: 22393129.

https://www.ncbi.nlm.nih.gov/pubmed/?term=22393129

 

Shared treatment decision making is often seen as a tool to help make major one-time decisions, for example, for major surgery or cancer treatment. This study suggests SDM may be important for chronic conditions as well. In this randomized trial, an asthma treatment regimen that resulted from an SDM process between the clinical team and patients was associated with improved adherence and better subjective and objective asthma outcomes.

  • Wilson SR, Strub P, Buist AS, Knowles SB, Lavori PW, Lapidus J, Vollmer WM; Better Outcomes of Asthma Treatment (BOAT) Study Group. Shared treatment decision making improves adherence and outcomes in poorly controlled asthma. Am J Respir Crit Care Med. 2010 Mar 15;181(6):566-77. doi: 10.1164/rccm.200906-0907OC. Epub 2009 Dec 17. PubMed PMID: 20019345 PMCID: PMC2841026.

https://www.ncbi.nlm.nih.gov/pubmed/20019345

 

Meta-Analyses

Some have raised concerns about the potential of decision aids and shared decision making to increase health inequities. This systematic review included 19 studies of SDM interventions, for which at least 50% of the sample was from underserved populations. Both the meta-analyses and narrative synthesis of the studies found a positive effect of shared decision-making interventions on underserved patients. In fact, SDM interventions appeared to benefit disadvantaged groups (e.g. lower literacy) more than those with higher literacy, education and socioeconomic status.   

  • Durand MA, Carpenter L, Dolan H, Bravo P, Mann M, Bunn F, Elwyn G. Do interventions designed to support shared decision-making reduce health inequalities? A systematic review and meta-analysis. PLoS One. 2014 Apr 15;9(4):e94670. doi: 10.1371/journal.pone.0094670

 

The latest update of this Cochrane review includes 87 trials, evaluating interventions focused on patients (such as decision aids or question prompt sheets), on clinicians (such as training) or both on shared decision making. Forty‐four studies looked at activities for patients only, while 28 studies looked at activities for both healthcare professionals and patients, and 15 studies looked at activities for healthcare professionals only. While studies in all three categories had tested many different activities to increase shared decision making by healthcare professionals, overall the authors could not be confident in the effectiveness of these activities because the certainty of the evidence was weak.

  • Légaré F, Adekpedjou R, Stacey D, Turcotte S, Kryworuchko J, Graham ID, Lyddiatt A, Politi MC, Thomson R, Elwyn G, Donner-Banzhoff N. Interventions for increasing the use of shared decision making by healthcare professionals. Cochrane Database Syst Rev. 2018 Jul 19;7:CD006732. doi: 10.1002/14651858.CD006732.pub4. Review. PubMed PMID: 30025154.

https://www.ncbi.nlm.nih.gov/pubmed/30025154

 

The Cochrane Library catalogs meta-analyses on different clinical questions. This meta-analysis, including 105 trials involving over 30,000 participants, is the most widely cited Cochrane review on any topic. In randomized trials, use of decision aids improved patient knowledge and many aspects of decision quality.

  • Stacey D, Légaré F, Lewis K, Barry MJ, Bennett CL, Eden KB, Holmes-Rovner M,

Llewellyn-Thomas H, Lyddiatt A, Thomson R, Trevena L. Decision aids for people

facing health treatment or screening decisions. Cochrane Database Syst Rev. 2017

Apr 12;4:CD001431. doi: 10.1002/14651858.CD001431.pub5. Review. PubMed PMID:

28402085.

https://www.ncbi.nlm.nih.gov/pubmed/?term=28402085