The development of clinical practice guidelines in oncology presents unique problems and challenges due to the heterogeneity of disease presentations and the complexity of therapeutic decisions. Guidelines should incorporate not only standard outcomes measures such as survival but, if feasible, quality of life measures, patient preferences, and cost-effectiveness analyses. Although clinical guidelines are being promulgated as a means of assisting physicians in making therapeutic decisions, another purpose of guidelines implementation reflects the goals of managed care, ie, to promote practice conformity and reduce the cost of care. Methods to monitor physicians' adherence to guidelines are expected to increase as a means of ensuring compliance. This article reviews the process of developing two common types of guidelines used in oncology: path guidelines (using stage II breast cancer as a paradigm) and boundary guidelines (such as the ASCO growth factor guidelines). [ONCOLOGY 9(Suppl):177-183, 1995]
A s the US health-care system increasingly relies on managed care mechanisms to direct patient management, new methods are needed to assist providers, payers, and policymakers in implementing this transformation. A method that currently figures prominently in the planning of many health organizations is the derivation of clinical practice guidelines .
Given the heterogeneity of disease presentations and the complexity of therapeutic decisions, the development of guidelines in oncology presents unique problems and challenges. As in all aspects of health-care planning, concepts and objectives must be precisely defined at the outset, so that the planning process has clear direction and a solid underpinning.
The classic definition of clinical practice guidelines is "systematically developed statements to assist practitioners and patients in decisions about appropriate health care for a specific clinical circumstance". This definition is useful in that it focuses guidelines developers on the concept of guidelines as an assistance to clinical decision making. As guidelines are developed, reference to this aim will assist oncologists in deciding whether the recommendations are useful. If a clinician can use a guideline in arriving at a medical decision, then it has been framed correctly. If, because of vagueness or lack of specific direction, it does not provide any substantive guidance, the guideline is not providing meaningful assistance in patient management.
In reality, the recent emphasis on guidelines stems from a more concrete goal than assistance in clinical decision making. The reason for the tremendous energies being directed toward guidelines development is the belief that they are a vehicle for assuring conformity of practice [3,4]. A more pragmatic definition of guidelines might be that they are a set of directives reflecting the most appropriate management of a clinical situation, whose goal is to promote conformity in the delivery of medical care. While not absolute, this definition makes guidelines more prescriptive and more realistically reflects the underlying reasons for the resurgent interest in this area.
The assumption that guidelines can actually promote and result in conformity must still be viewed as unproved . Although, theoretically, there is good reason to believe that they will achieve this goal, the appropriate evaluation and assessment studies have not been performed, and at this stage the entire process must be considered experimental. The reasons for striving for conformity in practice through the use of guidelines stem from the major aims of managed care and may be listed as follows:
1. The use of clinical practice guidelines will eliminate inappropriate interventions . This concept is based primarily on health services research studies that have demonstrated the high prevalence of inappropriate procedures using evaluations by experts.
2. The cost of care can be more accurately gauged. One of the prime reasons that many groups are currently developing guidelines is to develop standard packages of care for which costs can be analyzed by financial and administrative experts, so that they can be used in managed care contracts. The methodology for these costing analyses is still not well defined, and for a guideline to obtain the specificity and comprehensiveness that will permit the accurate estimate of standard costs will require extensive economic modeling.
3. The cost of care may be driven down . One of the presumptions of conformity to guidelines prescriptions is that it will prevent overutilization of medical services. While this may certainly be true, it is also true that guidelines may uncover areas of underutilization of medical care and lead to increased medical costs . If the more widespread use of guidelines leads to universal compliance with currently accepted guidelines for adjuvant therapy of early-stage breast cancer, the cost of medical care, at least in the short term, may increase. Although economic modeling would suggest that this is a "good buy"[ 9], the overall direction of health-care spending may be up, not down, as a result of conformity to a guideline.
4. Quality of care can be defined in terms of adherence to guidelines. In response to the mandates of managed care, the issuing of "report cards" and the credentialing of physicians and health-care providers are becoming increasingly important. The derivation of medical review criteria and performance measures will lead to comparisons of physicians' practices with standards for adherence to guidelines and assignment of levels of quality of care to specific providers . The determination of appropriate indicators of guidelines adherence and the implementation of efficient computerized systems to monitor these indicators will become areas of intense investigation in the next few years. On balance, it is probable that conformity, insofar as it eliminates inappropriate practices, will benefit patients, but the assumption must be made that it will not be a straight-jacket that precludes necessary modifications to accommodate individual patient needs.
The guideline process involves not only development but also validation, dissemination, and assessment of impact. The current approaches to guidelines development have been well described by Woolf . Informal consensus methods consist of a group of experts deriving a set of guidelines based on their expertise, with no explicit definition of the data used or the process for reaching consensus. The formal consensus process involves bringing together recognized experts for a formal presentation of available data. The experts are then left to their own devices on how to digest the data and use it in arriving at their recommendations. The NIH consensus process is a prominent example of the use of this methodology.
The third approach, evidence-based guidelines, is the method currently considered to be the soundest for deriving objective guidelines. The process utilizes a formal review of the literature, with evaluation of the strength of the evidence based on explicit criteria. This categorization and presentation of the data allow clinicians using the guidelines to assess the strength of the evidence underlying the recommendations and, by extension, the strength of the specific guideline.
The fourth method, as promulgated by David Eddy and coworkers, has been termed the explicit method. . This method attempts to assess the magnitude and probability of outcomes, and use the results of this analysis in choosing between alternative practices. Unfortunately, for the bulk of oncology clinical situations, the quantitative data that would permit guidelines developers to use this process are not available.
There is a plethora of terminology related to systematically derived tools to assist in managed care. It is useful to distinguish between two major classes: clinical practice guidelines, which detail the appropriate tests and treatments, and critical pathways, which lay out the plan of how to perform these tests and treatments. Critical pathways are basically centered on the timing of medical procedures  and are probably best derived at the local level. Clinical practice guidelines may be divided into two types: path guidelines and boundary guidelines, which are discussed below.
During the guidelines development process, it is imperative to define the outcome measures that will be used in deriving the recommendations prior to embarking on the specific guidelines effort . The most relevant outcomes in oncology are survival and improved quality of life. Although the methodology for assessing quality of life is still in a developmental stage, in many instances, data exist that allow quality of life outcome measures to be factored into guidelines development. The two other outcomes of importance in oncology--cost effectiveness and patient preference--are not currently used to any significant degree in guidelines development. The methodology for incorporating patient preference into guidelines in a systematic way must still be developed . Economic analyses, for the most part, are cost-minimization studies. Since data from cost-effectiveness or cost-utility studies are not available for most oncologic practices or procedures, it may prove difficult to incorporate economic considerations into oncology guidelines .
An example of the importance of determining the relevant outcomes prior to deriving guidelines was apparent in the deliberations of the American Society of Clinical Oncology (ASCO) growth factor guidelines panel . The panel's recommendations depended on whether the outcomes to be considered were secondary outcomes (such as decreased hospital days, decreased days on antibiotics, or a decrease in infections) or the primary outcome of increased survival. In many boundary guidelines processes, the first several hours of discussion must focus on the appropriate outcomes to use in framing the guidelines. If consensus about outcomes is not achieved, the panel is at risk of deriving a set of recommendations that are internally inconsistent, if not frankly contradictory.