Clinical practice guidelines (guidelines) have been a familiar part of clinical practice for decades, but their importance and consequent proliferation worldwide is a more recent phenomenon. The increasing interest in guidelines is due to several health system factors – the need to cut costs, newer health care financing arrangements, variation in health service delivery mechanisms, and the transition of medicine toward more multidisciplinarity. Guidelines are often included in legal contracts between providers and purchasers due to the need to contain rising health-care costs[1,2] and concerns about overuse of interventions and investigations.[3] Guidelines thus are being used not only for clinical decision-making but also as a standard framework for measuring quality of care. Guidelines thus provide the technical basis for setting rules of procedures for operation of health facilities and clinics, define health-care budgets, and spending, determination of what costs should be reimbursed by insurers, formulating essential medicine lists, and influence pharmaceuticals-related trade policies.

The increasing importance of guidelines has meant that the recommendations within it, and consequently, the methods used to formulate these recommendations has come under increased scrutiny. In response, the concept of guidelines and the way it is being developed has also evolved over time. The review discusses this evolution with a focus on the use of evidence in the guideline development process and also provides an international overview of guideline development process at the country level

The modern history of guidelines began in 1992, with the Institute of Medicine, United States of America (IOM, USA) published a report titled “Clinical Practice Guidelines: Directions for a New Program” which for the first time formally defined guidelines.[4] This marked the beginning of an era, where the profile of guidelines increased exponentially owing to several health system issues. During this period, the number of guidelines increases rapidly from just 374 indexed in MEDLINE in 1993 to 980 in 1996.[5] Even though the IOM, USA, document had noted the importance of having a systematic process of development of clinical practice guidelines,[4] it continued to be based on expert opinions. Research indicated that the ability of a guideline to improve quality of care and improve health system performance depended on several factors during the guideline development process. Expert opinions varied not only between different specialties of expert clinicians but also from within clinicians of the same specialty and between those clinicians who made guidelines and clinicians who actually implemented them.[6,7,8] It was also found that the composition of the guideline development group influenced the recommendations[9,10] and that the recommendations made by clinical experts were often in conflict with the best available research evidence.[11] A rigorous process of identifying and evaluating research evidence and adapting them appropriately in a transparent manner with effective management of conflict of interests during the guideline development process[12,13] was thus found to be critical for a guideline to be able to provide a meaningful framework against which medical quality of care can be measured and important health systems’ decisions be based on.

The use of research evidence for developing guidelines has its roots in of two larger movements which took the world of medicine and health care by storm since the 1990s.

The first of these movements was a result of the HIV/AIDS epidemic with the USA as it is the epicenter. HIV/AIDS activists in the USA constantly argued that clinical trials were not only sites for scientific activity but also sites for clinical care. However, an insurance-based healthcare financing system in the USA meant coverage could be denied based on clinical practice guidelines. For activists, this implied that the focus of their activity could no longer be restricted to demands for increased funding for research. The activists demanded greater say in understanding the use and interpretation of research evidence to formulate recommendations for guidelines. Activists not only used their political power and took on professional societies, insurance companies to secure a place in drug development, regulation and guidelines development panels but also helped forge “new social relationships and identities, new institutions, and new facts and beliefs in the process.”[14] Activists were not only vocal about how their priorities were different from those of clinicians resulting in negative clinical outcomes but were also able to project themselves as credible participants in design, conduct, and interpretation of clinical trials for formulating recommendations – an arena that had always been exclusive for credentialed experts.[15]

Patient or lay participation in health care decision-making had implications beyond AIDS as it broke the cultural authority health-care professionals till then have been able to hold on to for centuries. It changed the dynamic of the doctor-patient relationship and blurred the boundaries between society and science.[14] This was a subtle but firm change in the guideline ecostructure as opinions of experts were no longer taken for granted, even in matters which were technical in nature. It has changed the very nature of what constitutes as being “credible” in health policy or guideline development process.

The evidence-based medicine movement on both sides of the Atlantic was the other movement which had a more profound and direct influence in advocating for the greater role of evidence in guideline development and this continues till date. Although the roots of evidence-based medicine have been planted much[16] earlier the movement caught steam only in 1992 when researchers from Canada and USA collaborated with each other to form the evidence-based medicine working group.[17] Across the Atlantic in United Kingdom, the Cochrane Collaboration was formed in 1993.[16] The practice of evidence-based medicine was described as “ integrating individual clinical expertise with the best available external clinical evidence from systematic research.”[18]

The requirement of guideline panels to be objectively informed about the current status of research evidence on efficacy and safety of alternative health-care interventions is well fulfilled by a systematic review. A systematic review systematically searches for all available research evidence (published or unpublished), critically evaluates the quality of available evidence, and provides an evidence summary for a particular intervention in comparison to an alternative. The element of transparency of judgments used in critical appraisal of quality of evidence in a systematic review additionally allows guideline panels to make judgments about their utility and acceptability. In addition, systematic reviews by collating all evidence on a particular research question into a single study serves a practical purpose in the current age of “information overload”[19] where it is impossible for any single health professional to be updated of all evidence. It also prevents any bias in selection of individual studies for informing guideline development. Guideline panels use systematic reviews of health-care interventions, diagnostic tests, prognostic markers, cost-effectiveness analyses, and even systematic reviews of qualitative studies to understand values, perceptions, and preferences of patients, health-care staff, and policy makers to inform the guideline development process.

The influence of these two movements in changing the concept of guidelines has been reflected in the definition of guidelines given by major international organizations over time and has been summarized in Table 1. Over time organizations had included the need for research evidence and later specifically inculcated the need for systematic reviews in informing the guideline development process in an objective and transparent manner. As, for example, in 2007, it was found that recommendations in the World Health Organization (WHO) guidelines were not based on systematic search and appraisal of evidence but on expert opinions.[26] In response to the ensuing public outcry, the WHO responded by developing a Guideline Review Committee to implement and oversee quality assurance mechanisms for guideline development. A follow-up evaluation in 2013 found that the quality of WHO guidelines have improved[27] on several counts.