reflects a number of factors, including a lack of physician awareness, a lack of agreement, and inertia (Cabana et al., 1999). Moreover, there are general concerns regarding the applicability of guidelines at the individual level. Guidelines are meant to define practices that meet the needs of most patients under most circumstances (Hunt et al., 2001). They aggregate the harms and benefits of interventions across a group of patients defined by clinical criteria rather than to individual patients.
In addition, they often focus on interventions related to a single condition and individual studies covered by the systematic reviews underpinning the guideline may exclude patients with multiple comorbidities (O’Connor, 2005). Practice guidelines may also apply to only a limited subset of the population and not address the needs of groups such as the elderly (Boyd et al., 2005). And, as described earlier, interpreting multiple guidelines on the same clinical topic may be difficult especially when there is contradictory guidance.
Tierney (2001) argues that guidelines, no matter how well crafted, must undergo “local translation” to be relevant and consistent with local clinical practice standards. However, this type of translation process may lock in some of the local variation that the guidelines are meant to reduce. Generally, to gain wide acceptance, physicians must accept guidelines as best practice (Ayanian et al., 1998; Fried et al., 2006). Yet physicians often do not agree that the standards being promoted through clinical practice guidelines represent the best course of action for their patients (Cabana et al., 1999). In fact, some physicians have accused guidelines of being invalid, unreliable, and irrelevant (Grilli et al., 2000).
Guidelines have limited shelf-lives given the rapid accumulation of new scientific knowledge and changes in practice stemming from new medical technologies and other advances. A review that looked at 17 guidelines published by the AHCPR in the 1990s estimated that about half of the guidelines had become outdated after 5.8 years (Shekelle et al., 2001). The authors concluded that guidelines be reassessed for their validity every 3 years.
To stay current, the organizations that issue guidelines must monitor the medical literature and be prepared to update the guideline. This standard is currently enforced by the NGC, which will not retain the guidelines in its database unless they have been developed, reviewed, or revised within the last 5 years.