OBJECTIVES: While there are many factors that influence patient outcomes, delays in treatment can negatively impact morbidity and mortality. This study reviews the evidence on the impact of early versus delayed treatment initiation on patient outcomes.

METHODS: A search was conducted for Medline-indexed original research articles, systematic reviews, and/or meta-analyses that examined the impact of early vs. delayed treatment initiation on patient outcomes. The evidence was summarized by drug class and/or disease condition.

RESULTS: For several conditions, the impact of treatment delays is heterogeneous, either because the literature is equivocal, because patients who receive expedited treatment are more frequently suffering from later stages of disease, or because delays in treatment may not actually impact outcomes. However, most of the literature found for anticonvulsants, antidepressants, and antipsychotics suggests that delayed treatment is associated with poor outcomes. For example, several studies of antipsychotics found that delays in treatment can not only result in worse outcomes but may be a factor in developing treatment resistant schizophrenia. Similarly, for antiretrovirals, substantial evidence suggests that the risk for mortality and progression to acquired immunodeficiency syndrome appeared to be reduced among people living with HIV with early initiation of antiretroviral therapy. Also, studies among patients with autoimmune diseases such as multiple sclerosis and Crohn’s disease have shown that early treatment initiation was associated with improved outcomes. Early treatment of bleeds in hemophilia patients has also been shown to benefit clinical outcomes.

CONCLUSIONS: This review identifies numerous diseases and/or drug classes wherein published evidence indicates that delayed treatment initiation is associated with poor outcomes. Our findings have direct implications for recently proposed changes under Medicare (e.g. Part B step therapy, Part D protected drug classes). To the extent that such changes may delay treatment initiation, our findings raise caution given the potential adverse impact on patient outcomes.