More than 80% of hospitals in the United States use critical pathways as care strategies for at least some patients.¹ Critical pathways are management plans that specify goals for patients and the corresponding ideal sequence and timing of staff actions to achieve those goals with optimal efficiency.² Implementation of critical pathways, developed for myriad diseases and admitting diagnoses, usually requires a substantial time commitment by a multidisciplinary development team.² Such endeavors are largely regarded as worthwhile by healthcare managers who have "embraced critical pathways as a method to reduce variation in care, decrease resource utilization, and potentially improve healthcare quality."³ 

The major goal of a critical pathway is to maximize clinical efficiency of care by reducing patient length of stay (LOS) and resource utilization. By closely coordinating care by both nursing and medical staff from the time a patient is admitted until hospital discharge, pathways are theoretically well suited to minimize waste and inefficient care. Unfortunately, evaluation of the effectiveness of critical pathways has been inadequate.^4,5 The University of Michigan Medical Center, a tertiary-care academic medical center, has been using critical pathways for more than a decade. To evaluate the effectiveness of critical pathways at that center, we assessed whether these clinical management plans have been successful in reducing patient LOS and resource utilization. 

METHODS 

Setting 

The University of Michigan Medical Center, an 872-bed hospital with a level-1 trauma center, is a primary referral hospital in Southeastern Michigan. Critical pathways have been developed and widely implemented for various disorders and admitting diagnoses at the University of Michigan Medical Center since 1991. 

Pathway Development and Implementation 

Pathway development at the University of Michigan Medical Center entailed a multidisciplinary process, usually led by either a physician or nurse with special expertise or interest in the disease process focused on by the pathway. For each pathway, 4 steps usually occurred. (1) A series of meetings were held, often during the course of several months, in which evidence from both published literature and expert opinion were used to develop a final version of the pathway for use in patients with the diagnosis of interest. (2) The pathway was then disseminated to the nursing and medical staff providing clinical care to patients with the diagnosis under consideration. (3) In addition to educating the nursing and medical staff about the specifics of the pathway, copies of the pathway were available in each clinical area for future reference. (4) A person was appointed as pathway "leader" so that modifications could be made in a coordinated manner as needed in response to new information. For a few pathways, the clinical staff occasionally used the pathway as an orientation tool for new house officers or nurses. In their final versions pathways were generally formatted as Gantt charts, thereby outlining the suggested processes of care using a time-task matrix.² Of note, no type of incentive-financial or otherwise-was offered to encourage pathway use. 

Data 

We identified all critical pathways initiated in our medical center between 1993 and 1996 in which at least 50 adult patients were evaluated in the year preceding and succeeding pathway implementation. Thirteen pathways satisfied inclusion criteria. The diagnoses (or procedures) covered by these pathways were the following: acute myocardial infarction, acute pancreatitis, asthma, breast surgery, cesarean section (C-section), community-acquired pneumonia (CAP), hip arthroplasty, kidney transplantation, knee arthroplasty, liver transplantation, lung lobectomy, percutaneous transluminal coronary angioplasty (PTCA), and radical nephrectomy. We used ICD-9 procedure or diagnosis codes to identify patients who would be considered for management by each pathway. As we were primarily interested in the effectiveness of pathways as a management method, we included patients whether or not they were actually managed on the particular pathway. (If this were a clinical intervention, our approach could be termed an intention-to-treat analysis.) 

We excluded patients transferred into our hospital for continued inpatient care, as most such patients likely would not have been managed by a pathway. We also excluded LOS outliers, defined as those patients with a LOS more than 3 standard deviations above the geometric mean for their corresponding diagnosis-related group (DRG). We excluded outliers for 2 reasons. First, we believe that such patients are fundamentally different from the population we wished to generalize about and are not part of the target population for the application of critical pathways. Specifically, outlier patients tend to have very severe or complex illness (or occasionally social issues) requiring a completely different management approach than that used in most routine cases. The pathways concept itself is not suited for addressing extreme situations; indeed, the strategy is based on clinical experience with routine cases. Second, even if we thought extreme outliers in this study were part of the same population as the other cases, there are statistical reasons to assess them differently. In situations in which extreme skew exists, a variety of techniques are commonly used. We believe that outright deletion did not provide a substantially different result from the down-weighting that would have occurred with the other statistical techniques that we would have had to use if we had left the DRG outliers in the sample (e.g., median or quartile regression). 

Analysis