ASSESSMENT OF OUTCOME IN SHOULDER ARTHROPLASTY

Dr. Ernest Anthony Codman, a pioneer in surgery and science of the shoulder, was also a pioneer in the field of outcomes research. In his landmark address to the Philadelphia County Medical Society in 1913, titled "The Product of a Hospital," Codman discussed many of the issues that have lately resurfaced with the recent interest in outcomes research. 5 He called for the standardization of reporting data, so that the work done at different hospitals could be compared. He discussed fiscal and clinical efficiency in the delivery of health care. He identified regional variation of medical services and offered insight into the cause of such variation, and he stressed the fundamental principle that the result to the patient is the central issue determining the outcome of medical or surgical treatment. These last two issues—recognition of regional variation and patient-based evaluation—are the foundations upon which the whole field of modern outcomes research has been based. For many years Codman's efforts were underappreciated, yet these pivotal issues raised in 1913 are the same issues being examined today. The recent emphasis on outcomes research stems from the impression that health care expenditures in the United States are excessive. Research conducted in the 1970s and 1980s demonstrated that there is significant regional variation in the use of certain medical services. This implies that in high-utilization areas, inefficient or unnecessary services are being provided, and that in low-utilization areas, patients may not be receiving adequate medical care. In order to accurately assess this regional variation and the effect of our treatments on patients, outcomes research requires two major approaches, reflected in Codman's original concepts. First, assessments must be standardized to allow for comparison of data between institutions and treatment methods; and second, the assessments used for outcomes research should emphasize the patient's perception of the outcome of medical and surgical treatment. Although rarely done in the past, all assessments should be tested for reliability and validity before clinical use. 11 Reliability ensures that repeated administrations of an assessment will give the same results. An assessment has test-retest reliability if it produces the same results when given different times under the same conditions. Internal reliability is present when an assessment evaluating similar conditions produces similar results. Validity ensures that the assessments measure outcomes accurately. The three approaches used to measure validity are content validity, which determines if all of the important aspects of a condition are covered by the assessment; criterion validity, which ensures that the scores produced by the assessment correlate with accepted standards; and construct validity, which demonstrates that the assessment produces results consistent with the existing understanding of the field, or with other assessments. Current research efforts are directed toward the development of a single standard assessment that may be used to evaluate the outcome of patients who have undergone shoulder arthroplasty. Currently, however, a consensus as to the best way to evaluate shoulder arthroplasty patients has not been reached, and several different assessments have been used (Table 1). Unfortunately, only a few of these assessments have been evaluated for reliability or validity. These assessments tend to fall into a hierarchy of the following three levels: general health assessments, global shoulder assessments, and disease-specific evaluations. Each of these levels of assessment provides a different perspective on the patient's outcome.