Use of grade membership analysis to profile the practice styles of individual physicians in the management of acute low back pain

Abstract

The objective of this study was to investigate Grade of Membership analysis (GoM) as a means of profiling the practice styles of individual physicians. GoM uses maximum likelihood techniques to estimate occurrences of management items that define unique practice styles. It also provides statistical estimates (grade of membership coefficients) of how well each individual physician's practice fits the identified styles. Data sources were responses to a mailed survey asking 814 physicians to select from predetermined management options in three scenarios depicting patients with acute low back pain. Four distinct types of practice style were identified: watchful waiting; investigative; guideline based; and physiotherapy focused. Most physicians were characterized by high grades of membership in the two profiles that most closely matched existing guidelines for the management of acute low back pain. GoM successfully identified characteristic practice styles, and the GoM coefficients obtained provided descriptions of individual management approaches. GoM is data driven and less subject to judgment than opinion-based measures of performance. It has several potential applications in identifying physicians for whom some form of intervention would be beneficial.

Introduction

The extensive literature on practice variations has focused on two issues: the need to understand differences between the practice styles of physicians, and the need to foster evidence-based medicine. Medical services increasingly need to provide experimental evidence of clinical benefit in order to obtain the broad support of health professionals, regulatory agencies, and payors [1]. However, providers of services may have personal styles of practice that do not reflect current medical standards. Efforts have therefore been directed towards profiling health professionals and measuring their performance in order to better understand why practice varies and to improve the quality of care 2, 3.

The individual physician–patient encounter is a unique and complex situation shaped by the patient's symptoms and expectations, the physician's knowledge, attitudes, and training, and many other environmental factors. Several approaches have been used to try to describe the practice patterns of physicians. They include stratification according to diagnosis-related groups 4, 5, the development of appropriateness scores for single medical procedures 6, 7 or operations 8, 9, 10, the use of standardized patients 11, 12 or written case scenarios 13, 14, and the time-honored method of individual peer assessment [15].

Different approaches describe physician performance in different ways. For example, measures of appropriateness of care are generally used when the focus is on quality of care, whereas measures of cost or the intensity of resource use are preferred when describing the economic consequences of healthcare. However, such one-dimensional assessments of performance cannot be expected to fully reflect the complexity and multidimensional nature of the clinical encounter. A similar challenge in the field of continuing medical education is often met by describing performance as a combination of several dimensions 16, 17, 18, 19. For example, when assessing the ability of medical residents to conduct an objective structured clinical examination, medical expertise might be summarized in terms of ability to interact with the patient, conduct an adequate examination, gather diagnostic evidence, and formulate an appropriate plan of therapeutic action. The development of these types of measures, however, is subjective, time consuming, and complex, and involves a consensus of opinion from many experts.

The ideal measure would be less dependent on opinion and more descriptive of the multidimensionality of management techniques. Grade of Membership analysis (GoM) is a multivariable statistical technique suited for this type of problem 20, 21, 22. It simultaneously estimates several characteristic types of practice style and estimates the grade of membership of each physician within each style. For example, a style might be described as “highly investigative” or “minimal diagnostic,” and the grade of membership coefficient for each would tell the physician the extent to which his/her behavior is identified by those terms.

The present article reports the application of GoM to responses to a mailed survey of Ontario physicians concerning the management of low back pain (LBP) [23]. Analysis of the survey and identification of practice styles were guided by the 1994 Agency for Health Care Policy and Research (AHCPR) practice guidelines on the management of acute LBP [24].