Review: Effectiveness of local opinion leaders varies
ACP J Club. 1998 Jan-Feb;128:23. doi:10.7326/ACPJC-1998-128-1-023
Thomson MA, Oxman AD, Haynes RB, et al. Local opinion leaders to improve health professional practice and health care outcomes. In: The Cochrane Database of Systematic Reviews [updated 03 June 1997]. In the Cochrane Library [database on disk and CD-ROM]. The Cochrane Collaboration, Issue 3. Oxford: Update Software; 1997.
To evaluate the effectiveness of using local opinion leaders in improving health professional practice and health care outcomes.
A search was done in MEDLINE (1966 to 1995) using the following terms: professional education, influential, opinion leader, clinical competence, clinical trial, random allocation, randomized controlled trials, double-blind method, single-blind method, placebos, and random. In addition, the Research and Development Resource Base in Continuing Medical Education was searched and references of relevant studies were reviewed.
Randomized controlled trials were selected in which the participants were health care providers (not solely students), the intervention included the use of health care providers who were perceived to be educationally influential, and provider performance or health care outcomes were assessed.
Data were extracted by 2 independent reviewers and included targeted behaviors, participant characteristics, intervention characteristics, patient outcomes, and methodologic qualities.
6 trials met the inclusion criteria. The opinion leaders were educationally influential health professionals identified by their peers, and the targeted participants were community-based physicians in 4 trials and hospital-based nurses in 2 trials. Differences among the studies, including participants, settings, and outcomes, precluded pooling for a summary estimate of effect. 2 trials showed a substantial benefit resulting from the use of opinion leaders compared with no intervention. 1 trial showed that use of an opinion leader to encourage vaginal birth after cesarean section led to a 77% absolute improvement in the number of women offered a trial of labor and an 11% absolute reduction in nonvaginal births. The second trial showed a 24% absolute reduction in suboptimum urinary catheter care by nurses who had access to an opinion leader. 3 trials by the same group of authors gave varying results. Aspirin use and physical therapy increased in the group with access to an opinion leader in a trial of rheumatoid arthritis, but only physical therapy use increased in a trial of osteoarthritis. Corticosteroid use decreased in both. A trial of the management of chronic lung disease, in which bronchodilator use was encouraged and intermittent positive-pressure ventilation was discouraged by the opinion leaders, showed increased use of bronchodilators but no difference in use of intermittent positive-pressure ventilation.
Of 6 trials of opinion leaders, 5 showed positive effects on some aspects of the process of care. However, only 3 studies tested effects on patient outcomes and only 1 of these was positive.
Sources of funding: Primarily from the U.K. National Health Service with other funding from 5 Canadian, 3 U.K., 3 Norwegian, and 2 U.S. agencies.
For article reprint: Not available.
Opinions are undoubtedly important in the practice of medicine. Indeed, the Delphi method of gathering opinions has been a recognized means of problem solving for many years. It has been used in small-scale projects and large national initiatives—for example, the Drug Efficacy Study from the U.S. National Academy of Sciences done in the 1960s (1). The objectives of the review by Thomson and colleagues were to measure the effectiveness of local opinion leaders and other complementary interventions compared with no intervention or with other interventions and to assess the influence of local opinion leaders on community-based compared with university-based health care providers.
Several interesting questions arise from this review: How is an opinion leader identified? Who is affected by the local opinion leader? What is the geographic area of influence of that local opinion leader? What is the duration of the opinion leader's influence?
Wennberg's small area analyses (2) have identified that practice variation may occur from city to city and from hospital to hospital. This variation is expected to be reduced by the development of pathways and guidelines. Although they are being developed by national organizations, they must be willingly accepted by hospital medical staff members and tailored to fit the care given by the physicians at that institution. In the studies identified by Thomson and colleagues, the sites of the studies varied from > 1 city to multiple hospitals in 1 city to randomly chosen hospital wards within 1 hospital. The smaller the geographic area being studied, the greater the potential Hawthorne effect.
With respect to duration of influence, the time from intervention to evaluation varied from 2 to 24 months. Even if an influence can produce a favorable outcome, unless it is repeated its effect is certain to wane.
The most important aspect of this review may be that it reveals the paucity of well-controlled studies that have attempted to identify the effectiveness of opinion leaders and the influence of temporal and geographic variations on their effectiveness.
Edward L. Middleman, MD, MPH
Methodist Hospitals of DallasDallas, Texas, USA