Evidence-based medicine in primary care: qualitative study of family physicians

Background

The objectives of this study were: a) to examine physician attitudes to and experience of the practice of evidence-based medicine (EBM) in primary care; b) to investigate the influence of patient preferences on clinical decision-making; and c) to explore the role of intuition in family practice.

Method

Qualitative analysis of semi-structured interviews of 15 family physicians purposively selected from respondents to a national survey on EBM mailed to a random sample of Canadian family physicians.

Results

Participants mainly welcomed the promotion of EBM in the primary care setting. A significant number of barriers and limitations to the implementation of EBM were identified. EBM is perceived by some physicians as a devaluation of the 'art of medicine' and a threat to their professional/clinical autonomy. Issues regarding the trustworthiness and credibility of evidence were of great concern, especially with respect to the influence of the pharmaceutical industry. Attempts to become more evidence-based often result in the experience of conflicts. Patient factors exert a powerful influence on clinical decision-making and can serve as trumps to research evidence. A widespread belief that intuition plays a vital role in primary care reinforced views that research evidence must be considered alongside other factors such as patient preferences and the clinical judgement and experience of the physician.

Discussion

Primary care physicians are increasingly keen to consider research evidence in clinical decision-making, but there are significant concerns about the current model of EBM. Our findings support the proposed revisions to EBM wherein greater emphasis is placed on clinical expertise and patient preferences, both of which remain powerful influences on physician behaviour.

     

Integration of Genomic and Transcriptional Features in Pancreatic Cancer Reveals Increased Cell Cycle Progression in Metastases

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Spontaneous pneumothorax in primary cavitating lung carcinoma

Primary cavitating lung carcinomas have not previously been described with spontaneous pneumothorax as the presenting manifestation. Two patients whose pneumothoraces resulted in the initial diagnosis of a primary cavitary lung carcinoma are described. Pathologic evidence of vascular invasion suggests tumor necrosis with secondary rupture into the pleural space as a likely mechanism for pneumothorax.     

Aortic dissection: magnetic resonance imaging

Fifteen patients with suspected or known aortic dissection were imaged with magnetic resonance (MR). Thirteen of these patients were eventually shown to have dissection. In most instances the diagnosis was established by aortography and/or computed tomography (CT) prior to the MR study. Surgical proof (6/13) and/or aortographic proof (10/13) were available in 11/13 patients with aortic dissection. MR demonstrated the intimal flap and determined whether the dissection was type A or type B. In addition, MR: differentiated between the true and false lumens; determined the origins of the celiac, superior mesenteric, and renal arteries from the true or false lumen in the cases where the dissection extended into the abdominal aorta (8/12); allowed post-surgical surveillance of the dissection; and identified aortoannular ectasia in the three patients who had Marfan syndrome. In addition to the 13 cases with dissection, there were two cases in whom the diagnosis of dissection was excluded by MR. Our early experience suggests that MR can serve as the initial imaging test in clinically suspected cases of aortic dissection and that the information provided by MR is sufficient to manage many cases. Additionally, MR obviates the use of iodinated contrast media.     

Peripheral vascular disease: correlation of MR imaging and angiography

The capability of magnetic resonance (MR) imaging for detecting aortic, iliac, and femoral stenoses and occlusions was evaluated. Multisection spin-echo studies at 0.35 tesla were obtained of the infrarenal aorta to the femoral bifurcation in 24 patients, all of whom had undergone intraarterial angiography within 14 days of imaging. Transaxial MR images were compared with the angiograms. Arterial stenoses and occlusions in these vessels detected by MR imaging correlated with angiographic findings in 91% of the instances. Protrusional atherosclerotic plaques and occlusions and stenoses in the aortoiliac region were demonstrated accurately on MR images; complications of previous vascular surgery, such as aneurysms at sites of previous anastomoses or endarterectomy, were also identified. Due to the limited spatial resolution, MR images failed to demonstrate some femoral stenoses. MR imaging may be used for evaluation of aortoiliac vascular disease and for follow-up study after surgical revascularization. However, the limited spatial resolution, noncomposite display of the aortoiliofemoral circulation, and lack of evaluation of peripheral runoff provided by current MR imaging techniques militate against its replacing angiography prior to vascular intervention.     

Pulmonary hemorrhage in children with glomerulonephritis

Pulmonary hemorrhage may occur in patients with immune-mediated glomerulonephritis. This association can be seen in a variety of disorders including systemic lupus erythematosus, vasculitis, Wegener's granulomatosis, anaphylactoid purpura and Goodpasture's syndrome. Immune mechanisms, such as immune complexes and/or autoantibodies, play a role in the pathogenesis of pulmonary and glomerular injury. Acute pulmonary hemorrhage can lead to respiratory failure and has a high mortality. Therapy with immunosuppressive agents such as pulse methylprednisolone and cyclophosphamide will control the hemorrhage and improve pulmonary function in most cases.     

1,25-Dihydroxyvitamin D3 inhibits the passive transfer of cellular immunity by a myelin basic protein-specific T cell clone.

1,25-Dihydroxyvitamin D3 [1,25-(OH)2D3] and related analogs have been shown to exert immunoinhibitory effects on activated lymphocytes in vitro. However, the effects of the hormone on the mammalian immune response in vivo have not been well studied. To examine the possible immunoactions of 1,25-(OH)2D3 in vivo, we employed a murine model of experimental autoimmune encephalomyelitis (EAE). In this model, T helper lymphocyte clones developed from lines of lymphocytes reactive to myelin basic protein (MBP) confer MBP immunoreactivity and demyelinating central nervous system disease on syngeneic, naive recipients of the T cell clone. Similar to peripheral blood mononuclear cells incubated with mitogen, the T cell clone evaluated in this study expressed a high-affinity specific receptor for 1,25-(OH)2D3 (VDR; K(in) = 0.03 nM) upon exposure to MBP. The MBP-stimulated clone elicited a ninefold enhancement of the local delayed hypersensitivity (DTH) response when as few as 0.5 x 10(5) cells of the T cell clone were injected into the foot pad of recipient mice. The DTH response in the recipient was completely blocked when the clone was preincubated with greater than or equal to 10(-8) M 1,25-(OH)2D3 before transfer; the half-maximal inhibitory concentration of hormone (EC50) was 5 x 10(-9) M. These data indicate that exposure of antigen-reactive T helper lymphocytes to a VDR saturating concentration of 1,25-(OH)2D3 can dramatically lessen the expression of immunoreactivity in vivo.     

Overlapping visual fields and ipsilateral retinal projections in turtles.

The possible relationship between overlap of the visual fields and the importance of ipsilateral retinal projections was investigated in the two Chelonian genera Chinemys and Trionyx. Of these two species, Trionyx has more frontally located eyes, yet ipsilateral retinal projections could not be demonstrated by radioautography. In Chinemys, on the other hand, the ipsilateral retinothalamic projections are extensive. It is suggested that, in contrast to Trionyx, the anatomic substrate of stereoscopic vision in Chinemys may be similar to that in mammals.