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      What Observational Studies Can Offer Decision Makers

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          Observational studies, for example cohort and case-control studies in which patients are allocated treatment on a non-random basis, are thought by some investigators to be flawed. This view results from the fact that, unlike experimental methods (randomized controlled trials; RCTs), the results of such observational studies are vulnerable to confounding. However, this view assumes that satisfactory adjustment of differences in risk or prognosis between treatment groups is impossible and it ignores some of the limitations of RCTs. While many of the problems involved in conducting RCTs could be overcome, the practical implications for researchers and funding bodies mean this is often not possible. In such circumstances, observational studies offer an alternative to an absence of any scientific evidence. While making use of observational methods, researchers must acknowledge the associated limitations: the inevitable inability to take unknown confounders into account, non-blinding of practitioners and patients, and the inclusion of practitioners’ and patients’ treatment preferences.

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          Most cited references 3

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          Explanatory and pragmatic attitudes in therapeutical trials

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            A comparison of transurethral surgery with watchful waiting for moderate symptoms of benign prostatic hyperplasia. The Veterans Affairs Cooperative Study Group on Transurethral Resection of the Prostate.

            Transurethral resection of the prostate is the most common surgical treatment for benign prostatic hyperplasia. We conducted a multicenter randomized trial to compare this surgery with watchful waiting in men with moderate symptoms of benign prostatic hyperplasia. Of 800 men over the age of 54 years who were screened between July 1986 and July 1989, 556 (mean [+/- SD] age, 66 +/- 5 years) were studied (280 in the surgery group and 276 in the watchful-waiting group). Patients' symptoms and the degree to which they were bothered by urinary difficulties were measured with standardized questionnaires and medical evaluations. The primary outcome measure was treatment failure, which was defined as the occurrence of any of the following: death, repeated or intractable urinary retention, a residual urinary volume over 350 ml, the development of bladder calculus, new and persistent incontinence, a high symptom score, or a doubling of the serum creatinine concentration. Patients were followed for three years. Of the men randomly assigned to the surgery group, 249 underwent surgery within two weeks after the assignment. Surgery was not associated with impotence or urinary incontinence. The average follow-up period was 2.8 years. In an intention-to-treat analysis, there were 23 treatment failures in the surgery group, as compared with 47 in the watchful-waiting group (relative risk, 0.48; 95 percent confidence interval, 0.30 to 0.77). Of the men assigned to the watchful-waiting group, 65 (24 percent) underwent surgery within three years after the assignment. Surgery was associated with improvement in symptoms and in scores for urinary difficulties and interference with activities of daily living (P < 0.001 for all comparisons). The outcomes of surgery were best for the men who were most bothered by urinary symptoms at base line. For men with moderate symptoms of benign prostatic hyperplasia, surgery is more effective than watchful waiting in reducing the rate of treatment failure and improving genitourinary symptoms. Watchful waiting is usually a safe alternative for men who are less bothered by urinary difficulty or who wish to delay surgery.
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              Symptom status and quality of life following prostatectomy

               F J Fowler (1988)

                Author and article information

                Horm Res Paediatr
                Hormone Research in Paediatrics
                S. Karger AG
                June 1999
                17 November 2004
                : 51
                : Suppl 1
                : 44-49
                Department of Public Health & Policy, London School of Hygiene & Tropical Medicine, London, UK
                53135 Horm Res 1999;51(suppl 1):44–49
                © 2004 S. Karger AG, Basel

                Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher. Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug. Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.

                Page count
                References: 26, Pages: 6
                Evidence-Based Medicine


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