Original article
The role of before-after studies of therapeutic impact in the evaluation of diagnostic technologies

https://doi.org/10.1016/0021-9681(86)90051-2Get rights and content

Abstract

Studies in which clinicians' therapeutic plans are determined before and after application of a new test offer an attractive alternative to randomized trials as a strategy for establishing the usefulness of diagnostic technologies. To maximize scientific credibility such studies should include a number of design features: specific clinical questions should be addressed; consecutive patients presenting with a clinical problem should be entered; the test's accuracy should be assessed; and changes in therapy should be described in sufficient detail to allow an estimate of the impact on patient outcome.

Even with attention to these issues, the validity of before-after studies of therapeutic impact is limited by possible discrepancies between clinicians' stated plans and actual behavior, and by the often tenuous link between change in therapy and patient benefit. Before-after designs will be most useful in primary investigations which, if positive, should be followed by more rigorous studies to establish patient benefit.

References (30)

  • AH Robbins et al.

    Observations on the medical efficacy of computed tomography of the chest and abdomen

    Am J Roentgenol

    (1978)
  • AF Connors et al.

    Evaluation of right-heart catheterization in the critically ill patient without acute myocardial infarction

    N Engl J Med

    (1983)
  • L Goldman et al.

    Ordering patterns and clinical impact of cardiovascular nuclear medicine procedures

    Circulation

    (1980)
  • JT Hanlon et al.

    The contribution of echocardiography to the community practice of cardiology. A prospective study

    Chest

    (1984)
  • JI Lichtenstein et al.

    The effectiveness of panendoscopy on diagnostic and therapeutic about chronic abdominal pain

    J Clin Gastroenterol

    (1980)
  • Cited by (67)

    • Influence of cone beam computed tomography on endodontic treatment planning: A systematic review

      2022, Journal of Dentistry
      Citation Excerpt :

      Validated tools for the assessment of therapeutic efficacy studies are limited [10]. Potential bias in the studies were examined based on Guyatt's critique [13]. Risk of bias assessment was performed using a modification of the Quality Assessment of Diagnostic Accuracy Studies (QUADAS) tool [14] (Appendix Table 2).

    • The impact of endoscopic ultrasound on the management and outcome of patients with oesophageal cancer: an update of a systematic review

      2022, Clinical Radiology
      Citation Excerpt :

      This was appropriate because the review confirmed there were many low-quality studies describing heterogeneous results that were mostly poorly reported. Studies with and without a comparison group were included to present all published data, but there were few studies without significant risk of bias from which to draw strong conclusions about the impact of EUS on recurrence and survival rates.67 Lastly, publication bias could not be evaluated, but it was assumed that the estimates of effect size reported here are likely to be at the higher end of those observed in routine clinical practice.

    • Decision making about healthcare-related tests and diagnostic test strategies. Paper 2: a review of methodological and practical challenges

      2017, Journal of Clinical Epidemiology
      Citation Excerpt :

      This design is mainly appropriate for measuring the added accuracy or efficacy of an add-on test [35]. The main criticism of this design is that clinicians’ reported plans during a research study may differ from their decision-making in an actual scenario, and so implementation of the test may not produce the same results achieved in RCTs [36]. Some investigators use case–control study designs in an attempt to determine accuracy of a test.

    • Systematic survey of randomized trials evaluating the impact of alternative diagnostic strategies on patient-important outcomes

      2017, Journal of Clinical Epidemiology
      Citation Excerpt :

      This hierarchy implies that smaller subsets of patients will benefit from a test as researchers advance from simply measuring diagnostic accuracy to evaluating improvements in outcomes (Appendix Fig. 1 on the journal's Web site at www.elsevier.com) [9]. When, despite demonstration of test accuracy, patient benefit remains in doubt, randomized clinical trials (RCTs) that address the impact of alternative diagnostic strategies on patient-important outcomes are required [6–8,10–12]. This principle is well established for screening tests, and investigators have conducted many trials of screening tests.

    View all citing articles on Scopus

    Dr Guyatt is a Career Scientist of the Ontario Ministry of Health.

    View full text