Evidence-Based Medicine

Evidence-based medicine (EBM) represents a new paradigm in healthcare. Decision-making in medicine, which is never easy, is complicated further by the rapid proliferation of new preventive, diagnostic, and therapeutic alternatives for the same clinical condition. The EBM movement is intended to promote the conscious, explicit, and rational utilization of the best clinical evidence available to make decisions most appropriate for individual patients.1

Sound clinical decisions depend upon a combination of physician clinical expertise, external evidence, and patient preference information: (i) without clinical expertise, diagnosis and treatment must rely upon a "cookbook" approach; (ii) without current best evidence, the most advanced diagnostic and treatment strategies may not be implemented. At the same time, external evidence is by itself insufficient because it may be inapplicable or inappropriate for an individual patient; and (iii) without consideration for the needs, circumstances and preferences of individual patients, benefit of treatment is diminished by non-adherence.2

The Vest® System: Peer-Reviewed Evidence

The immediate goal of Airway Clearance Therapy is to clear pulmonary secretions effectively and reliably. Among dozens of clinical studies and laboratory studies of High Frequency Chest Wall Oscillation (HFCWO) published in adjudicated journals, those specifically designed to measure secretion clearance and/or impact on short- and long-term pulmonary function are cited below.

Secretion Clearance — The following randomized controlled trials (RCTs) of The Vest® Airway Clearance System published in the peer-reviewed literature demonstrate it's superiority to professionally administered Chest Physiotherapy in terms of volume of mucus cleared.

  • Hansen (1990): Significantly more mucus was cleared using HFCWO in contrast to CPT in a study including randomized CF patients.
  • Kluft (1996): Significantly more mucus was cleared using HFCWO in contrast to CPT in a study including randomized stable CF patients.

The studies cited below demonstrate the significant effectiveness and equivalence of therapy with The Vest®System to professionally administered CPT in terms of volume of mucus cleared:

  • Braggion (1995): In a study comparing CPT, PEP, and HFCWO in randomized CF patients, all three methods resulted in equal but significantly increased sputum production.
  • Scherer (1998): Using HFCWO, Oral Airway Oscillation, and two forms of CPT, non-randomized stable CF patients achieved equal but significantly enhanced secretion expectoration with all three methods.

The Vest® System received FDA clearance to market as an airway secretion clearance device. The clinical relevance of the studies cited above is that they identify a modality that clears secretions effectively and reliably.

Pulmonary Function — Pulmonary function tests (PFTs) are fairly specific measures of lung performance. Results reflect, among other things, the infection/inflammation status of the lungs. For this reason, it is worthwhile to determine whether Airway Clearance Therapy affects PFTs. Both short- and long-term non-randomized controlled trials demonstrated the positive effects of HFCWO on pulmonary function in certain patients.

  • Arens (1994): In a short-term RCT, equal but important improvements in pulmonary function and clinical status were achieved in acutely ill CF patients receiving either CPT or HFCWO.
  • Warwick (1991): In a long term non-randomized (retrospective-prospective) study comparing CPT and HFCWO in CF patients, patients receiving HFCWO obtained impressive stability in PFT scores and, in many cases, significant clinical improvement.

The studies summarized above provide statistically significant evidence of the effectiveness of therapy with The Vest® System as a method for secretion clearance and as an intervention to mitigate decline in pulmonary function.

  • In all six studies, The Vest® System was equivalent or superior to CPT.
  • In all studies, the goals of secretion clearance and/or maintenance of PFTs were accomplished; no significant adverse events occurred.
  • Because in-home CPT is rarely administered with the standard of rigor achieved in hospitals or outpatient clinics, research results may overstate the efficacy of CPT.

The Vest® System: Supplementary Research

Additional studies have been published as abstracts, and as papers in professional publications, or are presently in the clinical trials stage of development. The following are among those of particular clinical interest:

  • Anbar (1998): In this retrospective/prospective study of the effects of HFCWO on the PFTs of 54 CF patients, those who previously used CPT obtained a 7% improvement in FEV1 after three months of HFCWO, those previously untreated obtained average FEV1 improvements of 11%. Significantly, these outcomes were achieved with treatment averages of only 19 therapy minutes/day.
  • Oermann (2000): In a study to compare efficacy, safety, and patient acceptance of CPT, the Flutter® Valve, and HFCWO administered via The Vest® System, patients expressed a clear preference for The Vest® System. The link between patient satisfaction and treatment adherence is documented in terms of significantly fewer missed therapies among users of The Vest® System compared with either CPT or Flutter® users.
  • Burnett (1993): A controlled study comparing CPT and HFCWO in CF patients demonstrated significantly greater secretion clearance with HFCWO.
  • Rumbak (2001): In an outcomes assessment of COPD patients after 90 days of therapy with The Vest® System, patients who completed the study and elected to continue therapy demonstrated clinically and statistically significant reductions in dyspnea and gains in general health, exercise tolerance, and treatment satisfaction and adherence.
  • Babcock (2002): This prospective study demonstrated that use of HFCWO as part of lung procurement protocol increased the quality and quantity of lungs available for transplantation.
  1. Reilly BM, Hart A, Evans AT. Evidence-based medicine: a passing fancy or the future of primary care? Dis Mon 1998; Aug.: 370-399.
  2. Smyth Roselind L. Evidence-based pediatric pulmonary medicine: How can it help? Pediatric Pulmonology 1998; 25: 118-127.