6 Evidence-Based Medicine in the Diagnosis and Treatment of Chronic Rhinosinusitis

Chronic rhinosinusitis (CRS) is a complex disorder that has many potential etiologies and associated disorders. There are few, if any, predictable etiologies. The spectrum of disease can vary dramatically from individual to individual and the responsiveness to treatment is often unpredictable. As a result, there are multiple potential diagnostic approaches and many differing treatment options that may be used in isolation or in combination. The literature related to CRS is growing rapidly in an effort to add some clarity to this problem and to improve treatment. Unfortunately, much of the CRS literature is poorly controlled and there is little level A or level B evidence. This chapter will attempt to identify the highest quality of the reported evidence to establish the most predictable principles of evidence-based management of CRS. The evidence is then broken down into four grades from A (best evidence) to D (worst evidence) and then subcategorized into eight levels of evidence (1a, 1b, 2a, 2b, 3a, 3b, 4, and 5).1 Where possible, the highest evidence in the different areas will be discussed. This chapter will focus on the treatment of CRS because the scope of this chapter does not allow for an evaluation of the evidence as it relates to diagnosis.

Definitions

To evaluate the quality of the evidence, it is important to rely on a well-defined statement. Until 2003, CRS was not clearly defined and the general term sinusitis was commonly used. In 1997, a general categorization of rhinosinusitis was applied to these disorders because it was clear that both the nose and sinuses are involved.² A task force under the direction of the Sinus and Allergy Health Partnership and supported by the American Rhinologic Society, the American Academy of Otolaryngic Allergy, and the American Academy of Otolaryngology-Head and Neck Surgery used the literature to create universally acceptable definitions for rhinosinusitis and CRS.³

The task force proposed that because it has become clear that inflammation is the major universal finding in all patients with rhinosinusitis, newer definitions have been developed to describe rhinosinusitis. The newer definitions are as follows: Rhinosinusitis is a group of disorders characterized by inflammation of the mucosa of the nose and paranasal sinuses. Chronic rhinosinusitis is rhinosinusitis of at least 12 consecutive weeks’ duration. Therefore, CRS is a group of disorders characterized by inflammation of the mucosa of the nose and paranasal sinuses of at least 12 consecutive weeks’ duration.³ This definition was supported by a large multispecialty group of otolaryngologists and allergists representing six national societies⁴ and was used to identify articles from the literature to include in this review.

Antibiotics and Antifungals

There are several reviews that suggest the roles of antimicrobials and antifungals in the management of CRS. A thorough review in 2005 by the European Academy of Allergology and Clinical Immunology (EAACI), along with the European Rhinologic Society, examined the literature in relationship to the treatment of CRS and nasal polyps.⁵ They graded the evidence from A (strong evidence) to D (no evidence). They also tried to determine the relevance of the evidence. Although there was good evidence of the effectiveness of antibiotics for the treatment of acute bacterial rhinosinusitis (ABRS), the overall evidence for antimicrobial treatment of CRS was poor.⁵ The evidence for oral antibiotics used for less than 2 weeks was graded at level 3 (case–control trials) but with a recommendation of C with no relevance. For a long-term treatment with antibiotics, the data were also rated a recommendation C but with some relevance. There was poor evidence to support either short-term or long-term antibiotic treatment for nasal polyps.⁵

A Cochrane Collaboration review in 2001 also looked at the evidence for antibiotics in comparison with placebo in the treatment of CRS without polyps.⁶ A thorough review of the literature identified only one study where antibiotics were compared with placebo in CRS without polyps. Their findings state that “There is limited evidence from one small study to support the use of systemic antibiotics for the curative treatment of chronic rhinosinusitis in adults.”⁶ This recommendation also suggested that the risk of bias supporting the results in this one study was high. Their final recommendations were that further good quality trials, with large sample sizes, are needed to evaluate the use of antibiotics in CRS.⁶ Finally, Clinical Practice Guidelines published in 2007 by the American Academy of Otolaryngology-Head and Neck Surgery recommend antibiotics for the treatment of ABRS and suggest a benefit of nasal irrigations in CRS; however, no mention is made regarding the antimicrobial treatment in CRS.⁷

One application of antibiotics may be for the reduction of inflammation associated with CRS by low-dose, long-term macrolide therapy. A review in 2009 suggests that “low-dose, long-duration macrolide therapy is a viable option for patients refractory to standard medical or surgical therapy,” although the authors admit that this is based on limited evidence and that even in the best circumstances, the control of symptoms would be expected to be modest and not fully controlled.8 “Daily clarithromycin (250 mg), azithromycin (250 mg), or roxithromycin (150 mg) should be continued for at least 12 weeks to achieve measurable results.”⁸

There has been a substantial interest in the role of nasal antibiotic irrigations or nebulized antibiotics for the treatment of CRS.⁹ In addition, there has been recent recognition of the potential roles of biofilms and superantigens that are produced by bacteria and may play a role in the etiology, propagation, or potentially resisting therapy.^3,4 In such cases, antibiotic irrigants or nebulization may be of benefit. Despite this interest, controlled studies have been poorly performed or were not randomized. In addition, given that there is some evidence to support the use of nasal irrigations independently, it is hard to isolate the effects of antibiotics in comparison with irrigations alone. Although anecdotal cases of good responsiveness are seen in clinical practice there is little evidence to support the use of antibiotic irrigations in CRS with or without polyps.

The effectiveness of oral antibiotics in the treatment of CRS either with or without polyps is poor. Oral antibiotics may be considered in patients who develop an acute purulent exacerbation of CRS. Whether or not antibiotic irrigations have an effect under these circumstances is not known, although controlling infection or even colonization of methicillin-resistant Staphylococcus aureus by mupirocin irrigations would seem reasonable.

There has been a substantial interest in the role of fungus in the development of inflammation in CRS.^10,11 One of the problems with assessing the role of fungus is that there are numerous ways in which fungus can be relevant in rhinosinusitis: acute fungal infections, allergic fungal rhinosinusitis (AFS), and chronic nonimmunoglobulin E-mediated inflammation. Overall there is a sense that “the current evidence supports the notion that AFS is part of a spectrum of severe CRS with polyps,”¹² but that an immunologic response to fungus is not universally associated with rhinosinusitis.¹¹ Furthermore, although there is some evidence that anti-inflammatory therapy may be an effective treatment in patients who may have fungal-mediated CRS, there is very little good evidence that either systemic or topical antifungal therapy has any role in the treatment of CRS either with or without polyps. The EAACI report suggests that there were no data supporting the role of systemic antifungals and that the level of recommendation for topical antifungals is a D.⁵ A systematic review of the literature, published in 2011, does not support the use of topical amphotericin B for the treatment of CRS.¹³

Saline Irrigations

Saline irrigations are frequently used to treat patients with sinonasal symptoms. Initially there was only anecdotal evidence and saline irrigations were regarded as a homeopathic therapy to be adjunctively used with other medical therapy for chronic sinusitis. However, during the past decade there has been increasing evidence that saline irrigations are not only inexpensive and well tolerated but also have a valuable role in improving sinonasal health and quality of life in patients with CRS.

Saline solution can be administered to the nasal cavity by a variety of devices including bottle, spray, or nebulizer. There is no standard recipe for making saline solution. While some solutions are isotonic, others have hypertonic and buffered concentrations. Personal preference typically determines the concentration used; however, many practitioners prefer hypertonic saline solution as it has been associated with increased mucociliary clearance. A study by Talbot et al demonstrated an increased mucociliary clearance of saccharin after using buffered hypertonic saline irrigations in healthy volunteers.¹⁴ Interestingly, another study by Ural et al demonstrated decreased mucociliary transit times with hypertonic saline irrigations in patients with chronic sinusitis. In contrast, patients with allergic rhinitis and acute sinusitis had improved mucociliary clearance with isotonic saline irrigations.¹⁵

Several studies demonstrate benefits from using hypertonic and isotonic saline irrigations. Rabago et al¹⁶ conducted a 6-month randomized control trial testing the efficacy of daily hypertonic saline irrigations in patients with sinusitis. Subjective outcomes were measured with the Medical Outcomes Survey Short Form-12, the Rhinosinusitis Disability Index, and a Single-Item Sinus-Symptom Severity Assessment. Not only did the experimental subjects report an overall improvement of sinus-related quality of life, but they also reported fewer 2-week periods with sinus-related symptoms (p < 0.05), less use of antibiotics (p < 0.05), and less use of nasal spray (p = 0.06).¹⁶ In the subsequent study, which was an uncontrolled 12-month follow-up study, there was still a sustained improvement in the quality of life in patients using hypertonic saline nasal irrigations for sinonasal symptoms.¹⁷ In contrast, the usage of isotonic saline irrigations was demonstrated in a study by Bachmann et al.¹⁸ This randomized controlled double-blind trial compared the effectiveness of endonasal irrigations with isotonic EMS salt (balneotherapeutic water) solution to that of isotonic sodium chloride solution in the treatment of adult patients with CRS. Subjective complaints, endonasal endoscopy, and radiography results revealed a significant improvement in both groups (p = 0.0001). In comparison, the two groups were not significantly different in outcome.¹⁸

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