INTRODUCTION: To analyze the epidemiological characteristics of placebo controlled randomized trials (RCTs) that evaluated the effectiveness of medical treatments over placebo in laryngopharyngeal reflux (LPR).
MATERIAL AND METHODS: PubMed, Cochrane database, and Scopus were assessed for subject headings using the PRISMA recommendations. Placebo RCTs published between 1990 and 2018 describing clinical evolution throughout LPR treatment were extracted and analyzed for evidence-based level, number of patients, inclusion and exclusion criteria, gender, age, symptoms and signs used as therapeutic outcomes, and treatment schemes.
RESULTS: The database search identified 15 placebo RCTs with a total of 763 patients. The mean age of patients was 48.59 years and 52.68% of patients were female. Among the 15 placebo RCTs, 9 have demonstrated a partial or total superiority of a medical treatment over placebo. Most of authors based the LPR diagnosis on symptoms and signs without additional examination. Our analysis reveals an important heterogeneity between studies with regard to the diagnosis criteria, treatment schemes and signs and symptoms used as therapeutic outcomes. Many commonly reported signs and symptoms related to LPR were not used as therapeutic outcomes. Half of the authors did not prescribe diet and behavioral changes along the treatment.
CONCLUSION: The controversy in the RCTs about the superiority of medical treatment over placebo in LPR disease is probably due to discrepancies in the diagnosis method, exclusion criteria, therapeutic schemes and the lack of comprehensive tools for the assessment of signs and symptoms. In this context, the LPR Study Group of Young-Otolaryngologists of the International Federations of Oto-Rhino-Laryngological Societies developed two new instruments to precisely assess signs and symptoms throughout the treatment. These two instruments could be used in future trials comparing medical treatment over placebo in LPR disease.