Voice outcomes of laryngopharyngeal reflux treatment: a systematic review of 1483 patients

The aim of this study is to explore voice quality modifications in laryngopharyngeal reflux (LPR) disease and to understand better the pathophysiological mechanisms underlying the development of communicative disability. Biological Abstracts, BioMed Central, Cochrane database, PubMed and Scopus were assessed for subject headings using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) recommendations. Relevant studies published between January 1990 and December 2015 describing the evaluation of voice quality in LPR disease were retrieved. Issues of clinical relevance, such as LPR diagnosis method, treatment efficacy and outcomes, were evaluated for each study. We determined the grade of recommendation for each publication according to the Oxford Centre for Evidence-Based Medicine evidence levels. The search identified 145 publications, of which 25 studies met the inclusion criteria for a total of 1483 LPR patients. Data were extracted by 2 independent physicians who identified 16 trials with a IIb evidence level, 7 trials with a IIa evidence level and 2 RCTs with a Ib evidence level where 4 patient-based instruments and 5 clinician-based instruments were used. The main voice assessment outcomes reported were hoarseness assessments by physicians or patients, followed by acoustic parameters; 15 and 14 articles, respectively, demonstrated significant improvements in subjective and objective voice assessments after treatment. The methodology used to measure acoustic parameters (i.e. sustained vowel duration, the sample portion choice for measurement, etc.) varied from one study to another. The majority of studies indicated that voice quality assessments (especially acoustic parameters) remain an interesting outcome to measure the effectiveness of treatment, but further studies using standardised and transparent methodology to measure acoustic parameters are necessary to confirm the place of each tool in the LPR disease evaluation.