Sensitivity, Specificity, and Reproducibility of the Brazilian Portuguese Version of the Reflux Symptom Index

The diagnosis of laryngopharyngeal reflux is controversial. There is currently no gold standard, so it relies mainly on suspicious clinical symptoms and videolaryngoscopic findings. Unfortunately these signs and symptoms are common to other causes of chronic laryngitis. Scoring systems have been proposed to reduce subjectivity in clinical diagnosis. The most widely used and accepted is the Reflux Symptom Index, which has already been translated into over 10 other languages.

Study the psychometric properties of the Brazilian Portuguese version of the Reflux Symptom Index (Índice de Sintomas de Refluxo - ISR).

One hundred and fifty-four adults, 88 with laryngopharyngeal reflux and 66 healthy controls, were studied over a 6-month period, responding to the ISR after thoroughly investigated on possible other causes of chronic laryngitis and the presence of gastroesophageal disease. Test and retest reliability was addressed by reapplying the score to a random subgroup of 101 subjects.

The ISR of subjects was significantly higher than that of controls (Student t test for independent samples, P < 0.001). The ISR also showed high temporal stability and reproducibility (ICC of 0.988 with a confidence interval of 0.982-0.992). The ISR at a cutoff of 13 points presented a sensitivity of 78.4%, a specificity of 95.4%, a false negative of 4.55%, a false positive of 21.59%, a positive predictive value of 95.83%, and a negative predictive value of 86.93%.

The ISR proved to be a valid and reliable diagnostic tool.