A Comparison of Rating Scales Used in the Diagnosis of Extraesophageal Reflux

Summary

Objective

To evaluate the level of agreement between reflux area index scores, the reflux symptom index (RSI), and the reflux finding score (RFS). Inter- and intrarater reliability of the RFS was assessed. A criterion of pH 5 was used to evaluate its effects on agreement.

Study Design

Adult participants were enrolled in this prospective study.

Methods

Eighty-two participants (72 patients and 10 controls) completed the RSI, videoendoscopy, and 24-hour pH probe monitoring. The reflux area index for extraesophageal reflux (EER) events was calculated at pH 4 and 5. Two speech-language pathologists and one otolaryngologist independently rated 36 endoscopic examinations using the RFS through a web-based system. A repeated rating of six examinations was completed.

Results

Chi-square revealed poor agreement between the diagnostic tools, regardless of which pH criterion was used. Intraclass correlation coefficients revealed fair interrater reliability of the RFS and moderate intrarater reliability. Independent-sample t tests for the RFS and reflux area index (RAI) scores failed to identify patients from normal controls.

Conclusions

The results of this study highlight the lack of agreement among the current available diagnostic tools for EER. Raters were not in agreement regarding the presence and severity of physical findings of EER. Results support the need for greater consensus among the clinical tools used in the diagnosis of EER. Physical rating scales may overidentify patients and would benefit from uniform scales and training. Assessing EER occurring at pH 5 may also yield important diagnostic information. Further research is needed to verify normative RAI cutpoints.

Introduction

Extraesophageal reflux (EER), also referred to as laryngopharyngeal reflux, pharyngeal reflux, or supraesophageal reflux, is the backflow of stomach contents into the larynx and pharynx. EER has been implicated in complaints, such as hoarseness, chronic cough, or throat clearing, a “lump in the throat” sensation, and difficulty swallowing,¹ as well as laryngoscopic findings of contact ulcers and granulomas, laryngeal carcinoma, and subglottic stenosis.² However, its diagnosis can be elusive, because symptoms are nonspecific and the physical findings are not always associated with the severity of those symptoms.2, 3, 4 A visual examination of the throat may not provide conclusive physical findings to explain the symptoms.² To date, 24-hour dual pH probe monitoring remains the “gold standard” for the diagnosis of EER, as declared by the American Academy of Otolaryngology,⁵ but may not be in full agreement with other clinical tools. A diagnosis of EER may not be valid unless a reliable means to diagnosis it exists.

Several instruments have been designed to aid in the diagnosis of EER. The reflux symptom index (RSI) is a self-administered nine-item outcome scale that assesses symptoms of EER in patients and has been used to accurately document symptom improvement of patients with EER. Based on a scoring range of 0–45, an RSI greater than 13 is considered indicative of EER.⁶ The reflux finding score (RFS) is an eight-item clinical severity scale applied by clinicians to assess physical findings of EER during fiberoptic laryngoscopy. Ranging in scores from 0 (no abnormal findings) to 26 (greatest possible score), the eight items encompass the most common laryngeal findings, such as vocal fold edema, postcommissure hypertrophy, and erythema. RFS scores greater than 7 are indicative of EER.⁷ However, several studies have demonstrated poor inter- and intrarater agreement with the RFS, which is a confounding factor in the accurate diagnosis of EER.8, 9

Data obtained from a pH probe study include the frequency, duration, and acidity levels of acid reflux events. The reflux area index (RAI) is a composite score of this information that has been “time corrected” for the total study length and is another proposed parameter to evaluate EER. RAI cutpoint scores were derived from studies10, 11 involving normal participants, in which mathematical calculations of the area under each pH level were computed. As the RAI4 represents more severe proximal reflux, the resulting cutpoint of 6.3 is lower as compared with 72.6 for RAI5. Although the parameter of pH 4 is widely used, some authors note that peptic injury to laryngeal and pharyngeal epithelium can occur at pH levels of 5¹² or even as high as 7.¹¹ A recent gastroenterology consensus report stated that the sensitivity of pH measurements could be improved by increasing the pH threshold from 4 to 5, almost doubling the number of reflux events detected.¹³ Furthermore, it has been suggested that these thresholds may explain the discordance between EER events, otolaryngologic symptoms, acid exposure levels, and laryngeal findings.¹⁴ This change may be reflected in traditional gastroesophageal reflux disease (GERD) studies, but its effects are largely unknown in the EER population.

The present investigation is designed to evaluate three areas: the level of agreement between the RSI, RFS, and pH probe monitoring results; inter- and intrarater reliability of the RFS; and the use of pH 5 as a new criterion for EER diagnosis.