Results
A total of 69 patients were enrolled in the study. Demographic parameters and baseline reflux symptoms are summarized in Table 1 . The male-to-female ratio was 25/43. The mean value of Age, BMI, and RSI were 55.93 ± 13.02, 24.8 ± 2.71, and 12.28 ± 6.19. The most severe reflux symptom was globus, with a mean value of 3.77 ± 1.7.
The 24hr MII-pH monitoring revealed the characteristics of pharyngeal reflux patterns. Table 2 shows the properties of pharyngeal reflux depending on acidity, event time, and body position. The number of weakly acidic pharyngeal reflux was high (3.41 ± 3.27), while acidic and weakly alkaline reflux were 0.93 ± 2.34 and 0.55 ± 1.02, respectively. The hourly incidence of daytime reflux, 0.229 ± 0.282, was statistically more frequent than that of nighttime reflux (0.097 ± 0.13; p < 0.001). The reason for using hourly incidence, and not the total number of reflux, is for even statistical comparison over the same observation time. In the analysis according to body position, the hourly incidence of pharyngeal reflux was statistically higher in the upright position (0.327 ± 0.339) than during the recumbent position (0.064 ± 0.117; p < 0.001).
We sought to evaluate the relationship between reflux episodes and mealtimes. The common mealtimes of enrolled patients were concentrated at 9:00–10:00 and 16:00–18:00 out of 24 hours (Figure 1A ). The high incidence of pharyngeal reflux was recorded at 10:00–11:00 and 19:00–20:00 out of 24 h (Figure 1B ). We found that the incidence of pharyngeal reflux increased after mealtime (Figure 1C ). Therefore, we compared the number of pharyngeal reflux episodes for 2 h before and after mealtime (Table 3 , Figure 2 ).Table 3 shows the comparison between pre- and post-prandial pharyngeal reflux frequency within 2 h around mealtime. All post-prandial reflux episodes (1.256 ± 0.878) were statistically more frequent than all pre-prandial reflux episodes (0.632 ± 0.548, p < 0.001). In classification according to acidity, the number of weakly acidic post-prandial reflux (0.853 ± 0.665) was significantly higher than that of pre-prandial weakly acidic reflux (0.433 ± 0.447, p < 0.001). The numbers of post-prandial acid reflux and pre-prandial acid reflux were 0.212 ± 0.420 and 0.134 ± 0.375, respectively (p = 0.11). The numbers of post-prandial weakly alkaline reflux and pre-prandial weakly alkaline reflux were 0.191 ± 0.390 and 0.065 ± 0.180 (p = 0.012), respectively. Figure 2 shows the frequency of pharyngeal reflux for all participants based on the center zero, which represented the mealtime. The number of post-prandial pharyngeal reflux was relatively larger than that of pre-prandial pharyngeal reflux.
Twenty-six patients were recruited as a normal control group, and pharyngeal reflux episodes were found in 5 patients on 24hr-MII-pH monitoring. The mean number of pharyngeal reflux episodes in the 5 patients was 1.4 times. Table 4 reveals whether there was a difference in the timing of post-prandial pharyngeal reflux between normal controls and LPR patients. Analyzing the time relationship between mealtime and pharyngeal reflux episodes, the timing of post-prandial reflux was 58.2 ± 61.8 minutes in the LPR patient group and 38.4 ± 34.2 minutes in the normal control group, with no statistical difference (p = 0.322).