## 3 Results and Discussion
### Characteristics of Study Patients According to the Cough Prevalence  
Table 2 shows the study participants' characteristics by cough frequency during the monitoring period. The median age in the group with frequent cough was higher than in those with less cough (56.0 vs. 16.0 years). BA prevalence in the frequent cough group was smaller than that in the less cough group (48.8% vs. 70.9%). These findings are consistent with the previous studies. A worldwide survey has shown that the most common age for the presentation was 60-69 years [19]. A Finnish adult community-based study has additionally reported that the mean age in subjects with chronic cough was 50.5 years and that age was a risk factor for chronic cough [20]. Other underlying diseases, including AC, SBS, and gastroesophageal reflux disease besides CVA, are common causes in adults, especially in Japanese [12; 21; 22; 23], while BA/CVA has been reported to be the most common cause in children with regard to the etiology of chronic cough [24]. There might be a higher cough response condition in middle-aged individuals with chronic cough compared to children and young adults with allergic asthma even under usual care taken together with a recent review [25], which has described that one of the clinical characteristics of adult-onset airway diseases is treatment resistance, compared with childhood-onset conditions.  
No differences in gender or body mass rank distribution were found between the two groups. While chronic cough has been known to be more prevalent in women than in men worldwide, this gender effect is suggested to be modulated by environmental and social influences, resulting in mixed results with regional differences [1]. As for body mass, obesity is a known risk factor for chronic cough and asthma [1, _A_], but some modifications due to environmental and social influences might attenuate the differences among study participants in the two Japanese regions.  
\begin{table}
\begin{tabular}{l c c c c} \hline \hline  & **Less Cough (\(n=55\))** & **Frequent Cough (\(n=43\))** & \(p\) **Value** \\ \hline Age, years & 16.0 (9.0, 63.0) & 56.0 (15.0, 70.0) & **0.018** \\ Men, \(n\) & 25 (45.5) & 14 (32.6) & 0.196 \\ Asthma, \(n\) & 39 (70.9) & 21 (48.8) & **0.026** \\ Height, cm & 153.8 (130.2, 162.6) & 157.0 (150.2, 163.0) & 0.147 \\ Weight, kg & 48.0 (29.0, 60.5) & 53.0 (46.5, 62.5) & 0.127 \\ Body mass rank (\(n=93\)) & & & 0.504 \\ Normal & 28 & 29 & \\ Overweight/obese & 13 & 9 & \\ Cough prevalence, \% & 0.0 (0.0, 0.0) & 50.0 (13.1, 87.0) & **<0.001** \\ \hline \hline \end{tabular} Data are expressed as median (interquartile range) or \(n\) (percentage), as appropriate. The \(p\) values of <0.05 are highlighted in bold.  
\end{table}
Table 2: Baseline characteristics of study participants according to the cough prevalence.  
\begin{table}
\begin{tabular}{l c c c} \hline \hline  & **Less Cough (\(n=55\))** & **Frequent Cough (\(n=43\))** & \(p\) **Value** \\ \hline Age, years & 16.0 (9.0, 63.0) & 56.0 (15.0, 70.0) & **0.018** \\ Men, \(n\) & 25 (45.5) & 14 (32.6) & 0.196 \\ Asthma, \(n\) & 39 (70.9) & 21 (48.8) & **0.026** \\ Height, cm & 153.8 (130.2, 162.6) & 157.0 (150.2, 163.0) & 0.147 \\ Weight, kg & 48.0 (29.0, 60.5) & 53.0 (46.5, 62.5) & 0.127 \\ Body mass rank (\(n=93\)) & & & 0.504 \\ Normal & 28 & 29 & \\ Overweight/obese & 13 & 9 & \\ Cough prevalence, \% & 0.0 (0.0, 0.0) & 50.0 (13.1, 87.0) & **<0.001** \\ \hline \hline \end{tabular} Data are expressed as median (interquartile range) or \(n\) (percentage), as appropriate. The \(p\) values of <0.05 are highlighted in bold.  
\end{table}
Table 1: Baseline characteristics of study participants in Kanazawa and Fukuoka.