## 3 Results
### Distribution and Sick Leave Days of Neck MSDs and Factors Associated Neck MSDs  
Table 2 shows the distributions of total MSDs and neck MSDs and the mean and SD (standard deviation) of sick leave days by workers' company size, occupation, age, MSD type, and work experience. In the case of total MSDs according to occupations, electrician or plumber workers were most prevalent (259, 26.3%), followed by fitters (189, 19.2%), welders (183, 18.6%), installers (157, 15.9%), and painters (100, 10.2%). There was a significant difference in frequency distributions between neck MSDs and the other MSDs (\(\chi^{2}\) = 30.389, \(p\) < 0.001). The ratio of neck MSDs was the highest in the crane operator (35.2%), followed by grinding workers (14.0%). The mean of sick leave days for neck MSDs was the highest in grinding workers (541.3 days), followed by crane operators (500.5 days). The crane operator and grinding worker had a small share of total MSDs, but the incidence of neck MSDs and the mean of sick leave days were high. In the case of total MSDs according to worker's age, workers in their 50s had a large portion (29.3%), followed by 40s (27.1%). The ratio of neck MSDs was the highest in workers in their 50s (15.9%). According to age, there was no difference in frequency distributions between neck MSDs and the other MSDs (\(\chi^{2}\) = 5.250, \(p\) = 0.154). The mean of sick leave days for neck MSDs was the highest in springs for neck MSDs was the highest in workers in their 50s (450.5 days), followed by workers in \(\geq\)60 (408.2 days). In their 50s, the overall share of MSDs and the incidence of neck MSDs were high, and the average number of sick leave days was also high. \begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Variable**} & \multicolumn{2}{c}{**Total MSDs**} & \multicolumn{2}{c}{**Neck MSDs**} & \multicolumn{2}{c}{**Sick Leave Days**} & \multicolumn{2}{c}{**Logistic Regression on Neck**} \\ \cline{2-11}  & \(N\) & \(N\)/985 & \(n\) & \% & \(n\)/\(N\) & **Mean** & **SD** & **OR** & **[95\% CI]** & \(p\) \\ \hline \multirow{4}{*}{Occupation Welder (Ref)} & 985 & 100\% & 122 & 100\% & 12.4\% & 402  
In the case of total MSDs according to MSD type, a rupture was the most prevalent type of injury (40.2%), followed by a herniated disc (38.6%) and sprain (21.2%). There was a significant difference in frequency distributions between neck MSDs and the other MSDs according to MSD type (\(\chi^{2}\) = 221.696, \(p\) < 0.001). The neck MSDs only experienced herniated disc, and the mean of sick leave days was 402.2 days. In the case of total MSDs according to the worker's work experience, workers with \(\geq\)20 years of work experience had a large portion (38.2%). There was no difference in frequency distributions between neck MSDs and the other MSDs according to work experience (\(\chi^{2}\) = 5.040, \(p\) = 0.283). The mean of sick leave days for neck MSDs was the highest in workers with 10-19 years of work experience (558.5 days). In the case of total MSDs according to company size, companies with \(\geq\)1000 workers were the most frequent (63.1%), followed by companies with 100-999 workers (17.8%). The ratio of neck MSDs was the highest at companies with \(\geq\)1000 workers (13.8%), followed by companies with 100-999 workers (11.4%). According to company size, there was no difference in frequency distributions between neck MSDs and the other MSDs (\(\chi^{2}\) = 4.048, \(p\) = 0.256). The larger the company size, the more MSDs occurred. The ratio of neck MSDs also showed a higher trend as the company size increased. The mean of sick leave days for neck MSDs was the highest at companies with \(<\)30 workers (483.4 days). Table 2 also shows the binary logistic regression analysis result on neck MSDs with five predictors: company size, occupations, age, MSD type, and work experience. The factors significantly related to neck MSDs were occupation and age (classification table value = 88.6%).