## 3 Results
### Correlation of the AHI, ODI, T90, and TIB  
To determine the overall correlation of the AHI, ODI, T90, and TIB, [PERSON]'s correlation was calculated for 100 pairs of examinations (first and second polygraphic recordings). The Pearson's correlations for the AHI, ODI, T90, and TIB are 0.9199, 0.9282, 0.8126, and 0.4993, respectively. These results represent a strong correlation in the case of AHI, ODI, and T90, but only a moderate of correlation was measured for TIB (Tables 2 and 3). To determine the severity-range-specific relationship of the first and second polygraphic examinations, [PERSON]'s correlations of the AHI, ODI, T90, and TIB were calculated for each severity group. The results are presented in Tables 2 and 3. The correlation of AHI was good for the severe group, moderate for the mild group, and low for the moderate and negative groups. In case of the ODI, the correlation was good for the severe, mild, and negative groups, and was medium for the moderate group. In case of T90, the correlation was high for the severe and mild groups, and low for the moderate and negative groups. The values are shown in Table 2. \begin{table}
\begin{tabular}{l c c c c c} \hline  & & **Negative** & **Mild** & **Moderate** & **Severe** \\ \cline{2-6}  & & **Mean SD** & **Mean SD** & **Mean SD** & **Mean SD** \\ \hline
2 nd PG & AHI (/h) & 2.81 (1.51) & 9.27 (3.11) & 21.64 (3.64) & 54.82 (18.35) \\  & ODI (\%) & 5.36 (2.4) & 14.83 (11.69) & 30.95 (10.85) & 51.25 (18.92) \\  & T90 (\%) & 0.3 (0.61) & 8.89 (22.07) & 22.02 (25.25) & 33.81 (24.32) \\  & MinO2(\%) & 88.5 (2.88) & 84.1 (5.67) & 77.6 (5.02) & 68.3 (11.69) \\  & TIB (min) & 437.9 (102.6) & 456.4 (125.4) & 435.9 (100.6) & 420.7 (80.2) \\  & Num. & 10 & 29 & 21 & 40 \\ \hline \end{tabular}  
* Mean: average, SD: standard deviation, AHI: Apnea-Hypopnea Index, ODI: Oxygen Desaturation Index, T90: Time spent below 90% of oxygen saturation, MinO2: Minimal oxygen saturation level, TIB: Time In Bed, Num.: Number of elements in a given severity group.  
\end{table} 
Table 1: _Cont._ \begin{table}
\begin{tabular}{l c c c c c c c} \hline  & \multicolumn{2}{c}{**AHI1-2**} & \multicolumn{2}{c}{**ODII-2**} & \multicolumn{2}{c}{**T901-2**} & \multicolumn{2}{c}{**TIB1-2**} \\ \cline{2-7}  & **Pearson** & \(p\) & **Pearson** & \(p\) & **Pearson** & \(p\) & **Person** & \(p\) \\ \hline Total & 0.9199 & 0.001 & 0.9282 & 0.001 & 0.8126 & 0.001 & 0.4993 & 0.001 \\ Negative & 0.1380 & 0.7446 & 0.7005 & 0.053 & 0.3363 & 0.4153 & 0.7767 & 0.0234 \\ Mild & 0.6329 & 0.002 & 0.8319 & 0.001 & 0.9842 & 0.001 & 0.3720 & 0.0469 \\ Moderate & 0.1419 & 0.4823 & 0.4696 & 0.0135 & 0.2928 & 0.1383 & 0.5329 & 0.0042 \\ Severe & 0.7947 & 0.001 & 0.8465 & 0.001 & 0.8652 & 0.001 & 0.6016 & 0.001 \\ Moderate and severe together & 0.8634 & 0.001 & 0.8792 & 0.001 & 0.6983 & 0.001 & 0.5552 & 0.001 \\ \hline \end{tabular}  
* AHI1-2: Correlation of the apnea-hypopnea index of the first and second examinations. ODI1-2: Correlation of the oxygen desaturation index of the first and second examinations. T90: Correlation of the percentage of time spent below 90% oxygen saturation. Negative, Mild, Moderate, and Severe: severity ranking obstructive sleep apnea syndrome according to the AASM classification. Total: the result of all the examinations of the 100 patients. Moderate and severe: moderate and severe groups together.  
\end{table} 
Table 2: [PERSON]’s correlation of the AHI, ODI, T90, and TIB of the two consecutive polygraphic examinations (see text). \begin{table}
\begin{tabular}{l c c c} \hline  & **Searity Rank** & **Pattern** \\ \multicolumn{1}{c}{\multirow{2}{*}{**Sample Size**}} & **\(p\)** & \(p\)** \\ \hline Moderate and severe: & 63 & 0.5619 & 0.1289 \\ Total & 98 & 1.0 & 1.454 \\ \hline \end{tabular}  
\(p\): two-tailed probability. The high \(p\) values show the lack of significant differences between the two examinations of the patients.  
\end{table}