*3.4. Predictors of Anxiety in the Nine Countries*

Similarly to the previous analyses, the multiple logistic regression was conducted for anxiety to find predictors among demographic and health-related variables among university students in each country. In Colombian students (Table S12), only comparative PH was found to be a significant predictor of anxiety (estimate = 1.35, 95% *CI* = 0.132, 2.560, *SE* = 0.46, OR = 3.84, *Z* = 2.17, Wald's χ2(1) = 4.72, *p* < 0.05). However, the bootstrapping procedure did not confirm it (BCa 95% *CI*<sup>B</sup> = −0.266, 2.819). The model's fit was sufficient, χ2(143) = 25.58, *p* < 0.01, *R*<sup>2</sup> CS = 0.15, *R*<sup>2</sup> McF = 0.13, *R*<sup>2</sup> <sup>N</sup> = 0.21. All estimates of the multivariate logistic regressions are shown in Figure 4.


**Figure 4.** Logistic regression estimates heatmap for anxiety symptoms among university students from Colombia, Czechia, Germany, Israel, Poland, Russia, Slovenia, Turkey, and Ukraine. Positive estimates are marked in red, negative estimates are marked in blue. PIC = Perceived Impact of COVID-19 on Students' Well-being. \* *p* < 0.05, \*\* *p* < 0.01, \*\*\* *p* < 0.001.

Among students in Czechia (Table S13), the following predictors of anxiety were found: study level (estimate = 1.35, 95% *CI* = 0.132, 2.560, *SE* = 0.46, OR = 3.84, *Z* = 2.17, Wald's χ2(1) = 4.72, *p* < 0.05), exposure to the coronavirus (estimate = 1.35, 95% *CI* = (0.132, 2.560), *SE* = 0.46, OR = 3.84, *Z* = 2.17, Wald's χ2(1) = 4.72, *p* < 0.05), PIC-qualifications (estimate = 1.35, 95% *CI* = 0.132, 2.560, *SE* = 0.46, OR = 3.84, *Z* = 2.17, Wald's χ2(1) = 4.72, *p* < 0.05), PIC-economic status, PA (estimate = 1.35, 95% *CI* = 0.132, 2.560, *SE* = 0.46, OR = 3.84, *Z* = 2.17, Wald's χ2(1) = 4.72, *p* < 0.05), and comparative PH (estimate = 1.35, 95% *CI* = 0.132, 2.560, *SE* = 0.46, OR = 3.84, *Z* = 2.17, Wald's χ2(1) = 4.72, *p* < 0.05). However, bootstrap showed a significant effect only for exposure to the coronavirus (BCa 95% *CI*<sup>B</sup> = 0.024, 1.764) and PIC-social relationships (BCa 95% *CI*<sup>B</sup> = 0.100, 2.533). The model presents a good fit, χ2(296) = 48.69, *p* < 0.001, *R*<sup>2</sup> CS = 0.15, *R*<sup>2</sup> McF = 0.21, *R*<sup>2</sup> <sup>N</sup> = 0.27.

The model of regression did not find any statistically significant predictors of anxiety in the sample of German university students (Table S14). Moreover, bootstrap did not show significance. However, the model's fit was satisfactory with χ2(255) = 33.35, *p* < 0.001, *R*<sup>2</sup> CS = 0.12, *R*<sup>2</sup> McF = 0.30, *R*<sup>2</sup> <sup>N</sup> = 0.35.

In the sample of students from Israel (Table S15), the following predictors of anxiety were revealed: gender (estimate = 1.03, 95% *CI* = 0.155, 1.901, *SE* = 0.45, OR = 2.80, *Z* = 2.31, Wald's χ2(1) = 5.32, *p* < 0.05; BCa 95% *CI*<sup>B</sup> = 0.039, 2.007), and total PIC (estimate = 1.96, 95% *CI* = 0.757, 3.172) *SE* = 0.62, OR = 7.13, *Z* = 3.19, Wald's χ2(1) = 10.17, *p* < 0.001; BCa 95% *CI*<sup>B</sup> = 0.471, 3.300), which was also confirmed using the bootstrap procedure. The level of study and PH were not included in the model because these variables did not

sufficiently meet the criteria. The goodness of fit for the regression model was adequate, χ2(189) = 48.23, *p* < 0.001, *R*<sup>2</sup> CS = 0.22, *R*<sup>2</sup> McF = 0.19, *R*<sup>2</sup> <sup>N</sup> = 0.30.

Among Polish participants (Table S16), four predictors of anxiety were presented in the regression model: place of residence (estimate = −0.66, 95% *CI* = −1.271, −0.039, *SE* = 0.31, OR = 0.52, *<sup>Z</sup>* <sup>=</sup> −2.09, Wald's <sup>χ</sup>2(1) = 4.35, *<sup>p</sup>* < 0.05), exposure to the coronavirus (estimate = 0.77, 95% *CI* = 0.165, 1.365, *SE* = 0.31, OR = 2.15, *Z* = 2.50, Wald's χ2(1) = 6.24, *p* < 0.05), PIC-social relationships (estimate = 1.24, 95% *CI* = 0.513, 1.970, *SE* = 0.37, OR = 3.46, *Z* = 3.40, Wald's χ2(1) = 11.15, *p* < 0.001), and PH (estimate = 1.98, 95% *CI* = 0.297, 3.689, *SE* = 0.86, OR = 7.23, *Z* = 2.31, Wald's χ2(1) = 5.32, *p* < 0.05). However, only two of these were confirmed by the bootstrapping method: exposure (BCa 95% *CI*<sup>B</sup> = 0.069, 1.403) and PIC-social relationships (BCa 95% *CI*<sup>B</sup> = 0.432, 2.004). The model of regression presented a good fit, χ2(288) = 64.78, *p* < 0.001, *R*<sup>2</sup> CS = 0.19, *R*<sup>2</sup> McF = 0.16, *R*<sup>2</sup> <sup>N</sup> = 0.26.

The perceived impact of the coronavirus on social relationships was the sole predictor of anxiety for Russian university students (Table S17), estimate = 1.15, 95% *CI* = 0.446, 1.843, *SE* = 0.36, OR = 3.14, *Z* = 3.21, Wald's χ2(1) = 10.32, *p* < 0.001; BCa 95% *CI*<sup>B</sup> = 0.318, 1.973. The regression model showed a sufficient fit, χ2(271) = 34.05, *p* < 0.001, *R*<sup>2</sup> CS = 0.11, *R*2 McF = 0.10, *R*<sup>2</sup> <sup>N</sup> = 0.16.

Although the model's fit statistics were appropriate, χ2(197) = 53.424, *p* < 0.001, *R*2 CS = 0.23, *R*<sup>2</sup> McF = 0.22, *R*<sup>2</sup> <sup>N</sup> = 0.33, the variables included into the regression model were not found to be predictors of anxiety in the sample of Slovenian students (Table S18).

In the Turkish group of students, gender (estimate = 0.66, 95% *CI* = 0.162, 1.151, *SE* = 0.25, OR = 1.93, *Z* = 2.60, Wald's χ2(1) = 6.77, *p* < 0.01) and exposure to the coronavirus (estimate = 0.68, 95% *CI* = 0.032, 1.319, *SE* = 0.33, OR = 1.97, *Z* = 2.06, Wald's χ2(1) = 4.24, *p* < 0.05) were found to be significant predictors of anxiety (Table S19). However, only gender was confirmed by the bootstrapping test (BCa 95% *CI*<sup>B</sup> = 0.111, 1.175). The regression model's fit was adequate, χ2(294) = 43.17, *p* < 0.001, *R*<sup>2</sup> CS = 0.13, *R*<sup>2</sup> McF = 0.10, *R*<sup>2</sup> <sup>N</sup> = 0.18.

Both gender (estimate = 0.88, 95% *CI* = 0.148, 1.603, *SE* = 0.37, OR = 2.40, *Z* = 2.36, Wald's χ2(1) = 5.57, *p* < 0.05) and PIC-social relationships (estimate = 0.82, 95% *CI* = 037, 1.593, *SE* = 0.40, OR = 2.26, *Z* = 2.05, Wald's χ2(1) = 4.21, *p* < 0.05) were shown to be significant predictors of anxiety in the sample of Ukrainian university students (Table S20). However, when bootstrap was performed, only gender was a predictor of anxiety (BCa 95% *CI*<sup>B</sup> = 0.101, 1.639).
