Participants were 96 patients with the mean age of 43.05 (SD = 11.31). About 57 percent of them were married, and the rest were either single or widowed. Education Diploma or less was 69%. The mean and standard deviation (SD) of defense mechanisms and the QoL variables are reported in
Table 1. Repression defense mechanism is the most strongly correlated with QoL in fatigue aspect (r = 0.21, P < 0.05). Identification and introjection defense mechanisms had a high correlation with QoL in pain aspect (r = 0.22, P < 0.05). Rationalization defense mechanism is strongly correlated with QoL in insomnia aspect (r = -0.36, P < 0.05). A canonical correlation analysis was performed to investigate the canonical relationship between defense mechanism and QoL variables. The findings showed that null hypothesis, based on which all canonical correlation were zero in society, was rejected (Wilks' Lambda = 0.023, P < 0.001). Also, the next null hypothesis based on the fact that the remaining thirteen canonical correlations were zero was rejected (Wilks' Lambda = 0.063, P < 0.05). Thus, two distinct and significant linear combinations can be considered between variables. Canonical correlation, eigenvalues and their significance test is reported in
Table 2. The first and the second canonical correlation coefficients were significant between variables at the intensity of 0.79 and 0.69 (
Figure 1), respectively. For the first canonical function in the left set of variables (latent variables of defense mechanisms) displacement defense mechanism had the most canonical loading with - 0.59 canonical loading. After that, regression defense mechanism with canonical loading - 0.53 had the most canonical loading. Thus, the latent variable of defense mechanism, (variable 1) the first canonical function, was saturated with displacement and regression mechanism. In another dimension of the right side variables (latent variable of QoL) QoL in physical and cognitive aspects with 0.48 canonical loading had the most canonical loading. Then, the QoL in role aspect with the 0.48 canonical loading had the greatest canonical loading. Thus, the latent variable of QoL was saturated in the first canonical function of QoL in physical, cognitive and role. These relationships indicated that excessive use of displacement and regression mechanisms are associated with lower levels of QoL in the physical, cognitive and role aspects. The severity of this canonical relationship was 0.79. Raw and standard coefficients are reported in
Table 3. Canonical model test is plotted in
Figure 1. For the second canonical function in the left set of variables (latent variables of defense mechanisms), projection defense mechanism had the most canonical loading with - 0.52 canonical loading. After that, reaction formation defense mechanism with canonical loading - 0.47 had the most canonical loading. Thus, the latent variable of defense mechanism in the second canonical function was saturated with projection and reaction formation mechanism. In another dimension for the right side variables (latent variable of QoL), QoL in cognitive aspects with 0.48 canonical loading had the most canonical loading. Then, the QoL in role aspect with the 0.40 canonical loading had the greatest canonical loading. Thus, the latent variable of QoL was saturated (variable 2) in second canonical function of QoL in cognitive and role aspects. These relationships indicated that excessive use of projection and reaction formation mechanisms are associated with lower levels of QoL in cognitive and role aspects and the severity of this canonical relationship was 0.69 (
Table 3 and
Figure 1). Adequacy and redundancy canonical function coefficients are reported in
Table 4. Thus, we can conclude that variables load on the first latent variable (defense mechanisms) are more associated with this structure, in comparison with second complex of variable collection or latent variable QoL. A similar argument holds true for latent variable of QoL. In canonical function 1, adequacy coefficient of latent variable of QoL, was 0.312, while the redundancy coefficient was 0.198 (
Table 4).