Two hundred and seventy-seven PwS were available for analysis. The mean ± sd for age of all study participants was 43.82 ± 8.43. The mean ± sd for education was 10.97 ± 3.00 years, for BPRS was 9.53 ± 6.66, for QoL was 60.27 ± 15.57, for TDQ score was 9.86 ± 10.06, for SDI was 27.24 ± 24.70.
We used the non-parametric M-W U test to analyze the relationship between age, educational level, QoL, depression, SDI and its items and gender. Table 1 showed that there was significant relation between age, BPRS, SDI in total scale, solitary, dyadic, comparative items and gender. Male participants were younger than female participants (p = 0.014), male participants had higher BPRS (p = 0.019) and higher SDI and its items (p < 0.001). Table 2 showed that there was significant relation between SDI, solitary, dyadic, comparative items with the combination of obesity and gender in K-W H test.
Table 1
The comparison of quality of life, depression and sexual desire by gender
variable
|
female
(n = 83)
|
male
(n = 194)
|
P value
|
Age
|
45.49 ± 7.28
|
43.11 ± 8.80
|
0.014*
|
Education level
|
11.07 ± 3.29
|
10.93 ± 2.88
|
0.871
|
BPRS
|
8.35 ± 6.86
|
10.04 ± 6.53
|
0.019*
|
BMI
|
25.65 ± 3.98
|
24.88 ± 3.98
|
0.252
|
Quality of life
|
59.40 ± 15.96
|
60.64 ± 15.43
|
0.461
|
Depression
|
10.04 ± 9.78
|
9.36 ± 10.37
|
0.572
|
Sexual desire total
|
14.31 ± 17.71
|
32.77 ± 25.23
|
< 0.001*
|
Solitary
|
3.94 ± 6.03
|
9.18 ± 8.17
|
< 0.001*
|
Dyadic
|
7.37 ± 9.98
|
16.01 ± 13.76
|
< 0.001*
|
Comparative
|
2.83 ± 3.62
|
7.53 ± 5.70
|
< 0.001*
|
Using Mann-Whitney U test |
* Significantly different (p-value < 0.05) |
BPRS: Brief Psychiatric Rating Scale; BMI: Body Mass Index |
Table 2
The comparison of quality of life, depression and sexual desire by the combination of gender and BMI
|
female BMI < 27
|
female
BMI ≧ 27
|
male
BMI < 27
|
male
BMI ≧ 27
|
|
variable
|
(n = 55)
|
(n = 28)
|
(n = 137)
|
(n = 57)
|
P value
|
Age
|
45.60 ± 7.30
|
45.29 ± 7.35
|
43.71 ± 8.81
|
41.67 ± 8.68
|
0.133
|
Education level
|
11.44 ± 3.08
|
10.36 ± 3.62
|
10.95 ± 2.82
|
10.89 ± 3.05
|
0.197
|
BPRS
|
8.24 ± 7.28
|
8.57 ± 6.08
|
9.72 ± 6.57
|
10.82 ± 6.41
|
0.072
|
Quality of life
|
59.31 ± 16.87
|
59.57 ± 14.28
|
61.94 ± 16.31
|
57.53 ± 12.66
|
0.130
|
Depression
|
9.62 ± 9.38
|
10.86 ± 9.45
|
8.78 ± 9.34
|
12.19 ± 12.27
|
0.303
|
Sexual desire total
|
12.49 ± 16.58
|
17.89 ± 19.58
|
31.30 ± 25.71
|
36.30 ± 23.89
|
< 0.001*
|
Solitary
|
3.47 ± 5.90
|
4.86 ± 6.46
|
8.69 ± 8.13
|
10.35 ± 8.30
|
< 0.001*
|
Dyadic
|
6.49 ± 9.15
|
9.11 ± 11.43
|
15.15 ± 13.93
|
18.07 ± 13.23
|
< 0.001*
|
Comparative
|
2.44 ± 3.46
|
3.61 ± 3.86
|
7.42 ± 5.91
|
7.81 ± 5.22
|
< 0.001*
|
Using Kruskal-Wallis H test |
* Significantly different (p-value < 0.05) |
BPRS: Brief Psychiatric Rating Scale |
In this study, we divided participants with schizophrenia to three groups of below 20 years old, 20–29 years old, and not less than 30 years old in the onset age of mental illness. Then we used K-W H test to compare the means of educational level (or BPRS, QoL, depression and SDI) for three groups of illness onset age. Table 3 showed that participants with schizophrenia illness and late onset age had a significantly higher QoL scores (p = 0.03), lower depression score (p = 0.012).
Table 3
The comparison of quality of life, depression and sexual desire by illness onset age
|
< 20 y/o
(n = 85)
|
20–29 y/o
(n = 145)
|
≥ 30 y/o
(n = 47)
|
p-value
|
Age
|
39.62 ± 8.17
|
44.24 ± 7.68
|
50.13 ± 6.82
|
< 0.001*
|
Education level
|
10.91 ± 2.80
|
10.89 ± 3.06
|
11.36 ± 3.21
|
0.549
|
BPRS
|
10.25 ± 6.57
|
9.50 ± 6.85
|
8.36 ± 6.19
|
0.271
|
Quality of life
|
57.52 ± 15.30
|
60.53 ± 15.29
|
64.45 ± 16.22
|
0.030*
|
Depression
|
11.88 ± 10.13
|
9.39 ± 10.11
|
7.64 ± 9.33
|
0.012*
|
Sexual desire total
|
27.95 ± 25.18
|
28.60 ± 25.67
|
21.74 ± 20.03
|
0.368
|
Solitary
|
7.65 ± 8.12
|
8.12 ± 8.29
|
5.94 ± 6.61
|
0.418
|
Dyadic
|
14.00 ± 14.09
|
14.05 ± 13.68
|
10.43 ± 10.33
|
0.473
|
Comparative
|
6.20 ± 5.83
|
6.34 ± 5.74
|
5.32 ± 4.65
|
0.726
|
Using Kruskal-Wallis H test |
*Significantly different (p-value < 0.05) |
BPRS: Brief Psychiatric Rating Scale |
Similarly, K-W H test was performed in four groups of less than 10 years, 10–19 years, 20–29 years, and ≧ 30 years in the illness duration. Table 4 showed that there were significant relationships between illness duration and SDI total score (p = 0.005), dyadic item (p = 0.002), comparative item (p = 0.008). There was no significant difference between the four groups in the educational level, BPRS, QoL, depression score and SDI (solitary item).
Table 4
The comparison of quality of life, depression and sexual desire by illness duration
|
< 10 years (n = 27)
|
10–19 years (n = 90)
|
20–29 years (n = 119)
|
≥ 30 years (n = 41)
|
p-value
|
Education level
|
11.44 ± 2.98
|
10.64 ± 2.87
|
10.97 ± 2.96
|
11.39 ± 3.43
|
0.450
|
BPRS
|
7.41 ± 6.63
|
10.46 ± 6.43
|
9.55 ± 6.83
|
8.88 ± 6.52
|
0.100
|
Quality of life
|
60.00 ± 17.29
|
57.99 ± 15.72
|
61.87 ± 14.91
|
58.20 ± 15.48
|
0.249
|
Depression
|
7.30 ± 8.75
|
11.53 ± 11.518
|
9.32 ± 9.37
|
9.44 ± 9.12
|
0.253
|
Sexual desire
|
31.00 ± 22.76
|
33.76 ± 25.87
|
22.37 ± 22.82
|
24.59 ± 25.77
|
0.005*
|
Solitary
|
8.00 ± 7.57
|
9.24 ± 8.82
|
6.66 ± 7.30
|
6.51 ± 7.89
|
0.091
|
Dyadic
|
16.15 ± 12.40
|
16.90 ± 14.13
|
10.52 ± 11.98
|
12.39 ± 14.17
|
0.002*
|
Comparative
|
7.62 ± 6.36
|
7.62 ± 5.96
|
5.66 ± 5.45
|
5.18 ± 5.78
|
0.008*
|
Using Kruskal-Wallis H test |
*Significantly different (p-value < 0.05) |
BPRS: Brief Psychiatric Rating Scale |
The results of multiple logistic regression analysis indicated significant ORs for BPRS (OR = 0.918, 95% CI = 0.878–0.960, p < 0.001), depression (OR = 0.952, 95% CI = 0.923–0.982, p = 0.002), SDI (OR = 1.013, 95% CI = 1.002–1.024, p = 0.018), respectively. Depression and BPRS had negatively correlated on the probability of good QoL. Sexual desire had positively correlated on the probability of good QoL (Table 5).
Table 5
The related variables affect the probability of good life quality by the multiple logistic regression
|
coefficient
|
S.E.
|
p-value
|
OR
|
LCL
|
UCL
|
constant
|
0.813
|
0.262
|
|
|
|
|
BPRS
|
-0.086
|
0.023
|
< 0.001*
|
0.918
|
0.878
|
0.960
|
Depression
|
-0.049
|
0.016
|
0.002*
|
0.952
|
0.923
|
0.982
|
Sexual desire
|
0.013
|
0.006
|
0.018*
|
1.013
|
1.002
|
1.024
|
The reference group is total score of life quality < 59. |
*Significantly different (p-value < 0.05) |
BPRS: Brief Psychiatric Rating Scale |
Finally, we used structure equation model (SEM) to explore the association of BPRS, TDQ, SDI and QoL. BPRS was divided into five items: Anxiety, Inactive, Disorder, Activating and Hostile; TDQ was divided into three items: Thinking, Physiology and Psychology. SDI was divided into three items: Dyadic, Solitary and Comparative. QoL was divided into four items: environment, social relations, psychological level and physiological level.
In Fig. 1, the overall fit assessment indicator of the SEM model was χ2/df = 1.671 with a goodness-of-fit index of 0.937, adjusted goodness of-fit index of 0.912, and approximated root mean square error of 0.049, which all reached the standards χ2/df < 5, goodness-of-fit index ≥ 0.9, adjusted goodness-of-fit index > 0.9, approximated root means square error < 0.05)
By Amos, the structural reliabilities of the four dimensions—namely, BPRS, depression, SD, and QoL-were 0.779, 0.760, 0.870 and 0.858, respectively, and the average extracted variances were 0.548, 0.718, 0.811, and 0.720. Structural reliabilities of all dimensions were more than 0.7 and extracted variances were also all greater than 0.5. Hence, this model had a reliable fit for the internal structure. Figure 1 showed that 73% of BPRS can be interpreted by mental status, and 60% of depression can be interpreted by mental status. The influence of each dimension was explained as follows.
-
Influence of SD on mental status: Sexual desire has significant, proportional, and direct influence on mental status.
-
Influence of SD on QoL: Sexual desire has no direct relation on QoL; however, via mental status, it has an indirect influence.
-
Influence of mental status on QoL: Mental status has significant, inversely proportional, and direct influence on QoL.
The path coefficient estimates and t values of standardized model are as follows: SD to mental status: 0.17 (t = 2.059, p < 0.05), and mental status to QoL: -0.53 (t =- 4.212, p < 0.001). The overall model structure can be simplified as shown in Fig. 2.
The influences among variables can be grouped into direct effects, indirect effects, and overall effects. Overall effects which is the sum of the direct effects and indirect effects. Sexual desire has a direct effect of 0.17 to mental status and an indirect effect of 0; mental status has a direct effect of -0.53 to QoL and an indirect effect of 0; the SD has an indirect effect, with an indirect effect coefficient of -0.0901, which is found by multiplying the two direct effects 0.17 × (-0.53). Hence, mental status has a bigger overall effect coefficient on QoL than that of SD.