Fatigue of systemic lupus erythematosus in China: contributors and effects on the quality of life

Figures & data

Table 1 Baseline characteristics of SLE patients and healthy controls

Variables	Cases (n=119)	Controls (n=105)	P-value
Gender, female, n (%)	115 (96.6)	100 (95.2)	0.848
Age (years), mean ± SD	36.16±11.80	36.63±10.00	0.750
BMI (kg/m^2), mean ± SD	22.47±3.82	22.24±2.98	0.632
Marital status, n (%)			0.605
Married	93 (78.2)	85 (81.0)
Unmarried	26 (21.8)	20 (19.0)
Education, n (%)			0.095
≤9 years	62 (52.1)	43 (41.0)
>9 years	57 (47.9)	62 (59.0)
Occupation, n (%)			0.167
Employed	57 (47.9)	60 (57.1)
Unemployed	62 (52.1)	45 (42.9)
Yearly income (yuan), n (%)			0.138
<15,000	31 (26.1)	28 (26.7)
15,000–33,000	58 (48.7)	39 (37.1)
>33,000	30 (25.2)	38 (36.2)
Personal health insurance, n (%)			0.889
Yes	76 (63.9)	68 (64.8)
No	43 (36.1)	37 (35.2)
Smoking use, yes, n (%)	1 (0.8)	1 (1.0)	1.000
Alcohol use, yes, n (%)	3 (2.5)	8 (7.6)	0.078
Exercise, n (%)			0.082
Yes	43 (36.1)	50 (47.6)
No	76 (63.9)	55 (52.4)
Disease duration (years), mean ± SD	6.58±5.51
SLEDAI, mean ± SD	4.32±3.36
Use of hormones (mg/d), n (%)
≤7.5	74 (62.2)
>7.5	45 (37.8)

Abbreviations: BMI, body mass index; SLEDAI, Systemic Lupus Erythematosus Disease Activity Index; SLE, systemic lupus erythematosus.

Figure 1 Comparison of fatigue and quality of life in cases and controls.

Note: Y-axes represent the number corresponding to the mean of the x-coordinate variable, both are numeric values.
Abbreviations: FSS, Fatigue Severity Scale; HADS, Hospital Anxiety and Depression Scale; MCS, Mental Components Summary; PCS, Physical Components Summary; SF-36, the Short Form 36 health survey.

Table 2 Differences between non-fatigued patients and fatigued patients in SLE

Variables	FSS<4 (n=51)	FSS≥4 (n=68)	P-value
Female	51 (100)	64 (94.1)	0.212
Age (years)	37.14±13.80	35.43±10.09	0.457
BMI (kg/m^2)	22.69±4.09	22.30±3.63	0.588
Marital status			0.701
Married	39 (76.5)	54 (79.4)
Unmarried	12 (23.5)	14 (20.6)
Education			0.832
≤9 years	26 (51.0)	36 (52.9)
>9 years	25 (49.0)	32 (47.1)
Occupation			0.368
Employed	22 (43.1)	35 (51.5)
Unemployed	29 (56.9)	33 (48.5)
Yearly income (yuan)			0.406
<15,000	12 (23.5)	19 (27.9)
15,000–33,000	23 (45.1)	35 (51.5)
>33,000	16 (31.4)	14 (20.6)
Personal health insurance			0.582
Yes	34 (66.7)	42 (61.8)
No	17 (33.3)	26 (38.2)
Smoking use, yes	0 (0.0)	1 (1.5)	1.000
Alcohol use, yes	0 (0.0)	3 (4.4)	0.353
Exercise			0.869
Yes	18 (35.3)	25 (36.8)
No	33 (64.7)	43 (63.2)
Disease duration (years)	5.40±5.12	7.47±5.66	0.041*
SLEDAI	4.37±3.44	4.28±3.33	0.882
Use of hormones (mg/d)			0.623
≤7.5	33 (64.7)	41 (60.3)
>7.5	18 (35.3)	27 (39.7)
HADS-A	4.86±4.10	6.87±3.71	0.006**
HADS-D	3.76±3.23	5.93±3.52	0.001**
Subjective sleep quality	0.98±0.58	1.22±0.64	0.038*
Sleep latency	0.96±1.00	1.21±0.97	0.181
Sleep duration	0.80±0.96	0.72±0.91	0.630
Habitual sleep efficiency	0.53±0.78	0.79±1.02	0.111
Sleep disorders	1.04±0.49	1.32±0.53	0.003**
Use of sleep medications	0.12±0.59	0.18±0.67	0.618
Daytime dysfunction	0.47±0.54	0.65±0.59	0.098
PSQI total	4.90±3.31	6.09±3.43	0.060

Note:

* P<0.05,

** P<0.01.

Abbreviations: BMI, body mass index; FSS, Fatigue Severity Scale; HADS, Hospital Anxiety and Depression Scale; PSQI, the Pittsburgh Sleep Quality Index; SLEDAI, Systemic Lupus Erythematosus Disease Activity Index; SLE, systemic lupus erythematosus.

Table 3 Stepwise logistic regression analysis of demographic, medical and psychological variables in relation to FSS in SLE patients

	Fatigue	Beta	SE	P-value	Exp (B)	(95% CI)
Step 1	Disease duration	0.060	0.039	0.126	1.061	0.983, 1.146
	HADS-A	−0.017	0.082	0.836	0.983	0.837, 1.154
	HADS-D	0.163	0.092	0.078	1.177	0.982, 1.411
	Subjective sleep quality	0.148	0.354	0.676	1.160	0.579, 2.322
	Sleep disorders	0.810	0.449	0.072	2.247	0.931, 5.421
Step 2	Disease duration	0.060	0.039	0.127	1.061	0.983, 1.146
	HADS-D	0.149	0.066	0.023	1.161	1.020, 1.321
	Subjective sleep quality	0.138	0.351	0.695	1.148	0.577, 2.283
	Sleep disorders	0.796	0.444	0.073	2.216	0.928, 5.289
Step 3	Disease duration	0.061	0.039	0.115	1.063	0.985, 1.148
	HADS-D	0.158	0.062	0.011	1.171	1.036, 1.324
	Sleep disorders	0.818	0.441	0.064	2.265	0.955, 5.372
Step 4	HADS-D	0.158	0.062	0.010*	1.171	1.038, 1.321
	Sleep disorders	0.889	0.434	0.041*	2.433	1.039, 5.694

Note:

* P<0.05.

Abbreviations: FSS, Fatigue Severity Scale; HADS, Hospital Anxiety and Depression Scale; SLE, systemic lupus erythematosus.

Table 4 Effects of fatigue on quality of life in SLE patients

Variables	FSS<4 (n=51)	FSS≥4 (n=68)	P-value
PF	86.86±15.59	69.85±21.67	<0.01**
RP	68.14±41.86	38.60±40.39	<0.01**
BP	87.24±17.70	78.85±22.07	0.028*
GH	59.96±19.45	40.94±20.30	<0.01**
VT	68.73±16.97	52.13±17.18	<0.01**
SF	81.62±16.84	72.24±20.92	0.010*
RE	82.35±32.22	51.47±42.88	<0.01**
MH	71.45±16.86	60.94±15.35	0.001**
SF-36 PCS	75.55±19.69	57.06±19.34	<0.01**
SF-36 MCS	76.04±16.92	59.20±19.71	<0.01**

Note:

* P<0.05,

** P<0.01.

Abbreviations: BP, body pain; FSS, Fatigue Severity Scale; GH, general health perception; MCS, Mental Components Summary; MH, mental health; PCS, Physical Components Summary; PF, physical function; RE, role limitations due to emotional problems; RP, role limitations due to physical problems; SF, social function; SF-36, the Short Form 36 health survey; VT, energy/vitality; SLE, systemic lupus erythematosus.