Table 2.
Multiple linear regression analysis: combined effect of self-efficacy and either depression, age or educational attainment on the adjusted mean of fatigue
| Self-efficacy to manage symptoms by depression (p value for the interaction=0.04) | |||||
| Symptom SE level (T-score) |
Depression severity category | Adjusted mean* (95% CI) | Depression severity comparison | Mean difference (95% CI) | P value |
| Low Symptom SE (T-score=35) |
1. None | 59.8 (57.8 to 61.9) | 2 vs 1 | 2.9 (−0.1 to 6.0) | 0.06 |
| 2. Mild | 62.8 (60.4 to 65.1) | 3 vs 1§ | 3.3 (0.5 to 6.2) | 0.02 | |
| 3. Moderate/severe | 63.2 (61.0 to 65.3) | 3 vs 2 | 0.4 (−2.6 to 3.4) | 0.8 | |
| Mean Symptom SE (T-score=48.1) |
1. No | 55.5 (54.4 to 56.6) | 2 vs 1§ | 3.4 (1.8 to 5.0) | <0.001 |
| 2. Mild | 58.9 (57.6 to 60.3) | 3 vs 1§ | 6.8 (4.7 to 8.9) | <0.001 | |
| 3. Moderate/severe | 62.3 (60.5 to 64.2) | 3 vs 2§ | 3.4 (1.3 to 5.6) | 0.002 | |
| High Symptom SE (T-score=55) |
1. None | 53.2 (52.1 to 54.4) | 2 vs 1§ | 3.6 (1.5 to 5.8) | 0.001 |
| 2. Mild | 56.9 (54.9 to 58.9) | 3 vs 1§ | 8.7 (5.8 to 11.5) | <0.001 | |
| 3. Moderate/severe | 61.9 (59.2 to 64.6) | 3 vs 2§ | 5.0 (1.8 to 8.3) | 0.003 | |
| Self-efficacy to manage symptoms by education (p value for the interaction=0.05) | |||||
| Symptom SE level (T-score) |
Educational attainment category | Adjusted mean† (95% CI) | Educational attainment comparison | Mean difference | P value |
| Low Symptom SE (T-score=35) |
1. High school or below | 58.7 (56.9 to 60.6) | 2 vs 1 | 2.4 (−0.2 to 5.0) | 0.07 |
| 2. Some college | 61.1 (59.0 to 63.2) | 3 vs 1§ | 4.4 (1.5 to 7.4) | 0.003 | |
| 3. Bachelor’s degree or above | 63.2 (60.6 to 65.7) | 3 vs 2 | 2.0 (−1.0 to 5.1) | 0.2 | |
| Mean Symptom SE (T-score=48.1) |
1. High school or below | 55.9 (54.7 to 57.2) | 2 vs 1§ | 3.2 (1.7 to 4.7) | <0.001 |
| 2. Some college | 59.2 (58.0 to 60.3) | 3 vs 1§ | 2.2 (0.5 to 3.8) | 0.009 | |
| 3. Bachelor’s degree or above | 58.1 (56.8 to 59.4) | 3 vs 2 | −1.0 (−2.6 to 0.6) | 0.2 | |
| High Symptom SE (T-score=55) |
1. High school or below | 54.5 (53.0 to 56.0) | 2 vs 1§ | 3.6 (1.6 to 5.6) | <0.001 |
| 2. Some college | 58.1 (56.6 to 59.6) | 3 vs 1 | 1.0 (−1.1 to 3.0) | 0.4 | |
| 3. Bachelor’s degree or above | 55.4 (53.9 to 56.9) | 3 vs 2§ | −2.7 (−4.7 to −0.6) | 0.01 | |
| Self-efficacy to manage medications and treatments by depression (p value for the interaction=0.009) | |||||
| Treatment SE level (T-score) |
Depression severity category | Adjusted mean‡ (95% CI) | Depression severity comparison | Mean difference | P value |
| Low Treatment SE (T-score=35) |
1. None | 57.4 (55.6 to 59.1) | 2 vs 1 | 2.2 (−0.3 to 4.8) | 0.08 |
| 2. Mild | 59.6 (57.7 to 61.6) | 3 vs 1§ | 4.3 (1.7 to 6.9) | 0.001 | |
| 3. Moderate/severe | 61.6 (59.7 to 63.6) | 3 vs 2 | 2.0 (−0.6 to 4.6) | 0.1 | |
| Mean Treatment SE (T-score=46.2) |
1. None | 55.1 (53.9 to 56.2) | 2 vs 1§ | 4.1 (2.5 to 5.7) | <0.001 |
| 2. Mild | 59.2 (57.8 to 60.5) | 3 vs 1§ | 7.3 (5.3 to 9.2) | <0.001 | |
| 3. Moderate/severe | 62.3 (60.7 to 64.0) | 3 vs 2§ | 3.2 (1.2 to 5.2) | 0.002 | |
| High Treatment (T-score=55) |
1. None | 53.2 (51.9 to 54.5) | 2 vs 1§ | 5.6 (3.3 to 7.9) | <0.001 |
| 2. Mild | 58.8 (56.8 to 60.8) | 3 vs 1§ | 9.6 (7.0 to 12.3) | <0.001 | |
| 3. Moderate/severe | 62.8 (60.4 to 65.3) | 3 vs 2§ | 4.1 (1.1 to 7.1) | 0.008 | |
*Adjusted for symptom SE, age, education, work status, insurance, disease duration, disease activity (SLAQ) and organ damage (SA-BILD).
†Adjusted for symptom SE, depression, age, work status, insurance, disease duration, disease activity (SLAQ) and organ damage (SA-BILD).
‡Adjusted for treatment SE, age, education, work status, insurance, disease duration, SLAQ and organ damage (SA-BILD).
§Bold values indicate a statistically significant difference between the two groups.
SA-BILD, Self-Administered Brief Index of Lupus Damage; SE, self-efficacy; SLAQ, Systemic Lupus Activity Questionnaire.