Table 3. Crude and adjusted odds ratios (95% confidence intervals), for modifiable factors predicting clinically significant fatigue.
| Outcome | Category | No Clinically Significant Fatigue, n(%).(FSS mean score <4) | Clinically Significant Fatigue, n(%).(FSS mean score ≥4) | p | Crude OR (95% CI) | Adjusted OR (95% CI) |
|---|---|---|---|---|---|---|
| Smoking | Never | 381 (37.3) †† | 640 (62.7) † | <0.001 | 1.00 (reference) | 1.00 (reference) |
| Former | 307 (35.6) | 556 (64.4) | 1.08 (0.89–1.30) | 0.79 (0.63–1.00) * | ||
| Current | 47 (19.0) † | 201 (81.0) †† | 2.55 (1.81–3.58)*** | 1.34 (0.87–2.08) | ||
| Total N | 735 (34.5) | 1395 (65.5) | ||||
| Alcohol | Low | 378 (29.2) † | 916 (70.8) †† | <0.001 | 1.00 (reference) | 1.00 (reference) |
| Moderate | 345 (42.7) †† | 463 (57.3) † | 0.55 (0.46–0.67) *** | 0.75 (0.61–0.94) * | ||
| High | 6 (35.3) | 11 (64.7) | 0.76 (0.28–2.06) | 0.70 (0.23–2.14) | ||
| Total N | 729 (34.4) | 1390 (65.6) | ||||
| Exercise (IPAQ) | Low | 169 (19.4) † | 702 (80.6) †† | <0.001 | 1.00 (reference) | 1.00 (reference) |
| Moderate | 262 (38.8) †† | 413 (61.2) † | 0.38 (0.30–0.48) *** | 0.52 (0.40–0.67) *** | ||
| High | 297 (52.3) †† | 271 (47.7) † | 0.22 (0.17–0.28) *** | 0.32 (0.24–0.42) *** | ||
| Total N | 728 (34.4) | 1386 (65.6) | ||||
| Vitamin D | None | 87 (23.1) † | 289 (76.9) †† | <0.001 | 1.00 (reference) | 1.00 (reference) |
| 1–5000 IU | 448 (35.1) | 829 (64.9) | 0.56(0.43–0.73) *** | 0.70 (0.51–0.95) * | ||
| > 5000 IU | 175 (41.8) †† | 244 (58.2) † | 0.42 (0.31–0.57) *** | 0.59(0.41–0.85) ** | ||
| Total N | 710 (34.3) | 1362 (65.7) | ||||
| Omega 3 | No | 217 (28.4) † | 548 (71.6) †† | <0.001 | 1.00 (reference) | 1.00 (reference) |
| Yes | 514 (37.8) †† | 845 (62.2) † | 0.65 (0.54–0.79) *** | 0.86 (0.68–1.08) | ||
| Total N | 731 (34.4) | 1393 (65.6) | ||||
| Omega 3 type | None | 217 (28.4) † | 548 (71.6) †† | <0.001 | 1.00 (reference) | 1.00 (reference) |
| Fish oil^ | 275 (37.0) | 469 (63.0) | 0.68 (0.54–0.84) *** | 0.84 (0.65–1.08) | ||
| Flaxseed oil | 89 (46.6) †† | 102 (53.4) † | 0.45 (0.33–0.63) *** | 0.63 (0.43–0.93) * | ||
| Both fish and flaxseed oil | 143 (38.2) | 231 (61.8) | 0.64 (0.49–0.83) ** | 0.97 (0.71–1.33) | ||
| Total N | 724 (34.9) | 1350 (65.1) | ||||
| Omega 3 dose | None | 217 (28.4) † | 548 (71.6) †† | <.001 | 1.00 (reference) | 1.00 (reference) |
| 1–10mls | 339 (36.1) | 599 (63.9) | 0.70 (0.57–0.86) *** | 0.90 (0.70–1.14) | ||
| 11–20mls | 101 (46.5) †† | 116 (53.5) † | 0.46 (.33–0.62) *** | 0.72 (0.49–1.03) | ||
| 21+mls | 56 (40.6) | 82 (59.4) | 0.58 (.40-.84) ** | 0.76 (0.49–1.17) | ||
| Total N | 713 (34.6) | 1345 (65.4) | ||||
| Fish consumption | Less than once per week | 160 (26.1) † | 454 (73.9) †† | <0.001 | 1.00 (reference) | 1.00 (reference) |
| 1–2 times per week | 280 (32.9) | 571 (67.1) | 0.72 (0.57–0.91) ** | 0.88(0.67–1.16) | ||
| 3 or more days per week | 296 (44.4) †† | 371 (55.6) † | 0.44 (0.35–0.56) *** | 0.66 (0.49–0.89) ** | ||
| Total N | 736 (34.5) | 1396 (65.5) | ||||
| Meditation | Never | 337 (33.2) | 678 (66.8) | .363 | 1.00 (reference) | 1.00 (reference) |
| Less than once per week | 165 (34.5) | 313 (66.5) | 0.94 (0.75–1.19) | 1.11 (0.85–1.46) | ||
| Once or more per week | 234 (36.6) | 405 (63.4) | 0.86 (0.70–1.06) | 1.02 (0.79–1.30) | ||
| Total N | 736 (34.5) | 1396 (65.5) | ||||
| Social support | 6 or more | 122 (42.8) †† | 163 (57.2) † | 0.001 | 1.00 (reference) | 1.00 (reference) |
| 2–5 | 439 (28.6) | 823 (71.4) | 1.40 (1.08–1.82) * | 1.16 (0.86–1.58) | ||
| 1 | 132 (34.8) † | 329 (65.2) †† | 1.87 (1.37–2.54) *** | 1.30 (0.90–1.87) | ||
| None | 33 (30.8) | 74 (69.2) | 1.68 (1.05–2.69) * | 0.94 (.53–1.68) | ||
| Total N | 726 (34.3) | 1389 (65.7) | ||||
| Body Mass Index (WHO classification) | Normal | 473 (41.8) | 659 (58.2) | <0.001 | 1.00 (reference) | 1.00 (reference) |
| Underweight | 34 (39.8) †† | 53(60.2) † | 1.09 (0.70–1.69) | 0.93 (0.56–1.55) | ||
| Overweight | 143 (29.2) † | 347 (70.8) †† | 1.74(1.39–2.19) *** | 1.46 (1.12–1.90) ** | ||
| Obese | 81 (20.0) † | 325 (80.0) †† | 2.88 (2.20–3.78) *** | 1.75 (1.28–2.40) *** | ||
| Total N | 732 (34.6) | 1384 (65.4) | ||||
| Dietary Habits Questionnaire (modified) | Upper (fourth) quartile | 246 (47.0) †† | 277 (53.0) † | <0.001 | 1.00 (reference) | 1.00 (reference) |
| Third quartile | 180 (37.9) | 295 (62.1) | 1.46 (1.13–1.87) ** | 1.31 (0.98–1.75) | ||
| Second quartile | 150 (31.3) | 329 (68.7) | 1.95 (1.50–2.52) *** | 1.52 (1.12–2.07) ** | ||
| Lower (first) quartile | 104 (21.5) † | 379 (78.5) †† | 3.24 (2.45–4.27) *** | 2.02 (1.44–2.83) *** | ||
| Total N | 680 (34.7) | 1280 (65.3) | ||||
| Disease Modifying Drug use | Never | 278 (39.7) †† | 423 (60.3) † | <.001 | 1.00 (reference) | 1.00 (reference) |
| Current only | 245 (35.7) | 441 (64.3) | 1.183 (0.95–1.47) | 1.37 (1.05–1.79)** | ||
| Current and previous | 108 (27.6) † | 284 (72.4) †† | 1.73 (1.32–2.26) *** | 1.76 (1.26–2.44) *** | ||
| Previous but not current | 104 (29.1) † | 254 (70.9) †† | 1.61 (1.22–2.11) *** | 1.36 (0.97–1.90) | ||
| Total N | 735 (34.4) | 1402 (65.6) |
Adjusted OR: Odds ratios of screening positive for fatigue adjusted for: age, gender, level of education, employment status, marital status, country of birth, number of children, number of comorbidities, level of disability, and positive depression screen. Neither MS type nor years since diagnosis were included as covariates since these variables were highly correlated with disability and age respectively. Age at diagnosis was not included as a covariate as it was highly correlated with current age, and both relapse rate and disease activity were excluded as covariates as these data were provided for those with relapsing remitting MS only. HRQOL was not included as a covariate as these data were significantly associated with comorbidities, depression, and disability.
†† denotes category significantly over-represented according to adjusted standardized residuals.
† Denotes category significantly under-represented according to adjusted standardized residuals.
*<0.05
**<0.01
***≤0.001