Table 2.
Logistic regression model examining associations with severe fatigue (RAND(SF)-Vitality ≤35)
| B (SE) | Wald statistic | r a | Odds ratio | |
|---|---|---|---|---|
| Fibromyalgia | 1.35 (0.07) | 368.16*** | 0.23 | 3.86 |
| Multiple rheumatic diseases without FMb | 0.49 (0.11) | 20.95*** | 0.05 | 1.63 |
| Disease durationc | −0.27 (0.08) | 11.60** | 0.04 | 0.76 |
| Genderd | −0.12 (0.10) | 1.69 | 0.00 | 0.88 |
| Age | −0.01 (0.003) | 11.15** | 0.04 | 0.99 |
| Years of educatione | −0.30 (0.07) | 19.87*** | 0.05 | 0.74 |
| Marital statusf | ||||
| Single | −0.08 (0.09) | 0.93 | 0.00 | 0.92 |
| Separated/widowed | 0.01 (0.11) | 0.03 | 0.00 | 1.01 |
| Languageg | ||||
| English | 1.12 (0.12) | 88.44*** | 0.11 | 3.08 |
| French | 1.81 (0.13) | 208.62*** | 0.17 | 6.11 |
| German | 0.94 (0.12) | 65.64*** | 0.09 | 2.57 |
| Portuguese | 0.34 (0.11) | 10.46** | 0.03 | 1.41 |
| Spanish | 0.74 (0.08) | 78.35*** | 0.10 | 2.09 |
* = p < 0.05; ** = p < 0.01; *** = p < 0.001; “Variance” explained by the total model, Nagelkerke’s R 2 = 0.23
a r is the logistic pseudo partial correlation, i.e., the explanatory value attributable to a single independent variable after taking into account all other independent variables
bHaving multiple rheumatic diseases without fibromyalgia (FM): yes = 1, no = 0
cDisease duration is log transformed
dGender: male = 1 and female = 0
eYears of education: >14 years = 1, ≤14 years = 0
fMarital status: two dummy variables with “in a relationship” as reference category
gLanguage: five dummy variables with Dutch as reference category