Table 5b: Reduced Logistic Regression Model of HAQ-DI, Disease Type, Disease Duration and Self-Reported Physically Demand-ing Work on WD. Variables: Sex, Age, and ‘Less than High School Education’ were Removed from the Model

Explanatory Variable (X) βX Estimate Standard Error Odds Ratio Wald Test p-Value
 N 148 - - -
 HAQ-DI score  1.858 0.348 6.412 <0.001
 Disease type 0.016
 Indicator lcSSc 1.239 0.549 3.451 0.024
 Indicator dcSSc 1.314 0.574 3.721 0.022
 Self-reported disease duration 0.041 0.022 1.041 0.069
 Self-reported physically demanding work 1.119 0.45 3.062 0.013
 Constant -3.565 0.654 0.028 <0.001

Equation: Logit (p) = ln [p/(1-p)] = -2.930 + 1.775[HAQ-DI] + 0.743[lcSSc] + 1.316[dcSSc] + 0.043[SR duration] where p = proportion with WD.