Table 3

Multivariable models for assessing the slope of disability over time, adjusting for the influence of age, gender, non-white ethnicity, baseline disease duration, body mass index and smoking status

Model/covariateObservations in the model (n)β Coefficient (slope of the time–trend line)95% CI
Overall, annually53 019−0.0170−0.018 to −0.015
 Age <65 years29 591−0.0160−0.018 to −0.014
 Age ≥65 years23 428−0.0199−0.022 to −0.018
 Men only11 158−0.0270−0.031 to −0.024
 Women only41 861−0.0140−0.016 to −0.012
 Caucasians only48 481−0.0170−0.019 to −0.016
 All non-Caucasians4538−0.0170−0.019 to −0.010
 African–Americans1068−0.0110−0.02 to 0.007
 Non-smokers only43 473−0.0190−0.02 to −0.017
 Smokers only9696−0.0080−0.012 to −0.004
 Baseline disease duration <3 years9696−0.0080−0.011 to −0.004
 Body mass index ≥309953−0.0210−0.024 to −0.018
 Body mass index <3043 066−0.0160−0.017 to −0.014
  • Our primary outcome (dependent variable) was the trend (slope) of the HAQ-DI score over time. In multivariable regression models, our adjustments included gender, ethnicity and baseline measures of age, disease duration and smoking. We also took into account the patient's calendar year of entry into the ARAMIS cohort to allow for the possibility of bias due to time trends in recruitment.

  • ARAMIS, Arthritis, Rheumatism and Aging Medical Information System; DMARD, disease-modifying anti-rheumatic drug; HAQ-DI, Health Assessment Questionnaire Disability Index.