Table 3.

Sensitivity analyses for effects of risk factors on incident AS, by multivariate logistic regression.

OR95% CIp
A. Cases with higher probability of true AS diagnosis (n = 60 patients and 33,127 controls)i,iii
  Female sex0.790.47–1.340.39
  Ageii0.950.93–0.97< 0.001
  HTN2.081.17–3.700.013
  Smoking
    Never smoker1Reference
    Former smoker1.030.50–2.130.93
    Current smoker1.821.03–3.190.04
B. Excluding “first time” AS before HUNT2 (n = 64 patients and 33,127 controls)i,iii
  Female sex1.60.95–2.700.08
  Ageii0.960.94–0.980.001
  HTN2.191.25–3.840.006
  Smoking
    Never smoker1Reference
    Former smoker1.110.53–2.320.77
    Current smoker2.611.51–4.530.001
C. Cases with higher probability of true AS diagnosis excluding “first time” AS before HUNT2 (n = 36 patients and 33,127 controls)i,iii
  Female sex1.280.65–2.530.48
  Ageii0.960.93–0.990.006
  HTN2.471.18–5.120.017
  Smoking
    Never smoker1Reference
    Former smoker0.770.27–2.180.62
    Current smoker2.271.12–4.620.024
D. Cases with higher probability of true AS diagnosis excluding “first time” AS before HUNT2 and hospital diagnosis 1997–2002 (n = 31 patients and 33,127 controls)i,iii
  Female sex1.710.80–3.630.17
  Ageii0.960.93–0.990.006
  Hypertension2.811.26–6.270.012
  Smoking
    Never smoker1Reference
    Former smoker0.740.23–2.320.60
    Current smoker2.341.09–5.030.029
  • i Cases with complete data. No. missing for control cases: sex and age: 0; BMI: 132 (0.4%); diabetes 33 (0.1%); HTN: 122 (0.4%); previous CV disease: 107 (0.3%); never/present/former smoker: 1876 (5.3%); pack-yrs HUNT2: 2432 (6.9%); change in smoking habits HUNT2 to HUNT3: 4334 (12.3%). No. missing for incident AS cases: sex, age, BMI, diabetes, HTN, previous CV disease: 0; smoking panel A: 5 (7.7%); smoking panel B: 8 (11.1%); smoking panel C: 4 (10.0%); smoking panel D: 3 (8.8%).

  • ii Continuous variable, OR per 1 unit change.

  • iii Model also adjusted for BMI, diabetes, and previous CV disease. AS: ankylosing spondylitis; BMI: body mass index; HTN: hypertension; CVD: cardiovascular disease.