Table 1

Baseline characteristics of patients with ankylosing spondylitis (AS) and controls

CharacteristicPatients with ASControlsp Value
n=3809(%)n=26 197(%)
Males2686(70.5)18 519(70.7)
Age at index date (years)
 16–29728(19.1)5085(19.4)
 30–391038(27.3)7172(27.4)
 40–49817(21.4)5674(21.7)
 50–59570(15.0)3870(14.8)
 60–69376(9.9)2551(9.7)
 70–79206(5.4)1399(5.3)
 80+74(1.9)446(1.7)
BMI
 <20204(5.4)1280(4.9)0.21
 20–251046(27.5)6934(26.5)0.20
 25–30879(23.1)6066(23.2)0.91
 >30447(11.7)3086(11.8)0.94
 Unknown1223(32.4)8831(33.7)0.10
Smoking status
 Never1668(43.8)11 962(45.7)0.03
 Current1403(36.8)8256(31.5)<0.01
 Ex569(14.9)3605(13.8)0.05
 Unknown169(4.4)2374(9.1)<0.01
Alcohol use
 Yes2612(68.6)17 468(66.7)0.02
 No596(15.6)3251(12.4)<0.01
 Unknown601(15.8)5478(20.9)<0.01
Disease history
 Any cardiovascular disease216(5.7)1317(5.0)0.09
  IHD164(4.3)898(3.4)<0.01
  AMI69(1.8)354(1.4)0.02
  Stroke44(1.2)317(1.2)0.77
  Heart failure24(0.6)108(0.4)0.06
  Peripheral vascular disease38(1.0)246(0.9)0.73
 Hypertension316(8.3)2007(7.7)0.17
 Acute renal failure3(0.1)16(0.1)0.69
 Chronic renal failure2(0.1)62(0.2)0.02
 Hypercholesterolaemia165(4.3)1127(4.3)0.93
 Diabetes mellitus150(3.9)795(3.0)<0.01
History of drug use 6 months before the index date
 Any antihypertensives509(13.4)2902(11.1)<0.01
  β-blockers199(5.2)1276(4.9)0.35
  Loop diuretics92(2.4)380(1.5)<0.01
  Thiazide diuretics173(4.5)967(3.7)0.01
  ACE-I or ANG-II-R248(6.5)1449(5.5)0.01
  Calcium channel antagonist177(4.7)985(3.8)<0.01
 Antiplatelet agents206(5.4)1142(4.4)<0.01
 Nitrates94(2.5)391(1.5)<0.01
 Antidiabetics*107(2.8)586(2.2)0.03
 Statins233(6.1)1363(5.2)0.02
 Asthma medication†289(7.6)1661(6.3)<0.01
 NSAIDs1731(45.4)2163(8.3)<0.01
  COX-2 inhibitors225(5.9)114(0.4)<0.01
  Naproxen only303(8.0)298(1.1)<0.01
  Other traditional NSAIDs1582(41.5)2071(7.9)<0.01
  • Bold typeface indicates statistical significance (p<0.05). A χ2 test was performed to compare patients with AS and controls.

  • *Antidiabetics, including insulin.

  • †Asthma medication, including bronchodilators, inhaled corticosteroids, leukotriene receptor antagonists, β-2 agonists and theophylline.

  • AMI, acute myocardial infarction; ANG-II-R, angiotensin II receptor antagonist; AS, ankylosing spondylitis; BMI, body mass index; COX-2 inhibitors, cyclo-oxygenase-2 inhibitors; IHD, ischaemic heart disease; NSAIDs, non-steroidal anti-inflammatory drugs.