α indicates ICD9: 714.0
juvenile inflammatory arthritis in patients 16 years old or younger, and those diagnosed as rheumatoid arthritis in patients over 16 years old.
β indicates atrial fibrillation (ICD-9: 427.31), hypertension (ICD-9: 401-405), and acute myocardial infarction: Any hospitalization with a diagnosis of ICD-9: 410.x, coronary heart disease (ICD-9: 410–414), heart failure (ICD-9: 398.91, 402.01, 402.11, 402.91, 404.01, 404.03, 404.11, 404.13, 404.91, 404.93, or 428), cerebral vascular accident (CVA) (ICD-9: 430–438), deep vein thrombosis (DVT), and pulmonary thromboembolism (PE): PE (ICD-9: 415.1), iatrogenic PE (ICD-9: 415.11) and DVT (ICD-9: 453.8)
γ indicates hyperlipidemias (ICD-9: 272), diabetes mellitus (ICD-9: 250), and thyroid disorders: thyroid cancer (ICD-9: 193), hypothyroidism (ICD-9: 244), hyperthyroidism (ICD-9: 242), and thyroiditis (ICD-9: 245)
δindicates gout (ICD-9: 274), hip fracture (ICD-9: 820), operation codes 7855, 7925, 7935, 7995, or 8152, and inflammatory bowel disease: ulcerative colitis (ICD-9: 556), Crohn’s disease (ICD-9: 555), and psoriasis (ICD-9: 696, 696.1, and 696.8)
ε indicates malignancy (ICD-9: 140–208) and lymphoma (ICD-9: 200, 201, 202, or 203)
ζ indicates tuberculosis (ICD-9: 010.x–018.x) and viral hepatitis: HBV (ICD-9: 070.2, 0.70.3, and V02.61) and HCV (ICD-9: 070.41, 070.44, 070.51, 070.54, V02.62)
η indicates chronic obstructive pulmonary disease (ICD-9: 491, 492, and 496), asthma (ICD-9: 493), chronic kidney disease (ICD-9: 582, 583, 585, 586, and 588), and chronic liver diseases (ICD-9: 456.0–456.2, 571.2, 571.4–571.6, and 572)
p-value demonstrates the chi-square analysis between each comorbidity and the usage of biologic agents.
* indicates p<0.05
N1 indicates biologics users
N2 indicates non-biologics users
Table 3. Outcomes of crude and multivariate-adjusted hazard ratio (HR) of each comorbidity in rheumatoid arthritis patients.