Table 2.

Predictors of time to flare.

Variables	Unadjusted		Adjusted
	HR (95% CI)	p-value	HR (95% CI)	p-value
Vaccine type
BNT162b2 Pfizer-BioNTech	1.0	0.06
mRNA-1273 Moderna	1.2 (1–1.5)
Age
≤52	1.0		1.0
53-65	0.8 (0.7–0.97)	0.02	0.6 (0.5–0.8)	<0.001
>66	0.8 (0.7–0.9)	0.002	0.7 (0.6–0.8)	<0.001
Ethnicity
Chinese	1.0		1.0
Malay	1.0 (0.8–1.3)	0.78	0.7 (0.4–1.1)	0.14
Indian	1.2 (1–1.5)	0.08	1.0 (0.8–1.3)	0.75
Others	0.8 (0.5–1.1)	0.10	0.7 (0.5–0.9)	0.006
Gender
Male	1.0
Female	0.9 (0.8–1.1)	0.53
Disease group
Connective Tissue Disease	1.0		1.0
Vasculitis	1.4 (0.9–2.2)	0.18	1.2 (0.7–1.8)	0.67
Inflammatory arthritis	1.9 (1.6–2.2)	<0.001	1.5 (1.2–2.0)	0.001
Others	1.3 (0.8–2.2)	0.35	1.4 (0.8–2.5)	0.28
Active disease
No	1.0		1.0
Yes	1.7 (1.4–2.1)	<0.001	1.4 (1.2–1.6)	<0.001
Glucocorticoids
None	1.0		1.0
Pred≤7.5 mga	1.4 (1.2–1.6)	<0.001	1.5 (1.2–1.8)	<0.001
Pred >7.5 mga	1.7 (1.2–2.3)	0.002	1.7 (1–3.0)	0.05
Treatment
None	1.0		1.0
Hydroxychloroquine only	0.9 (0.7–1.2)	0.48	1.1 (0.7–1.7)	0.55
csDMARDsb	1.9 (1.5–2.3)	<0.001	1.5 (1.1–2.0)	0.005
Immunosuppressantsc	1.2 (0.9–1.6)	0.16	1.2 (1.1–1.4)	0.004
bDMARDs or JAKid	1.9 (1.4–2.5)	<0.001	1.3 (0.9–1.7)	0.11

Multivariate analysis has been adjusted for number of vaccine doses. In the adjusted model, 96.8% of subjects (4327 out of 4627 subjects) were used.

Significant p-value in bold.

^aOr equivalent dose in prednisolone.

^bcsDMARDs = conventional synthetic disease modifying anti-rheumatic drugs which included Methotrexate, Sulfasalazine and Leflunomide.

^cImmunosuppressants include Cyclosporin A, Cyclophosphamide, Azathioprine, Mycophenolate Mofetil, Mycophenolate Sodium, Tacrolimus.

^dbDMARDs or JAKi = biological disease modifying anti-rheumatic drugs or Janus Kinase inhibitors.