Table 1.

Association between IIV and consultation for joint pain, new corticosteroid prescription and RA flare

Outcome	Risk period	Events (n)	Person-time (days)	IRR (95% CI)*	P value*
Joint pain	Unexposed	9977	2 712 373	1.00	< 0.001
	15 days prevaccination	788	160 775	1.29 (1.20 to 1.39)
	Postvaccination intervals
	0–14 days	479	150 314	0.84 (0.77 to 0.92)	< 0.001
	15–30 days	567	160 842	0.94 (0.86 to 1.02)	0.127
	31–60 days	1121	321 024	0.93 (0.88 to 0.99)	0.025
	61–90 days	1069	319 890	0.90 (0.84 to 0.96)	0.001
Corticosteroid prescription	Unexposed	9470	2 266 070	1.00	<0.001
	15 days prevaccination	704	135 493	1.21 (1.12 to 1.31)
	Postvaccination intervals
	0–14 days	539	126 625	1.00 (0.91 to 1.09)	0.924
	15–30 days	554	135 515	0.96 (0.88 to 1.04)	0.338
	31–60 days	1151	270 109	1.00 (0.95 to 1.07)	0.876
	61–90 days	1182	268 968	1.04 (0.98 to 1.11)	0.184
RA flare	Unexposed	460	153 247	1.00	0.785
	15 days prevaccination	24	8957	0.95 (0.64 to 1.41)
	Postvaccination intervals
	0–14 days	27	8400	0.97 (0.65 to 1.45)	0.888
	15–30 days	29	9000	1.12 (0.78 to 1.62	0.525
	31–60 days	59	18 000	1.06 (0.80 to 1.39)	0.693
	61–90 days	46	17 978	0.81 (0.59 to 1.10)	0.180

*Statistically significant results are in bold (p<0.05).

IIV, inactivated influenza vaccine; IRR, incidence rate ratio; RA, rheumatoid arthritis.