Table 2.

Incidence rates and hazard ratio of new-onset rheumatoid arthritis among patients with pemphigus (cohort study design)

	Patients with pemphigus	Controls
Follow-up time, PY	14,046.0	70,378.5
Median follow-up time, years (range)	6.9 (0.0–13.0)	6.9 (0.0–13.0)
Number of events	15	25
Incidence rate/1000 PY	1.07	0.36
95% CI	0.62-1.72	0.24-0.52
	HR (95% CI)	P value
Crude	3.00 (1.58–5.69)	0.001
Adjusted*	2.54 (1.3–4.92)	0.006
Sensitivity analysis**
Crude	3.30 (1.70–6.45)	< 0.001
Adjusted*	2.56 (1.30–5.05)	0.007

Abbreviations: HR, hazard ratio; CI, confidence interval; PY, person-year

*Following the adjustment for age, sex, ethnicity, socioeconomic status, comorbidities, and healthcare utilization

**Sensitivity analysis included only pemphigus patients under prolonged “pemphigus-specific treatments”

Italic: significant value