Table 4. Frequency of exacerbations and elevated serum IgG antibody titer against Porphyromonas gingivalis.

	Normal-IgG titer(n = 44)	High-IgG titer(n = 49)	p value
Exacerbation frequency, per year
Median (25th–75th percentiles)	1 (0–2)	0 (0–1)	0.045
Mean	1.2	0.8
Rate of patients with frequent exacerbations, n (%)	17 (38.6)	7 (14.3)	0.009

High-IgG titer group includes subjects whose titers against Porphyromonas gingivalis (PgFDC381 and/or PgSu63) are above mean+2SD of healthy subsets [20].

Frequent exacerbations” are defined as ≥2 exacerbations per year.