Table 4. Association between selected characteristics and sero-protection proportion (titer ≥ 1:40).

			Crude analysis			Multivariate model1*			Multivariate model2**
Category	N	n(%)	OR	(95%CI)	P value	OR	(95%CI)	P value	OR	(95%CI)	P value
Sex
Male	36	25 (69)	1.00			1.00
Female	12	10 (83)	2.20	(0.41–11.8)	0.356	1.74	(0.12–24.4)	0.681
Age
<57	15	13 (87)	1.00			1.00			1.00
57-64	14	11 (79)	0.56	(0.08–4.01)	0.567	0.28	(0.02–3.86)	0.343	0.22	(0.02–2.24)	0.202
65+	19	11 (58)	0.21	(0.04–1.21)	0.081	0.16	(0.02–1.57)	0.116	0.09	(0.01–0.77)	0.028
			(Trend P = 0.066)			(Trend P = 0.137)			(Trend P=0.033)
Type 1	7	5 (71)	1.00			1.00
Type 2	41	30 (73)	1.09	(0.18–6.47)	0.924	1.10	(0.04–28.0)	0.956
Duration of disease (years)
<10	24	17 (71)	1.00			1.00
10+	24	18 (75)	1.24	(0.35–4.43)	0.746	1.13	(0.21–6.12)	0.886
HbA1c (%)
<6.5	10	8 (80)	1.00			1.00			1.00
6.5–7.5	20	16 (80)	1.00	(0.15–6.67)	1.000	0.93	(0.09-–9.32)	0.948	1.22	(0.15–10.1)	0.853
7.6+	18	11 (61)	0.39	(0.06–2.42)	0.313	0.10	(0.007–1.45)	0.091	0.16	(0.02–1.57)	0.115
			(Trend P =0.224)			(Trend P =0.071)			(Trend P =0.074)
Body mass index (kg/m2)
<22.1	13	9 (69)	1.00			1.00			1.00
22.1-23.8	16	10 (63)	0.74	(0.16–3.50)	0.705	1.27	(0.17–9.24)	0.815	1.02	(0.17–6.16)	0.980
23.9+	19	16 (84)	2.37	(0.43–13.0)	0.321	9.17	(0.85–99.2)	0.068	7.15	(0.84–60.6)	0.071
			(Trend P =0.295)			(Trend P =0.078)			(Trend P =0.079)
Treatment of DM
Insulin-	21	14 (67)	1.00			1.00
Insulin+	27	21 (78)	1.75	(0.49–6.31)	0.393	1.69	(0.25–11.6)	0.592
Prevaccination titer
<1:10	37	26 (70)	1.00			1.00
1: 10-1:20	11	9 (82)	1.90	(0.35–10.3)	0.454	2.92	(0.25–34.8)	0.397

Logistic regression model. *Model included all variables in the table. **Model included age, HbA1c and BMI.