Table 6. Multivariable Poisson regression for risk factors for diphtheria patients presenting with pseudomembrane and lymphadenopathy, Cox’s Bazar, Bangladesh, November 10, 2017 to November 10, 2019.

			Presence of pseudomembrane				Presence of GCL
			Unadjusted		Adjusted		Unadjusted		Adjusted
Independent variable	Level	N	RR (95% CI)	p-value	RR (95% CI)	p-value	RR (95% CI)	p-value	RR (95% CI)	p-value
Age group	0–6	1,729	Reference	-	Reference	-	Reference	-	Reference	-
	7–14	3,309	1.28 (1.15–1.42)	<0.001	1.42 (1.19–1.71)	<0.001	0.93 (0.84–1.03)	0.165	0.96 (0.85–1.10)	0.569
	15+	2,020	1.42 (1.27–1.59)	<0.001	1.66 (1.38–2.02)	<0.001	0.71 (0.63–0.80)	<0.001	0.69 (0.59–0.80)	<0.001
Sex	Female	3,938	Reference	-	-	-	Reference	-	Reference	-
	Male	3,126	0.93 (0.86–1.01)	0.100	-	-	1.16 (1.07–1.27)	<0.001	1.11 (1.00–1.24)	0.052
Vaccination doses	0 (ref.)	1,876	Reference	-	Reference	-	Reference	-	Reference	-
	1	510	0.67 (0.55–0.81)	<0.001	0.77 (0.62–0.94)	0.013	1.00 (0.86–1.15)	1.000	0.99 (0.85–1.16)	0.947
	2	493	0.72 (0.59–0.87)	0.001	0.87 (0.71–1.06)	0.172	1.06 (0.91–1.22)	0.452	1.00 (0.85–1.16)	0.962
	3	382	0.54 (0.42–0.68)	<0.001	0.64 (0.50–0.82)	0.001	0.71 (0.58–0.85)	<0.001	0.68 (0.56–0.83)	<0.001
Period	Pre-campaign	2,927	Reference	-	Reference	-	Reference	-	Reference	-
	Campaign era*	3,617	0.77 (0.71–0.83)	<0.001	0.54 (0.45–0.65)	<0.001	2.27 (2.06–2.51)	<0.001	0.79 (0.66–0.93)	0.006

* Patients were divided into 2 periods, according to the date of symptom onset relative to the completion of the first round of MVC.

Covariates with a p-value of < = 0.1 were included in the multivariate model.

CI, confidence interval; GCL, gross cervical lymphadenopathy; MVC, mass vaccination campaign; RR, risk ratio.