Table 1. Sensitivity, specificity, and positive and negative predictive values of indirect immunofluorescent assays for the diagnosis of scrub typhus and murine typhus by using admission filter paper blood spots^* .

						Kappa statistic (95% CI)
Disease	Antibody type	Sensitivity, % (95% CI)	Specificity, % (95% CI)	PPV, % (95% CI)	NPV, % (95% CI)	FP	Serum
Scrub typhus	IgM	95(76-100)	88 (48-100)	95 (76-100)	87 (48-100)	0.55 (0.32-0.78)	0.67 (0.40-0.94)
	IgG	90(70-99)	100(59-100)	100 (83-100)	77 (40-97)	0.66 (0.43-0.89)	0.61 (0.36-0.86)
Murine typhus	IgM	91 (72-99)	100(63-100)	100(84-100)	80 (45-98)	0.56 (0.33-0.79)	0.59 (0.36-0.82)
	IgG	92 (73-99)	100(54-100)	100(85-100)	75 (35-97)	0.69 (0.44-0.94)	0.65 (0.42-0.88)

CI = confidence interval; PPV = positive predictive value; NPV = negative predictive value; FP = filter paper blood spots. The comparator gold standard was diagnosis based on indirect immunofluorescent assays (IFAs) using paired admission-phase and convalescent-phase serum samples. Positive results were defined as IgM or IgG titers ≥ 1:400 or a four-fold increase in titer.¹⁵Kappa statistics (95% CI) for inter-observer agreement between the two readers for murine typhus and scrub typhus IFA on admission-phase serum samples and FPs are also given.

Table 1. Sensitivity, specificity, and positive and negative predictive values of indirect immunofluorescent assays for the diagnosis of scrub typhus and murine typhus by using admission filter paper blood spots* .

Table 1. Sensitivity, specificity, and positive and negative predictive values of indirect immunofluorescent assays for the diagnosis of scrub typhus and murine typhus by using admission filter paper blood spots^* .