Use of a T cell interferon gamma release assay in the investigation for suspected active tuberculosis in a low prevalence area

Table 6 Multiple logistic regression analysis of factors potentially associated with QFT-results in TB-patients (after controlling for sex and extrapulmonary TB)

Factor	Number of observations	Est. beta-coefficient	OR*	95% CI	p-value
Bacteriologically verified diagnosis	65	-0.022	0.98	0.20–4.78	0.977
TST cut off 10 mm	40	-0.666	0.51	0.21–1.28	0.153
TST cut off 15 mm	40	1.384	3.99	0.72–22.15	0.114
Immune suppression**	65	-0.680	0.51	0.15–1.76	0.284
TB incidence of native country (new cases/100 000 pop.)	65	0.003			0.200
Body Mass Index (BMI)	58	0.146			0.110
Hemoglobin (mg/L)	59	0.022			0.181
Erythrocyte Sedimentation Rate (mm)	41	-0.005			0.995
C-reactive protein (CRP;mg/L)	59	-0.007			0.124
White blood cell count (WBC; × 10⁹/L)	60	-0.568			<0.001

*Odds ratios (defined as the exponent of the estimated beta) are not shown for TB incidence of native country, BMI, Hb, ESR, CRP and WBC since these variables are not dichotomous.
** Immune suppression defined as HIV-infection, ongoing immunosuppressive treatment, cancer, diabetes, alcohol or drug abuse

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