Diagnosis of Urinary Tract Infections by Urine Flow Cytometry: Adjusted Cut-Off Values in Different Clinical Presentations

Table 3

Established cut-off values for UFC bacterium and leucocyte counts per μL with the highest Youden’s index and the corresponding diagnostic performance in the validation sample in predicting significant bacterial growth in urine culture in different clinical scenarios.

Subgroup (no. in validation set)	Highest Youden’s index		Diagnostic performance using the established cut-offs
	Lc (/μL)	Bact (/μL)	Sensitivity (%) (95% CI)	Specificity (%) (95% CI)	LR(+)	LR(-)
Sex
Male ()	74	71	94.5 (84.9, 98.9)	71.2 (61.4, 79.6)	3.28	0.08
Female ()	169	2883	89 (79.5, 95.1)	79.7 (68.8, 88.2)	4.39	0.14
Age
>65 ()	57	63	95.5 (87.5, 99.1)	60.0 (48.0, 71.1)	2.39	0.07
≤65 ()	169	150	96.7 (88.7, 99.6)	64.1 (54.0, 73.3)	2.69	0.05
Dysuria
Yes ()	205	87	96.6 (82.2, 99.9)	66.7 (46.0, 83.5)	2.90	0.05
No ()	74	441	93.3 (87.3, 97.7)	74.8 (67.1, 81.5)	3.73	0.08
Urinary frequency
Yes ()	108	409	100 (83.2, 100)	55.6 (30.8, 78.5)	2.25	—
No ()	74	83	96.3 (90.8, 99)	60.6 (52.6, 68.2)	2.45	0.06
Fever (>38.0°C)^1
Yes ()	108	527	91.7 (77.5, 98.2)	88.3 (77.4, 95.2)	7.86	0.09
No ()	171	99	94.5 (87.6, 98.2)	61.0 (51.6, 69.9)	2.42	0.09
UTI-specific abdominal pain^2
Yes ()	169	128	96.9 (83.8, 99.9)	46.2 (26.6, 66.6)	1.80	0.07
No ()	69	83	95.8 (89.7, 98.9)	59.9 (51.6, 67.7)	2.40	0.07
Diabetes
Yes ()	76	1061	88.2 (72.5, 96.7)	77.5 (61.5, 89.2)	3.92	0.15
No ()	137	441	96.8 (91.0, 99.3)	77.5 (69.7, 84.2)	4.31	0.04
Renal insufficiency
Yes ()	74	63	95.1 (83.5, 99.4)	56.4 (42.3, 69.7)	2.18	0.08
No ()	108	470	94.3 (87.1, 98.1)	76.4 (67.9, 83.6)	4.00	0.08
Immunosuppression
Yes ()	74	127	97.3 (85.8, 99.9)	72.6 (60.9, 82.4)	3.55	0.04
No ()	151	470	94.5 (87.6, 98.2)	74.3 (64.8, 82.3)	3.68	0.07

¹One patient in the validation set did not have sufficient data to determine if °C. ²This includes lower abdominal, suprapubic, and flank pain. Abbreviations: AUC: area under the receiver operating curve; Bact: UFC bacterium counts; CI: confidence interval; Lc: UFC leucocyte counts; LR: likelihood ratio; SBU: significant bacterial growth in urine culture; UFC: urine flow cytometry; UTI: urinary tract infection.