TABLE 1.

Estimated values comparing clinimetric parameters between colorimetric RT-LAMP and RT-qPCR on the detection of SARS-CoV-2 for molecular diagnosis of COVID-19.

RT-qPCR	Colorimetric RT-LAMP		Metrics % (95% CI)
Ct value	Positive	Negative	Sensitivity	Specificity	Accuracy	PPV	NPV
15–30	171	0	100 (98–100)	100 (94.5–100)	100	100	100
15–32	199	4	98 (95–99.5)	100 (94.5–100)	99.95	100	99.95 (99.8–100)
15–34	221	13	94 (90.7–97)	100 (94.5–100)	99.90	100	99.9 (99.7–100)
15–36	245	29	89 (85.1–93)	100 (94.5–100)	99.74	100	99.7 (99.6–99.8)
15–40	254	48	84 (79.4–88)	100 (94.5–100)	99.60	100	99.6 (99.5–99.7)
Negative	0	65

Sensitivity: probability that the test result will be positive when the disease is present (true positive rate) = true positive/(true positives + false negatives); Specificity: probability that a test result will be negative when the disease is not present (true-negative rate) = true negatives/(true negatives + false positives); accuracy, PPV, and NPV depending on COVID-19 disease prevalence that was considered here as 2.5% according to the average value of two surveys during May and June 2020 (Hallal et al., 2020). PPV is the probability that the disease is present when the test is positive, whereas NPV is the probability that the disease is not present when the test is negative, and both are calculated as follows: PPV = sensitivity × prevalence/sensitivity × prevalence + (1 – specificity) × (1 – prevalence); NPV = specificity × (1 – prevalence)/(1 – sensitivity) × prevalence + specificity × (1 – prevalence); accuracy is the overall probability that a patient is correctly classified and is calculated as follows: =sensitivity × prevalence + specificity × (1 – prevalence). All calculations were performed using MedCalc (https://www.medcalc.org/) and VassarStats—Clinical Research Calculators (http://vassarstats.net/).