Table 2.

Correlates of genotyping failure for all specimens analysed from 2016 to 2019

Predictor Variable	Genotyping failure n/N (%)	Unadjusted OR	p-value	Adjusted OR	p-value
Specimen type
DBS	1926/3836 (50.2)	1	< 0.0001		< 0.0001
Plasma	422/3001 (14.1)	0.16 (0.14–0.18)		0.10 (0.08–0.14)
Pre-genotyping viral load testing
Not done	1398/3893 (35.9)	1	0.002		0.023
Done	950/2944 (32.3)	0.85 (0.77–0.94)		0.64 (0.13–0.56)
Viral load
1001–10,000 cps/mL	634/1165 (54.4)	1	< 0.0001		< 0.0001
> 10,000–50,000 cps/mL	197/755 (25.4)	0.28 (0.23–0.35)		0.3 (0.24–0.38)
> 50,000–200,000 cps/mL	81/609 (13.3)	0.13 (0.10–0.17)		0.14 (0.11–0.19)
> 200,000 cps/mL	38/392 (9.7)	0.09 (0.06–0.13)		0.10 (0.07–0.14)
Specimen source
Research studies	745/3533 (21.1)	1	< 0.0001		0.005
Routine clinical diagnosis	1603/3304 (48.5)	3.5 (3.17–3.92)		1.4 (1.10–1.75)

Each denominator represents the number of specimens of that specific category