Table 2.

Potential predictors of bacterial burden in longitudinal sputum and face-mask samples over 24 h

	24-h face-mask IS6110 output		24-h face-mask RD9 output
	Correlation coefficient (95% CI)	p value	Correlation coefficient (95% CI)	p value
Age	−0·26 (−0·61 to 0·17)	0·21	−0·13 (−0·52 to 0·30)	0·53
Gender	..	0·89	..	0·47
HIV status	..	0·48	..	0·68
CD4 count*	−0·28 (−0·65 to 0·20)	0·23	−0·11 (−0·53 to 0·36)	0·65
Duration of symptoms, weeks	0·18 (−0·26 to 0·55)	0·41	0·11 (−0·31 to 0·48)	0·56
Chest radiography grade†	−0·22 (−0·59 to 0·23)	0·32	−0·07 (−0·48 to 0·36)	0·75
Presence of cavitation on chest radiography†	..	0·52	..	0·38
Sputum acid-fast bacilli grade‡	−0·08 (−0·54 to 0·41)	0·75	−0·02 (−0·49 to 0·47)	0·95
Sputum Xpert MTB/RIF grade	0·02 (−0·40 to 0·43)	0·92	−0·04 (−0·45 to 0·37)	0·84
Sputum culture§	0·14 (−0·38 to 0·59)	0·58	0·07 (−0·44 to 0·54)	0·79
Cough frequency	0·10 (−0·33 to 0·50)	0·63	0·07 (−0·35 to 0·47)	0·73
Patient's perception of cough severity, visual analogue scale¶	0·28 (−0·18 to 0·63)	0·21	0·31 (−0·15 to 0·65)	0·53
Started tuberculosis treatment	..	0·68	..	0·91
24-h sputum PCR signal content	0·17 (−0·30 to 0·57)	0·47	0·15 (−0·31 to 0·56)	0·49

Data represent the ability of variables to predict levels of IS6110 and RD9 signals detected in face-mask samples over 24 h, analysed by Spearman's correlation for continuous variables and the Mann-Whitney U test for categorical data.

^*CD4 count was recorded for all 20 HIV-positive patients.

^†Chest radiography grade and presence of cavitation was recorded for 23 patients.

^‡Sputum acid-fast bacilli grade available for 17 patients.

^§Sputum culture results available for 16 patients.

^¶Visual analogue scale recorded for 22 patients.