TABLE 2.

Cox proportional hazards regression model showing the association of variables with the occurrence of QTc prolongation^a in the 24-week treatment

Variable	n (%)	Results for:b
		Univariable		Multivariable
		HR (95% CI)	P value	Model A		Model B		Model C		Model D
				HR (95% CI)	P value	HR (95% CI)	P value	HR (95% CI)	P value	HR (95% CI)	P value
Factors selected
Sex
Male	856 (70.5)	1 [Reference]		1 [Reference]		1 [Reference]		1 [Reference]		1 [Reference]
Female	359 (29.5)	1.53 (1.15–2.02)	0.003	1.53 (1.15–2.04)	0.003	1.52 (1.17–2.05)	0.003	1.63 (1.23–2.16)	<0.001	1.52 (1.15–2.03)	0.003
QTc baseline numeric, ms
QTc squared						0.32 (0.27–0.39)	<0.001	0.77 (0.73–0.82)	<0.001
QTc						1.00 (1.00–1.00)	<0.001	1.00 (1.00–1.00)	0.052
QTc baseline, categorical
395-424. ms	569 (46.8)	1 [Reference]		1 [Reference]						1 [Reference]
<395 ms	267 (22.0)	4.12 (2.97–5.7.3)	<0.001	4.48 (3.21–6.23)	<0.001					4.64 (3.33–6.48)	<0.001
>425 ms	379 (31.2)	3.65 (2.67–5.00)	<0.001	3.43 (2.50–4.73)	<0.001					3.48 (2.53–4.78)	<0.001
Drug resistance
Pre-XDR	963 (79.3)	1 [Reference]		1 [Reference]		1 [Reference]		1 [Reference]		1 [Reference]
XDR	252 (20.7)	1.90 (1.42–2.54)	<0.001	1.64 (1.26–2.14)	<0.001	1.53 (1.17–2.01)	<0.001	1.62 (1.24–2.11)	<0.001	1.60 (1.23–2.09)	<0.001
Creatinine
≥60 mmol/L	816 (67.2)	1 [Reference]		1 [Reference]		1 [Reference]		1 [Reference]		1 [Reference]
<60 mmol/L	399 (32.8)	1.49 (1.17–1.89)	<0.001	1.43 (1.08–1.89)	0.011	1.42 (1.08–1.86)	0.017	1.29 (0.97–1.70)	0.073	1.44 (1.10–1.90)	0.009
Clofazimine
No	539 (44.4)	1 [Reference]		1 [Reference]		1 [Reference]		1 [Reference]		1 [Reference]
Yes	676 (55.6)	2.93 (2.21–3.89)	<0.001	2.93 (2.19–3.92)	<0.001	3.23 (2.42–4.32)	<0.001	2.83 (2.11–3.80)	<0.001	2.74 (2.04–3.67)	<0.001
Levofloxacin
No	815 (67.1)	1 [Reference]		1 [Reference]		1 [Reference]		1 [Reference]		1 [Reference]
Yes	400 (32.9)	1.02 (0.79–1.31)	0.889	1.29 (0.99–1.69)	0.061	1.35 (1.03–1.76)	0.062	1.13 (0.97–1.70)	0.138	1.26 (0.96–1.65)	0.092
Moxifloxacin
No	975 (80.2)	1 [Reference]		1 [Reference]		1 [Reference]		1 [Reference]		1 [Reference]
Yes	240 (19.8)	0.87 (0.64–1.19)	0.378	1.15 (0.82–1.61)	0.412	1.18 (0.84–1.65)	0.257	1.18 (0.85–1.67)	0.445	1.13 (0.81–1.59)	0.461
Age, yrs		1.04 (1.01–1.07)	0.006					1.03 (1.00–1.06)	0.035	1.03 (1.01–1.07)	0.009
BMI (kg/m2)		0.95 (0.90–0.99)	0.049					0.96 (0.92–1.00)	0.098
Previous TB
No	303 (24.9)	1 [Reference]								1 [Reference]
Yes	912 (75.1)	1.37 (1.02–1.85)	<0.036							1.28 (0.94–1.73)	0.071
Diabetes
No	910 (74.9)	1 [Reference]						1 [Reference]		1 [Reference]
Yes	305 (25.1)	0.48 (0.27–0.83)	0.030					0.69 (0.43–1.09)	0.102	0.59 (0.38–0.94)	0.059
Blood potassium (mmol/L)
3.8–4.2	526 (43.3)	1 [Reference]
<3.8	291 (24.0)	1.17 (0.83–1.65)	0.360					1.39 (1.03–1.87)	0.033
>4.2	398 (32.8)	1.24 (0.82–1.55)	0.451					1.27 (0.95–1.70)	0.101
Factors not selected
Blood calcium (mmol/L)
<2.2	422 (34.7)	1 [Reference]
>2.2	793 (32.8)	1.13 (0.85–1.50)	0.418
Linezolid
No	149 (12.3)	1 [Reference]
Yes	1066 (87.7)	1.36 (0.91–2.02)	0.133
Cycloserine
No	195 (16.0)	1 [Reference]
Yes	1020 (84.0)	0.99 (0.72–1.36)	0.938

^aQTc prolongation, the first occurrence of a QTc prolongation event, defined as an QTc interval of ≥500 ms or an increase in an QTc interval of ≥60 ms compared with the baseline QTc at admission.

^bReference represents the reference group to be compared.