Table 2.

Univariable and Multivariable Drivers of Cluster Growth (Incident Infection Defined as Estimated Date of Infection ≤1 Year of Sequencing Date)

Predictora	Univariable Model					Multivariable Model
	Coef	Coef SE	HR	(95% CI)	P Value	Coef	Coef SE	HR	(95% CI)	P Value
Proportion of incidentb	5.27	0.66	194.87	(53.09–715.20)	<.001	3.76	0.48	43.09	(16.90–109.86)	<.001
Cluster size	0.32	0.01	1.37	(1.33–1.41)	<.001	0.29	0.01	1.33	(1.29–1.37)	<.001
Proportion of Hispanic ethnicityb	–0.35	0.14	0.70	(.53–.92)	.011	–0.46	0.19	0.63	(.43–.92)	.017
Median No. of sex partnersc	–0.01	0.01	0.99	(.98–1.01)	.289	…	…	…	…
Cluster start pre-2005d	0.90	0.15	2.45	(1.81–3.31)	<.001	0.35	0.17	1.42	(1.02–1.97)	.036
Median age of clustere	–0.05	0.01	0.95	(.93–.97)	<.001	–0.04	0.01	0.96	(.94–.97)	<.001
Proportion of unsuppressedb	0.52	0.12	1.69	(1.33–2.14)	<.001	0.30	0.16	1.35	(.98–1.86)	.069

Abbreviations: CI, confidence interval; Coef, coefficient; HR, hazard ratio; SE, standard error.

^aAll predictors use clusters as the reference for evaluation.

^bProportion as decimal, not percentage. For example, an increase in the proportion of incident infections from 0 to 50% would correspond to HR of exp(0.5 × 3.76) = 6.55, with the other predictors held constant.

^cMedian number of sex partners in the past month at time of enrollment for each linked case.

^dTime invariant.

^eMedian age of cluster, which includes median ages of all individuals in cluster, up to but not including the individual linked at latest event time.