TABLE 2.

Studies that evaluated the association between TTV load and infection in kidney transplant recipients

Study designa	TX period	Included patients	Endpoint; timing	Patients with event; infectious events	PCR	Main association	Limitationsb
Cohort80	2016	71	Infection leading to medical measure; months 4–12 post-TX	22; 41	IH	TTV 1 mo before event–infection	Interim analysis; secondary endpoint
Cohort74	2014–2016	221	Infection leading to medical measure/opportunistic infection + malignancy; <12 mo post-TX	51; 65	C	TTV 1 mo post-TX–subsequent event	Two main endpoints; multiple testing; missing information on model design/some major determinants of TTV not included
Cohort81	2015–2016	116	BKV viremia; <12 mo post-TX	24; 24	C	NA	Multiple testing; no effect size adjustment
Cohort75	2016–2018	274	Infection leading to medical measure; months 4–12 post-TX	127; 193	IH	TTV 1 mo before event–infection	Secondary endpoint
Case-control82,c	2011–2016	145	CMV viremia; <4 mo post-TX	35; 35	IH	TTV days 0 to 10 post-TX–CMV	Possible selection bias; main analyses include LTX; multiple testing; no effect size adjustment
Case-control79	2012–2014	66	BKV viremia; <2 y post-TX	50; 50	C	TTV–BKV month 6 post-TX	Possible selection bias; multiple testing; no effect size adjustment
Case-control83	2014–2016	215	BKV viremia; <12 mo post-TX	47; 47	C	TTV 1 mo post-TX–subsequent BKV	No data on subject selection; multiple testing; missing information on model design/some major determinants of TTV not included
Case-control21	2003–2013	389	BKV and CMV viremia; <12 mo post-TX	182; 105/77d	IH	TTV kinetic–time to infection	CMV secondary endpoint

^aThe studies are listed according to their design and date of their online publication.

^bAll studies followed a noninterventional and single-center design.

^cKidney and liver transplant recipients.

^dOne hundred five BKV and 77 CMV.

BKV, BK polyomavirus; C, commercial; CMV, cytomegalovirus; IH, in-house; LTX, liver transplantation; NA, not available; PCR, polymerase chain reaction; TTV, torque teno virus; TX, transplantation.